Revert D2926896 WebWorkers: Move web worker impl to JSCExecutor

Reviewed By: lexs

Differential Revision: D2982150

fb-gh-sync-id: c75d05988df50b9788608e7c1bf00c4952ccfce1
shipit-source-id: c75d05988df50b9788608e7c1bf00c4952ccfce1
This commit is contained in:
Andy Street 2016-02-26 05:55:56 -08:00 committed by Facebook Github Bot 0
parent 50141f9d3f
commit c32e5fd84f
9 changed files with 312 additions and 229 deletions

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@ -226,18 +226,24 @@ public class CatalystInstanceImpl implements CatalystInstance {
listener.onTransitionToBridgeIdle();
}
}
Systrace.unregisterListener(mTraceListener);
// We can access the Bridge from any thread now because we know either we are on the JS thread
// or the JS thread has finished via ReactQueueConfiguration#destroy()
mBridge.dispose();
}
private void synchronouslyDisposeBridgeOnJSThread() {
final SimpleSettableFuture<Void> bridgeDisposeFuture = new SimpleSettableFuture<>();
mReactQueueConfiguration.getJSQueueThread().runOnQueue(
new Runnable() {
@Override
public void run() {
mBridge.dispose();
bridgeDisposeFuture.set(null);
}
});
new Runnable() {
@Override
public void run() {
mBridge.dispose();
bridgeDisposeFuture.set(null);
}
});
bridgeDisposeFuture.getOrThrow();
}

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@ -30,7 +30,7 @@ public class SimpleSettableFuture<T> implements Future<T> {
* Sets the result. If another thread has called {@link #get}, they will immediately receive the
* value. set or setException must only be called once.
*/
public void set(@Nullable T result) {
public void set(T result) {
checkNotSet();
mResult = result;
mReadyLatch.countDown();

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@ -8,6 +8,7 @@ LOCAL_SRC_FILES := \
Bridge.cpp \
JSCExecutor.cpp \
JSCHelpers.cpp \
JSCWebWorker.cpp \
MethodCall.cpp \
Platform.cpp \
Value.cpp \

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@ -57,6 +57,7 @@ react_library(
'JSCTracing.cpp',
'JSCMemory.cpp',
'JSCLegacyProfiler.cpp',
'JSCWebWorker.cpp',
'Platform.cpp',
],
headers = [
@ -70,6 +71,7 @@ react_library(
'Executor.h',
'JSCExecutor.h',
'JSCHelpers.h',
'JSCWebWorker.h',
'MessageQueueThread.h',
'MethodCall.h',
'JSModulesUnbundle.h',

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@ -3,8 +3,7 @@
#include "JSCExecutor.h"
#include <algorithm>
#include <condition_variable>
#include <mutex>
#include <atomic>
#include <sstream>
#include <string>
#include <glog/logging.h>
@ -91,52 +90,6 @@ JSCExecutor::JSCExecutor(Bridge *bridge, const std::string& cacheDir, const foll
m_deviceCacheDir(cacheDir),
m_messageQueueThread(MessageQueues::getCurrentMessageQueueThread()),
m_jscConfig(jscConfig) {
initOnJSVMThread();
}
JSCExecutor::JSCExecutor(
Bridge *bridge,
int workerId,
JSCExecutor *owner,
const std::string& script,
const std::unordered_map<std::string, std::string>& globalObjAsJSON,
const folly::dynamic& jscConfig) :
m_bridge(bridge),
m_workerId(workerId),
m_owner(owner),
m_deviceCacheDir(owner->m_deviceCacheDir),
m_messageQueueThread(MessageQueues::getCurrentMessageQueueThread()),
m_jscConfig(jscConfig) {
// We post initOnJSVMThread here so that the owner doesn't have to wait for
// initialization on its own thread
m_messageQueueThread->runOnQueue([this, script, globalObjAsJSON] () {
initOnJSVMThread();
installGlobalFunction(m_context, "postMessage", nativePostMessage);
for (auto& it : globalObjAsJSON) {
setGlobalVariable(it.first, it.second);
}
// TODO(9604438): Protect against script does not exist
std::string scriptSrc = WebWorkerUtil::loadScriptFromAssets(script);
// TODO(9994180): Throw on error
loadApplicationScript(scriptSrc, script);
});
}
JSCExecutor::~JSCExecutor() {
*m_isDestroyed = true;
if (m_messageQueueThread->isOnThread()) {
terminateOnJSVMThread();
} else {
m_messageQueueThread->runOnQueueSync([this] () {
terminateOnJSVMThread();
});
}
}
void JSCExecutor::initOnJSVMThread() {
m_context = JSGlobalContextCreateInGroup(nullptr, nullptr);
s_globalContextRefToJSCExecutor[m_context] = this;
installGlobalFunction(m_context, "nativeFlushQueueImmediate", nativeFlushQueueImmediate);
@ -165,20 +118,18 @@ void JSCExecutor::initOnJSVMThread() {
#endif
}
void JSCExecutor::terminateOnJSVMThread() {
// terminateOwnedWebWorker mutates m_ownedWorkers so collect all the workers
// to terminate first
JSCExecutor::~JSCExecutor() {
// terminateWebWorker mutates m_webWorkers so collect all the workers to terminate first
std::vector<int> workerIds;
for (auto& it : m_ownedWorkers) {
workerIds.push_back(it.first);
for (auto it = m_webWorkers.begin(); it != m_webWorkers.end(); it++) {
workerIds.push_back(it->first);
}
for (int workerId : workerIds) {
terminateOwnedWebWorker(workerId);
terminateWebWorker(workerId);
}
s_globalContextRefToJSCExecutor.erase(m_context);
JSGlobalContextRelease(m_context);
m_context = nullptr;
}
void JSCExecutor::loadApplicationScript(
@ -215,10 +166,6 @@ void JSCExecutor::loadApplicationUnbundle(
}
void JSCExecutor::flush() {
if (m_owner != nullptr) {
// Web workers don't support native modules yet
return;
}
// TODO: Make this a first class function instead of evaling. #9317773
std::string calls = executeJSCallWithJSC(m_context, "flushedQueue", std::vector<folly::dynamic>());
m_bridge->callNativeModules(calls, true);
@ -310,114 +257,56 @@ void JSCExecutor::loadModule(uint32_t moduleId) {
evaluateScript(m_context, source, sourceUrl);
}
int JSCExecutor::addWebWorker(
const std::string& script,
JSValueRef workerRef,
JSValueRef globalObjRef) {
static std::atomic_int nextWorkerId(1);
int workerId = nextWorkerId++;
// WebWorker impl
Object globalObj = Value(m_context, globalObjRef).asObject();
auto workerMQT = WebWorkerUtil::createWebWorkerThread(workerId, m_messageQueueThread.get());
std::unique_ptr<JSCExecutor> worker;
workerMQT->runOnQueueSync([this, &worker, &script, &globalObj, workerId] () {
worker.reset(new JSCExecutor(m_bridge, workerId, this, script, globalObj.toJSONMap(), m_jscConfig));
});
Object workerObj = Value(m_context, workerRef).asObject();
workerObj.makeProtected();
m_ownedWorkers.emplace(std::piecewise_construct, std::forward_as_tuple(workerId), std::forward_as_tuple(std::move(worker), std::move(workerObj)));
return workerId;
JSGlobalContextRef JSCExecutor::getContext() {
return m_context;
}
void JSCExecutor::postMessageToOwnedWebWorker(int workerId, JSValueRef message, JSValueRef *exn) {
auto worker = m_ownedWorkers.at(workerId).getExecutor();
std::string msgString = Value(m_context, message).toJSONString();
std::shared_ptr<bool> isWorkerDestroyed = worker->m_isDestroyed;
worker->m_messageQueueThread->runOnQueue([isWorkerDestroyed, worker, msgString] () {
if (*isWorkerDestroyed) {
return;
}
worker->receiveMessageFromOwner(msgString);
});
std::shared_ptr<MessageQueueThread> JSCExecutor::getMessageQueueThread() {
return m_messageQueueThread;
}
void JSCExecutor::postMessageToOwner(JSValueRef msg) {
std::string msgString = Value(m_context, msg).toJSONString();
std::shared_ptr<bool> ownerIsDestroyed = m_owner->m_isDestroyed;
m_owner->m_messageQueueThread->runOnQueue([workerId=m_workerId, owner=m_owner, ownerIsDestroyed, msgString] () {
if (*ownerIsDestroyed) {
return;
}
owner->receiveMessageFromOwnedWebWorker(workerId, msgString);
});
}
void JSCExecutor::onMessageReceived(int workerId, const std::string& json) {
Object& worker = m_webWorkerJSObjs.at(workerId);
void JSCExecutor::receiveMessageFromOwnedWebWorker(int workerId, const std::string& json) {
Object* workerObj;
try {
workerObj = &m_ownedWorkers.at(workerId).jsObj;
} catch (std::out_of_range& e) {
// Worker was already terminated
return;
}
Value onmessageValue = workerObj->getProperty("onmessage");
Value onmessageValue = worker.getProperty("onmessage");
if (onmessageValue.isUndefined()) {
return;
}
JSValueRef args[] = { createMessageObject(json) };
JSValueRef args[] = { JSCWebWorker::createMessageObject(m_context, json) };
onmessageValue.asObject().callAsFunction(1, args);
flush();
}
void JSCExecutor::receiveMessageFromOwner(const std::string& msgString) {
CHECK(m_owner) << "Received message in a Executor that doesn't have an owner!";
int JSCExecutor::addWebWorker(const std::string& script, JSValueRef workerRef) {
static std::atomic_int nextWorkerId(0);
int workerId = nextWorkerId++;
JSValueRef args[] = { createMessageObject(msgString) };
Value onmessageValue = Object::getGlobalObject(m_context).getProperty("onmessage");
onmessageValue.asObject().callAsFunction(1, args);
m_webWorkers.emplace(std::piecewise_construct, std::forward_as_tuple(workerId), std::forward_as_tuple(workerId, this, script));
Object workerObj = Value(m_context, workerRef).asObject();
workerObj.makeProtected();
m_webWorkerJSObjs.emplace(workerId, std::move(workerObj));
return workerId;
}
void JSCExecutor::terminateOwnedWebWorker(int workerId) {
auto worker = m_ownedWorkers.at(workerId).getExecutor();
std::shared_ptr<MessageQueueThread> workerMQT = worker->m_messageQueueThread;
m_ownedWorkers.erase(workerId);
workerMQT->quitSynchronous();
void JSCExecutor::postMessageToWebWorker(int workerId, JSValueRef message, JSValueRef *exn) {
JSCWebWorker& worker = m_webWorkers.at(workerId);
worker.postMessage(message);
}
Object JSCExecutor::createMessageObject(const std::string& msgJson) {
Value rebornJSMsg = Value::fromJSON(m_context, String(msgJson.c_str()));
Object messageObject = Object::create(m_context);
messageObject.setProperty("data", rebornJSMsg);
return messageObject;
void JSCExecutor::terminateWebWorker(int workerId) {
JSCWebWorker& worker = m_webWorkers.at(workerId);
worker.terminate();
m_webWorkers.erase(workerId);
m_webWorkerJSObjs.erase(workerId);
}
// Native JS hooks
JSValueRef JSCExecutor::nativePostMessage(
JSContextRef ctx,
JSObjectRef function,
JSObjectRef thisObject,
size_t argumentCount,
const JSValueRef arguments[],
JSValueRef *exception) {
if (argumentCount != 1) {
*exception = makeJSCException(ctx, "postMessage got wrong number of arguments");
return JSValueMakeUndefined(ctx);
}
JSValueRef msg = arguments[0];
JSCExecutor *webWorker = s_globalContextRefToJSCExecutor.at(JSContextGetGlobalContext(ctx));
webWorker->postMessageToOwner(msg);
return JSValueMakeUndefined(ctx);
}
static JSValueRef makeInvalidModuleIdJSCException(
JSContextRef ctx,
@ -508,7 +397,6 @@ JSValueRef JSCExecutor::nativeStartWorker(
std::string scriptFile = Value(ctx, arguments[0]).toString().str();
JSValueRef worker = arguments[1];
JSValueRef globalObj = arguments[2];
JSCExecutor *executor;
try {
@ -518,7 +406,7 @@ JSValueRef JSCExecutor::nativeStartWorker(
return JSValueMakeUndefined(ctx);
}
int workerId = executor->addWebWorker(scriptFile, worker, globalObj);
int workerId = executor->addWebWorker(scriptFile, worker);
return JSValueMakeNumber(ctx, workerId);
}
@ -549,7 +437,7 @@ JSValueRef JSCExecutor::nativePostMessageToWorker(
return JSValueMakeUndefined(ctx);
}
executor->postMessageToOwnedWebWorker((int) workerDouble, arguments[1], exception);
executor->postMessageToWebWorker((int) workerDouble, arguments[1], exception);
return JSValueMakeUndefined(ctx);
}
@ -580,7 +468,7 @@ JSValueRef JSCExecutor::nativeTerminateWorker(
return JSValueMakeUndefined(ctx);
}
executor->terminateOwnedWebWorker((int) workerDouble);
executor->terminateWebWorker((int) workerDouble);
return JSValueMakeUndefined(ctx);
}

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@ -7,10 +7,9 @@
#include <unordered_map>
#include <folly/json.h>
#include <JavaScriptCore/JSContextRef.h>
#include "Executor.h"
#include "JSCHelpers.h"
#include "Value.h"
#include "JSCWebWorker.h"
namespace facebook {
namespace react {
@ -28,26 +27,10 @@ private:
folly::dynamic m_jscConfig;
};
class JSCExecutor;
class WorkerRegistration : public noncopyable {
public:
explicit WorkerRegistration(std::unique_ptr<JSCExecutor> executor, Object jsObj) :
jsObj(std::move(jsObj)),
executor(std::move(executor)) {}
JSCExecutor* getExecutor() {
return executor.get();
}
Object jsObj;
private:
std::unique_ptr<JSCExecutor> executor;
};
class JSCExecutor : public JSExecutor {
class JSCExecutor : public JSExecutor, public JSCWebWorkerOwner {
public:
/**
* Must be invoked from thread this Executor will run on.
* Should be invoked from the JS thread.
*/
explicit JSCExecutor(Bridge *bridge, const std::string& cacheDir, const folly::dynamic& jscConfig);
~JSCExecutor() override;
@ -77,43 +60,26 @@ public:
virtual void handleMemoryPressureCritical() override;
void installNativeHook(const char *name, JSObjectCallAsFunctionCallback callback);
virtual void onMessageReceived(int workerId, const std::string& message) override;
virtual JSGlobalContextRef getContext() override;
virtual std::shared_ptr<MessageQueueThread> getMessageQueueThread() override;
private:
JSGlobalContextRef m_context;
std::unordered_map<int, JSCWebWorker> m_webWorkers;
std::unordered_map<int, Object> m_webWorkerJSObjs;
Bridge *m_bridge;
int m_workerId = 0; // if this is a worker executor, this is non-zero
JSCExecutor *m_owner = nullptr; // if this is a worker executor, this is non-null
std::shared_ptr<bool> m_isDestroyed = std::shared_ptr<bool>(new bool(false));
std::unordered_map<int, WorkerRegistration> m_ownedWorkers;
std::string m_deviceCacheDir;
std::shared_ptr<MessageQueueThread> m_messageQueueThread;
std::unique_ptr<JSModulesUnbundle> m_unbundle;
folly::dynamic m_jscConfig;
/**
* WebWorker constructor. Must be invoked from thread this Executor will run on.
*/
explicit JSCExecutor(
Bridge *bridge,
int workerId,
JSCExecutor *owner,
const std::string& script,
const std::unordered_map<std::string, std::string>& globalObjAsJSON,
const folly::dynamic& jscConfig);
void initOnJSVMThread();
void terminateOnJSVMThread();
int addWebWorker(const std::string& script, JSValueRef workerRef);
void postMessageToWebWorker(int worker, JSValueRef message, JSValueRef *exn);
void flush();
void flushQueueImmediate(std::string queueJSON);
void terminateWebWorker(int worker);
void loadModule(uint32_t moduleId);
int addWebWorker(const std::string& script, JSValueRef workerRef, JSValueRef globalObjRef);
void postMessageToOwnedWebWorker(int worker, JSValueRef message, JSValueRef *exn);
void postMessageToOwner(JSValueRef result);
void receiveMessageFromOwnedWebWorker(int workerId, const std::string& message);
void receiveMessageFromOwner(const std::string &msgString);
void terminateOwnedWebWorker(int worker);
Object createMessageObject(const std::string& msgData);
void flushQueueImmediate(std::string queueJSON);
static JSValueRef nativeStartWorker(
JSContextRef ctx,
@ -136,13 +102,6 @@ private:
size_t argumentCount,
const JSValueRef arguments[],
JSValueRef *exception);
static JSValueRef nativePostMessage(
JSContextRef ctx,
JSObjectRef function,
JSObjectRef thisObject,
size_t argumentCount,
const JSValueRef arguments[],
JSValueRef *exception);
static JSValueRef nativeRequire(
JSContextRef ctx,
JSObjectRef function,

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@ -0,0 +1,153 @@
// Copyright 2004-present Facebook. All Rights Reserved.
#include "JSCWebWorker.h"
#include <unistd.h>
#include <condition_variable>
#include <mutex>
#include <unordered_map>
#include <glog/logging.h>
#include <folly/Memory.h>
#include "JSCHelpers.h"
#include "MessageQueueThread.h"
#include "Platform.h"
#include "Value.h"
#include <JavaScriptCore/JSValueRef.h>
namespace facebook {
namespace react {
// TODO(9604425): thread safety
static std::unordered_map<JSContextRef, JSCWebWorker*> s_globalContextRefToJSCWebWorker;
JSCWebWorker::JSCWebWorker(int id, JSCWebWorkerOwner *owner, std::string scriptSrc) :
id_(id),
scriptName_(std::move(scriptSrc)),
owner_(owner) {
ownerMessageQueueThread_ = owner->getMessageQueueThread();
CHECK(ownerMessageQueueThread_) << "Owner MessageQueue must not be null";
workerMessageQueueThread_ = WebWorkerUtil::createWebWorkerThread(id, ownerMessageQueueThread_.get());
CHECK(workerMessageQueueThread_) << "Failed to create worker thread";
workerMessageQueueThread_->runOnQueue([this] () {
initJSVMAndLoadScript();
});
}
JSCWebWorker::~JSCWebWorker() {
CHECK(isTerminated()) << "Didn't terminate the web worker before releasing it!";;
}
void JSCWebWorker::postMessage(JSValueRef msg) {
std::string msgString = Value(owner_->getContext(), msg).toJSONString();
workerMessageQueueThread_->runOnQueue([this, msgString] () {
if (isTerminated()) {
return;
}
JSValueRef args[] = { createMessageObject(context_, msgString) };
Value onmessageValue = Object::getGlobalObject(context_).getProperty("onmessage");
onmessageValue.asObject().callAsFunction(1, args);
});
}
void JSCWebWorker::terminate() {
if (isTerminated()) {
return;
}
isTerminated_.store(true, std::memory_order_release);
if (workerMessageQueueThread_->isOnThread()) {
terminateOnWorkerThread();
} else {
std::mutex signalMutex;
std::condition_variable signalCv;
bool terminationComplete = false;
workerMessageQueueThread_->runOnQueue([&] () mutable {
std::lock_guard<std::mutex> lock(signalMutex);
terminateOnWorkerThread();
terminationComplete = true;
signalCv.notify_one();
});
std::unique_lock<std::mutex> lock(signalMutex);
signalCv.wait(lock, [&terminationComplete] { return terminationComplete; });
}
}
void JSCWebWorker::terminateOnWorkerThread() {
s_globalContextRefToJSCWebWorker.erase(context_);
JSGlobalContextRelease(context_);
context_ = nullptr;
workerMessageQueueThread_->quitSynchronous();
}
bool JSCWebWorker::isTerminated() {
return isTerminated_.load(std::memory_order_acquire);
}
void JSCWebWorker::initJSVMAndLoadScript() {
CHECK(!isTerminated()) << "Worker was already finished!";
CHECK(!context_) << "Worker JS VM was already created!";
context_ = JSGlobalContextCreateInGroup(
NULL, // use default JS 'global' object
NULL // create new group (i.e. new VM)
);
s_globalContextRefToJSCWebWorker[context_] = this;
// TODO(9604438): Protect against script does not exist
std::string script = WebWorkerUtil::loadScriptFromAssets(scriptName_);
evaluateScript(context_, String(script.c_str()), String(scriptName_.c_str()));
installGlobalFunction(context_, "postMessage", nativePostMessage);
}
void JSCWebWorker::postMessageToOwner(JSValueRef msg) {
std::string msgString = Value(context_, msg).toJSONString();
ownerMessageQueueThread_->runOnQueue([this, msgString] () {
owner_->onMessageReceived(id_, msgString);
});
}
JSValueRef JSCWebWorker::nativePostMessage(
JSContextRef ctx,
JSObjectRef function,
JSObjectRef thisObject,
size_t argumentCount,
const JSValueRef arguments[],
JSValueRef *exception) {
if (argumentCount != 1) {
*exception = makeJSCException(ctx, "postMessage got wrong number of arguments");
return JSValueMakeUndefined(ctx);
}
JSValueRef msg = arguments[0];
JSCWebWorker *webWorker = s_globalContextRefToJSCWebWorker.at(JSContextGetGlobalContext(ctx));
if (webWorker->isTerminated()) {
return JSValueMakeUndefined(ctx);
}
webWorker->postMessageToOwner(msg);
return JSValueMakeUndefined(ctx);
}
/*static*/
Object JSCWebWorker::createMessageObject(JSContextRef context, const std::string& msgJson) {
Value rebornJSMsg = Value::fromJSON(context, String(msgJson.c_str()));
Object messageObject = Object::create(context);
messageObject.setProperty("data", rebornJSMsg);
return std::move(messageObject);
}
}
}

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@ -0,0 +1,94 @@
// Copyright 2004-present Facebook. All Rights Reserved.
#include <atomic>
#include <functional>
#include <mutex>
#include <string>
#include <thread>
#include <queue>
#include <JavaScriptCore/JSValueRef.h>
#include "Value.h"
namespace facebook {
namespace react {
class MessageQueueThread;
/**
* A class that can own the lifecycle, receive messages from, and dispatch messages
* to JSCWebWorkers.
*/
class JSCWebWorkerOwner {
public:
/**
* Called when a worker has posted a message with `postMessage`.
*/
virtual void onMessageReceived(int workerId, const std::string& message) = 0;
virtual JSGlobalContextRef getContext() = 0;
/**
* Should return the owner's MessageQueueThread. Calls to onMessageReceived will be enqueued
* on this thread.
*/
virtual std::shared_ptr<MessageQueueThread> getMessageQueueThread() = 0;
};
/**
* Implementation of a web worker for JSC. The web worker should be created from the owner's
* (e.g., owning JSCExecutor instance) JS MessageQueueThread. The worker is responsible for
* creating its own MessageQueueThread.
*
* During operation, the JSCExecutor should call postMessage **from its own MessageQueueThread**
* to send messages to the worker. The worker will handle enqueueing those messages on its own
* MessageQueueThread as appropriate. When the worker has a message to post to the owner, it will
* enqueue a call to owner->onMessageReceived on the owner's MessageQueueThread.
*/
class JSCWebWorker {
public:
explicit JSCWebWorker(int id, JSCWebWorkerOwner *owner, std::string script);
~JSCWebWorker();
/**
* Post a message to be received by the worker on its thread. This must be called from
* ownerMessageQueueThread_.
*/
void postMessage(JSValueRef msg);
/**
* Synchronously quits the current worker and cleans up its VM.
*/
void terminate();
/**
* Whether terminate() has been called on this worker.
*/
bool isTerminated();
static Object createMessageObject(JSContextRef context, const std::string& msgData);
private:
void initJSVMAndLoadScript();
void postRunnableToEventLoop(std::function<void()>&& runnable);
void postMessageToOwner(JSValueRef result);
void terminateOnWorkerThread();
int id_;
std::atomic_bool isTerminated_ = ATOMIC_VAR_INIT(false);
std::string scriptName_;
JSCWebWorkerOwner *owner_ = nullptr;
std::shared_ptr<MessageQueueThread> ownerMessageQueueThread_;
std::unique_ptr<MessageQueueThread> workerMessageQueueThread_;
JSGlobalContextRef context_ = nullptr;
static JSValueRef nativePostMessage(
JSContextRef ctx,
JSObjectRef function,
JSObjectRef thisObject,
size_t argumentCount,
const JSValueRef arguments[],
JSValueRef *exception);
};
}
}

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@ -2,9 +2,7 @@
#pragma once
#include <condition_variable>
#include <functional>
#include <mutex>
namespace facebook {
namespace react {
@ -16,24 +14,6 @@ class MessageQueueThread {
virtual bool isOnThread() = 0;
// quitSynchronous() should synchronously ensure that no further tasks will run on the queue.
virtual void quitSynchronous() = 0;
void runOnQueueSync(std::function<void()>&& runnable) {
std::mutex signalMutex;
std::condition_variable signalCv;
bool runnableComplete = false;
runOnQueue([&] () mutable {
std::lock_guard<std::mutex> lock(signalMutex);
runnable();
runnableComplete = true;
signalCv.notify_one();
});
std::unique_lock<std::mutex> lock(signalMutex);
signalCv.wait(lock, [&runnableComplete] { return runnableComplete; });
}
};
}}