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-rw-r--r--xpcom/threads/nsThreadPool.cpp611
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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 09:37:24 +0000