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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsThreadManager_h__
#define nsThreadManager_h__
#include "nsIThreadManager.h"
#include "nsThread.h"
#include "mozilla/ShutdownPhase.h"
class nsIRunnable;
class nsIThread;
namespace mozilla {
class IdleTaskManager;
class SynchronizedEventQueue;
class TaskQueue;
template <typename T>
class NeverDestroyed;
} // namespace mozilla
class BackgroundEventTarget;
class nsThreadManager : public nsIThreadManager {
public:
NS_DECL_ISUPPORTS
NS_DECL_NSITHREADMANAGER
static nsThreadManager& get();
nsresult Init();
// Shutdown all threads other than the main thread. This function should only
// be called on the main thread of the application process.
void ShutdownNonMainThreads();
// Finish shutting down all threads. This function must be called after
// ShutdownNonMainThreads and will delete the BackgroundEventTarget and
// take the main thread event target out of commission, but without
// releasing the underlying nsThread object.
void ShutdownMainThread();
// Release the underlying main thread nsThread object.
void ReleaseMainThread();
// Called by nsThread to inform the ThreadManager it exists. This method
// must be called when the given thread is the current thread.
void RegisterCurrentThread(nsThread& aThread);
// Called by nsThread to inform the ThreadManager it is going away. This
// method must be called when the given thread is the current thread.
void UnregisterCurrentThread(nsThread& aThread);
// Returns the current thread. Returns null if OOM or if ThreadManager isn't
// initialized. Creates the nsThread if one does not exist yet.
nsThread* GetCurrentThread();
// Returns true iff the currently running thread has an nsThread associated
// with it (ie; whether this is a thread that we can dispatch runnables to).
bool IsNSThread() const;
// CreateCurrentThread sets up an nsThread for the current thread. It uses the
// event queue and main thread flags passed in. It should only be called once
// for the current thread. After it returns, GetCurrentThread() will return
// the thread that was created. GetCurrentThread() will also create a thread
// (lazily), but it doesn't allow the queue or main-thread attributes to be
// specified.
nsThread* CreateCurrentThread(mozilla::SynchronizedEventQueue* aQueue);
nsresult DispatchToBackgroundThread(
nsIRunnable* aEvent, nsIEventTarget::DispatchFlags aDispatchFlags);
already_AddRefed<mozilla::TaskQueue> CreateBackgroundTaskQueue(
const char* aName);
~nsThreadManager();
void EnableMainThreadEventPrioritization();
void FlushInputEventPrioritization();
void SuspendInputEventPrioritization();
void ResumeInputEventPrioritization();
static bool MainThreadHasPendingHighPriorityEvents();
nsIThread* GetMainThreadWeak() { return mMainThread; }
// Low level methods for interacting with the global thread list. Be very
// careful when holding `ThreadListMutex()` as no new threads can be started
// while it is held.
mozilla::OffTheBooksMutex& ThreadListMutex() MOZ_RETURN_CAPABILITY(mMutex) {
return mMutex;
}
bool AllowNewXPCOMThreads() MOZ_EXCLUDES(mMutex);
bool AllowNewXPCOMThreadsLocked() MOZ_REQUIRES(mMutex) {
return mState == State::eActive;
}
mozilla::LinkedList<nsThread>& ThreadList() MOZ_REQUIRES(mMutex) {
return mThreadList;
}
private:
friend class mozilla::NeverDestroyed<nsThreadManager>;
nsThreadManager();
nsresult SpinEventLoopUntilInternal(
const nsACString& aVeryGoodReasonToDoThis,
nsINestedEventLoopCondition* aCondition,
mozilla::ShutdownPhase aShutdownPhaseToCheck);
static void ReleaseThread(void* aData);
enum class State : uint8_t {
// The thread manager has yet to be initialized.
eUninit,
// The thread manager is active, and operating normally.
eActive,
// The thread manager is in XPCOM shutdown. New calls to NS_NewNamedThread
// will fail, as all XPCOM threads are required to be shutting down.
eShutdown,
};
unsigned mCurThreadIndex; // thread-local-storage index
RefPtr<nsThread> mMainThread;
mutable mozilla::OffTheBooksMutex mMutex;
// Current state in the thread manager's lifecycle. See docs above.
State mState MOZ_GUARDED_BY(mMutex);
// Global list of active nsThread instances, including both explicitly and
// implicitly created threads.
//
// NOTE: New entries to this list _may_ be added after mAllowNewThreads has
// been cleared, but only for implicitly created thread wrappers which are
// not shut down during XPCOM shutdown.
mozilla::LinkedList<nsThread> mThreadList MOZ_GUARDED_BY(mMutex);
// Shared event target used for background runnables.
RefPtr<BackgroundEventTarget> mBackgroundEventTarget MOZ_GUARDED_BY(mMutex);
};
#define NS_THREADMANAGER_CID \
{/* 7a4204c6-e45a-4c37-8ebb-6709a22c917c */ \
0x7a4204c6, \
0xe45a, \
0x4c37, \
{0x8e, 0xbb, 0x67, 0x09, 0xa2, 0x2c, 0x91, 0x7c}}
#endif // nsThreadManager_h__
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