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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 01:47:29 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 01:47:29 +0000 |
commit | 0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d (patch) | |
tree | a31f07c9bcca9d56ce61e9a1ffd30ef350d513aa /xpcom/threads/nsThreadPool.cpp | |
parent | Initial commit. (diff) | |
download | firefox-esr-0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d.tar.xz firefox-esr-0ebf5bdf043a27fd3dfb7f92e0cb63d88954c44d.zip |
Adding upstream version 115.8.0esr.upstream/115.8.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'xpcom/threads/nsThreadPool.cpp')
-rw-r--r-- | xpcom/threads/nsThreadPool.cpp | 611 |
1 files changed, 611 insertions, 0 deletions
diff --git a/xpcom/threads/nsThreadPool.cpp b/xpcom/threads/nsThreadPool.cpp new file mode 100644 index 0000000000..362e18f5a7 --- /dev/null +++ b/xpcom/threads/nsThreadPool.cpp @@ -0,0 +1,611 @@ +/* -*- 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 "nsThreadPool.h" + +#include "nsCOMArray.h" +#include "ThreadDelay.h" +#include "nsThreadManager.h" +#include "nsThread.h" +#include "nsThreadUtils.h" +#include "prinrval.h" +#include "mozilla/Logging.h" +#include "mozilla/ProfilerLabels.h" +#include "mozilla/ProfilerRunnable.h" +#include "mozilla/SchedulerGroup.h" +#include "mozilla/ScopeExit.h" +#include "mozilla/SpinEventLoopUntil.h" +#include "nsThreadSyncDispatch.h" + +#include <mutex> + +using namespace mozilla; + +static LazyLogModule sThreadPoolLog("nsThreadPool"); +#ifdef LOG +# undef LOG +#endif +#define LOG(args) MOZ_LOG(sThreadPoolLog, mozilla::LogLevel::Debug, args) + +static MOZ_THREAD_LOCAL(nsThreadPool*) gCurrentThreadPool; + +void nsThreadPool::InitTLS() { gCurrentThreadPool.infallibleInit(); } + +// DESIGN: +// o Allocate anonymous threads. +// o Use nsThreadPool::Run as the main routine for each thread. +// o Each thread waits on the event queue's monitor, checking for +// pending events and rescheduling itself as an idle thread. + +#define DEFAULT_THREAD_LIMIT 4 +#define DEFAULT_IDLE_THREAD_LIMIT 1 +#define DEFAULT_IDLE_THREAD_TIMEOUT PR_SecondsToInterval(60) + +NS_IMPL_ISUPPORTS_INHERITED(nsThreadPool, Runnable, nsIThreadPool, + nsIEventTarget) + +nsThreadPool* nsThreadPool::GetCurrentThreadPool() { + return gCurrentThreadPool.get(); +} + +nsThreadPool::nsThreadPool() + : Runnable("nsThreadPool"), + mMutex("[nsThreadPool.mMutex]"), + mEventsAvailable(mMutex, "[nsThreadPool.mEventsAvailable]"), + mThreadLimit(DEFAULT_THREAD_LIMIT), + mIdleThreadLimit(DEFAULT_IDLE_THREAD_LIMIT), + mIdleThreadTimeout(DEFAULT_IDLE_THREAD_TIMEOUT), + mIdleCount(0), + mQoSPriority(nsIThread::QOS_PRIORITY_NORMAL), + mStackSize(nsIThreadManager::DEFAULT_STACK_SIZE), + mShutdown(false), + mRegressiveMaxIdleTime(false), + mIsAPoolThreadFree(true) { + LOG(("THRD-P(%p) constructor!!!\n", this)); +} + +nsThreadPool::~nsThreadPool() { + // Threads keep a reference to the nsThreadPool until they return from Run() + // after removing themselves from mThreads. + MOZ_ASSERT(mThreads.IsEmpty()); +} + +nsresult nsThreadPool::PutEvent(nsIRunnable* aEvent) { + nsCOMPtr<nsIRunnable> event(aEvent); + return PutEvent(event.forget(), 0); +} + +nsresult nsThreadPool::PutEvent(already_AddRefed<nsIRunnable> aEvent, + uint32_t aFlags) { + // Avoid spawning a new thread while holding the event queue lock... + + bool spawnThread = false; + uint32_t stackSize = 0; + nsCString name; + { + MutexAutoLock lock(mMutex); + + if (NS_WARN_IF(mShutdown)) { + return NS_ERROR_NOT_AVAILABLE; + } + LOG(("THRD-P(%p) put [%d %d %d]\n", this, mIdleCount, mThreads.Count(), + mThreadLimit)); + MOZ_ASSERT(mIdleCount <= (uint32_t)mThreads.Count(), "oops"); + + // Make sure we have a thread to service this event. + if (mThreads.Count() < (int32_t)mThreadLimit && + !(aFlags & NS_DISPATCH_AT_END) && + // Spawn a new thread if we don't have enough idle threads to serve + // pending events immediately. + mEvents.Count(lock) >= mIdleCount) { + spawnThread = true; + } + + nsCOMPtr<nsIRunnable> event(aEvent); + LogRunnable::LogDispatch(event); + mEvents.PutEvent(event.forget(), EventQueuePriority::Normal, lock); + mEventsAvailable.Notify(); + stackSize = mStackSize; + name = mName; + } + + auto delay = MakeScopeExit([&]() { + // Delay to encourage the receiving task to run before we do work. + DelayForChaosMode(ChaosFeature::TaskDispatching, 1000); + }); + + LOG(("THRD-P(%p) put [spawn=%d]\n", this, spawnThread)); + if (!spawnThread) { + return NS_OK; + } + + nsCOMPtr<nsIThread> thread; + nsresult rv = NS_NewNamedThread( + mThreadNaming.GetNextThreadName(name), getter_AddRefs(thread), nullptr, + {.stackSize = stackSize, .blockDispatch = true}); + if (NS_WARN_IF(NS_FAILED(rv))) { + return NS_ERROR_UNEXPECTED; + } + + bool killThread = false; + { + MutexAutoLock lock(mMutex); + if (mShutdown) { + killThread = true; + } else if (mThreads.Count() < (int32_t)mThreadLimit) { + mThreads.AppendObject(thread); + if (mThreads.Count() >= (int32_t)mThreadLimit) { + mIsAPoolThreadFree = false; + } + } else { + // Someone else may have also been starting a thread + killThread = true; // okay, we don't need this thread anymore + } + } + LOG(("THRD-P(%p) put [%p kill=%d]\n", this, thread.get(), killThread)); + if (killThread) { + // We never dispatched any events to the thread, so we can shut it down + // asynchronously without worrying about anything. + ShutdownThread(thread); + } else { + thread->Dispatch(this, NS_DISPATCH_IGNORE_BLOCK_DISPATCH); + } + + return NS_OK; +} + +void nsThreadPool::ShutdownThread(nsIThread* aThread) { + LOG(("THRD-P(%p) shutdown async [%p]\n", this, aThread)); + + // This is either called by a threadpool thread that is out of work, or + // a thread that attempted to create a threadpool thread and raced in + // such a way that the newly created thread is no longer necessary. + // In the first case, we must go to another thread to shut aThread down + // (because it is the current thread). In the second case, we cannot + // synchronously shut down the current thread (because then Dispatch() would + // spin the event loop, and that could blow up the world), and asynchronous + // shutdown requires this thread have an event loop (and it may not, see bug + // 10204784). The simplest way to cover all cases is to asynchronously + // shutdown aThread from the main thread. + SchedulerGroup::Dispatch( + TaskCategory::Other, + NewRunnableMethod("nsIThread::AsyncShutdown", aThread, + &nsIThread::AsyncShutdown)); +} + +NS_IMETHODIMP +nsThreadPool::SetQoSForThreads(nsIThread::QoSPriority aPriority) { + MutexAutoLock lock(mMutex); + mQoSPriority = aPriority; + + // We don't notify threads here to observe the change, because we don't want + // to create spurious wakeups during idle. Rather, we want threads to simply + // observe the change on their own if they wake up to do some task. + + return NS_OK; +} + +// This event 'runs' for the lifetime of the worker thread. The actual +// eventqueue is mEvents, and is shared by all the worker threads. This +// means that the set of threads together define the delay seen by a new +// event sent to the pool. +// +// To model the delay experienced by the pool, we can have each thread in +// the pool report 0 if it's idle OR if the pool is below the threadlimit; +// or otherwise the current event's queuing delay plus current running +// time. +// +// To reconstruct the delays for the pool, the profiler can look at all the +// threads that are part of a pool (pools have defined naming patterns that +// can be user to connect them). If all threads have delays at time X, +// that means that all threads saturated at that point and any event +// dispatched to the pool would get a delay. +// +// The delay experienced by an event dispatched when all pool threads are +// busy is based on the calculations shown in platform.cpp. Run that +// algorithm for each thread in the pool, and the delay at time X is the +// longest value for time X of any of the threads, OR the time from X until +// any one of the threads reports 0 (i.e. it's not busy), whichever is +// shorter. + +// In order to record this when the profiler samples threads in the pool, +// each thread must (effectively) override GetRunnningEventDelay, by +// resetting the mLastEventDelay/Start values in the nsThread when we start +// to run an event (or when we run out of events to run). Note that handling +// the shutdown of a thread may be a little tricky. + +NS_IMETHODIMP +nsThreadPool::Run() { + nsCOMPtr<nsIThread> current; + nsThreadManager::get().GetCurrentThread(getter_AddRefs(current)); + + bool shutdownThreadOnExit = false; + bool exitThread = false; + bool wasIdle = false; + TimeStamp idleSince; + nsIThread::QoSPriority threadPriority = nsIThread::QOS_PRIORITY_NORMAL; + + // This thread is an nsThread created below with NS_NewNamedThread() + static_cast<nsThread*>(current.get()) + ->SetPoolThreadFreePtr(&mIsAPoolThreadFree); + + nsCOMPtr<nsIThreadPoolListener> listener; + { + MutexAutoLock lock(mMutex); + listener = mListener; + LOG(("THRD-P(%p) enter %s\n", this, mName.BeginReading())); + + // Go ahead and check for thread priority. If priority is normal, do nothing + // because threads are created with default priority. + if (threadPriority != mQoSPriority) { + current->SetThreadQoS(threadPriority); + threadPriority = mQoSPriority; + } + } + + if (listener) { + listener->OnThreadCreated(); + } + + MOZ_ASSERT(!gCurrentThreadPool.get()); + gCurrentThreadPool.set(this); + + do { + nsCOMPtr<nsIRunnable> event; + TimeDuration delay; + { + MutexAutoLock lock(mMutex); + + // Before getting the next event, we can adjust priority as needed. + if (threadPriority != mQoSPriority) { + current->SetThreadQoS(threadPriority); + threadPriority = mQoSPriority; + } + + event = mEvents.GetEvent(lock, &delay); + if (!event) { + TimeStamp now = TimeStamp::Now(); + uint32_t idleTimeoutDivider = + (mIdleCount && mRegressiveMaxIdleTime) ? mIdleCount : 1; + TimeDuration timeout = TimeDuration::FromMilliseconds( + static_cast<double>(mIdleThreadTimeout) / idleTimeoutDivider); + + // If we are shutting down, then don't keep any idle threads. + if (mShutdown) { + exitThread = true; + } else { + if (wasIdle) { + // if too many idle threads or idle for too long, then bail. + if (mIdleCount > mIdleThreadLimit || + (mIdleThreadTimeout != UINT32_MAX && + (now - idleSince) >= timeout)) { + exitThread = true; + } + } else { + // if would be too many idle threads... + if (mIdleCount == mIdleThreadLimit) { + exitThread = true; + } else { + ++mIdleCount; + idleSince = now; + wasIdle = true; + } + } + } + + if (exitThread) { + if (wasIdle) { + --mIdleCount; + } + shutdownThreadOnExit = mThreads.RemoveObject(current); + + // keep track if there are threads available to start + mIsAPoolThreadFree = (mThreads.Count() < (int32_t)mThreadLimit); + } else { + current->SetRunningEventDelay(TimeDuration(), TimeStamp()); + + AUTO_PROFILER_LABEL("nsThreadPool::Run::Wait", IDLE); + + TimeDuration delta = timeout - (now - idleSince); + LOG(("THRD-P(%p) %s waiting [%f]\n", this, mName.BeginReading(), + delta.ToMilliseconds())); + mEventsAvailable.Wait(delta); + LOG(("THRD-P(%p) done waiting\n", this)); + } + } else if (wasIdle) { + wasIdle = false; + --mIdleCount; + } + } + if (event) { + if (MOZ_LOG_TEST(sThreadPoolLog, mozilla::LogLevel::Debug)) { + MutexAutoLock lock(mMutex); + LOG(("THRD-P(%p) %s running [%p]\n", this, mName.BeginReading(), + event.get())); + } + + // Delay event processing to encourage whoever dispatched this event + // to run. + DelayForChaosMode(ChaosFeature::TaskRunning, 1000); + + if (profiler_thread_is_being_profiled( + ThreadProfilingFeatures::Sampling)) { + // We'll handle the case of unstarted threads available + // when we sample. + current->SetRunningEventDelay(delay, TimeStamp::Now()); + } + + LogRunnable::Run log(event); + AUTO_PROFILE_FOLLOWING_RUNNABLE(event); + event->Run(); + // To cover the event's destructor code in the LogRunnable span + event = nullptr; + } + } while (!exitThread); + + if (listener) { + listener->OnThreadShuttingDown(); + } + + MOZ_ASSERT(gCurrentThreadPool.get() == this); + gCurrentThreadPool.set(nullptr); + + if (shutdownThreadOnExit) { + ShutdownThread(current); + } + + LOG(("THRD-P(%p) leave\n", this)); + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::DispatchFromScript(nsIRunnable* aEvent, uint32_t aFlags) { + nsCOMPtr<nsIRunnable> event(aEvent); + return Dispatch(event.forget(), aFlags); +} + +NS_IMETHODIMP +nsThreadPool::Dispatch(already_AddRefed<nsIRunnable> aEvent, uint32_t aFlags) { + LOG(("THRD-P(%p) dispatch [%p %x]\n", this, /* XXX aEvent*/ nullptr, aFlags)); + + if (NS_WARN_IF(mShutdown)) { + return NS_ERROR_NOT_AVAILABLE; + } + + NS_ASSERTION(aFlags == NS_DISPATCH_NORMAL || aFlags == NS_DISPATCH_AT_END, + "unexpected dispatch flags"); + PutEvent(std::move(aEvent), aFlags); + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::DelayedDispatch(already_AddRefed<nsIRunnable>, uint32_t) { + return NS_ERROR_NOT_IMPLEMENTED; +} + +NS_IMETHODIMP +nsThreadPool::RegisterShutdownTask(nsITargetShutdownTask*) { + return NS_ERROR_NOT_IMPLEMENTED; +} + +NS_IMETHODIMP +nsThreadPool::UnregisterShutdownTask(nsITargetShutdownTask*) { + return NS_ERROR_NOT_IMPLEMENTED; +} + +NS_IMETHODIMP_(bool) +nsThreadPool::IsOnCurrentThreadInfallible() { + return gCurrentThreadPool.get() == this; +} + +NS_IMETHODIMP +nsThreadPool::IsOnCurrentThread(bool* aResult) { + MutexAutoLock lock(mMutex); + if (NS_WARN_IF(mShutdown)) { + return NS_ERROR_NOT_AVAILABLE; + } + + *aResult = IsOnCurrentThreadInfallible(); + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::Shutdown() { return ShutdownWithTimeout(-1); } + +NS_IMETHODIMP +nsThreadPool::ShutdownWithTimeout(int32_t aTimeoutMs) { + nsCOMArray<nsIThread> threads; + nsCOMPtr<nsIThreadPoolListener> listener; + { + MutexAutoLock lock(mMutex); + if (mShutdown) { + return NS_ERROR_ILLEGAL_DURING_SHUTDOWN; + } + mShutdown = true; + mEventsAvailable.NotifyAll(); + + threads.AppendObjects(mThreads); + mThreads.Clear(); + + // Swap in a null listener so that we release the listener at the end of + // this method. The listener will be kept alive as long as the other threads + // that were created when it was set. + mListener.swap(listener); + } + + nsTArray<nsCOMPtr<nsIThreadShutdown>> contexts; + for (int32_t i = 0; i < threads.Count(); ++i) { + nsCOMPtr<nsIThreadShutdown> context; + if (NS_SUCCEEDED(threads[i]->BeginShutdown(getter_AddRefs(context)))) { + contexts.AppendElement(std::move(context)); + } + } + + // Start a timer which will stop waiting & leak the thread, forcing + // onCompletion to be called when it expires. + nsCOMPtr<nsITimer> timer; + if (aTimeoutMs >= 0) { + NS_NewTimerWithCallback( + getter_AddRefs(timer), + [&](nsITimer*) { + for (auto& context : contexts) { + context->StopWaitingAndLeakThread(); + } + }, + aTimeoutMs, nsITimer::TYPE_ONE_SHOT, + "nsThreadPool::ShutdownWithTimeout"); + } + + // Start a counter and register a callback to decrement outstandingThreads + // when the threads finish exiting. We'll spin an event loop until + // outstandingThreads reaches 0. + uint32_t outstandingThreads = contexts.Length(); + RefPtr onCompletion = NS_NewCancelableRunnableFunction( + "nsThreadPool thread completion", [&] { --outstandingThreads; }); + for (auto& context : contexts) { + context->OnCompletion(onCompletion); + } + + mozilla::SpinEventLoopUntil("nsThreadPool::ShutdownWithTimeout"_ns, + [&] { return outstandingThreads == 0; }); + + if (timer) { + timer->Cancel(); + } + onCompletion->Cancel(); + + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetThreadLimit(uint32_t* aValue) { + MutexAutoLock lock(mMutex); + *aValue = mThreadLimit; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetThreadLimit(uint32_t aValue) { + MutexAutoLock lock(mMutex); + LOG(("THRD-P(%p) thread limit [%u]\n", this, aValue)); + mThreadLimit = aValue; + if (mIdleThreadLimit > mThreadLimit) { + mIdleThreadLimit = mThreadLimit; + } + + if (static_cast<uint32_t>(mThreads.Count()) > mThreadLimit) { + mEventsAvailable + .NotifyAll(); // wake up threads so they observe this change + } + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetIdleThreadLimit(uint32_t* aValue) { + MutexAutoLock lock(mMutex); + *aValue = mIdleThreadLimit; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetIdleThreadLimit(uint32_t aValue) { + MutexAutoLock lock(mMutex); + LOG(("THRD-P(%p) idle thread limit [%u]\n", this, aValue)); + mIdleThreadLimit = aValue; + if (mIdleThreadLimit > mThreadLimit) { + mIdleThreadLimit = mThreadLimit; + } + + // Do we need to kill some idle threads? + if (mIdleCount > mIdleThreadLimit) { + mEventsAvailable + .NotifyAll(); // wake up threads so they observe this change + } + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetIdleThreadTimeout(uint32_t* aValue) { + MutexAutoLock lock(mMutex); + *aValue = mIdleThreadTimeout; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetIdleThreadTimeout(uint32_t aValue) { + MutexAutoLock lock(mMutex); + uint32_t oldTimeout = mIdleThreadTimeout; + mIdleThreadTimeout = aValue; + + // Do we need to notify any idle threads that their sleep time has shortened? + if (mIdleThreadTimeout < oldTimeout && mIdleCount > 0) { + mEventsAvailable + .NotifyAll(); // wake up threads so they observe this change + } + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetIdleThreadTimeoutRegressive(bool* aValue) { + MutexAutoLock lock(mMutex); + *aValue = mRegressiveMaxIdleTime; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetIdleThreadTimeoutRegressive(bool aValue) { + MutexAutoLock lock(mMutex); + bool oldRegressive = mRegressiveMaxIdleTime; + mRegressiveMaxIdleTime = aValue; + + // Would setting regressive timeout effect idle threads? + if (mRegressiveMaxIdleTime > oldRegressive && mIdleCount > 1) { + mEventsAvailable + .NotifyAll(); // wake up threads so they observe this change + } + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetThreadStackSize(uint32_t* aValue) { + MutexAutoLock lock(mMutex); + *aValue = mStackSize; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetThreadStackSize(uint32_t aValue) { + MutexAutoLock lock(mMutex); + mStackSize = aValue; + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::GetListener(nsIThreadPoolListener** aListener) { + MutexAutoLock lock(mMutex); + NS_IF_ADDREF(*aListener = mListener); + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetListener(nsIThreadPoolListener* aListener) { + nsCOMPtr<nsIThreadPoolListener> swappedListener(aListener); + { + MutexAutoLock lock(mMutex); + mListener.swap(swappedListener); + } + return NS_OK; +} + +NS_IMETHODIMP +nsThreadPool::SetName(const nsACString& aName) { + MutexAutoLock lock(mMutex); + if (mThreads.Count()) { + return NS_ERROR_NOT_AVAILABLE; + } + mName = aName; + return NS_OK; +} |