mirror of
https://github.com/mozilla/gecko-dev.git
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303 lines
8.4 KiB
C++
303 lines
8.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsThreadManager.h"
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#include "nsThread.h"
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#include "nsThreadUtils.h"
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#include "nsIClassInfoImpl.h"
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#include "nsTArray.h"
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#include "nsAutoPtr.h"
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#ifdef MOZ_CANARY
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#include <fcntl.h>
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#include <unistd.h>
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#endif
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using namespace mozilla;
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#ifdef XP_WIN
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#include <windows.h>
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DWORD gTLSThreadIDIndex = TlsAlloc();
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#elif defined(NS_TLS)
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NS_TLS mozilla::threads::ID gTLSThreadID = mozilla::threads::Generic;
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#endif
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typedef nsTArray< nsRefPtr<nsThread> > nsThreadArray;
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//-----------------------------------------------------------------------------
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static void
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ReleaseObject(void *data)
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{
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static_cast<nsISupports *>(data)->Release();
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}
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static PLDHashOperator
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AppendAndRemoveThread(PRThread *key, nsRefPtr<nsThread> &thread, void *arg)
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{
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nsThreadArray *threads = static_cast<nsThreadArray *>(arg);
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threads->AppendElement(thread);
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return PL_DHASH_REMOVE;
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}
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// statically allocated instance
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NS_IMETHODIMP_(nsrefcnt) nsThreadManager::AddRef() { return 2; }
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NS_IMETHODIMP_(nsrefcnt) nsThreadManager::Release() { return 1; }
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NS_IMPL_CLASSINFO(nsThreadManager, nullptr,
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nsIClassInfo::THREADSAFE | nsIClassInfo::SINGLETON,
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NS_THREADMANAGER_CID)
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NS_IMPL_QUERY_INTERFACE1_CI(nsThreadManager, nsIThreadManager)
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NS_IMPL_CI_INTERFACE_GETTER1(nsThreadManager, nsIThreadManager)
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//-----------------------------------------------------------------------------
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nsresult
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nsThreadManager::Init()
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{
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// Child processes need to initialize the thread manager before they
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// initialize XPCOM in order to set up the crash reporter. This leads to
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// situations where we get initialized twice.
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if (mInitialized)
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return NS_OK;
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if (PR_NewThreadPrivateIndex(&mCurThreadIndex, ReleaseObject) == PR_FAILURE)
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return NS_ERROR_FAILURE;
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mLock = new Mutex("nsThreadManager.mLock");
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#ifdef MOZ_CANARY
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const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
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const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
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char* env_var_flag = getenv("MOZ_KILL_CANARIES");
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sCanaryOutputFD = env_var_flag ? (env_var_flag[0] ?
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open(env_var_flag, flags, mode) :
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STDERR_FILENO) : 0;
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#endif
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// Setup "main" thread
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mMainThread = new nsThread(nsThread::MAIN_THREAD, 0);
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nsresult rv = mMainThread->InitCurrentThread();
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if (NS_FAILED(rv)) {
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mMainThread = nullptr;
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return rv;
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}
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// We need to keep a pointer to the current thread, so we can satisfy
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// GetIsMainThread calls that occur post-Shutdown.
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mMainThread->GetPRThread(&mMainPRThread);
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#ifdef XP_WIN
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TlsSetValue(gTLSThreadIDIndex, (void*) mozilla::threads::Main);
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#elif defined(NS_TLS)
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gTLSThreadID = mozilla::threads::Main;
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#endif
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mInitialized = true;
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return NS_OK;
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}
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void
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nsThreadManager::Shutdown()
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{
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MOZ_ASSERT(NS_IsMainThread(), "shutdown not called from main thread");
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// Prevent further access to the thread manager (no more new threads!)
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//
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// XXX What happens if shutdown happens before NewThread completes?
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// Fortunately, NewThread is only called on the main thread for now.
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//
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mInitialized = false;
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// Empty the main thread event queue before we begin shutting down threads.
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NS_ProcessPendingEvents(mMainThread);
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// We gather the threads from the hashtable into a list, so that we avoid
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// holding the hashtable lock while calling nsIThread::Shutdown.
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nsThreadArray threads;
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{
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MutexAutoLock lock(*mLock);
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mThreadsByPRThread.Enumerate(AppendAndRemoveThread, &threads);
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}
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// It's tempting to walk the list of threads here and tell them each to stop
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// accepting new events, but that could lead to badness if one of those
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// threads is stuck waiting for a response from another thread. To do it
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// right, we'd need some way to interrupt the threads.
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//
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// Instead, we process events on the current thread while waiting for threads
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// to shutdown. This means that we have to preserve a mostly functioning
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// world until such time as the threads exit.
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// Shutdown all threads that require it (join with threads that we created).
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for (uint32_t i = 0; i < threads.Length(); ++i) {
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nsThread *thread = threads[i];
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if (thread->ShutdownRequired())
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thread->Shutdown();
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}
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// In case there are any more events somehow...
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NS_ProcessPendingEvents(mMainThread);
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// There are no more background threads at this point.
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// Clear the table of threads.
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{
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MutexAutoLock lock(*mLock);
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mThreadsByPRThread.Clear();
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}
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// Normally thread shutdown clears the observer for the thread, but since the
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// main thread is special we do it manually here after we're sure all events
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// have been processed.
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mMainThread->SetObserver(nullptr);
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mMainThread->ClearObservers();
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// Release main thread object.
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mMainThread = nullptr;
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mLock = nullptr;
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// Remove the TLS entry for the main thread.
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PR_SetThreadPrivate(mCurThreadIndex, nullptr);
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}
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void
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nsThreadManager::RegisterCurrentThread(nsThread *thread)
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{
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MOZ_ASSERT(thread->GetPRThread() == PR_GetCurrentThread(), "bad thread");
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MutexAutoLock lock(*mLock);
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++mCurrentNumberOfThreads;
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if (mCurrentNumberOfThreads > mHighestNumberOfThreads) {
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mHighestNumberOfThreads = mCurrentNumberOfThreads;
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}
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mThreadsByPRThread.Put(thread->GetPRThread(), thread); // XXX check OOM?
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NS_ADDREF(thread); // for TLS entry
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PR_SetThreadPrivate(mCurThreadIndex, thread);
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}
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void
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nsThreadManager::UnregisterCurrentThread(nsThread *thread)
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{
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MOZ_ASSERT(thread->GetPRThread() == PR_GetCurrentThread(), "bad thread");
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MutexAutoLock lock(*mLock);
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--mCurrentNumberOfThreads;
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mThreadsByPRThread.Remove(thread->GetPRThread());
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PR_SetThreadPrivate(mCurThreadIndex, nullptr);
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// Ref-count balanced via ReleaseObject
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}
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nsThread *
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nsThreadManager::GetCurrentThread()
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{
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// read thread local storage
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void *data = PR_GetThreadPrivate(mCurThreadIndex);
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if (data)
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return static_cast<nsThread *>(data);
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if (!mInitialized) {
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return nullptr;
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}
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// OK, that's fine. We'll dynamically create one :-)
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nsRefPtr<nsThread> thread = new nsThread(nsThread::NOT_MAIN_THREAD, 0);
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if (!thread || NS_FAILED(thread->InitCurrentThread()))
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return nullptr;
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return thread.get(); // reference held in TLS
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}
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NS_IMETHODIMP
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nsThreadManager::NewThread(uint32_t creationFlags,
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uint32_t stackSize,
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nsIThread **result)
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{
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// No new threads during Shutdown
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if (NS_WARN_IF(!mInitialized))
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return NS_ERROR_NOT_INITIALIZED;
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nsThread *thr = new nsThread(nsThread::NOT_MAIN_THREAD, stackSize);
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if (!thr)
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return NS_ERROR_OUT_OF_MEMORY;
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NS_ADDREF(thr);
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nsresult rv = thr->Init();
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if (NS_FAILED(rv)) {
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NS_RELEASE(thr);
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return rv;
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}
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// At this point, we expect that the thread has been registered in mThread;
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// however, it is possible that it could have also been replaced by now, so
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// we cannot really assert that it was added.
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*result = thr;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsThreadManager::GetThreadFromPRThread(PRThread *thread, nsIThread **result)
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{
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// Keep this functioning during Shutdown
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if (NS_WARN_IF(!mMainThread))
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return NS_ERROR_NOT_INITIALIZED;
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if (NS_WARN_IF(!thread))
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return NS_ERROR_INVALID_ARG;
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nsRefPtr<nsThread> temp;
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{
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MutexAutoLock lock(*mLock);
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mThreadsByPRThread.Get(thread, getter_AddRefs(temp));
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}
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NS_IF_ADDREF(*result = temp);
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return NS_OK;
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}
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NS_IMETHODIMP
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nsThreadManager::GetMainThread(nsIThread **result)
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{
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// Keep this functioning during Shutdown
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if (NS_WARN_IF(!mMainThread))
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return NS_ERROR_NOT_INITIALIZED;
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NS_ADDREF(*result = mMainThread);
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return NS_OK;
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}
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NS_IMETHODIMP
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nsThreadManager::GetCurrentThread(nsIThread **result)
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{
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// Keep this functioning during Shutdown
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if (NS_WARN_IF(!mMainThread))
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return NS_ERROR_NOT_INITIALIZED;
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*result = GetCurrentThread();
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if (!*result)
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return NS_ERROR_OUT_OF_MEMORY;
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NS_ADDREF(*result);
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return NS_OK;
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}
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NS_IMETHODIMP
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nsThreadManager::GetIsMainThread(bool *result)
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{
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// This method may be called post-Shutdown
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*result = (PR_GetCurrentThread() == mMainPRThread);
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return NS_OK;
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}
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uint32_t
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nsThreadManager::GetHighestNumberOfThreads()
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{
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MutexAutoLock lock(*mLock);
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return mHighestNumberOfThreads;
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}
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