gecko-dev/xpcom/threads/nsThread.h

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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 nsThread_h__
#define nsThread_h__
#include "mozilla/Mutex.h"
#include "nsIIdlePeriod.h"
#include "nsIThreadInternal.h"
#include "nsISupportsPriority.h"
#include "nsEventQueue.h"
#include "nsThreadUtils.h"
#include "nsString.h"
#include "nsTObserverArray.h"
#include "mozilla/Attributes.h"
#include "mozilla/NotNull.h"
#include "nsAutoPtr.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/UniquePtr.h"
namespace mozilla {
class CycleCollectedJSContext;
}
using mozilla::NotNull;
// A native thread
class nsThread
: public nsIThreadInternal
, public nsISupportsPriority
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIEVENTTARGET
NS_DECL_NSITHREAD
NS_DECL_NSITHREADINTERNAL
NS_DECL_NSISUPPORTSPRIORITY
using nsIEventTarget::Dispatch;
enum MainThreadFlag
{
MAIN_THREAD,
NOT_MAIN_THREAD
};
nsThread(MainThreadFlag aMainThread, uint32_t aStackSize);
// Initialize this as a wrapper for a new PRThread, and optionally give it a name.
nsresult Init(const nsACString& aName = NS_LITERAL_CSTRING(""));
// Initialize this as a wrapper for the current PRThread.
nsresult InitCurrentThread();
// The PRThread corresponding to this thread.
PRThread* GetPRThread()
{
return mThread;
}
// If this flag is true, then the nsThread was created using
// nsIThreadManager::NewThread.
bool ShutdownRequired()
{
return mShutdownRequired;
}
// Clear the observer list.
void ClearObservers()
{
mEventObservers.Clear();
}
void
SetScriptObserver(mozilla::CycleCollectedJSContext* aScriptObserver);
uint32_t
RecursionDepth() const;
void ShutdownComplete(NotNull<struct nsThreadShutdownContext*> aContext);
void WaitForAllAsynchronousShutdowns();
#ifdef MOZ_CRASHREPORTER
enum class ShouldSaveMemoryReport
{
kMaybeReport,
kForceReport
};
static bool SaveMemoryReportNearOOM(ShouldSaveMemoryReport aShouldSave);
#endif
private:
void DoMainThreadSpecificProcessing(bool aReallyWait);
void GetIdleEvent(nsIRunnable** aEvent, mozilla::MutexAutoLock& aProofOfLock);
void GetEvent(bool aWait, nsIRunnable** aEvent,
mozilla::MutexAutoLock& aProofOfLock);
protected:
class nsChainedEventQueue;
class nsNestedEventTarget;
friend class nsNestedEventTarget;
friend class nsThreadShutdownEvent;
virtual ~nsThread();
bool ShuttingDown()
{
return mShutdownContext != nullptr;
}
static void ThreadFunc(void* aArg);
// Helper
already_AddRefed<nsIThreadObserver> GetObserver()
{
nsIThreadObserver* obs;
nsThread::GetObserver(&obs);
return already_AddRefed<nsIThreadObserver>(obs);
}
// Wrappers for event queue methods:
nsresult PutEvent(nsIRunnable* aEvent, nsNestedEventTarget* aTarget);
nsresult PutEvent(already_AddRefed<nsIRunnable> aEvent,
nsNestedEventTarget* aTarget);
nsresult DispatchInternal(already_AddRefed<nsIRunnable> aEvent,
uint32_t aFlags, nsNestedEventTarget* aTarget);
struct nsThreadShutdownContext* ShutdownInternal(bool aSync);
// Wrapper for nsEventQueue that supports chaining.
class nsChainedEventQueue
{
public:
explicit nsChainedEventQueue(mozilla::Mutex& aLock)
: mNext(nullptr)
, mEventsAvailable(aLock, "[nsChainedEventQueue.mEventsAvailable]")
, mProcessSecondaryQueueRunnable(false)
{
mNormalQueue =
mozilla::MakeUnique<nsEventQueue>(mEventsAvailable,
nsEventQueue::eSharedCondVarQueue);
// Both queues need to use the same CondVar!
mSecondaryQueue =
mozilla::MakeUnique<nsEventQueue>(mEventsAvailable,
nsEventQueue::eSharedCondVarQueue);
}
bool GetEvent(bool aMayWait, nsIRunnable** aEvent,
mozilla::MutexAutoLock& aProofOfLock);
void PutEvent(nsIRunnable* aEvent, mozilla::MutexAutoLock& aProofOfLock)
{
RefPtr<nsIRunnable> event(aEvent);
PutEvent(event.forget(), aProofOfLock);
}
void PutEvent(already_AddRefed<nsIRunnable> aEvent,
mozilla::MutexAutoLock& aProofOfLock)
{
RefPtr<nsIRunnable> event(aEvent);
nsCOMPtr<nsIRunnablePriority> runnablePrio =
do_QueryInterface(event);
uint32_t prio = nsIRunnablePriority::PRIORITY_NORMAL;
if (runnablePrio) {
runnablePrio->GetPriority(&prio);
}
MOZ_ASSERT(prio == nsIRunnablePriority::PRIORITY_NORMAL ||
prio == nsIRunnablePriority::PRIORITY_HIGH);
if (prio == nsIRunnablePriority::PRIORITY_NORMAL) {
mNormalQueue->PutEvent(event.forget(), aProofOfLock);
} else {
mSecondaryQueue->PutEvent(event.forget(), aProofOfLock);
}
}
bool HasPendingEvent(mozilla::MutexAutoLock& aProofOfLock)
{
return mNormalQueue->HasPendingEvent(aProofOfLock) ||
mSecondaryQueue->HasPendingEvent(aProofOfLock);
}
nsChainedEventQueue* mNext;
RefPtr<nsNestedEventTarget> mEventTarget;
private:
mozilla::CondVar mEventsAvailable;
mozilla::UniquePtr<nsEventQueue> mNormalQueue;
mozilla::UniquePtr<nsEventQueue> mSecondaryQueue;
// Try to process one high priority runnable after each normal
// priority runnable. This gives the processing model HTML spec has for
// 'Update the rendering' in the case only vsync messages are in the
// secondary queue and prevents starving the normal queue.
bool mProcessSecondaryQueueRunnable;
};
class nsNestedEventTarget final : public nsIEventTarget
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIEVENTTARGET
nsNestedEventTarget(NotNull<nsThread*> aThread,
NotNull<nsChainedEventQueue*> aQueue)
: mThread(aThread)
, mQueue(aQueue)
{
}
NotNull<RefPtr<nsThread>> mThread;
// This is protected by mThread->mLock.
nsChainedEventQueue* mQueue;
private:
~nsNestedEventTarget()
{
}
};
// This lock protects access to mObserver, mEvents, mIdleEvents,
// mIdlePeriod and mEventsAreDoomed. All of those fields are only
// modified on the thread itself (never from another thread). This
// means that we can avoid holding the lock while using mObserver
// and mEvents on the thread itself. When calling PutEvent on
// mEvents, we have to hold the lock to synchronize with
// PopEventQueue.
mozilla::Mutex mLock;
nsCOMPtr<nsIThreadObserver> mObserver;
mozilla::CycleCollectedJSContext* mScriptObserver;
// Only accessed on the target thread.
nsAutoTObserverArray<NotNull<nsCOMPtr<nsIThreadObserver>>, 2> mEventObservers;
NotNull<nsChainedEventQueue*> mEvents; // never null
nsChainedEventQueue mEventsRoot;
// mIdlePeriod keeps track of the current idle period. If at any
// time the main event queue is empty, calling
// mIdlePeriod->GetIdlePeriodHint() will give an estimate of when
// the current idle period will end.
nsCOMPtr<nsIIdlePeriod> mIdlePeriod;
mozilla::CondVar mIdleEventsAvailable;
nsEventQueue mIdleEvents;
int32_t mPriority;
PRThread* mThread;
uint32_t mNestedEventLoopDepth;
uint32_t mStackSize;
// The shutdown context for ourselves.
struct nsThreadShutdownContext* mShutdownContext;
// The shutdown contexts for any other threads we've asked to shut down.
nsTArray<nsAutoPtr<struct nsThreadShutdownContext>> mRequestedShutdownContexts;
bool mShutdownRequired;
// Set to true when events posted to this thread will never run.
bool mEventsAreDoomed;
MainThreadFlag mIsMainThread;
// Set to true if this thread creates a JSRuntime.
bool mCanInvokeJS;
};
#if defined(XP_UNIX) && !defined(ANDROID) && !defined(DEBUG) && HAVE_UALARM \
&& defined(_GNU_SOURCE)
# define MOZ_CANARY
extern int sCanaryOutputFD;
#endif
#endif // nsThread_h__