gecko-dev/dom/workers/WorkerThread.cpp

351 lines
8.8 KiB
C++

/* -*- 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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "WorkerThread.h"
#include "mozilla/Assertions.h"
#include "mozilla/ipc/BackgroundChild.h"
#include "nsIThreadInternal.h"
#include "WorkerPrivate.h"
#include "WorkerRunnable.h"
#ifdef DEBUG
#include "nsThreadManager.h"
#endif
namespace mozilla {
namespace dom {
namespace workers {
using namespace mozilla::ipc;
namespace {
// The C stack size. We use the same stack size on all platforms for
// consistency.
const uint32_t kWorkerStackSize = 256 * sizeof(size_t) * 1024;
} // namespace
WorkerThreadFriendKey::WorkerThreadFriendKey()
{
MOZ_COUNT_CTOR(WorkerThreadFriendKey);
}
WorkerThreadFriendKey::~WorkerThreadFriendKey()
{
MOZ_COUNT_DTOR(WorkerThreadFriendKey);
}
class WorkerThread::Observer final
: public nsIThreadObserver
{
WorkerPrivate* mWorkerPrivate;
public:
explicit Observer(WorkerPrivate* aWorkerPrivate)
: mWorkerPrivate(aWorkerPrivate)
{
MOZ_ASSERT(aWorkerPrivate);
aWorkerPrivate->AssertIsOnWorkerThread();
}
NS_DECL_THREADSAFE_ISUPPORTS
private:
~Observer()
{
mWorkerPrivate->AssertIsOnWorkerThread();
}
NS_DECL_NSITHREADOBSERVER
};
WorkerThread::WorkerThread()
: nsThread(nsThread::NOT_MAIN_THREAD, kWorkerStackSize)
, mWorkerPrivateCondVar(mLock, "WorkerThread::mWorkerPrivateCondVar")
, mWorkerPrivate(nullptr)
, mOtherThreadsDispatchingViaEventTarget(0)
#ifdef DEBUG
, mAcceptingNonWorkerRunnables(true)
#endif
{
}
WorkerThread::~WorkerThread()
{
MOZ_ASSERT(!mWorkerPrivate);
MOZ_ASSERT(!mOtherThreadsDispatchingViaEventTarget);
MOZ_ASSERT(mAcceptingNonWorkerRunnables);
}
// static
already_AddRefed<WorkerThread>
WorkerThread::Create(const WorkerThreadFriendKey& /* aKey */)
{
MOZ_ASSERT(nsThreadManager::get());
RefPtr<WorkerThread> thread = new WorkerThread();
if (NS_FAILED(thread->Init())) {
NS_WARNING("Failed to create new thread!");
return nullptr;
}
return thread.forget();
}
void
WorkerThread::SetWorker(const WorkerThreadFriendKey& /* aKey */,
WorkerPrivate* aWorkerPrivate)
{
MOZ_ASSERT(PR_GetCurrentThread() == mThread);
if (aWorkerPrivate) {
{
MutexAutoLock lock(mLock);
MOZ_ASSERT(!mWorkerPrivate);
MOZ_ASSERT(mAcceptingNonWorkerRunnables);
mWorkerPrivate = aWorkerPrivate;
#ifdef DEBUG
mAcceptingNonWorkerRunnables = false;
#endif
}
mObserver = new Observer(aWorkerPrivate);
MOZ_ALWAYS_SUCCEEDS(AddObserver(mObserver));
} else {
MOZ_ALWAYS_SUCCEEDS(RemoveObserver(mObserver));
mObserver = nullptr;
{
MutexAutoLock lock(mLock);
MOZ_ASSERT(mWorkerPrivate);
MOZ_ASSERT(!mAcceptingNonWorkerRunnables);
MOZ_ASSERT(!mOtherThreadsDispatchingViaEventTarget,
"XPCOM Dispatch hapenning at the same time our thread is "
"being unset! This should not be possible!");
while (mOtherThreadsDispatchingViaEventTarget) {
mWorkerPrivateCondVar.Wait();
}
#ifdef DEBUG
mAcceptingNonWorkerRunnables = true;
#endif
mWorkerPrivate = nullptr;
}
}
}
nsresult
WorkerThread::DispatchPrimaryRunnable(const WorkerThreadFriendKey& /* aKey */,
already_AddRefed<nsIRunnable>&& aRunnable)
{
nsCOMPtr<nsIRunnable> runnable(aRunnable);
#ifdef DEBUG
MOZ_ASSERT(PR_GetCurrentThread() != mThread);
MOZ_ASSERT(runnable);
{
MutexAutoLock lock(mLock);
MOZ_ASSERT(!mWorkerPrivate);
MOZ_ASSERT(mAcceptingNonWorkerRunnables);
}
#endif
nsresult rv = nsThread::Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
nsresult
WorkerThread::DispatchAnyThread(const WorkerThreadFriendKey& /* aKey */,
already_AddRefed<WorkerRunnable>&& aWorkerRunnable)
{
// May be called on any thread!
#ifdef DEBUG
{
const bool onWorkerThread = PR_GetCurrentThread() == mThread;
{
MutexAutoLock lock(mLock);
MOZ_ASSERT(mWorkerPrivate);
MOZ_ASSERT(!mAcceptingNonWorkerRunnables);
if (onWorkerThread) {
mWorkerPrivate->AssertIsOnWorkerThread();
}
}
}
#endif
nsCOMPtr<nsIRunnable> runnable(aWorkerRunnable);
nsresult rv = nsThread::Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
// We don't need to notify the worker's condition variable here because we're
// being called from worker-controlled code and it will make sure to wake up
// the worker thread if needed.
return NS_OK;
}
NS_IMPL_ISUPPORTS_INHERITED0(WorkerThread, nsThread)
NS_IMETHODIMP
WorkerThread::DispatchFromScript(nsIRunnable* aRunnable, uint32_t aFlags)
{
nsCOMPtr<nsIRunnable> runnable(aRunnable);
return Dispatch(runnable.forget(), aFlags);
}
NS_IMETHODIMP
WorkerThread::Dispatch(already_AddRefed<nsIRunnable>&& aRunnable, uint32_t aFlags)
{
// May be called on any thread!
nsCOMPtr<nsIRunnable> runnable(aRunnable); // in case we exit early
// Workers only support asynchronous dispatch.
if (NS_WARN_IF(aFlags != NS_DISPATCH_NORMAL)) {
return NS_ERROR_UNEXPECTED;
}
const bool onWorkerThread = PR_GetCurrentThread() == mThread;
#ifdef DEBUG
if (runnable && !onWorkerThread) {
nsCOMPtr<nsICancelableRunnable> cancelable = do_QueryInterface(runnable);
{
MutexAutoLock lock(mLock);
// Only enforce cancelable runnables after we've started the worker loop.
if (!mAcceptingNonWorkerRunnables) {
MOZ_ASSERT(cancelable,
"Only nsICancelableRunnable may be dispatched to a worker!");
}
}
}
#endif
WorkerPrivate* workerPrivate = nullptr;
if (onWorkerThread) {
// No need to lock here because it is only modified on this thread.
MOZ_ASSERT(mWorkerPrivate);
mWorkerPrivate->AssertIsOnWorkerThread();
workerPrivate = mWorkerPrivate;
} else {
MutexAutoLock lock(mLock);
MOZ_ASSERT(mOtherThreadsDispatchingViaEventTarget < UINT32_MAX);
if (mWorkerPrivate) {
workerPrivate = mWorkerPrivate;
// Incrementing this counter will make the worker thread sleep if it
// somehow tries to unset mWorkerPrivate while we're using it.
mOtherThreadsDispatchingViaEventTarget++;
}
}
nsresult rv;
if (runnable && onWorkerThread) {
RefPtr<WorkerRunnable> workerRunnable = workerPrivate->MaybeWrapAsWorkerRunnable(runnable.forget());
rv = nsThread::Dispatch(workerRunnable.forget(), NS_DISPATCH_NORMAL);
} else {
rv = nsThread::Dispatch(runnable.forget(), NS_DISPATCH_NORMAL);
}
if (!onWorkerThread && workerPrivate) {
// We need to wake the worker thread if we're not already on the right
// thread and the dispatch succeeded.
if (NS_SUCCEEDED(rv)) {
MutexAutoLock workerLock(workerPrivate->mMutex);
workerPrivate->mCondVar.Notify();
}
// Now unset our waiting flag.
{
MutexAutoLock lock(mLock);
MOZ_ASSERT(mOtherThreadsDispatchingViaEventTarget);
if (!--mOtherThreadsDispatchingViaEventTarget) {
mWorkerPrivateCondVar.Notify();
}
}
}
if (NS_WARN_IF(NS_FAILED(rv))) {
return rv;
}
return NS_OK;
}
uint32_t
WorkerThread::RecursionDepth(const WorkerThreadFriendKey& /* aKey */) const
{
MOZ_ASSERT(PR_GetCurrentThread() == mThread);
return mNestedEventLoopDepth;
}
NS_IMPL_ISUPPORTS(WorkerThread::Observer, nsIThreadObserver)
NS_IMETHODIMP
WorkerThread::Observer::OnDispatchedEvent(nsIThreadInternal* /* aThread */)
{
MOZ_CRASH("OnDispatchedEvent() should never be called!");
}
NS_IMETHODIMP
WorkerThread::Observer::OnProcessNextEvent(nsIThreadInternal* /* aThread */,
bool aMayWait)
{
mWorkerPrivate->AssertIsOnWorkerThread();
// If the PBackground child is not created yet, then we must permit
// blocking event processing to support SynchronouslyCreatePBackground().
// If this occurs then we are spinning on the event queue at the start of
// PrimaryWorkerRunnable::Run() and don't want to process the event in
// mWorkerPrivate yet.
if (aMayWait) {
MOZ_ASSERT(CycleCollectedJSRuntime::Get()->RecursionDepth() == 2);
MOZ_ASSERT(!BackgroundChild::GetForCurrentThread());
return NS_OK;
}
mWorkerPrivate->OnProcessNextEvent();
return NS_OK;
}
NS_IMETHODIMP
WorkerThread::Observer::AfterProcessNextEvent(nsIThreadInternal* /* aThread */,
bool /* aEventWasProcessed */)
{
mWorkerPrivate->AssertIsOnWorkerThread();
mWorkerPrivate->AfterProcessNextEvent();
return NS_OK;
}
} // namespace workers
} // namespace dom
} // namespace mozilla