nsThreadManager.cpp
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla code.
*
* The Initial Developer of the Original Code is Google Inc.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@meer.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
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* decision by deleting the provisions above and replace them with the notice
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* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "nsThreadManager.h"
#include "nsThread.h"
#include "nsThreadUtils.h"
#include "nsIClassInfoImpl.h"
#include "nsTArray.h"
#include "nsAutoPtr.h"
#include "nsCycleCollectorUtils.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;
}
//-----------------------------------------------------------------------------
nsThreadManager nsThreadManager::sInstance;
// statically allocated instance
NS_IMETHODIMP_(nsrefcnt) nsThreadManager::AddRef() { return 2; }
NS_IMETHODIMP_(nsrefcnt) nsThreadManager::Release() { return 1; }
NS_IMPL_CLASSINFO(nsThreadManager, NULL,
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 (!mThreadsByPRThread.Init())
return NS_ERROR_OUT_OF_MEMORY;
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 = nsnull;
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()
{
NS_ASSERTION(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 (PRUint32 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(nsnull);
mMainThread->ClearObservers();
// Release main thread object.
mMainThread = nsnull;
mLock = nsnull;
// Remove the TLS entry for the main thread.
PR_SetThreadPrivate(mCurThreadIndex, nsnull);
}
void
nsThreadManager::RegisterCurrentThread(nsThread *thread)
{
NS_ASSERTION(thread->GetPRThread() == PR_GetCurrentThread(), "bad thread");
MutexAutoLock lock(*mLock);
mThreadsByPRThread.Put(thread->GetPRThread(), thread); // XXX check OOM?
NS_ADDREF(thread); // for TLS entry
PR_SetThreadPrivate(mCurThreadIndex, thread);
}
void
nsThreadManager::UnregisterCurrentThread(nsThread *thread)
{
NS_ASSERTION(thread->GetPRThread() == PR_GetCurrentThread(), "bad thread");
MutexAutoLock lock(*mLock);
mThreadsByPRThread.Remove(thread->GetPRThread());
PR_SetThreadPrivate(mCurThreadIndex, nsnull);
// 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 nsnull;
}
// 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 nsnull;
return thread.get(); // reference held in TLS
}
NS_IMETHODIMP
nsThreadManager::NewThread(PRUint32 creationFlags,
PRUint32 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;
}
NS_IMETHODIMP
nsThreadManager::GetIsCycleCollectorThread(bool *result)
{
*result = bool(NS_IsCycleCollectorThread());
return NS_OK;
}