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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