gecko/xpcom/threads/nsThreadManager.cpp

281 lines
7.7 KiB
C++

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