Seems you've managed to make a communication between CDT and your server. I
also checked `sockpp` which does not support websocket protocol out of box.
Probably, you should implement all required parts yourself.
I'm using Google Groups old UI which allows me to add image to the post,
it's next to the `Link`:
[image: Screenshot from 2020-08-20 21-58-22.png] <about:invalid#zClosurez>
But I also couldn't find it in the new UI, if you're using the new UI you
can switch back to the old UI, click settings (gear icon) at the top of the
page and click "Return to classic Google Groups", then you can attach an
image.
On Thursday, August 20, 2020 at 1:54:43 PM UTC+2, Immanuel Haffner wrote:
>
> Hi Elmi,
>
> thank you for checking. My biggest mistage was to write directly to a
> socket rather than use the WebSocket protocol. After doing so, i now see
> some messages in CDT. However, there are only 8 green and one last red
> message. I suppose the last message wasn't sent in full. The second last
> message was "Runtime.runIfWaitingForDebugger". There is no
> `Debugger.scriptExecuted` message, though.
>
> Checking V8 code I couldn't find `schedulePauseOnNextStatement`, who is
> invoking that?
>
> How do I attach an image to a Google Groups post?
>
> Elmi Ahmadov schrieb am Donnerstag, 20. August 2020 um 11:59:17 UTC+2:
>
>> I checked your code and you're missing
>> `runMessageLoopOnMessage`/`quitMessageLoopOnPause` and
>> `schedulePauseOnNextStatement` (this could be redundant), but in general,
>> these methods are necessary. in `runMessageLoopOnPause` method, you should
>> block the thread until there is a new message from CDT, in case there is a
>> breakpoint and CDT requires user action.
>> Maybe your code does not wait for a user action and execution is done
>> very quickly.
>>
>> Could you please post WS messages from CDT Network monitor tab? There
>> should be such response messages: *`Debugger.scriptExecuted`* and
>> *`Debugger.paused`*.
>> And one important thing is you have to execute your code after you got a
>> *`**Runtime.runIfWaitingForDebugger` *message from CDT.
>>
>>
>> On Thursday, August 20, 2020 at 10:36:30 AM UTC+2 haffner....@gmail.com
>> wrote:
>>
>>> Ok, I figured the cause for the segmentation violation. I must dispose
>>> of the inspector and the session and channel before disposing of the
>>> isolate. I am still left with "WebSocket disconnected". The CDT Network
>>> monitor says "Connection closed before receiving a handshake response".
>>> Maybe I did something wrong establishing a TCP connection?
>>>
>>> Immanuel Haffner schrieb am Donnerstag, 20. August 2020 um 10:07:27
>>> UTC+2:
>>>
>>>>
>>>> Hi again,
>>>>
>>>> I figured that the `chome-devtools://` part doesn't work in Chromium.
>>>> Using `devtools://` instead works. However, I get a segmentation
>>>> violation.
>>>>
>>>> Here is the code I wrote to connect the V8 inspector:
>>>>
>>>> struct ServerChannel : v8_inspector::V8Inspector::Channel
>>>> {
>>>> private:
>>>> sockpp::tcp_socket *socket_;
>>>>
>>>> public:
>>>> ServerChannel() { }
>>>>
>>>> void set_socket(sockpp::tcp_socket *socket) { socket_ = socket;
>>>> }
>>>>
>>>> private:
>>>> void sendResponse(int,
>>>> std::unique_ptr<v8_inspector::StringBuffer> message) override {
>>>> auto v8_sv = message->string();
>>>> socket_->write_n(v8_sv.characters8(), v8_sv.length());
>>>> }
>>>>
>>>> void
>>>> sendNotification(std::unique_ptr<v8_inspector::StringBuffer> message)
>>>> override {
>>>> auto v8_sv = message->string();
>>>> socket_->write_n(v8_sv.characters8(), v8_sv.length());
>>>> }
>>>>
>>>> void flushProtocolNotifications() override { }
>>>> };
>>>>
>>>> struct MyV8InspectorClient : v8_inspector::V8InspectorClient
>>>> {
>>>> private:
>>>> sockpp::tcp_acceptor acceptor_;
>>>> std::unique_ptr<ServerChannel> channel_;
>>>> std::unique_ptr<v8_inspector::V8Inspector> inspector_;
>>>> std::unique_ptr<v8_inspector::V8InspectorSession> session_;
>>>> int16_t port_;
>>>>
>>>> public:
>>>> MyV8InspectorClient(int16_t port, v8::Isolate *isolate)
>>>> : acceptor_(port)
>>>> , port_(port)
>>>> {
>>>> if (not acceptor_)
>>>> throw std::runtime_error("failed to initalize TCP
>>>> server");
>>>>
>>>> channel_ = std::make_unique<ServerChannel>();
>>>> inspector_ = v8_inspector::V8Inspector::create(isolate,
>>>> this);
>>>>
>>>> std::string state("mutable");
>>>> v8_inspector::StringView sv(reinterpret_cast<const
>>>> uint8_t*>(state.c_str()), state.length());
>>>> session_ = inspector_->connect(
>>>> /* contextGroupId= */ 1,
>>>> /* channel= */ channel_.get(),
>>>> /* state= */ sv
>>>> );
>>>> }
>>>>
>>>> MyV8InspectorClient(const MyV8InspectorClient&) = delete;
>>>> MyV8InspectorClient(MyV8InspectorClient&&) = default;
>>>>
>>>> ~MyV8InspectorClient() {
>>>> session_.reset();
>>>> inspector_.reset();
>>>> channel_.reset();
>>>> }
>>>>
>>>> void onMessage(std::string_view sv) {
>>>> v8_inspector::StringView msg(reinterpret_cast<const
>>>> uint8_t*>(sv.data()), sv.length());
>>>> session_->dispatchProtocolMessage(msg);
>>>> }
>>>>
>>>> void launch() {
>>>> std::cout << "WebSocket based Inspector Agent started.\n"
>>>> << "Open the following link in your
>>>> Chrome/Chromium browser:\n\n\t"
>>>> <<
>>>> "devtools://devtools/bundled/inspector.html?experiments=true&v8only=true&ws=
>>>> 127.0.0.1:" << port_
>>>> << '\n' << std::endl;
>>>>
>>>> auto socket =
>>>> std::make_unique<sockpp::tcp_socket>(acceptor_.accept());
>>>> if (not *socket)
>>>> throw std::runtime_error("failed to establish
>>>> connection to TCP client");
>>>> channel_->set_socket(socket.get());
>>>>
>>>> auto thread =
>>>> std::thread([this](std::unique_ptr<sockpp::tcp_socket> socket) {
>>>> uint8_t buf[512];
>>>> std::vector<uint8_t> msg;
>>>> msg.reserve(512);
>>>> std::size_t n;
>>>>
>>>> for (;;) {
>>>> std::cerr << "receiving bytes..." << std::endl;
>>>> while ((n = socket->read_n(buf, ARR_SIZE(buf))) > 0)
>>>> msg.insert(msg.end(), buf, buf + n); // append
>>>> recently read bytes to msg
>>>> if (not msg.empty()) {
>>>> std::cerr << "the received message is " <<
>>>> msg.size() << " bytes" << std::endl;
>>>> std::string_view
>>>> sv(reinterpret_cast<char*>(&msg[0]), msg.size());
>>>> this->onMessage(sv);
>>>> msg.clear();
>>>> }
>>>> std::this_thread::yield();
>>>> }
>>>> },
>>>> std::move(socket));
>>>> thread.detach();
>>>> }
>>>> };
>>>>
>>>> It's mostly taken from your example and condensed into a single class.
>>>> Instead of boost, I use sockpp for socket programming.i
>>>>
>>>> After creating a `v8::Isolate`, I do the following:
>>>>
>>>> inspector_ = std::make_unique<MyV8InspectorClient>(cdt_port,
>>>> isolate_);
>>>> inspector_->launch();
>>>>
>>>> However, when connecting to the inspector it says "WebSocket
>>>> disconnected" and the application crashes with a segmentation violation:
>>>>
>>>> AddressSanitizer:DEADLYSIGNAL
>>>> =================================================================
>>>> ==13072==ERROR: AddressSanitizer: SEGV on unknown address
>>>> 0x1d580000a838 (pc 0x561c8173e6b4 bp 0x7fff75fa6430 sp 0x7fff75fa6430 T0)
>>>> ==13072==The signal is caused by a READ memory access.
>>>> #0 0x561c8173e6b4 in v8::Isolate::GetHeapProfiler()
>>>> ../../../../../third-party/v8/v8/src/execution/isolate.h:1059:48
>>>> #1 0x561c82d3fd77 in
>>>> v8_inspector::V8HeapProfilerAgentImpl::stopTrackingHeapObjectsInternal()
>>>> ../../../../../third-party/v8/v8/src/inspector/v8-heap-profiler-agent-impl.cc:316:14
>>>> #2 0x561c82d3feb9 in
>>>> v8_inspector::V8HeapProfilerAgentImpl::disable()
>>>> ../../../../../third-party/v8/v8/src/inspector/v8-heap-profiler-agent-impl.cc:204:3
>>>> #3 0x561c8208f095 in
>>>> v8_inspector::V8InspectorSessionImpl::~V8InspectorSessionImpl()
>>>> ../../../../../third-party/v8/v8/src/inspector/v8-inspector-session-impl.cc:151:24
>>>> #4 0x561c8208f33d in
>>>> v8_inspector::V8InspectorSessionImpl::~V8InspectorSessionImpl()
>>>> ../../../../../third-party/v8/v8/src/inspector/v8-inspector-session-impl.cc:147:51
>>>> #5 0x561c80ec9eff in
>>>> std::default_delete<v8_inspector::V8InspectorSession>::operator()(v8_inspector::V8InspectorSession*)
>>>>
>>>> const
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:84:2
>>>> #6 0x561c80ec9d3e in
>>>> std::__uniq_ptr_impl<v8_inspector::V8InspectorSession,
>>>> std::default_delete<v8_inspector::V8InspectorSession>
>>>> >::reset(v8_inspector::V8InspectorSession*)
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:181:4
>>>> #7 0x561c80eca183 in
>>>> std::unique_ptr<v8_inspector::V8InspectorSession,
>>>> std::default_delete<v8_inspector::V8InspectorSession>
>>>> >::reset(v8_inspector::V8InspectorSession*)
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:455:7
>>>> #8 0x561c80ec7193 in
>>>> db::v8_helper::MyV8InspectorClient::~MyV8InspectorClient()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.hpp:74:18
>>>> #9 0x561c80ec723b in
>>>> db::v8_helper::MyV8InspectorClient::~MyV8InspectorClient()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.hpp:73:28
>>>> #10 0x561c80eb361f in
>>>> std::default_delete<db::v8_helper::MyV8InspectorClient>::operator()(db::v8_helper::MyV8InspectorClient*)
>>>>
>>>> const
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:84:2
>>>> #11 0x561c80eaede6 in
>>>> std::unique_ptr<db::v8_helper::MyV8InspectorClient,
>>>> std::default_delete<db::v8_helper::MyV8InspectorClient> >::~unique_ptr()
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:360:4
>>>> #12 0x561c80ea6e97 in db::V8Platform::~V8Platform()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.cpp:221:1
>>>> #13 0x561c80ea6f2b in db::V8Platform::~V8Platform()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.cpp:218:1
>>>> #14 0x561c80e9ea3f in
>>>> std::default_delete<db::WasmPlatform>::operator()(db::WasmPlatform*) const
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:84:2
>>>> #15 0x561c80e9e8f6 in std::unique_ptr<db::WasmPlatform,
>>>> std::default_delete<db::WasmPlatform> >::~unique_ptr()
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:360:4
>>>> #16 0x561c80e8efbd in db::WasmBackend::~WasmBackend()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/WebAssembly.hpp:110:8
>>>> #17 0x561c80e8efeb in db::WasmBackend::~WasmBackend()
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/WebAssembly.hpp:110:8
>>>> #18 0x561c80ccf1ff in
>>>> std::default_delete<db::Backend>::operator()(db::Backend*) const
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:84:2
>>>> #19 0x561c80ca8b16 in std::unique_ptr<db::Backend,
>>>> std::default_delete<db::Backend> >::~unique_ptr()
>>>> /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:360:4
>>>> #20 0x561c80c86dd9 in process_stream(std::istream&, char
>>>> const*, db::Diagnostic)
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/shell.cpp:151:13
>>>> #21 0x561c80c9a265 in main
>>>> /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/shell.cpp:675:13
>>>> #22 0x7f6259a37001 in __libc_start_main
>>>> (/usr/lib/libc.so.6+0x27001)
>>>> #23 0x561c80ba722d in _start
>>>> (/home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/bin/shell+0x117222d)
>>>>
>>>> AddressSanitizer can not provide additional info.
>>>> SUMMARY: AddressSanitizer: SEGV
>>>> ../../../../../third-party/v8/v8/src/execution/isolate.h:1059:48 in
>>>> v8::Isolate::GetHeapProfiler()
>>>>
>>>> Can you spot what's going wrong? I did not override
>>>> `V8InspectorClientImpl::runMessageLoopOnPause` like you did. Is this
>>>> necessary?
>>>>
>>>> Kind regards,
>>>> Immanuel
>>>> Elmi Ahmadov schrieb am Mittwoch, 19. August 2020 um 21:40:58 UTC+2:
>>>>
>>>>> Dear Immanuel,
>>>>>
>>>>> You've got the right idea from my example code. You need a websocket
>>>>> to create a communication channel between V8 Inspector and CDT.
>>>>> The URL to debug the code is usually as follows and it works for me.
>>>>>
>>>>> devtools:
>>>>> //devtools/bundled/inspector.html?experiments=true&v8only=true&ws=IP:WebSocketPort
>>>>>
>>>>> Without a minimal sample code it's difficult to say what you're
>>>>> missing.
>>>>> You can also use Chrome DevTools Network Activity tab (you need to
>>>>> open another Inspector console, see the screenshot), just filter *WS*
>>>>> to see what happens between your server and CDT, which helped me a lot.
>>>>>
>>>>>
>>>>> [image: Screenshot from 2020-08-19 21-37-48.png]
>>>>>
>>>>> There is another Chrome built-in feature that helped me is *Protocol
>>>>> Monitor*, you can here how to enable it:
>>>>> https://chromedevtools.github.io/devtools-protocol/
>>>>>
>>>>> On Wednesday, August 19, 2020 at 4:17:00 PM UTC+2, Immanuel Haffner
>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> Dear Elmi,
>>>>>>
>>>>>> thank you for your reply. I had a long look at your example. To be
>>>>>> honest, I find it a bit bloatet.
>>>>>>
>>>>>> Let me phrase in my own words what I have learned from your code:
>>>>>>
>>>>>> 1) I need a socket to receive messages from CDT and send responses
>>>>>> back to CDT.
>>>>>> 2) I must implement `v8_inspector::V8Inspector::Channel` to have
>>>>>> `sendResponse()` and `sendNotification()` send the respective message
>>>>>> over
>>>>>> the socket to CDT.
>>>>>> 3) I need an instance of `v8_inspector::V8InspectorClient`. I am not
>>>>>> sure whether I must overwrite anything from this class in a subclass. I
>>>>>> think the base class is actually fine...
>>>>>> 4) I must use `v8_inspector::V8Inspector::create()` to create an
>>>>>> instance of `v8_inspector::V8Inspector`. I believe this is where all the
>>>>>> inspector logic is implemented...
>>>>>> 5) Using the `V8Inspector` instance I create a
>>>>>> `v8_inspector::V8InspectorSession` by calling `connect()`. Here I must
>>>>>> pass
>>>>>> a reference to an instance of my `v8_inspector::V8Inspector::Channel`
>>>>>> subclass.
>>>>>> This was the basic setup. Now it's time to run the server loop.
>>>>>> 6) In a detached thread, read from the socket and pass the message on
>>>>>> by invoking `dispatchProtocolMessage()` on my instance
>>>>>> of `v8_inspector::V8InspectorSession`.
>>>>>>
>>>>>> When running my code, the TCP acceptor is set up and waiting for a
>>>>>> client. I visit `localhost:<PORT>` with Chromium (the chrome-devtool://
>>>>>> links just won't work). Then my application executes the WebAssembly and
>>>>>> the browser says the page isn't working (ERR_EMPTY_RESPONSE).
>>>>>>
>>>>>> What am I missing?
>>>>>> Elmi Ahmadov schrieb am Mittwoch, 19. August 2020 um 10:21:38 UTC+2:
>>>>>>
>>>>>>> Hi.
>>>>>>>
>>>>>>> I have an example project how to use V8 inspector API:
>>>>>>> https://github.com/ahmadov/v8_inspector_example. Hope this would
>>>>>>> help.
>>>>>>>
>>>>>>> Best regards
>>>>>>>
>>>>>>> On Wednesday, August 19, 2020 at 10:11:00 AM UTC+2, Immanuel Haffner
>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> I followed this V8 documentation [1] to embed V8 into my
>>>>>>>> application. The application compiles inputs to WebAssembly modules
>>>>>>>> and
>>>>>>>> executes them in embedded V8. Now I would like to debug these
>>>>>>>> WebAssembly
>>>>>>>> modules. Searching online brought me to ChromeDevTools and the
>>>>>>>> v8-inspector API. I mostly followed this guide [2] to set up a
>>>>>>>> `V8InspectorSession` and implemented the `V8Inspector::Channel`
>>>>>>>> interface
>>>>>>>> by creating a TCP server, waiting for a connection, and then in
>>>>>>>> `sendResponse()` and `sendNotification()` I simply send the message
>>>>>>>> over
>>>>>>>> the TCP socket.
>>>>>>>>
>>>>>>>> To debug, I launch chromium and connect to localhost on the port
>>>>>>>> where the TCP server was created. Sadly, this doesn't work. The
>>>>>>>> `sendResponse()` and `sendNotification()` methods are never invoked.
>>>>>>>>
>>>>>>>> Can someone please point me to a tutorial or give me some guidance?
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Immanuel
>>>>>>>>
>>>>>>>> [1] https://v8.dev/docs/embed
>>>>>>>> [2]
>>>>>>>> https://hyperandroid.com/2020/02/12/v8-inspector-from-an-embedder-standpoint/
>>>>>>>>
>>>>>>>
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