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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "mozilla/dom/JSExecutionManager.h"
#include "WorkerCommon.h"
#include "WorkerPrivate.h"
#include "mozilla/dom/DocGroup.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/StaticPtr.h"
namespace mozilla::dom {
JSExecutionManager* JSExecutionManager::mCurrentMTManager;
const uint32_t kTimeSliceExpirationMS = 50;
using RequestState = JSExecutionManager::RequestState;
static StaticRefPtr<JSExecutionManager> sSABSerializationManager;
void JSExecutionManager::Initialize() {
if (StaticPrefs::dom_workers_serialized_sab_access()) {
sSABSerializationManager = MakeRefPtr<JSExecutionManager>(1);
}
}
void JSExecutionManager::Shutdown() { sSABSerializationManager = nullptr; }
JSExecutionManager* JSExecutionManager::GetSABSerializationManager() {
return sSABSerializationManager.get();
}
RequestState JSExecutionManager::RequestJSThreadExecution() {
if (NS_IsMainThread()) {
return RequestJSThreadExecutionMainThread();
}
WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
if (!workerPrivate || workerPrivate->GetExecutionGranted()) {
return RequestState::ExecutingAlready;
}
MutexAutoLock lock(mExecutionQueueMutex);
MOZ_ASSERT(mMaxRunning >= mRunning);
if ((mExecutionQueue.size() + (mMainThreadAwaitingExecution ? 1 : 0)) <
size_t(mMaxRunning - mRunning)) {
// There's slots ready for things to run, execute right away.
workerPrivate->SetExecutionGranted(true);
workerPrivate->ScheduleTimeSliceExpiration(kTimeSliceExpirationMS);
mRunning++;
return RequestState::Granted;
}
mExecutionQueue.push_back(workerPrivate);
TimeStamp waitStart = TimeStamp::Now();
while (mRunning >= mMaxRunning || (workerPrivate != mExecutionQueue.front() ||
mMainThreadAwaitingExecution)) {
// If there is no slots available, the main thread is awaiting permission
// or we are not first in line for execution, wait until notified.
mExecutionQueueCondVar.Wait(TimeDuration::FromMilliseconds(500));
if ((TimeStamp::Now() - waitStart) > TimeDuration::FromSeconds(20)) {
// Crash so that these types of situations are actually caught in the
// crash reporter.
MOZ_CRASH();
}
}
workerPrivate->SetExecutionGranted(true);
workerPrivate->ScheduleTimeSliceExpiration(kTimeSliceExpirationMS);
mExecutionQueue.pop_front();
mRunning++;
if (mRunning < mMaxRunning) {
// If a thread woke up before that wasn't first in line it will have gone
// back to sleep, if there's more slots available, wake it now.
mExecutionQueueCondVar.NotifyAll();
}
return RequestState::Granted;
}
void JSExecutionManager::YieldJSThreadExecution() {
if (NS_IsMainThread()) {
MOZ_ASSERT(mMainThreadIsExecuting);
mMainThreadIsExecuting = false;
MutexAutoLock lock(mExecutionQueueMutex);
mRunning--;
mExecutionQueueCondVar.NotifyAll();
return;
}
WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
if (!workerPrivate) {
return;
}
MOZ_ASSERT(workerPrivate->GetExecutionGranted());
workerPrivate->CancelTimeSliceExpiration();
MutexAutoLock lock(mExecutionQueueMutex);
mRunning--;
mExecutionQueueCondVar.NotifyAll();
workerPrivate->SetExecutionGranted(false);
}
bool JSExecutionManager::YieldJSThreadExecutionIfGranted() {
if (NS_IsMainThread()) {
if (mMainThreadIsExecuting) {
YieldJSThreadExecution();
return true;
}
return false;
}
WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
if (workerPrivate && workerPrivate->GetExecutionGranted()) {
YieldJSThreadExecution();
return true;
}
return false;
}
RequestState JSExecutionManager::RequestJSThreadExecutionMainThread() {
MOZ_ASSERT(NS_IsMainThread());
if (mMainThreadIsExecuting) {
return RequestState::ExecutingAlready;
}
MutexAutoLock lock(mExecutionQueueMutex);
MOZ_ASSERT(mMaxRunning >= mRunning);
if ((mMaxRunning - mRunning) > 0) {
// If there's any slots available run, the main thread always takes
// precedence over any worker threads.
mRunning++;
mMainThreadIsExecuting = true;
return RequestState::Granted;
}
mMainThreadAwaitingExecution = true;
TimeStamp waitStart = TimeStamp::Now();
while (mRunning >= mMaxRunning) {
if ((TimeStamp::Now() - waitStart) > TimeDuration::FromSeconds(20)) {
// Crash so that these types of situations are actually caught in the
// crash reporter.
MOZ_CRASH();
}
mExecutionQueueCondVar.Wait(TimeDuration::FromMilliseconds(500));
}
mMainThreadAwaitingExecution = false;
mMainThreadIsExecuting = true;
mRunning++;
if (mRunning < mMaxRunning) {
// If a thread woke up before that wasn't first in line it will have gone
// back to sleep, if there's more slots available, wake it now.
mExecutionQueueCondVar.NotifyAll();
}
return RequestState::Granted;
}
AutoRequestJSThreadExecution::AutoRequestJSThreadExecution(
nsIGlobalObject* aGlobalObject, bool aIsMainThread) {
JSExecutionManager* manager = nullptr;
mIsMainThread = aIsMainThread;
if (mIsMainThread) {
mOldGrantingManager = JSExecutionManager::mCurrentMTManager;
nsPIDOMWindowInner* innerWindow = nullptr;
if (aGlobalObject) {
innerWindow = aGlobalObject->GetAsInnerWindow();
}
DocGroup* docGroup = nullptr;
if (innerWindow) {
docGroup = innerWindow->GetDocGroup();
}
if (docGroup) {
manager = docGroup->GetExecutionManager();
}
if (JSExecutionManager::mCurrentMTManager == manager) {
return;
}
if (JSExecutionManager::mCurrentMTManager) {
JSExecutionManager::mCurrentMTManager->YieldJSThreadExecution();
JSExecutionManager::mCurrentMTManager = nullptr;
}
} else {
WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
if (workerPrivate) {
manager = workerPrivate->GetExecutionManager();
}
}
if (manager &&
(manager->RequestJSThreadExecution() == RequestState::Granted)) {
if (NS_IsMainThread()) {
// Make sure we restore permission on destruction if needed.
JSExecutionManager::mCurrentMTManager = manager;
}
mExecutionGrantingManager = std::move(manager);
}
}
AutoYieldJSThreadExecution::AutoYieldJSThreadExecution() {
JSExecutionManager* manager = nullptr;
if (NS_IsMainThread()) {
manager = JSExecutionManager::mCurrentMTManager;
} else {
WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
if (workerPrivate) {
manager = workerPrivate->GetExecutionManager();
}
}
if (manager && manager->YieldJSThreadExecutionIfGranted()) {
mExecutionGrantingManager = std::move(manager);
if (NS_IsMainThread()) {
JSExecutionManager::mCurrentMTManager = nullptr;
}
}
}
} // namespace mozilla::dom