Hi Elmi,
thanks for being quiet for two weeks. I was on vacation. I will investigate
your latest remarks regarding string conversion and the message loop. I
will reply here. Would you be available for a call? Via Discord, Zoom, or
the like...
Regards
Am Mittwoch, 26. August 2020 21:58:31 UTC+2 schrieb Elmi Ahmadov:
>
> Hi Immanuel,
>
> Do you have any progress? Did you solve "Connection is closed" issue?
>
> On Friday, August 21, 2020 at 4:55:19 PM UTC+2, Elmi Ahmadov wrote:
>>
>> There could a few things that influence cut off messages, could you
>> please post how do you convert V8 `StringBuffer` message to a string format
>> that Boost can send to CDT.
>>
>> you have to implement `runMessageLoopOnPause` and
>> `schedulePauseOnNextStatement` methods to stop the execution.
>> If you don't implement your waiting logic in `runMessageLoopOnPause` it
>> will just execute without waiting a user action (I changed my example to
>> see how it behaves).
>>
>> If you have an example WebAssembly source code maybe you can use my
>> example to see how it works.
>> Analyzing the WebSocket messages really helps. I remember that I spend
>> almost one or two weeks to understand how it works.
>>
>> On Friday, August 21, 2020 at 11:56:30 AM UTC+2, Immanuel Haffner wrote:
>>>
>>> Hi Elmi,
>>>
>>> I am using boost web sockets now, just like you do ;) So cut off
>>> messages are not the fault of sockpp. In the "Console" tab of CDT i see an
>>> error
>>>
>>> Connection is closed, can't dispatch pending call
>>>
>>> I suspect that V8 simply finished execution, in which case I stop the
>>> WebSocket server and dispose of the inspector.
>>>
>>> To be precise, I want to debug a function of a WebAssembly module,
>>> called "run". This is how I invoke the function through the V8 API:
>>> /* Get the exports of the created WebAssembly instance. */
>>> auto exports = instance->Get(context,
>>> V8STR("exports")).ToLocalChecked().As<v8::Object>();
>>> auto run = exports->Get(context,
>>> V8STR("run")).ToLocalChecked().As<v8::Function>();
>>>
>>> /* Invoke the exported function `run` of the module. */
>>> args_t args { v8::Int32::New(isolate_, wasm_context.id), };
>>> const uint32_t head_of_heap = run->Call(context, context->Global(), 1,
>>> args).ToLocalChecked().As<v8::Int32>()->Value();
>>>
>>> Now how can I break/pause on entry to that function and inspect it in
>>> CDT? I tried invoking
>>> v8_inspector_session->schedulePauseOnNextStatement(...);
>>> But that did not help...
>>>
>>> I am confused and lost :/
>>> Your help is very appreciated Elmi
>>>
>>> Am Freitag, 21. August 2020 11:06:31 UTC+2 schrieb Elmi Ahmadov:
>>>>
>>>> Hi Immanuel,
>>>>
>>>> Seems the messages that come from V8 instance are cut off, maybe
>>>> because of sockpp. They are also not complete, there should be a response
>>>> for each request but in your case there are only 3 responses.
>>>>
>>>> The logic to wait the V8 instance should be done in
>>>> `runMessageLoopOnPause` method.
>>>> In my example, I'm calling a Boost method to get a new message from
>>>> CDT. So, until there is a new message the V8 instance would wait.
>>>>
>>>> On Friday, August 21, 2020 at 10:10:15 AM UTC+2, Immanuel Haffner wrote:
>>>>>
>>>>> Here is what the network messages in CDT look like:
>>>>>
>>>>> [image: cdt_network.png]
>>>>>
>>>>> I guess the execution doesn't wait for CDT. My WebAssembly function is
>>>>> executed right away and the connection is closed.
>>>>> How do I make my `v8::Isolate` instance wait for commands from CDT?
>>>>>
>>>>> Am Donnerstag, 20. August 2020 22:04:15 UTC+2 schrieb Elmi Ahmadov:
>>>>>>
>>>>>> 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]
>>>>>>
>>>>>>
>>>>>> 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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