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V8 Thread Demo
Raw
multi-thread.js
start(() => {
while(true)
{
print("a");
sleep(1000);
}
})
while(true)
{
print("b");
sleep(1000);
}
Raw
v8-multi-thread.cpp
// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <v8.h>
#include <libplatform/libplatform.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <chrono>
#include <thread>
#include <iostream>
/**
* This sample program shows how to implement a simple javascript shell
* based on V8. This includes initializing V8 with command line options,
* creating global functions, compiling and executing strings.
*
* For a more sophisticated shell, consider using the debug shell D8.
*/
v8::Local<v8::Context> CreateShellContext(v8::Isolate *isolate);
void RunShell(v8::Local<v8::Context> context, v8::Platform *platform);
int RunMain(v8::Isolate *isolate, v8::Platform *platform, int argc,
char *argv[]);
bool ExecuteString(v8::Isolate *isolate, v8::Local<v8::String> source,
v8::Local<v8::Value> name, bool print_result,
bool report_exceptions);
void Print(const v8::FunctionCallbackInfo<v8::Value> &args);
void Read(const v8::FunctionCallbackInfo<v8::Value> &args);
void Load(const v8::FunctionCallbackInfo<v8::Value> &args);
void Quit(const v8::FunctionCallbackInfo<v8::Value> &args);
void Version(const v8::FunctionCallbackInfo<v8::Value> &args);
v8::MaybeLocal<v8::String> ReadFile(v8::Isolate *isolate, const char *name);
void ReportException(v8::Isolate *isolate, v8::TryCatch *handler);
void Start(const v8::FunctionCallbackInfo<v8::Value> &args);
void Sleep(const v8::FunctionCallbackInfo<v8::Value> &args);
v8::Global<v8::Context> g_context;
v8::Isolate *isolate = nullptr;
static bool run_shell;
int main(int argc, char *argv[])
{
v8::V8::InitializeICUDefaultLocation(argv[0]);
v8::V8::InitializeExternalStartupData(argv[0]);
v8::Platform *platform = v8::platform::CreateDefaultPlatform();
v8::V8::InitializePlatform(platform);
v8::V8::Initialize();
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator =
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
isolate = v8::Isolate::New(create_params);
run_shell = (argc == 1);
int result;
{
v8::Locker locker(isolate);
v8::Isolate::Scope isolate_scope(isolate);
v8::HandleScope handle_scope(isolate);
v8::Local<v8::Context> context = CreateShellContext(isolate);
g_context.Reset(isolate, context);
if (context.IsEmpty())
{
fprintf(stderr, "Error creating context\n");
return 1;
}
v8::Context::Scope context_scope(context);
result = RunMain(isolate, platform, argc, argv);
if (run_shell)
RunShell(context, platform);
}
isolate->Dispose();
v8::V8::Dispose();
v8::V8::ShutdownPlatform();
delete platform;
delete create_params.array_buffer_allocator;
return result;
}
// Extracts a C string from a V8 Utf8Value.
const char *ToCString(const v8::String::Utf8Value &value)
{
return *value ? *value : "<string conversion failed>";
}
// Creates a new execution environment containing the built-in
// functions.
v8::Local<v8::Context> CreateShellContext(v8::Isolate *isolate)
{
// Create a template for the global object.
v8::Local<v8::ObjectTemplate> global = v8::ObjectTemplate::New(isolate);
// Bind the global 'print' function to the C++ Print callback.
global->Set(
v8::String::NewFromUtf8(isolate, "print", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Print));
// Bind the global 'read' function to the C++ Read callback.
global->Set(v8::String::NewFromUtf8(
isolate, "read", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Read));
// Bind the global 'load' function to the C++ Load callback.
global->Set(v8::String::NewFromUtf8(
isolate, "load", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Load));
// Bind the 'quit' function
global->Set(v8::String::NewFromUtf8(
isolate, "quit", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Quit));
// Bind the 'version' function
global->Set(
v8::String::NewFromUtf8(isolate, "version", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Version));
// Bind the 'sleep' function
global->Set(
v8::String::NewFromUtf8(isolate, "sleep", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Sleep));
// Bind the 'start' function
global->Set(
v8::String::NewFromUtf8(isolate, "start", v8::NewStringType::kNormal)
.ToLocalChecked(),
v8::FunctionTemplate::New(isolate, Start));
return v8::Context::New(isolate, NULL, global);
}
// The callback that is invoked by v8 whenever the JavaScript 'print'
// function is called. Prints its arguments on stdout separated by
// spaces and ending with a newline.
void Print(const v8::FunctionCallbackInfo<v8::Value> &args)
{
bool first = true;
for (int i = 0; i < args.Length(); i++)
{
v8::HandleScope handle_scope(args.GetIsolate());
if (first)
{
first = false;
}
else
{
printf(" ");
}
v8::String::Utf8Value str(args.GetIsolate(), args[i]);
const char *cstr = ToCString(str);
printf("%s", cstr);
}
printf("\n");
fflush(stdout);
}
// The callback that is invoked by v8 whenever the JavaScript 'read'
// function is called. This function loads the content of the file named in
// the argument into a JavaScript string.
void Read(const v8::FunctionCallbackInfo<v8::Value> &args)
{
if (args.Length() != 1)
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Bad parameters",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
v8::String::Utf8Value file(args.GetIsolate(), args[0]);
if (*file == NULL)
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
v8::Local<v8::String> source;
if (!ReadFile(args.GetIsolate(), *file).ToLocal(&source))
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
args.GetReturnValue().Set(source);
}
// The callback that is invoked by v8 whenever the JavaScript 'load'
// function is called. Loads, compiles and executes its argument
// JavaScript file.
void Load(const v8::FunctionCallbackInfo<v8::Value> &args)
{
for (int i = 0; i < args.Length(); i++)
{
v8::HandleScope handle_scope(args.GetIsolate());
v8::String::Utf8Value file(args.GetIsolate(), args[i]);
if (*file == NULL)
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
v8::Local<v8::String> source;
if (!ReadFile(args.GetIsolate(), *file).ToLocal(&source))
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error loading file",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
if (!ExecuteString(args.GetIsolate(), source, args[i], false, false))
{
args.GetIsolate()->ThrowException(
v8::String::NewFromUtf8(args.GetIsolate(), "Error executing file",
v8::NewStringType::kNormal)
.ToLocalChecked());
return;
}
}
}
// The callback that is invoked by v8 whenever the JavaScript 'quit'
// function is called. Quits.
void Quit(const v8::FunctionCallbackInfo<v8::Value> &args)
{
// If not arguments are given args[0] will yield undefined which
// converts to the integer value 0.
int exit_code =
args[0]->Int32Value(args.GetIsolate()->GetCurrentContext()).FromMaybe(0);
fflush(stdout);
fflush(stderr);
exit(exit_code);
}
void Version(const v8::FunctionCallbackInfo<v8::Value> &args)
{
args.GetReturnValue().Set(
v8::String::NewFromUtf8(args.GetIsolate(), v8::V8::GetVersion(),
v8::NewStringType::kNormal)
.ToLocalChecked());
}
// Reads a file into a v8 string.
v8::MaybeLocal<v8::String> ReadFile(v8::Isolate *isolate, const char *name)
{
FILE *file = fopen(name, "rb");
if (file == NULL)
return v8::MaybeLocal<v8::String>();
fseek(file, 0, SEEK_END);
size_t size = ftell(file);
rewind(file);
char *chars = new char[size + 1];
chars[size] = '\0';
for (size_t i = 0; i < size;)
{
i += fread(&chars[i], 1, size - i, file);
if (ferror(file))
{
fclose(file);
return v8::MaybeLocal<v8::String>();
}
}
fclose(file);
v8::MaybeLocal<v8::String> result = v8::String::NewFromUtf8(
isolate, chars, v8::NewStringType::kNormal, static_cast<int>(size));
delete[] chars;
return result;
}
// Process remaining command line arguments and execute files
int RunMain(v8::Isolate *isolate, v8::Platform *platform, int argc,
char *argv[])
{
for (int i = 1; i < argc; i++)
{
const char *str = argv[i];
if (strcmp(str, "--shell") == 0)
{
run_shell = true;
}
else if (strcmp(str, "-f") == 0)
{
// Ignore any -f flags for compatibility with the other stand-
// alone JavaScript engines.
continue;
}
else if (strncmp(str, "--", 2) == 0)
{
fprintf(stderr,
"Warning: unknown flag %s.\nTry --help for options\n", str);
}
else if (strcmp(str, "-e") == 0 && i + 1 < argc)
{
// Execute argument given to -e option directly.
v8::Local<v8::String> file_name =
v8::String::NewFromUtf8(isolate, "unnamed",
v8::NewStringType::kNormal)
.ToLocalChecked();
v8::Local<v8::String> source;
if (!v8::String::NewFromUtf8(isolate, argv[++i],
v8::NewStringType::kNormal)
.ToLocal(&source))
{
return 1;
}
bool success = ExecuteString(isolate, source, file_name, false, true);
while (v8::platform::PumpMessageLoop(platform, isolate))
continue;
if (!success)
return 1;
}
else
{
// Use all other arguments as names of files to load and run.
v8::Local<v8::String> file_name =
v8::String::NewFromUtf8(isolate, str, v8::NewStringType::kNormal)
.ToLocalChecked();
v8::Local<v8::String> source;
if (!ReadFile(isolate, str).ToLocal(&source))
{
fprintf(stderr, "Error reading '%s'\n", str);
continue;
}
bool success = ExecuteString(isolate, source, file_name, false, true);
while (v8::platform::PumpMessageLoop(platform, isolate))
continue;
if (!success)
return 1;
}
}
return 0;
}
// The read-eval-execute loop of the shell.
void RunShell(v8::Local<v8::Context> context, v8::Platform *platform)
{
fprintf(stderr, "V8 version %s [sample shell]\n", v8::V8::GetVersion());
static const int kBufferSize = 256;
// Enter the execution environment before evaluating any code.
v8::Context::Scope context_scope(context);
v8::Local<v8::String> name(
v8::String::NewFromUtf8(context->GetIsolate(), "(shell)",
v8::NewStringType::kNormal)
.ToLocalChecked());
while (true)
{
char buffer[kBufferSize];
fprintf(stderr, "> ");
char *str = fgets(buffer, kBufferSize, stdin);
if (str == NULL)
break;
v8::HandleScope handle_scope(context->GetIsolate());
ExecuteString(
context->GetIsolate(),
v8::String::NewFromUtf8(context->GetIsolate(), str,
v8::NewStringType::kNormal)
.ToLocalChecked(),
name, true, true);
while (v8::platform::PumpMessageLoop(platform, context->GetIsolate()))
continue;
}
fprintf(stderr, "\n");
}
// Executes a string within the current v8 context.
bool ExecuteString(v8::Isolate *isolate, v8::Local<v8::String> source,
v8::Local<v8::Value> name, bool print_result,
bool report_exceptions)
{
v8::HandleScope handle_scope(isolate);
v8::TryCatch try_catch(isolate);
v8::ScriptOrigin origin(name);
v8::Local<v8::Context> context(isolate->GetCurrentContext());
v8::Local<v8::Script> script;
if (!v8::Script::Compile(context, source, &origin).ToLocal(&script))
{
// Print errors that happened during compilation.
if (report_exceptions)
ReportException(isolate, &try_catch);
return false;
}
else
{
v8::Local<v8::Value> result;
if (!script->Run(context).ToLocal(&result))
{
assert(try_catch.HasCaught());
// Print errors that happened during execution.
if (report_exceptions)
ReportException(isolate, &try_catch);
return false;
}
else
{
assert(!try_catch.HasCaught());
if (print_result && !result->IsUndefined())
{
// If all went well and the result wasn't undefined then print
// the returned value.
v8::String::Utf8Value str(isolate, result);
const char *cstr = ToCString(str);
printf("%s\n", cstr);
}
return true;
}
}
}
void ReportException(v8::Isolate *isolate, v8::TryCatch *try_catch)
{
v8::HandleScope handle_scope(isolate);
v8::String::Utf8Value exception(isolate, try_catch->Exception());
const char *exception_string = ToCString(exception);
v8::Local<v8::Message> message = try_catch->Message();
if (message.IsEmpty())
{
// V8 didn't provide any extra information about this error; just
// print the exception.
fprintf(stderr, "%s\n", exception_string);
}
else
{
// Print (filename):(line number): (message).
v8::String::Utf8Value filename(isolate,
message->GetScriptOrigin().ResourceName());
v8::Local<v8::Context> context(isolate->GetCurrentContext());
const char *filename_string = ToCString(filename);
int linenum = message->GetLineNumber(context).FromJust();
fprintf(stderr, "%s:%i: %s\n", filename_string, linenum, exception_string);
// Print line of source code.
v8::String::Utf8Value sourceline(
isolate, message->GetSourceLine(context).ToLocalChecked());
const char *sourceline_string = ToCString(sourceline);
fprintf(stderr, "%s\n", sourceline_string);
// Print wavy underline (GetUnderline is deprecated).
int start = message->GetStartColumn(context).FromJust();
for (int i = 0; i < start; i++)
{
fprintf(stderr, " ");
}
int end = message->GetEndColumn(context).FromJust();
for (int i = start; i < end; i++)
{
fprintf(stderr, "^");
}
fprintf(stderr, "\n");
v8::Local<v8::Value> stack_trace_string;
if (try_catch->StackTrace(context).ToLocal(&stack_trace_string) &&
stack_trace_string->IsString() &&
v8::Local<v8::String>::Cast(stack_trace_string)->Length() > 0)
{
v8::String::Utf8Value stack_trace(isolate, stack_trace_string);
const char *stack_trace_string = ToCString(stack_trace);
fprintf(stderr, "%s\n", stack_trace_string);
}
}
}
void Sleep(const v8::FunctionCallbackInfo<v8::Value> &args)
{
// std::cout << "Sleep 0" << std::endl;
v8::Unlocker unlocker(isolate);
// std::cout << "Sleep 1" << std::endl;
v8::Local<v8::Context> context = v8::Local<v8::Context>::New(isolate, g_context);
// std::cout << "Sleep 2" << std::endl;
int time = args[0]->Int32Value(context).FromMaybe(0);
std::this_thread::sleep_for(std::chrono::milliseconds(time));
// std::cout << "Sleep 3" << std::endl;
}
void do_work(v8::Global<v8::Function> func)
{
// std::cout << "do_work 0" << std::endl;
v8::Locker locker(isolate);
// std::cout << "do_work 1" << std::endl;
v8::Isolate::Scope isolate_scope(isolate);
// std::cout << "do_work 2" << std::endl;
v8::HandleScope handle_scope(isolate);
// std::cout << "do_work 3" << std::endl;
v8::Local<v8::Context> context = v8::Local<v8::Context>::New(isolate, g_context);
v8::Context::Scope context_scope(
v8::Local<v8::Context>::New(isolate, context));
// std::cout << "do_work 4" << std::endl;
v8::Local<v8::Function> fn = v8::Local<v8::Function>::New(isolate, func);
// std::cout << "do_work 5" << std::endl;
v8::Local<v8::Value> v = fn->Call(v8::Undefined(isolate), 0, NULL);
// std::cout << "do_work 6" << std::endl;
}
void Start(const v8::FunctionCallbackInfo<v8::Value> &args)
{
// std::cout << "Start start" << std::endl;
v8::Global<v8::Function> fn;
v8::Local<v8::Function> f = v8::Local<v8::Function>::Cast(args[0]);
fn.Reset(isolate, f);
std::thread new_thread(do_work, std::move(fn));
new_thread.detach();
// std::cout << "Start end" << std::endl;
}
@samuelastech
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Thanks @ErickWendel!

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