Source code
Revision control
Copy as Markdown
Other Tools
/* -*- 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
#ifndef nsThread_h__
#define nsThread_h__
#include "MainThreadUtils.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/DataMutex.h"
#include "mozilla/EventQueue.h"
#include "mozilla/LinkedList.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Mutex.h"
#include "mozilla/NotNull.h"
#include "mozilla/RefPtr.h"
#include "mozilla/TaskDispatcher.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtr.h"
#include "nsIDirectTaskDispatcher.h"
#include "nsIEventTarget.h"
#include "nsISerialEventTarget.h"
#include "nsISupportsPriority.h"
#include "nsIThread.h"
#include "nsIThreadInternal.h"
#include "nsTArray.h"
namespace mozilla {
class CycleCollectedJSContext;
class DelayedRunnable;
class SynchronizedEventQueue;
class ThreadEventQueue;
class ThreadEventTarget;
template <typename T, size_t Length>
class Array;
} // namespace mozilla
using mozilla::NotNull;
class nsIRunnable;
class nsThreadShutdownContext;
#define W3_LONGTASK_BUSY_WINDOW_MS 50
// Time a Runnable executes before we accumulate telemetry on it
#define LONGTASK_TELEMETRY_MS 30
// A class for managing performance counter state.
namespace mozilla {
class PerformanceCounterState {
public:
explicit PerformanceCounterState(
const uint32_t& aNestedEventLoopDepthRef, bool aIsMainThread = false,
const Maybe<uint32_t>& aLongTaskLength = Nothing())
: mNestedEventLoopDepth(aNestedEventLoopDepthRef),
mIsMainThread(aIsMainThread),
mLongTaskLength(aLongTaskLength),
// Does it really make sense to initialize these to "now" when we
// haven't run any tasks?
mLastLongTaskEnd(TimeStamp::Now()),
mLastLongNonIdleTaskEnd(mLastLongTaskEnd) {}
class Snapshot {
public:
Snapshot(uint32_t aOldEventLoopDepth, bool aOldIsIdleRunnable)
: mOldEventLoopDepth(aOldEventLoopDepth),
mOldIsIdleRunnable(aOldIsIdleRunnable) {}
Snapshot(const Snapshot&) = default;
Snapshot(Snapshot&&) = default;
private:
friend class PerformanceCounterState;
const uint32_t mOldEventLoopDepth;
const bool mOldIsIdleRunnable;
};
// Notification that a runnable is about to run. This captures a snapshot of
// our current state before we reset to prepare for the new runnable. This
// muast be called after mNestedEventLoopDepth has been incremented for the
// runnable execution. The performance counter passed in should be the one
// for the relevant runnable and may be null. aIsIdleRunnable should be true
// if and only if the runnable has idle priority.
Snapshot RunnableWillRun(TimeStamp aNow, bool aIsIdleRunnable);
// Notification that a runnable finished executing. This must be passed the
// snapshot that RunnableWillRun returned for the same runnable. This must be
// called before mNestedEventLoopDepth is decremented after the runnable's
// execution.
void RunnableDidRun(const nsCString& aName, Snapshot&& aSnapshot);
const TimeStamp& LastLongTaskEnd() const { return mLastLongTaskEnd; }
const TimeStamp& LastLongNonIdleTaskEnd() const {
return mLastLongNonIdleTaskEnd;
}
private:
// Called to report accumulated time, as needed, when we're about to run a
// runnable or just finished running one.
void MaybeReportAccumulatedTime(const nsCString& aName, TimeStamp aNow);
// Whether the runnable we are about to run, or just ran, is a nested
// runnable, in the sense that there is some other runnable up the stack
// spinning the event loop. This must be called before we change our
// mCurrentEventLoopDepth (when about to run a new event) or after we restore
// it (after we ran one).
bool IsNestedRunnable() const {
return mNestedEventLoopDepth > mCurrentEventLoopDepth;
}
// The event loop depth of the currently running runnable. Set to the max
// value of a uint32_t when there is no runnable running, so when starting to
// run a toplevel (not nested) runnable IsNestedRunnable() will test false.
uint32_t mCurrentEventLoopDepth = std::numeric_limits<uint32_t>::max();
// A reference to the nsThread's mNestedEventLoopDepth, so we can
// see what it is right now.
const uint32_t& mNestedEventLoopDepth;
// A boolean that indicates whether the currently running runnable is an idle
// runnable. Only has a useful value between RunnableWillRun() being called
// and RunnableDidRun() returning.
bool mCurrentRunnableIsIdleRunnable = false;
// Whether we're attached to the mainthread nsThread.
const bool mIsMainThread;
// what is considered a LongTask (in ms)
const Maybe<uint32_t> mLongTaskLength;
// The timestamp from which time to be accounted for should be measured. This
// can be the start of a runnable running or the end of a nested runnable
// running.
TimeStamp mCurrentTimeSliceStart;
// Information about when long tasks last ended.
TimeStamp mLastLongTaskEnd;
TimeStamp mLastLongNonIdleTaskEnd;
};
} // namespace mozilla
// A native thread
class nsThread : public nsIThreadInternal,
public nsISupportsPriority,
public nsIDirectTaskDispatcher,
private mozilla::LinkedListElement<nsThread> {
friend mozilla::LinkedList<nsThread>;
friend mozilla::LinkedListElement<nsThread>;
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIEVENTTARGET_FULL
NS_DECL_NSITHREAD
NS_DECL_NSITHREADINTERNAL
NS_DECL_NSISUPPORTSPRIORITY
NS_DECL_NSIDIRECTTASKDISPATCHER
enum MainThreadFlag { MAIN_THREAD, NOT_MAIN_THREAD };
nsThread(NotNull<mozilla::SynchronizedEventQueue*> aQueue,
MainThreadFlag aMainThread,
nsIThreadManager::ThreadCreationOptions aOptions);
private:
nsThread();
public:
// Initialize this as a named wrapper for a new PRThread.
nsresult Init(const nsACString& aName);
// Initialize this as a wrapper for the current PRThread.
nsresult InitCurrentThread();
// Get this thread's name, thread-safe.
void GetThreadName(nsACString& aNameBuffer);
// Set this thread's name. Consider using
// NS_SetCurrentThreadName if you are not sure.
void SetThreadNameInternal(const nsACString& aName);
private:
// Initializes the mThreadId and stack base/size members, and adds the thread
// to the ThreadList().
void InitCommon();
public:
// The PRThread corresponding to this thread.
PRThread* GetPRThread() const { return mThread; }
const void* StackBase() const { return mStackBase; }
size_t StackSize() const { return mStackSize; }
uint32_t ThreadId() const { return mThreadId; }
// If this flag is true, then the nsThread was created using
// nsIThreadManager::NewThread.
bool ShutdownRequired() { return mShutdownRequired; }
// Lets GetRunningEventDelay() determine if the pool this is part
// of has an unstarted thread
void SetPoolThreadFreePtr(mozilla::Atomic<bool, mozilla::Relaxed>* aPtr) {
mIsAPoolThreadFree = aPtr;
}
void SetScriptObserver(mozilla::CycleCollectedJSContext* aScriptObserver);
uint32_t RecursionDepth() const;
void ShutdownComplete(NotNull<nsThreadShutdownContext*> aContext);
void WaitForAllAsynchronousShutdowns();
static const uint32_t kRunnableNameBufSize = 1000;
static mozilla::Array<char, kRunnableNameBufSize> sMainThreadRunnableName;
mozilla::SynchronizedEventQueue* EventQueue() { return mEvents.get(); }
bool ShuttingDown() const { return mShutdownContext != nullptr; }
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
// Returns the size of this object, its PRThread, and its shutdown contexts,
// but excluding its event queues.
size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
size_t SizeOfEventQueues(mozilla::MallocSizeOf aMallocSizeOf) const;
void SetUseHangMonitor(bool aValue) {
MOZ_ASSERT(IsOnCurrentThread());
mUseHangMonitor = aValue;
}
private:
void DoMainThreadSpecificProcessing() const;
protected:
friend class nsThreadShutdownEvent;
virtual ~nsThread();
static void ThreadFunc(void* aArg);
// Helper
already_AddRefed<nsIThreadObserver> GetObserver() {
nsIThreadObserver* obs;
nsThread::GetObserver(&obs);
return already_AddRefed<nsIThreadObserver>(obs);
}
already_AddRefed<nsThreadShutdownContext> ShutdownInternal(bool aSync);
friend class nsThreadManager;
friend class nsThreadPool;
void MaybeRemoveFromThreadList();
// Whether or not these members have a value determines whether the nsThread
// is treated as a full XPCOM thread or as a thin wrapper.
//
// For full nsThreads, they will always contain valid pointers. For thin
// wrappers around non-XPCOM threads, they will be null, and event dispatch
// methods which rely on them will fail (and assert) if called.
RefPtr<mozilla::SynchronizedEventQueue> mEvents;
RefPtr<mozilla::ThreadEventTarget> mEventTarget;
// The number of outstanding nsThreadShutdownContext started by this thread.
// The thread will not be allowed to exit until this number reaches 0.
uint32_t mOutstandingShutdownContexts;
// The shutdown context for ourselves.
RefPtr<nsThreadShutdownContext> mShutdownContext;
mozilla::CycleCollectedJSContext* mScriptObserver;
// Our name.
mozilla::DataMutex<nsCString> mThreadName;
void* mStackBase = nullptr;
uint32_t mStackSize;
uint32_t mThreadId;
uint32_t mNestedEventLoopDepth;
mozilla::Atomic<bool> mShutdownRequired;
int8_t mPriority;
const bool mIsMainThread;
bool mUseHangMonitor;
const bool mIsUiThread;
mozilla::Atomic<bool, mozilla::Relaxed>* mIsAPoolThreadFree;
// Set to true if this thread creates a JSRuntime.
bool mCanInvokeJS;
// The time the currently running event spent in event queues, and
// when it started running. If no event is running, they are
// TimeDuration() & TimeStamp().
mozilla::TimeDuration mLastEventDelay;
mozilla::TimeStamp mLastEventStart;
mozilla::PerformanceCounterState mPerformanceCounterState;
mozilla::SimpleTaskQueue mDirectTasks;
};
class nsThreadShutdownContext final : public nsIThreadShutdown {
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSITHREADSHUTDOWN
private:
friend class nsThread;
friend class nsThreadShutdownEvent;
friend class nsThreadShutdownAckEvent;
nsThreadShutdownContext(NotNull<nsThread*> aTerminatingThread,
nsThread* aJoiningThread)
: mTerminatingThread(aTerminatingThread),
mTerminatingPRThread(aTerminatingThread->GetPRThread()),
mJoiningThreadMutex("nsThreadShutdownContext::mJoiningThreadMutex"),
mJoiningThread(aJoiningThread) {}
~nsThreadShutdownContext() = default;
// Must be called on the joining thread.
void MarkCompleted();
// NB: This may be the last reference.
NotNull<RefPtr<nsThread>> const mTerminatingThread;
PRThread* const mTerminatingPRThread;
// May only be accessed on the joining thread.
bool mCompleted = false;
nsTArray<nsCOMPtr<nsIRunnable>> mCompletionCallbacks;
// The thread waiting for this thread to shut down. Will either be cleared by
// the joining thread if `StopWaitingAndLeakThread` is called or by the
// terminating thread upon exiting and notifying the joining thread.
mozilla::Mutex mJoiningThreadMutex;
RefPtr<nsThread> mJoiningThread MOZ_GUARDED_BY(mJoiningThreadMutex);
bool mThreadLeaked MOZ_GUARDED_BY(mJoiningThreadMutex) = false;
};
#if defined(XP_UNIX) && !defined(ANDROID) && !defined(DEBUG) && HAVE_UALARM && \
defined(_GNU_SOURCE)
# define MOZ_CANARY
extern int sCanaryOutputFD;
#endif
#endif // nsThread_h__