BPF tracing istio/Envoy - Part4: Upstream/Downstream Event-Driven Collaboration of Envoy@Istio

Notice: The original article come from https://blog.mygraphql.com/en/posts/low-tec/trace/trace-istio/trace-istio-part4/ . If picture unclear, please redirect to the original article.

There is Chinese version too.

Why

I can’t believe that I really insisted on writing Part 4. Believe it or not, the “Why” section of each part is the hardest thing to write :) . If you’re reading this series for the first time, don’t worry, each section is relatively independent.

Introduction to Envoy you have saw earlier describes envoy’s features like this:

Written in C++, native to the lower level, no ‘GC stop the world’, so excellent performance

Asynchronous event driven, multiplexing, perfect solution to C10k problem

Because a single thread is responsible for multiple connections, the memory overhead of a large number of threads and the overhead of CPU context switching are reduced when large connections.

These descriptions, of course, have their reasonableness. But a lot of things that are beautiful from a distance, after macro magnification, may have a lot of interesting, valuable things. I believe that if we deep dive, it is always possible to make some meaningful optimizations for our actual operating environment and traffic characteristics. It may just be a modification of the configuration of an Envoy/Kernel, or it may be a modification of a line of Envoy’s code. Or your app’s behavior, such as the size of the buffer each time the socket is written.

All require to be based on understanding the implementation details. Unless you feel lucky or experience are particularly good that you can guess.

[BPF tracing istio/Envoy] series

Make a preview before you begin, [BPF tracing istio/Envoy] series (will be) include:

Part 1: Getting Started (Chinese)
Part 2: Booting, listening, and load-balance of threads(Chinese)
Part 3: Downstream connection accept, TLS handshake, and filter chain selection(Chinese)
Part 4: Upstream/Downstream Event-Driven Collaboration of Envoy@Istio (This article)
Part 5: L3/4 Network Fitler interaction
Part 6: HTTP filter
Part 7: HTTP router
Part 8: cluster/connection pool and outbound load balance

In this series, I’ll show you how to use bpftrace to “read” the object data in the memory of Envoy process which is written in C++11 on runtime. In order not to scare people away, I try show more pictures and less code. But some diagrams are a little complicated. Uncle Programmer began to tell stories. 🚜

High-level process of HTTP reverse proxy

The overall process of socket event-driven HTTP reverse proxy:

As you can see in the diagram, there are 4 types of events that drive the entire process. The next few sections are analyzed one by one.

To avoid getting lost in the details of each step at once, let’s take a look at the overall flow of all the steps:

Figure: Istio/Envoy module collaboration overview

Downstream Read Request collaboration

Figure: Downstream Read-Ready collaboration
Figure：Downstream Read-Ready collaboration

Explain the process in high-level:

Downstream socket readable callback.
Http::ConnectionManagerImpl reads data from downstreamthe socket, incrementally put into Http1::ConnectionImpl.
Http1::ConnectionImpl calls nghttp2 incrementally interprets http requests.
If nghttp2 believes that the HTTP Request request has been read completely, it calls Http::ServerConnection::onMessageCompleteBase().
Http::ServerConnection::onMessageCompleteBase() Stop downstream ReadReady listening.
Http::ServerConnection::onMessageCompleteBase() calls Http::FilterManager to initiate the decodeHeaders iteration of http filter chain.
In general, the last http filter of http filter chain is Router::Filter, and finally, Router::Filter::decodeHeaders() is called.
The logic of Router::Filter::decodeHeaders() will shown in next figure.

Figure: Downstream Request Router collaboration

Explain the process:

Router::Filter, Router::Filter::d ecodeHeaders() is called.
Select a cluster according to the configured Router rules.
If the Cluster connection pool object does not exist, create a new one.
Create a new Envoy::Router::UpstreamRequest object.
Call Envoy::Router::UpstreamRequest::encodeHeaders(bool end_stream) to encode HTTP header.
After a series of load balancing algorithms, match to the upstream host (endpoint).
If no available connection to selected upstream host from connection pool, then:
1. Open a new socket fd (not connected).
2. Register the WriteReady / Connected event for the upstream socket FD. Prepare to write an upstream request when the event callback occurs.
3. Initiate an asynchronous connection to upstream host with socket fd.
Associate downstream and upstream fd

Upstream Write Request Collaboration

Figure: Upstream Write Request Collaboration

Explain the process:

The first time upstream socket write ready callback.
Detect the callback event type is successful connection, then associating the upstream socket to ConnectionPool::ActiveClient.
Second time upstream socket write ready callback.
Detect the callback event type is writable to the connection, then write the upstream HTTP request.

Upstream Read Response Collaboration

Figure: Upstream Read-Response Collaboration

Downstream Write Response Collaboration

Figure: Downstream Write Response Collaboration

bpftrace output

Above figures are not only according to the source code, but also the output of the bpftrace script and tracepoint. The principle of the bpftrace script is:

Record downstream FD (file descriptor of socket), which can be thought of as the socket id in the process.
Add kernel tracepoint and application uprobe. Record the input, output and stack of the probe.
Associate downstream FD and upstream FD.

Of course, there are many details, but I am not going to talk about them one by one. Who wants to know more can contact me to discuss. The bpftrace script in the next section is more detail.

https://github.com/labilezhu/pub-diy/blob/main/low-tec/trace/trace-istio/trace-istio-part4/trace-envoy-filter-router.3.log

#### Downstream Read Request: accept downstream socket, So downstream socket FD=41

OS handshaked TCP:
01:22:11 4215   wrk:worker_0   172.30.207.129                          58708 172.21.206.232                          15006 0/4096
sys_exit_accept4 fd=41

        accept4+96
        Envoy::Network::IoSocketHandleImpl::accept(sockaddr*, unsigned int*)+82
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+216
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217
 

***** elapsed=1621361178: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZNSt3__110__function6__funcIZN5Envoy10Extensions15ListenerFilters12TlsInspector25TlsInspectorConfigFactory36createListenerFilterFactoryFromProtoERKN6google8protobuf7MessageERKNS_10shared_ptrINS2_7Network21ListenerFilterMatcherEEERNS2_6Server13Configuration22ListenerFactoryContextEEUlRNSD_21ListenerFilterManagerEE_NS_9allocatorISO_EEFvSN_EEclESN_

***** elapsed=1621785490: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZNSt3__128__invoke_void_return_wrapperIvE6__callIJRZN5Envoy10Extensions15ListenerFilters12TlsInspector25TlsInspectorConfigFactory36createListenerFilterFactoryFromProtoERKN6google8protobuf7MessageERKNS_10shared_ptrINS3_7Network21ListenerFilterMatcherEEERNS3_6Server13Configuration22ListenerFactoryContextEEUlRNSE_21ListenerFilterManagerEE_SO_EEEvDpOT_

***** elapsed=1630898092: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6FilterC1ENSt3__110shared_ptrINS2_6ConfigEEE

***** elapsed=1630908037: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6FilterC2ENSt3__110shared_ptrINS2_6ConfigEEE

***** elapsed=1631036930: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6Filter8onAcceptERNS_7Network23ListenerFilterCallbacksE

***** elapsed=1631045047: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6Filter6onReadEv

***** elapsed=1631070582: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_recvfrom, fd=41, ret=89

        recv+108


***** elapsed=1631085065: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6Filter16parseClientHelloEPKvm

#### Downstream Read Request: select network filter chain
***** elapsed=1631145371: tid=5327,comm=wrk:worker_0: TlsInspector*, probe=uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy10Extensions15ListenerFilters12TlsInspector6FilterD0Ev
comm:wrk:worker_0,tid:5327: Got setFilterChainName=0.0.0.0_8080, lenght=12

        Envoy::StreamInfo::StreamInfoImpl::setFilterChainName(absl::string_view)+0
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107

#### Downstream Read Request: listening to upstream FD event
***** elapsed=1631199672: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_ADD, fd=41, events=0x80000005
EPOLL_CTL_ADD/MOD ReadReady(EPOLLIN)
EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)
EPOLL_CTL_ADD/MOD EdgeTrigger

        epoll_ctl+14
        epoll_nochangelist_add+54
        evmap_io_add_+421
        event_add_nolock_+603
        event_add+54
        Envoy::Event::FileEventImpl::FileEventImpl(Envoy::Event::DispatcherImpl&, int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+362
        Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+284
        Envoy::Network::IoSocketHandleImpl::initializeFileEvent(Envoy::Event::Dispatcher&, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+126
        Envoy::Network::ConnectionImpl::ConnectionImpl(Envoy::Event::Dispatcher&, std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, Envoy::StreamInfo::StreamInfo&, bool)+1026
        Envoy::Network::ServerConnectionImpl::ServerConnectionImpl(Envoy::Event::Dispatcher&, std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, Envoy::StreamInfo::StreamInfo&, bool)+107
        Envoy::Event::DispatcherImpl::createServerConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, Envoy::StreamInfo::StreamInfo&)+70
        Envoy::Server::ActiveTcpListener::newConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::StreamInfo::StreamInfo, std::__1::default_delete<Envoy::StreamInfo::StreamInfo> >)+307
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107
        Envoy::Server::ActiveTcpListener::onAcceptWorker(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, bool, bool)+163
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+856
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0    : setsockopt: level=6, fd=41, optname=1, optval=1, optlen=4. 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl9addFilterENSt3__110shared_ptrINS0_6FilterEEE,FilterManagerImpl.this=0x559f98d38758,fd=41 

        Envoy::Network::FilterManagerImpl::addFilter(std::__1::shared_ptr<Envoy::Network::Filter>)+0
        std::__1::__function::__func<Envoy::Tcp::MetadataExchange::(anonymous namespace)::createFilterFactoryHelper(envoy::tcp::metadataexchange::config::MetadataExchange const&, Envoy::Server::Configuration::CommonFactoryContext&, Envoy::Tcp::MetadataExchange::FilterDirection)::$_0, std::__1::allocator<Envoy::Tcp::MetadataExchange::(anonymous namespace)::createFilterFactoryHelper(envoy::tcp::metadataexchange::config::MetadataExchange const&, Envoy::Server::Configuration::CommonFactoryContext&, Envoy::Tcp::MetadataExchange::FilterDirection)::$_0>, void (Envoy::Network::FilterManager&)>::operator()(Envoy::Network::FilterManager&)+93
        Envoy::Server::Configuration::FilterChainUtility::buildFilterChain(Envoy::Network::FilterManager&, std::__1::vector<std::__1::function<void (Envoy::Network::FilterManager&)>, std::__1::allocator<std::__1::function<void (Envoy::Network::FilterManager&)> > > const&)+50
        Envoy::Server::ActiveTcpListener::newConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::StreamInfo::StreamInfo, std::__1::default_delete<Envoy::StreamInfo::StreamInfo> >)+774
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107
        Envoy::Server::ActiveTcpListener::onAcceptWorker(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, bool, bool)+163
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+856
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl13addReadFilterENSt3__110shared_ptrINS0_10ReadFilterEEE,FilterManagerImpl.this=0x559f98d38758,fd=41 

        Envoy::Network::FilterManagerImpl::addReadFilter(std::__1::shared_ptr<Envoy::Network::ReadFilter>)+0
        virtual thunk to Envoy::Network::ConnectionImpl::addFilter(std::__1::shared_ptr<Envoy::Network::Filter>)+62
        std::__1::__function::__func<Envoy::Tcp::MetadataExchange::(anonymous namespace)::createFilterFactoryHelper(envoy::tcp::metadataexchange::config::MetadataExchange const&, Envoy::Server::Configuration::CommonFactoryContext&, Envoy::Tcp::MetadataExchange::FilterDirection)::$_0, std::__1::allocator<Envoy::Tcp::MetadataExchange::(anonymous namespace)::createFilterFactoryHelper(envoy::tcp::metadataexchange::config::MetadataExchange const&, Envoy::Server::Configuration::CommonFactoryContext&, Envoy::Tcp::MetadataExchange::FilterDirection)::$_0>, void (Envoy::Network::FilterManager&)>::operator()(Envoy::Network::FilterManager&)+93
        Envoy::Server::Configuration::FilterChainUtility::buildFilterChain(Envoy::Network::FilterManager&, std::__1::vector<std::__1::function<void (Envoy::Network::FilterManager&)>, std::__1::allocator<std::__1::function<void (Envoy::Network::FilterManager&)> > > const&)+50
        Envoy::Server::ActiveTcpListener::newConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::StreamInfo::StreamInfo, std::__1::default_delete<Envoy::StreamInfo::StreamInfo> >)+774
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107
        Envoy::Server::ActiveTcpListener::onAcceptWorker(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, bool, bool)+163
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+856
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl13addReadFilterENSt3__110shared_ptrINS0_10ReadFilterEEE,FilterManagerImpl.this=0x559f98d38758,fd=41 

        Envoy::Network::FilterManagerImpl::addReadFilter(std::__1::shared_ptr<Envoy::Network::ReadFilter>)+0
        std::__1::__function::__func<Envoy::Extensions::NetworkFilters::HttpConnectionManager::HttpConnectionManagerFilterConfigFactory::createFilterFactoryFromProtoTyped(envoy::extensions::filters::network::http_connection_manager::v3::HttpConnectionManager const&, Envoy::Server::Configuration::FactoryContext&)::$_7, std::__1::allocator<Envoy::Extensions::NetworkFilters::HttpConnectionManager::HttpConnectionManagerFilterConfigFactory::createFilterFactoryFromProtoTyped(envoy::extensions::filters::network::http_connection_manager::v3::HttpConnectionManager const&, Envoy::Server::Configuration::FactoryContext&)::$_7>, void (Envoy::Network::FilterManager&)>::operator()(Envoy::Network::FilterManager&)+353
        Envoy::Server::Configuration::FilterChainUtility::buildFilterChain(Envoy::Network::FilterManager&, std::__1::vector<std::__1::function<void (Envoy::Network::FilterManager&)>, std::__1::allocator<std::__1::function<void (Envoy::Network::FilterManager&)> > > const&)+50
        Envoy::Server::ActiveTcpListener::newConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::StreamInfo::StreamInfo, std::__1::default_delete<Envoy::StreamInfo::StreamInfo> >)+774
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107
        Envoy::Server::ActiveTcpListener::onAcceptWorker(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, bool, bool)+163
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+856
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl17onContinueReadingEPNS1_16ActiveReadFilterERNS0_16ReadBufferSourceE,FilterManagerImpl.this=0x559f98d38758,fd=41 

        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+0
        Envoy::Server::ActiveTcpListener::newConnection(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::StreamInfo::StreamInfo, std::__1::default_delete<Envoy::StreamInfo::StreamInfo> >)+774
        Envoy::Server::ActiveTcpSocket::newConnection()+377
        Envoy::Server::ActiveTcpSocket::continueFilterChain(bool)+107
        Envoy::Server::ActiveTcpListener::onAcceptWorker(std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, bool, bool)+163
        Envoy::Network::TcpListenerImpl::onSocketEvent(short)+856
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl17onContinueReadingEPNS1_16ActiveReadFilterERNS0_16ReadBufferSourceE,FilterManagerImpl.this=0x559f98d38758,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 

***** elapsed=1631443267: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1631456738: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=31393726, tid2epollNrFdReady=1
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=100 
***************************

#### Downstream Read Request: read HTTP Request
***** elapsed=1631475016: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98e26ee0, fd=41, events=0x26
libevent: EV_READ
libevent: EV_WRITE
libevent: EV_ET


***** elapsed=1631513821: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_readv, fd=41, ret=89

        readv+77
        Envoy::Network::IoSocketHandleImpl::readv(unsigned long, Envoy::Buffer::RawSlice*, unsigned long)+247
        Envoy::Network::IoSocketHandleImpl::read(Envoy::Buffer::Instance&, absl::optional<unsigned long>)+167
        Envoy::Network::RawBufferSocket::doRead(Envoy::Buffer::Instance&)+136
        Envoy::Network::ConnectionImpl::onReadReady()+753
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217


***** elapsed=1631527775: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_readv, fd=41, ret=-11

        readv+77
        Envoy::Network::IoSocketHandleImpl::readv(unsigned long, Envoy::Buffer::RawSlice*, unsigned long)+247
        Envoy::Network::IoSocketHandleImpl::read(Envoy::Buffer::Instance&, absl::optional<unsigned long>)+167
        Envoy::Network::RawBufferSocket::doRead(Envoy::Buffer::Instance&)+136
        Envoy::Network::ConnectionImpl::onReadReady()+753
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl6onReadEv,FilterManagerImpl.this=0x559f98d38758,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl17onContinueReadingEPNS1_16ActiveReadFilterERNS0_16ReadBufferSourceE,FilterManagerImpl.this=0x559f98d38758,fd=41 

        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+0
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl17onContinueReadingEPNS1_16ActiveReadFilterERNS0_16ReadBufferSourceE,FilterManagerImpl.this=0x559f98d38758,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98c07200,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98c07200,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
***** elapsed=1631671079: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_DEL, fd=41, events=0x80000005

#### Downstream Read Request: The HTTP Request from downstream has been read completely.(onMessageComplete()). Stop listening to the ReadReady event from downstream.
***** elapsed=1631678652: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_ADD, fd=41, events=0x80002004
EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)
EPOLL_CTL_ADD/MOD EdgeTrigger

        epoll_ctl+14
        epoll_nochangelist_add+54
        evmap_io_add_+421
        event_add_nolock_+603
        event_add+54
        Envoy::Network::ConnectionImpl::readDisable(bool)+1077
        Envoy::Http::Http1::ServerConnectionImpl::onMessageCompleteBase()+86
        Envoy::Http::Http1::ConnectionImpl::onMessageComplete()+637
        Envoy::Http::Http1::LegacyHttpParserImpl::Impl::Impl(http_parser_type, void*)::{lambda(http_parser*)#3}::__invoke(http_parser*)+31
        http_parser_execute+7959
        Envoy::Http::Http1::LegacyHttpParserImpl::execute(char const*, int)+31
        Envoy::Http::Http1::ConnectionImpl::dispatchSlice(char const*, unsigned long)+52
        Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+1151
        virtual thunk to Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+21
        Envoy::Http::ConnectionManagerImpl::onData(Envoy::Buffer::Instance&, bool)+76
        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+303
        Envoy::Network::ConnectionImpl::onReadReady()+1622
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 

#### Downstream Read Request: Watch events of the new upstream socket(FD=44). Preparing the callback of the `connected` event. The new socket is not connected currently.
***** elapsed=1632388633: tid=5327,comm=wrk:worker_0: register upstream event trigger:sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_ADD, fd=44, events=0x80000005
EPOLL_CTL_ADD/MOD ReadReady(EPOLLIN)
EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)
EPOLL_CTL_ADD/MOD EdgeTrigger

        epoll_ctl+14
        epoll_nochangelist_add+54
        evmap_io_add_+421
        event_add_nolock_+603
        event_add+54
        Envoy::Event::FileEventImpl::FileEventImpl(Envoy::Event::DispatcherImpl&, int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+362
        Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+284
        Envoy::Network::IoSocketHandleImpl::initializeFileEvent(Envoy::Event::Dispatcher&, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)+126
        Envoy::Network::ConnectionImpl::ConnectionImpl(Envoy::Event::Dispatcher&, std::__1::unique_ptr<Envoy::Network::ConnectionSocket, std::__1::default_delete<Envoy::Network::ConnectionSocket> >&&, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, Envoy::StreamInfo::StreamInfo&, bool)+1026
        Envoy::Network::ClientConnectionImpl::ClientConnectionImpl(Envoy::Event::Dispatcher&, std::__1::shared_ptr<Envoy::Network::Address::Instance const> const&, std::__1::shared_ptr<Envoy::Network::Address::Instance const> const&, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&)+283
        Envoy::Event::DispatcherImpl::createClientConnection(std::__1::shared_ptr<Envoy::Network::Address::Instance const>, std::__1::shared_ptr<Envoy::Network::Address::Instance const>, std::__1::unique_ptr<Envoy::Network::TransportSocket, std::__1::default_delete<Envoy::Network::TransportSocket> >&&, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&)+75
        Envoy::Upstream::HostImpl::createConnection(Envoy::Event::Dispatcher&, Envoy::Upstream::ClusterInfo const&, std::__1::shared_ptr<Envoy::Network::Address::Instance const> const&, Envoy::Network::TransportSocketFactory&, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const>)+561
        Envoy::Upstream::HostImpl::createConnection(Envoy::Event::Dispatcher&, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const>) const+126
        non-virtual thunk to Envoy::Upstream::HostImpl::createConnection(Envoy::Event::Dispatcher&, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const>) const+21
        Envoy::Http::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&, unsigned int, unsigned int)+112
        Envoy::Http::Http1::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&)+69
        std::__1::__function::__func<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0, std::__1::allocator<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0>, std::__1::unique_ptr<Envoy::ConnectionPool::ActiveClient, std::__1::default_delete<Envoy::ConnectionPool::ActiveClient> > (Envoy::Http::HttpConnPoolImplBase*)>::operator()(Envoy::Http::HttpConnPoolImplBase*&&)+40
        Envoy::Http::FixedHttpConnPoolImpl::instantiateActiveClient()+35
        Envoy::ConnectionPool::ConnPoolImplBase::tryCreateNewConnection(float)+1233
        Envoy::ConnectionPool::ConnPoolImplBase::newStream(Envoy::ConnectionPool::AttachContext&)+2001
        non-virtual thunk to Envoy::Http::HttpConnPoolImplBase::newStream(Envoy::Http::ResponseDecoder&, Envoy::Http::ConnectionPool::Callbacks&)+47
        Envoy::Extensions::Upstreams::Http::Http::HttpConnPool::newStream(Envoy::Router::GenericConnectionPoolCallbacks*)+70
        Envoy::Router::Filter::decodeHeaders(Envoy::Http::RequestHeaderMap&, bool)+14120
        Envoy::Http::FilterManager::decodeHeaders(Envoy::Http::ActiveStreamDecoderFilter*, Envoy::Http::RequestHeaderMap&, bool)+334
        Envoy::Http::ConnectionManagerImpl::ActiveStream::decodeHeaders(std::__1::unique_ptr<Envoy::Http::RequestHeaderMap, std::__1::default_delete<Envoy::Http::RequestHeaderMap> >&&, bool)+6139
        Envoy::Http::Http1::ServerConnectionImpl::onMessageCompleteBase()+279
        Envoy::Http::Http1::ConnectionImpl::onMessageComplete()+637
        Envoy::Http::Http1::LegacyHttpParserImpl::Impl::Impl(http_parser_type, void*)::{lambda(http_parser*)#3}::__invoke(http_parser*)+31
        http_parser_execute+7959
        Envoy::Http::Http1::LegacyHttpParserImpl::execute(char const*, int)+31
        Envoy::Http::Http1::ConnectionImpl::dispatchSlice(char const*, unsigned long)+52
        Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+1151
        virtual thunk to Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+21
        Envoy::Http::ConnectionManagerImpl::onData(Envoy::Buffer::Instance&, bool)+76
        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+303
        Envoy::Network::ConnectionImpl::onReadReady()+1622
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.add*Filter|FilterManagerImpl::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl13addReadFilterENSt3__110shared_ptrINS0_10ReadFilterEEE,FilterManagerImpl.this=0x559f98f08478,fd=41 

        Envoy::Network::FilterManagerImpl::addReadFilter(std::__1::shared_ptr<Envoy::Network::ReadFilter>)+0
        Envoy::Http::CodecClient::CodecClient(Envoy::Http::CodecType, std::__1::unique_ptr<Envoy::Network::ClientConnection, std::__1::default_delete<Envoy::Network::ClientConnection> >&&, std::__1::shared_ptr<Envoy::Upstream::HostDescription const>, Envoy::Event::Dispatcher&)+357
        Envoy::Http::CodecClientProd::CodecClientProd(Envoy::Http::CodecType, std::__1::unique_ptr<Envoy::Network::ClientConnection, std::__1::default_delete<Envoy::Network::ClientConnection> >&&, std::__1::shared_ptr<Envoy::Upstream::HostDescription const>, Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&)+70
        std::__1::__function::__func<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_1, std::__1::allocator<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_1>, std::__1::unique_ptr<Envoy::Http::CodecClient, std::__1::default_delete<Envoy::Http::CodecClient> > (Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase*)>::operator()(Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase*&&)+94
        Envoy::Http::FixedHttpConnPoolImpl::createCodecClient(Envoy::Upstream::Host::CreateConnectionData&)+35
        Envoy::Http::ActiveClient::initialize(Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase&)+113
        Envoy::Http::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&, unsigned int, unsigned int)+171
        Envoy::Http::Http1::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&)+69
        std::__1::__function::__func<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0, std::__1::allocator<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0>, std::__1::unique_ptr<Envoy::ConnectionPool::ActiveClient, std::__1::default_delete<Envoy::ConnectionPool::ActiveClient> > (Envoy::Http::HttpConnPoolImplBase*)>::operator()(Envoy::Http::HttpConnPoolImplBase*&&)+40
        Envoy::Http::FixedHttpConnPoolImpl::instantiateActiveClient()+35
        Envoy::ConnectionPool::ConnPoolImplBase::tryCreateNewConnection(float)+1233
        Envoy::ConnectionPool::ConnPoolImplBase::newStream(Envoy::ConnectionPool::AttachContext&)+2001
        non-virtual thunk to Envoy::Http::HttpConnPoolImplBase::newStream(Envoy::Http::ResponseDecoder&, Envoy::Http::ConnectionPool::Callbacks&)+47
        Envoy::Extensions::Upstreams::Http::Http::HttpConnPool::newStream(Envoy::Router::GenericConnectionPoolCallbacks*)+70
        Envoy::Router::Filter::decodeHeaders(Envoy::Http::RequestHeaderMap&, bool)+14120
        Envoy::Http::FilterManager::decodeHeaders(Envoy::Http::ActiveStreamDecoderFilter*, Envoy::Http::RequestHeaderMap&, bool)+334
        Envoy::Http::ConnectionManagerImpl::ActiveStream::decodeHeaders(std::__1::unique_ptr<Envoy::Http::RequestHeaderMap, std::__1::default_delete<Envoy::Http::RequestHeaderMap> >&&, bool)+6139
        Envoy::Http::Http1::ServerConnectionImpl::onMessageCompleteBase()+279
        Envoy::Http::Http1::ConnectionImpl::onMessageComplete()+637
        Envoy::Http::Http1::LegacyHttpParserImpl::Impl::Impl(http_parser_type, void*)::{lambda(http_parser*)#3}::__invoke(http_parser*)+31
        http_parser_execute+7959
        Envoy::Http::Http1::LegacyHttpParserImpl::execute(char const*, int)+31
        Envoy::Http::Http1::ConnectionImpl::dispatchSlice(char const*, unsigned long)+52
        Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+1151
        virtual thunk to Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+21
        Envoy::Http::ConnectionManagerImpl::onData(Envoy::Buffer::Instance&, bool)+76
        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+303
        Envoy::Network::ConnectionImpl::onReadReady()+1622
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0    : setsockopt: level=6, fd=44, optname=1, optval=1, optlen=4. 

#### Downstream Read Request: Initiate an asynchronous connection to upstream.
connecting to 8080:
01:23:36 4215     wrk:worker_0     127.0.0.6                               36383  172.21.206.232                          8080  

        connect+75
        Envoy::Network::IoSocketHandleImpl::connect(std::__1::shared_ptr<Envoy::Network::Address::Instance const>)+104
        Envoy::Network::SocketImpl::connect(std::__1::shared_ptr<Envoy::Network::Address::Instance const>)+64
        Envoy::Network::ClientConnectionImpl::connect()+650
        Envoy::Http::CodecClient::connect()+543
        Envoy::Http::CodecClientProd::CodecClientProd(Envoy::Http::CodecType, std::__1::unique_ptr<Envoy::Network::ClientConnection, std::__1::default_delete<Envoy::Network::ClientConnection> >&&, std::__1::shared_ptr<Envoy::Upstream::HostDescription const>, Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&)+694
        std::__1::__function::__func<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_1, std::__1::allocator<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_1>, std::__1::unique_ptr<Envoy::Http::CodecClient, std::__1::default_delete<Envoy::Http::CodecClient> > (Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase*)>::operator()(Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase*&&)+94
        Envoy::Http::FixedHttpConnPoolImpl::createCodecClient(Envoy::Upstream::Host::CreateConnectionData&)+35
        Envoy::Http::ActiveClient::initialize(Envoy::Upstream::Host::CreateConnectionData&, Envoy::Http::HttpConnPoolImplBase&)+113
        Envoy::Http::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&, unsigned int, unsigned int)+171
        Envoy::Http::Http1::ActiveClient::ActiveClient(Envoy::Http::HttpConnPoolImplBase&)+69
        std::__1::__function::__func<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0, std::__1::allocator<Envoy::Http::Http1::allocateConnPool(Envoy::Event::Dispatcher&, Envoy::Random::RandomGenerator&, std::__1::shared_ptr<Envoy::Upstream::Host const>, Envoy::Upstream::ResourcePriority, std::__1::shared_ptr<std::__1::vector<std::__1::shared_ptr<Envoy::Network::Socket::Option const>, std::__1::allocator<std::__1::shared_ptr<Envoy::Network::Socket::Option const> > > > const&, std::__1::shared_ptr<Envoy::Network::TransportSocketOptions const> const&, Envoy::Upstream::ClusterConnectivityState&)::$_0>, std::__1::unique_ptr<Envoy::ConnectionPool::ActiveClient, std::__1::default_delete<Envoy::ConnectionPool::ActiveClient> > (Envoy::Http::HttpConnPoolImplBase*)>::operator()(Envoy::Http::HttpConnPoolImplBase*&&)+40
        Envoy::Http::FixedHttpConnPoolImpl::instantiateActiveClient()+35
        Envoy::ConnectionPool::ConnPoolImplBase::tryCreateNewConnection(float)+1233
        Envoy::ConnectionPool::ConnPoolImplBase::newStream(Envoy::ConnectionPool::AttachContext&)+2001
        non-virtual thunk to Envoy::Http::HttpConnPoolImplBase::newStream(Envoy::Http::ResponseDecoder&, Envoy::Http::ConnectionPool::Callbacks&)+47
        Envoy::Extensions::Upstreams::Http::Http::HttpConnPool::newStream(Envoy::Router::GenericConnectionPoolCallbacks*)+70
        Envoy::Router::Filter::decodeHeaders(Envoy::Http::RequestHeaderMap&, bool)+14120
        Envoy::Http::FilterManager::decodeHeaders(Envoy::Http::ActiveStreamDecoderFilter*, Envoy::Http::RequestHeaderMap&, bool)+334
        Envoy::Http::ConnectionManagerImpl::ActiveStream::decodeHeaders(std::__1::unique_ptr<Envoy::Http::RequestHeaderMap, std::__1::default_delete<Envoy::Http::RequestHeaderMap> >&&, bool)+6139
        Envoy::Http::Http1::ServerConnectionImpl::onMessageCompleteBase()+279
        Envoy::Http::Http1::ConnectionImpl::onMessageComplete()+637
        Envoy::Http::Http1::LegacyHttpParserImpl::Impl::Impl(http_parser_type, void*)::{lambda(http_parser*)#3}::__invoke(http_parser*)+31
        http_parser_execute+7959
        Envoy::Http::Http1::LegacyHttpParserImpl::execute(char const*, int)+31
        Envoy::Http::Http1::ConnectionImpl::dispatchSlice(char const*, unsigned long)+52
        Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+1151
        virtual thunk to Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+21
        Envoy::Http::ConnectionManagerImpl::onData(Envoy::Buffer::Instance&, bool)+76
        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+303
        Envoy::Network::ConnectionImpl::onReadReady()+1622
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 
comm:wrk:worker_0,tid:5327: FilterManagerImpl.on*::uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy7Network17FilterManagerImpl16ActiveReadFilter10connectionEv,FilterManagerImpl.this=0x559f98996380,fd=41 

***** elapsed=1632608064: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1632618881: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=1145219, tid2epollNrFdReady=1
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=92 
***************************


***** elapsed=1632635526: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98e26ee0, fd=41, events=0x24
libevent: EV_WRITE
libevent: EV_ET


***** elapsed=1632654517: tid=5327,comm=wrk:worker_0: END:EventFired

#### Upstream Write Request: asynchronous upstream connection successed. Callbacking.
***** elapsed=1632659321: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98eb6540, fd=44, events=0x24
libevent: EV_WRITE
libevent: EV_ET

comm:wrk:worker_0,tid:5327: ConnPoolImplBase*attachStreamToClient: uprobe:/proc/4215/root/usr/local/bin/envoy:_ZN5Envoy14ConnectionPool16ConnPoolImplBase20attachStreamToClientERNS0_12ActiveClientERNS0_13AttachContextE 

        Envoy::ConnectionPool::ConnPoolImplBase::attachStreamToClient(Envoy::ConnectionPool::ActiveClient&, Envoy::ConnectionPool::AttachContext&)+0
        Envoy::ConnectionPool::ConnPoolImplBase::onConnectionEvent(Envoy::ConnectionPool::ActiveClient&, absl::string_view, Envoy::Network::ConnectionEvent)+497
        Envoy::Network::ConnectionImplBase::raiseConnectionEvent(Envoy::Network::ConnectionEvent)+59
        Envoy::Network::ConnectionImpl::raiseEvent(Envoy::Network::ConnectionEvent)+511
        Envoy::Network::ConnectionImpl::onWriteReady()+1648
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+818
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

#### Upstream Write Request:  Writing HTTP Request to upstream socket.
***** elapsed=1632741863: tid=5327,comm=wrk:worker_0: socket_write, probe=tracepoint:syscalls:sys_exit_writev, fd=44, ret=262

        writev+77
        Envoy::Network::IoSocketHandleImpl::writev(Envoy::Buffer::RawSlice const*, unsigned long)+263
        Envoy::Network::IoSocketHandleImpl::write(Envoy::Buffer::Instance&)+107
        Envoy::Network::RawBufferSocket::doWrite(Envoy::Buffer::Instance&, bool)+121
        Envoy::Network::ConnectionImpl::onWriteReady()+1876
        Envoy::Network::ConnectionImpl::raiseEvent(Envoy::Network::ConnectionEvent)+529
        Envoy::Network::ConnectionImpl::onWriteReady()+1648
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+818
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217


***** elapsed=1632756069: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1632764448: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=129648, tid2epollNrFdReady=2
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=60 
***************************

#### Upstream Read Response: upstream socket ReadReady callback
***** elapsed=1637821708: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98eb6540, fd=44, events=0x26
libevent: EV_READ
libevent: EV_WRITE
libevent: EV_ET

#### Upstream Read Response: 读 upstream HTTP Response
***** elapsed=1637898855: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_readv, fd=44, ret=4511

        readv+77
        Envoy::Network::IoSocketHandleImpl::readv(unsigned long, Envoy::Buffer::RawSlice*, unsigned long)+247
        Envoy::Network::IoSocketHandleImpl::read(Envoy::Buffer::Instance&, absl::optional<unsigned long>)+167
        Envoy::Network::RawBufferSocket::doRead(Envoy::Buffer::Instance&)+136
        Envoy::Network::ConnectionImpl::onReadReady()+753
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217


***** elapsed=1637915998: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_readv, fd=44, ret=-11

        readv+77
        Envoy::Network::IoSocketHandleImpl::readv(unsigned long, Envoy::Buffer::RawSlice*, unsigned long)+247
        Envoy::Network::IoSocketHandleImpl::read(Envoy::Buffer::Instance&, absl::optional<unsigned long>)+167
        Envoy::Network::RawBufferSocket::doRead(Envoy::Buffer::Instance&)+136
        Envoy::Network::ConnectionImpl::onReadReady()+753
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

***** elapsed=1638220184: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_DEL, fd=41, events=0x80002004

#### Upstream Read Response: The HTTP Response from upstream has been completely read, and the downstream WriteReady event has been watched, prepare to write the HTTP Response to downstream.
***** elapsed=1638231319: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_ADD, fd=41, events=0x80000005
EPOLL_CTL_ADD/MOD ReadReady(EPOLLIN)
EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)
EPOLL_CTL_ADD/MOD EdgeTrigger

        epoll_ctl+14
        epoll_nochangelist_add+54
        evmap_io_add_+421
        event_add_nolock_+603
        event_add+54
        Envoy::Network::ConnectionImpl::readDisable(bool)+938
        Envoy::Http::Http1::StreamEncoderImpl::~StreamEncoderImpl()+112
        non-virtual thunk to Envoy::Http::Http1::ServerConnectionImpl::onEncodeComplete()+54
        Envoy::Http::Http1::StreamEncoderImpl::endEncode()+166
        Envoy::Http::Http1::StreamEncoderImpl::encodeData(Envoy::Buffer::Instance&, bool)+340
        Envoy::Http::ConnectionManagerImpl::ActiveStream::encodeData(Envoy::Buffer::Instance&, bool)+679
        Envoy::Http::FilterManager::encodeData(Envoy::Http::ActiveStreamEncoderFilter*, Envoy::Buffer::Instance&, bool, Envoy::Http::FilterManager::FilterIterationStartState)+2138
        Envoy::Router::UpstreamRequest::decodeData(Envoy::Buffer::Instance&, bool)+230
        Envoy::Http::ResponseDecoderWrapper::decodeData(Envoy::Buffer::Instance&, bool)+59
        Envoy::Http::ResponseDecoderWrapper::decodeData(Envoy::Buffer::Instance&, bool)+59
        Envoy::Http::Http1::ClientConnectionImpl::onMessageCompleteBase()+619
        Envoy::Http::Http1::ConnectionImpl::onMessageComplete()+637
        Envoy::Http::Http1::LegacyHttpParserImpl::Impl::Impl(http_parser_type, void*)::{lambda(http_parser*)#3}::__invoke(http_parser*)+31
        http_parser_execute+7705
        Envoy::Http::Http1::LegacyHttpParserImpl::execute(char const*, int)+31
        Envoy::Http::Http1::ConnectionImpl::dispatchSlice(char const*, unsigned long)+52
        Envoy::Http::Http1::ConnectionImpl::dispatch(Envoy::Buffer::Instance&)+1151
        Envoy::Http::Http1::ClientConnectionImpl::dispatch(Envoy::Buffer::Instance&)+29
        Envoy::Http::CodecClient::onData(Envoy::Buffer::Instance&)+48
        Envoy::Http::CodecClient::CodecReadFilter::onData(Envoy::Buffer::Instance&, bool)+21
        Envoy::Network::FilterManagerImpl::onContinueReading(Envoy::Network::FilterManagerImpl::ActiveReadFilter*, Envoy::Network::ReadBufferSource&)+303
        Envoy::Network::ConnectionImpl::onReadReady()+1622
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92


***** elapsed=1638898463: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1638934709: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=1123611, tid2epollNrFdReady=1
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=56 
***************************


***** elapsed=1638955421: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98eb6540, fd=44, events=0x24
libevent: EV_WRITE
libevent: EV_ET


***** elapsed=1638975366: tid=5327,comm=wrk:worker_0: END:EventFired

#### Downstream Write Response: WriteReady callback from downstream socket.
***** elapsed=1638980295: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98e26ee0, fd=41, events=0x24
libevent: EV_WRITE
libevent: EV_ET

#### Downstream Write Response: writing the HTTP Response to downstream.
***** elapsed=1639253752: tid=5327,comm=wrk:worker_0: socket_write, probe=tracepoint:syscalls:sys_exit_writev, fd=41, ret=4631

        writev+77
        Envoy::Network::IoSocketHandleImpl::writev(Envoy::Buffer::RawSlice const*, unsigned long)+263
        Envoy::Network::IoSocketHandleImpl::write(Envoy::Buffer::Instance&)+107
        Envoy::Network::RawBufferSocket::doWrite(Envoy::Buffer::Instance&, bool)+121
        Envoy::Network::ConnectionImpl::onWriteReady()+1876
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+818
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217


***** elapsed=1639293010: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1639308346: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=354486, tid2epollNrFdReady=2
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=56 
***************************


***** elapsed=1643785802: tid=5327,comm=wrk:worker_0: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()
FileEventImpl*=0x559f98e26ee0, fd=41, events=0x26
libevent: EV_READ
libevent: EV_WRITE
libevent: EV_ET


***** elapsed=1643855427: tid=5327,comm=wrk:worker_0: socket_read, probe=tracepoint:syscalls:sys_exit_readv, fd=41, ret=0

        readv+77
        Envoy::Network::IoSocketHandleImpl::readv(unsigned long, Envoy::Buffer::RawSlice*, unsigned long)+247
        Envoy::Network::IoSocketHandleImpl::read(Envoy::Buffer::Instance&, absl::optional<unsigned long>)+167
        Envoy::Network::RawBufferSocket::doRead(Envoy::Buffer::Instance&)+136
        Envoy::Network::ConnectionImpl::onReadReady()+753
        Envoy::Network::ConnectionImpl::onFileEvent(unsigned int)+879
        std::__1::__function::__func<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5, std::__1::allocator<Envoy::Event::DispatcherImpl::createFileEvent(int, std::__1::function<void (unsigned int)>, Envoy::Event::FileTriggerType, unsigned int)::$_5>, void (unsigned int)>::operator()(unsigned int&&)+65
        Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int, short, void*)+92
        0x7fffffffe000
        event_base_loop+1953
        Envoy::Server::WorkerImpl::threadRoutine(Envoy::Server::GuardDog&, std::__1::function<void ()> const&)+621
        Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::__1::function<void ()>, absl::optional<Envoy::Thread::Options> const&)::{lambda(void*)#1}::__invoke(void*)+19
        start_thread+217

***** elapsed=1643880789: tid=5327,comm=wrk:worker_0: sys_enter_epoll_ctl, epfd=10, op=EPOLL_CTL_DEL, fd=41, events=0x80000005
sys_enter_close fd=41
delete fd2filterManagerImpl, fd=41
delete fd2filterManagerImpl=0x559f98d38758
delete fd2filterManagerImpl, fd=41
delete fd2filterManagerImpl=0x559f98996380

***** elapsed=1644006858: tid=5327,comm=wrk:worker_0: END:EventFired

******* WAKE-ROUND:END Summary *******
***** elapsed=1644056452: tid=5327,comm=wrk:worker_0: sys_enter_epoll_wait, runableDuaration=289169, tid2epollNrFdReady=1
*** last_epoll_wait_args: epfd=10, events=-1741049344, maxevents=32, timeout=52 
***************************

^C


@epoll_ctl_op[1]: EPOLL_CTL_ADD
@epoll_ctl_op[2]: EPOLL_CTL_DEL
@epoll_ctl_op[3]: EPOLL_CTL_MOD


@fd2sockopt[44, 6, 1, 1]: 1
@fd2sockopt[41, 6, 1, 1]: 1


@filterManagerImpl2fd[94143954060408]: 41
@filterManagerImpl2fd[94143950909952]: 41

bpftrace script

https://github.com/labilezhu/pub-diy/blob/main/low-tec/trace/trace-istio/trace-istio-part4/trace-envoy-filter-router.bt

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#!usr/bin/bpftrace
/*
IMPORT-ENV: $ENVOY_PID
args: $1=ENVOY_PID
*/

/*

#export PODID=`sudo crictl  pods | grep fortio-server | egrep '\bReady' | awk '{print $1}'`
#export CONTAINERID=`sudo crictl ps | grep $PODID | grep istio-proxy |  awk '{print $1}'`

kubectl -n idm-mark exec -it fortio-server -c  istio-proxy  -- bash -c 'ls -l /proc/`pgrep envoy`/ns/pid'
lrwxrwxrwx 1 istio-proxy istio-proxy 0 Mar 31 09:18 /proc/15/ns/pid -> 'pid:[4026532799]'
pgrep envoy | tee /dev/fd/2 | xargs -L 1 -I '{}' sudo ls -l /proc/'{}'/ns 

export PID=4215
export SCRIPT_HOME=`pwd`
export bpftrace_image=cndt-bcc-ub

docker run -it --rm --init  --privileged --name bpftrace -h bpftrace \
    --pid host \
    --net host \
    -e SCRIPT_HOME=$SCRIPT_HOME \
    -e PID=$PID \
    -e ENVOY_PID=$PID \
    -e BT=trace-envoy-filter-router.bt \
    -v /etc/localtime:/etc/localtime:ro \
    -v /sys:/sys:rw \
    -v /usr/src:/usr/src:rw \
    -v /lib/modules:/lib/modules:ro \
    -v ${SCRIPT_HOME}:${SCRIPT_HOME}:rw \
    $bpftrace_image \
    ${SCRIPT_HOME}/warp-bt.sh $PID
*/


/*
1. BPF Maps:

1.1. range tid map
- @watchedWakeRound[tid]=tid
       - sys_exit_accept4
       - FileEventImpl*assignEvents*
- @fdFired[tid]=$fd;
       - uprobe: *FileEventImpl*assignEvents*
       - uretprobe: *FileEventImpl*assignEvents*

1.2. fd map
- @fd2sockpair[$fd]=@sockpair[tid]
       - sys_exit_accept4
       - sys_enter_close
- @fd2sockopt[$fd, $level, $optname, $optval_int] = 1
       - sys_enter_setsockopt

- @filterManagerImpl2fd[arg0] = @fdFired[tid] // filterManagerImpl to downstream fd
- @fd2filterManagerImpl[$fd] = arg0 
- @fd2filterManagerImpl2[$fd] = arg0
- @downFD2upFD[$downFD] = $fd; //downstream fd to upstream fd
       - sys_enter_epoll_ctl
- @upFD[$fd] = $fd; //upstream fd list
       - sys_enter_epoll_ctl

1.3. temp tid map
- @sockpair[tid]=($sk->__sk_common.skc_daddr, $dport, $sk->__sk_common.skc_rcv_saddr, $lport);
- @sockpair_exist[tid]=1
- @watchedIo[tid]=fd

*/

#include <linux/in.h>
#include <linux/in6.h>
#include <linux/socket.h>
#include <net/sock.h>
// #include <sys/epoll.h>

// The event argument describes the object linked to the file descriptor fd.  The struct epoll_event is defined as:
// struct epoll_data_t {
//     int          fd;
// };

// struct epoll_event {
//     //a bit mask composed by ORing together zero or more of the following available event types
//     uint32_t     events;      /* Epoll events */

//     struct epoll_data_t data;        /* User data variable */
// };



BEGIN
{
	printf("Tracing Envoy. Hit Ctrl-C to end.\n");
       printf("#define EPOLL_CTL_ADD 1\n #define EPOLL_CTL_DEL 2\n #define EPOLL_CTL_MOD 3\n");

       @epoll_ctl_op[1]="EPOLL_CTL_ADD";
       @epoll_ctl_op[2]="EPOLL_CTL_DEL";
       @epoll_ctl_op[3]="EPOLL_CTL_MOD";


}

/*
Get the local and peer addresses when accepting the connection. And mark this round of wakeup need to be saved
 */
kretprobe:inet_csk_accept
/pid==$1 /
{
	$sk = (struct sock *)retval;
	$inet_family = $sk->__sk_common.skc_family;

	if ($inet_family == AF_INET || $inet_family == AF_INET6) {
		// initialize variable type:
		$daddr = ntop(0);
		$saddr = ntop(0);
		if ($inet_family == AF_INET) {
			$daddr = ntop($sk->__sk_common.skc_daddr);
			$saddr = ntop($sk->__sk_common.skc_rcv_saddr);
		} else {
			printf("not support IPv6.\n");
			return;
		}
		
		$lport = $sk->__sk_common.skc_num;

              // printf("accept(), port=%d\n", $lport);

              //only watch listen port 15006
		if( 15006 != $lport ) { 
			return;
		}

		$dport = $sk->__sk_common.skc_dport;
		$qlen  = $sk->sk_ack_backlog;
		$qmax  = $sk->sk_max_ack_backlog;

		// Destination port is big endian, it must be flipped
		$dport = ($dport >> 8) | (($dport << 8) & 0x00FF00);

              printf("OS handshaked TCP:\n");
		time("%H:%M:%S ");
		printf("%-6d %-14s ", pid, comm);
		printf("%-39s %-5d %-39s %-5d ", $daddr, $dport, $saddr,
		    $lport);
		printf("%d/%d\n", $qlen, $qmax);

		@sockpair[tid]=($sk->__sk_common.skc_daddr, $dport, $sk->__sk_common.skc_rcv_saddr, $lport);
		@sockpair_exist[tid]=1;

              @watchedWakeRound[tid]=tid;
	}
}

/**
 * Get newly connected FDs. And marked current libevent callback needs to be saved
 */
tracepoint:syscalls:sys_exit_accept4
/pid==$1 && @sockpair_exist[tid] /
{
	$fd = args->ret;
	if( $fd < 0 ) {
		return;
	}
	printf("sys_exit_accept4 fd=%d\n", $fd);
	@fd2sockpair[$fd]=@sockpair[tid];

       @fdFired[tid]=$fd;

	delete(@sockpair[tid]);
	delete(@sockpair_exist[tid]);
       printf("%s \n", ustack());
}

/**
 * save the sockopt of FD
 */
tracepoint:syscalls:sys_enter_setsockopt
/pid==$1/
{
       // socket opts: https://elixir.bootlin.com/linux/v5.16.3/source/include/uapi/linux/tcp.h#L92     
       $level = args->level;
       $fd = args->fd;

       if( @fd2sockpair[$fd].0 || @upFD[$fd] ) {
              $optname = args->optname;
              $optval = args->optval;
              $optval_int = *$optval;
              $optlen = args->optlen;
              // printf("\n########## setsockopt() ##########\n");
              printf("comm:%-16s: setsockopt: level=%d, fd=%d, optname=%d, optval=%d, optlen=%d. \n", comm, $level, $fd, $optname, $optval_int, $optlen);
              @fd2sockopt[$fd, $level, $optname, $optval_int] = 1;
       }
}



/*
Save the watching of FD by epoll

cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_epoll_ctl/format
 */
tracepoint:syscalls:sys_enter_epoll_ctl
/pid==$1/
{
       $fd=args->fd;
       $epollEvents = (uint32) (args->event->events);
       $op = args->op;
       if( @fd2sockpair[$fd].0 ) {

              printf("***** elapsed=%d: tid=%d,comm=%s: sys_enter_epoll_ctl, epfd=%d, op=%s, fd=%d, events=0x%x\n", 
                     elapsed, tid, comm, args->epfd, @epoll_ctl_op[$op], $fd, $epollEvents);


              if( $op == 1/*EPOLL_CTL_ADD*/ || $op == 3/*EPOLL_CTL_MOD*/ ) { //add watch epoll event
                     if( $epollEvents & (uint32)0x001 /*EPOLLIN*/ ) {
                            printf("EPOLL_CTL_ADD/MOD ReadReady(EPOLLIN)\n");
                     }
                     if( $epollEvents & (uint32)0x004 /*EPOLLOUT*/ ) {
                            printf("EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)\n");
                     }
                     if( $epollEvents & (1u << 31) /*EPOLLET*/ ) {
                            printf("EPOLL_CTL_ADD/MOD EdgeTrigger\n");
                     }
                     printf("%s\n", ustack(30));
              }
              
       } else {
              $downFD = @fdFired[tid];
              if( $downFD ) {//in downstream fd event callback, register upstream event trigger
                     @upFD[$fd] = $fd;
                     @downFD2upFD[$downFD] = $fd;

                     printf("***** elapsed=%d: tid=%d,comm=%s: register upstream event trigger:sys_enter_epoll_ctl, epfd=%d, op=%s, fd=%d, events=0x%x\n", 
                            elapsed, tid, comm, args->epfd, @epoll_ctl_op[$op], $fd, $epollEvents);


                     if( $op == 1/*EPOLL_CTL_ADD*/ || $op == 3/*EPOLL_CTL_MOD*/ ) { //add watch epoll event
                            if( $epollEvents & (uint32)0x001 /*EPOLLIN*/ ) {
                                   printf("EPOLL_CTL_ADD/MOD ReadReady(EPOLLIN)\n");
                            }
                            if( $epollEvents & (uint32)0x004 /*EPOLLOUT*/ ) {
                                   printf("EPOLL_CTL_ADD/MOD WriteReady(EPOLLOUT)\n");
                            }
                            if( $epollEvents & (1u << 31) /*EPOLLET*/ ) {
                                   printf("EPOLL_CTL_ADD/MOD EdgeTrigger\n");
                            }
                            printf("%s\n", ustack(60));
                     }                     
              }
       }
}

/*
The end of current wake Round/runnable Round, preparing for the next round.
cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_epoll_wait/format
 */
tracepoint:syscalls:sys_enter_epoll_wait
/pid==$1/
{

       if( @watchedWakeRound[tid] ) {
              $runnableStartTime=@tid2Waketime[tid];
              if( $runnableStartTime ) {
                     $runableDuaration = elapsed - $runnableStartTime;
                     printf("\n******* WAKE-ROUND:END Summary *******\n");
                     printf("***** elapsed=%d: tid=%d,comm=%s: sys_enter_epoll_wait, runableDuaration=%d, tid2epollNrFdReady=%d\n", 
                            elapsed, tid, comm, $runableDuaration, @tid2epollNrFdReady[tid]);
                     $tid_last_epoll_wait_args = @last_epoll_wait_args[tid];
                     if( $tid_last_epoll_wait_args.0  ) {
                            printf("*** last_epoll_wait_args: epfd=%d, events=%d, maxevents=%d, timeout=%d \n", 
                                   $tid_last_epoll_wait_args.0, $tid_last_epoll_wait_args.1, $tid_last_epoll_wait_args.2, $tid_last_epoll_wait_args.3);
                     }
                     printf("***************************\n\n");
              }
       }

       delete(@tid2Waketime[tid]);
       delete(@watchedWakeRound[tid]);
       delete(@tid2epollNrFdReady[tid]);

       //read in next sys_enter_epoll_wait
       @last_epoll_wait_args[tid]=(args->epfd, args->events, args->maxevents, args->timeout);
}

/*
The begining of wakeRound/runnableRound
cat /sys/kernel/debug/tracing/events/syscalls/sys_exit_epoll_wait/format
 */
tracepoint:syscalls:sys_exit_epoll_wait
/pid==$1/
{
       // printf("\n***** elapsed=%d: tid=%d,comm=%s: sys_enter_epoll_wait\n", elapsed, tid, comm);

       // printf("epfd: 0x%08lx, events: 0x%08lx, maxevents: 0x%08lx, timeout: 0x%08lx \n", 
       //        ((args->epfd)), ((args->events)), ((args->maxevents)), ((args->timeout)) );

       @tid2Waketime[tid]=elapsed;
       @tid2epollNrFdReady[tid]=args->ret;
}

/*
Monitor the begining of libevent callback for a FD. Save info to map.

Envoy::Event::FileEventImpl::assignEvents(unsigned int, event_base*)::$_1::__invoke(int fd, short events, void* fileEventImplThis)  !!!NOT!!: FileEventImpl::assignEvents()
C++11 Lambda expressions:
event_assign( &raw_event_, base, fd_, xxx, [](evutil_socket_t, short what, void* arg)-> void {}, this );

event_assign(): https://libevent.org/doc/event_8h.html#a3e49a8172e00ae82959dfe64684eda11
       event_assign	(	struct event * 	ev,
              struct event_base * 	base,
              evutil_socket_t 	fd,
              short 	events,
              event_callback_fn 	callback,
              void * 	callback_arg 
       )	

       https://libevent.org/doc/event_8h.html#aed2307f3d9b38e07cc10c2607322d758
       typedef void(* event_callback_fn) (evutil_socket_t, short, void *)
              fd	An fd or signal
              events	One or more EV_* flags
              arg	A user-supplied argument.
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*FileEventImpl*assignEvents*
/pid == $1/ 
{
       $fd = arg0;
       if( @fd2sockpair[$fd].0 || @upFD[$fd] ) {
              $libevent_events = arg1;

              printf("\n***** elapsed=%d: tid=%d,comm=%s: BEGIN:EventFired:FileEventImpl::assignEvents::eventCallback()\n", elapsed, tid, comm);
              printf("FileEventImpl*=%p, fd=%d, events=0x%x\n",arg2, $fd, $libevent_events);

              if( $libevent_events & (uint16)0x01 /*EV_TIMEOUT*/ ) {
                     printf("libevent: EV_TIMEOUT\n");
              }
              if( $libevent_events & (uint16)0x02 /*EV_TIMEOUT*/ ) {
                     printf("libevent: EV_READ\n");
              }
              if( $libevent_events & (uint16)0x04 /*EV_TIMEOUT*/ ) {
                     printf("libevent: EV_WRITE\n");
              }
              if( $libevent_events & (uint16)0x20 /*EV_TIMEOUT*/ ) {
                     printf("libevent: EV_ET\n");
              }
              if( $libevent_events & (uint16)0x80 /*EV_TIMEOUT*/ ) {
                     printf("libevent: EV_CLOSED\n");
              }
              
              printf("%s\n", kstack);
              @fdFired[tid]=$fd;
              @watchedWakeRound[tid]=tid;
       }
}

/*
Monitor the end of libevent callback for a FD. Save info to map.
*/
uretprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*FileEventImpl*assignEvents*
/pid == $1 && @fdFired[tid] / 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: END:EventFired\n", elapsed, tid, comm);
       delete(@fdFired[tid]);
}

/*
monitor socket read
*/
tracepoint:syscalls:sys_enter_read,tracepoint:syscalls:sys_enter_readv,tracepoint:syscalls:sys_enter_recv*
/pid == $1 && (@fd2sockpair[args->fd].0 || @upFD[args->fd] ) / 
{
       @watchedIo[tid]=args->fd;
}

tracepoint:syscalls:sys_exit_read,tracepoint:syscalls:sys_exit_readv,tracepoint:syscalls:sys_exit_recv*
/pid == $1 && @watchedIo[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: socket_read, probe=%s, fd=%d, ret=%d\n", elapsed, tid, comm, probe, @watchedIo[tid],args->ret);
       delete(@watchedIo[tid]);
       printf("%s\n", ustack(20));
}

/*
monitor socket write
*/
tracepoint:syscalls:sys_enter_write,tracepoint:syscalls:sys_enter_writev
/pid == $1 && ( @fd2sockpair[args->fd].0 || @upFD[args->fd] ) / 
{
       @watchedIo[tid]=args->fd;
}

tracepoint:syscalls:sys_exit_write,tracepoint:syscalls:sys_exit_writev
/pid == $1 && @watchedIo[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: socket_write, probe=%s, fd=%d, ret=%d\n", elapsed, tid, comm, probe, @watchedIo[tid], args->ret);
       delete(@watchedIo[tid]);
       printf("%s\n", ustack(20));
}


/*
Monitor TlsInspector functions
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*TlsInspector*
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: TlsInspector*, probe=%s\n", elapsed, tid, comm, probe);
}

/*
Monitor Application Protocols(APLN) detected.
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*ConnectionSocketImpl*setRequestedApplicationProtocols*
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: ConnectionSocketImpl::setRequestedApplicationProtocols\n", elapsed, tid, comm);
       // printf("%s", ustack);
}

//SslSocket::SslSocket
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZN5Envoy10Extensions16TransportSockets3Tls9SslSocketC2ENSt3__110shared_ptrINS_3Ssl7ContextEEENS2_12InitialStateERKNS5_IKNS_7Network22TransportSocketOptionsEEENS4_8functionIFNS5_INS6_10HandshakerEEENS4_10unique_ptrI6ssl_stN4bssl8internal7DeleterISK_EEEEiPNS6_18HandshakeCallbacksEEEE
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}

// setTransportSocketCallbacks
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZN5Envoy10Extensions16TransportSockets3Tls9SslSocket27setTransportSocketCallbacksERNS_7Network24TransportSocketCallbacksE
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}


// SslSocket::doRead
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZN5Envoy10Extensions16TransportSockets3Tls9SslSocket6doReadERNS_6Buffer8InstanceE
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}


// SslSocket::doWrite
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZN5Envoy10Extensions16TransportSockets3Tls9SslSocket7doWriteERNS_6Buffer8InstanceEb
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}

// SslSocket::onSuccess
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZThn16_N5Envoy10Extensions16TransportSockets3Tls9SslSocket9onSuccessEP6ssl_st
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}

// SslSocket::connection
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZThn16_NK5Envoy10Extensions16TransportSockets3Tls9SslSocket10connectionEv
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}

// SslSocket::connection
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZThn16_NK5Envoy10Extensions16TransportSockets3Tls9SslSocket10connectionEv
/pid == $1 && @fdFired[tid]/ 
{
       printf("\n***** elapsed=%d: tid=%d,comm=%s: SslSocket*, probe=%s\n", elapsed, tid, comm, probe);
       printf("%s\n", ustack(10));
}

/*
Monitor the name of the selected Network Fitler Chain
void setFilterChainName(absl::string_view filter_chain_name)
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:_ZN5Envoy10StreamInfo14StreamInfoImpl18setFilterChainNameEN4absl11string_viewE 
/pid == $1 && @fdFired[tid]/ 
{ 
/**
[Assembly 2: Calling convention](https://cs61.seas.harvard.edu/site/2018/Asm2/)

1. A structure argument that fits in a single machine word (64 bits/8 bytes) is passed in a single register.
   
    Example: `struct small { char a1, a2; }`

2. A structure that fits in two to four machine words (16–32 bytes) is passed in sequential registers, as if it were multiple arguments.
   
    Example: `struct medium { long a1, a2; }`
*/
    $filterName = str(reg("si"));
    $filterNameLength = reg("dx");

    // printf("tid:%d: Got setFilterChainName=%s, lenght=%d\n %s \n", tid, $filterName, $filterNameLength, ustack ); 
    printf("comm:%s,tid:%d: Got setFilterChainName=%s, lenght=%d\n", comm, tid, $filterName, $filterNameLength ); 

    if( $filterNameLength > 0 ) {
        printf("%s\n", ustack(3));
    }
}

/*
Monitor FilterManagerImpl::add*Filter()
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*FilterManagerImpl*add*Filter*,uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*FilterManagerImpl*FilterManagerImpl*
/pid == $1 && @fdFired[tid]/ 
{ 
       if( @upFD[@fdFired[tid]] ) {
              return;
       }

       $fd = @fdFired[tid];
       @filterManagerImpl2fd[arg0] = $fd;
       if( @fd2filterManagerImpl[$fd] ) {
              @fd2filterManagerImpl2[$fd] = arg0;
       } else {
              @fd2filterManagerImpl[$fd] = arg0;
       }
       printf("comm:%s,tid:%d: FilterManagerImpl.add*Filter|FilterManagerImpl::%s,FilterManagerImpl.this=%p,fd=%d \n", comm, tid, probe, arg0, $fd);
       printf("%s\n", ustack(40));
}

/*
Monitor FilterManagerImpl::on*()
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*FilterManagerImpl*on*
/pid == $1 && @fdFired[tid]/ 
{ 
       if( @upFD[@fdFired[tid]] ) {
              return;
       }

       $fd = @fdFired[tid];
       @filterManagerImpl2fd[arg0] = $fd;
       if( @fd2filterManagerImpl[$fd] ) {
              @fd2filterManagerImpl2[$fd] = arg0;
       } else {
              @fd2filterManagerImpl[$fd] = arg0;
       }
       printf("comm:%s,tid:%d: FilterManagerImpl.on*::%s,FilterManagerImpl.this=%p,fd=%d \n", comm, tid, probe, arg0, $fd); 
}

/*
Monitor ConnPoolImplBase::attachStreamToClient()
*/
uprobe:/proc/${ENVOY_PID}/root/usr/local/bin/envoy:*ConnPoolImplBase*attachStreamToClient*
/pid == $1 && @fdFired[tid]/ 
{ 
       printf("comm:%s,tid:%d: ConnPoolImplBase*attachStreamToClient: %s \n", comm, tid, probe); 
       printf("%s\n", ustack(40));
}

/*
Monitor socket connect upstream
*/
kprobe:tcp_connect
/pid == $1/
{
       $sk = ((struct sock *)arg0);
       $inet_family = $sk->__sk_common.skc_family;

       if ($inet_family == AF_INET || $inet_family == AF_INET6)
       {
              if ($inet_family == AF_INET)
              {
                     $daddr = ntop($sk->__sk_common.skc_daddr);
                     $saddr = ntop($sk->__sk_common.skc_rcv_saddr);
              }
              else
              {
                     $daddr = ntop($sk->__sk_common.skc_v6_daddr.in6_u.u6_addr8);
                     $saddr = ntop($sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr8);
              }
              $lport = $sk->__sk_common.skc_num;
              $dport = $sk->__sk_common.skc_dport;

              // Destination port is big endian, it must be flipped
              $dport = ($dport >> 8) | (($dport << 8) & 0x00FF00);

              // only watch listen port 8080
              if (8080 != $dport)
              {
                     return;
              }

              printf("connecting to 8080:\n");
              time("%H:%M:%S ");
              printf("%-8d %-16s ", pid, comm);
              printf("%-39s %-6d %-39s %-6d\n", $saddr, $lport, $daddr, $dport);
              printf("%s\n", ustack(40));
       }
}


/*
Monitor FD close. Clear up the related BPF map.
cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_close/format
*/
tracepoint:syscalls:sys_enter_close
/pid==$1/
{
	$fd = args->fd;
	if( $fd < 0 ) {
		return;
	}

       delete(@upFD[$fd]);

       if( @fd2sockpair[$fd].0 ) {
              printf("sys_enter_close fd=%d\n", $fd);
       }
       else {
              return;
       }
	delete(@fd2sockpair[$fd]);

       /////

       $filterManagerImpl = @fd2filterManagerImpl[$fd];
       if( $filterManagerImpl ) {
              printf("delete fd2filterManagerImpl, fd=%d\n", $fd );
              delete( @fd2filterManagerImpl[$fd] );
       }

       if( @filterManagerImpl2fd[$filterManagerImpl] ) {
              printf("delete fd2filterManagerImpl=%p\n", $filterManagerImpl );
              delete(@filterManagerImpl2fd[$filterManagerImpl]);
       }


       $filterManagerImpl = @fd2filterManagerImpl2[$fd];
       if( $filterManagerImpl ) {
              printf("delete fd2filterManagerImpl, fd=%d\n", $fd );
              delete( @fd2filterManagerImpl2[$fd] );
       }

       if( @filterManagerImpl2fd[$filterManagerImpl] ) {
              printf("delete fd2filterManagerImpl=%p\n", $filterManagerImpl );
              delete(@filterManagerImpl2fd[$filterManagerImpl]);
       }

       delete(@upFD[@downFD2upFD[$fd]]);
       delete(@downFD2upFD[$fd]);
}

END
{
       clear(@last_epoll_wait_args);
       clear(@tid2Waketime);
       clear(@tid2epollNrFdReady);
}

End

This part, from a socket event-driven perspective, study the main process of Envoy as a reverse proxy. I think I learned something, How about you?

ending
This is an old photo taken a few years ago.