mirror of
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304 lines
8.1 KiB
C++
304 lines
8.1 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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*/
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/*
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A stack-based lock object that makes using PRLock a bit more
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convenient. It acquires the monitor when constructed, and releases
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it when it goes out of scope.
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For example,
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class Foo {
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private:
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PRLock* mLock;
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public:
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Foo(void) {
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mLock = PR_NewLock();
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}
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virtual ~Foo(void) {
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PR_DestroyLock(mLock);
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}
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void ThreadSafeMethod(void) {
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// we're don't hold the lock yet...
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nsAutoLock lock(mLock);
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// ...but now we do.
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// we even can do wacky stuff like return from arbitrary places w/o
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// worrying about forgetting to release the lock
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if (some_weird_condition)
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return;
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// otherwise do some other stuff
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}
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void ThreadSafeBlockScope(void) {
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// we're not in the lock here...
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{
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nsAutoLock lock(mLock);
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// but we are now, at least until the block scope closes
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}
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// ...now we're not in the lock anymore
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}
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};
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*/
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#ifndef nsAutoLock_h__
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#define nsAutoLock_h__
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#include "nscore.h"
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#include "prlock.h"
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#include "prlog.h"
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class NS_COM nsAutoLockBase {
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protected:
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nsAutoLockBase() {}
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enum nsAutoLockType {eAutoLock, eAutoMonitor, eAutoCMonitor};
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#ifdef DEBUG
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nsAutoLockBase(void* addr, nsAutoLockType type);
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~nsAutoLockBase();
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void* mAddr;
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nsAutoLockBase* mDown;
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nsAutoLockType mType;
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#else
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nsAutoLockBase(void* addr, nsAutoLockType type) {}
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~nsAutoLockBase() {}
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#endif
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};
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// If you ever decide that you need to add a non-inline method to this
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// class, be sure to change the class declaration to "class NS_COM
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// nsAutoLock".
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class NS_COM nsAutoLock : public nsAutoLockBase {
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private:
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PRLock* mLock;
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PRBool mLocked;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoLock(void) {}
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nsAutoLock(nsAutoLock& /*aLock*/) {}
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nsAutoLock& operator =(nsAutoLock& /*aLock*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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#if (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95))
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static void* operator new(size_t /*size*/) throw () {
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#else
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static void* operator new(size_t /*size*/) {
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#endif
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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public:
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nsAutoLock(PRLock* aLock)
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: nsAutoLockBase(aLock, eAutoLock),
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mLock(aLock),
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mLocked(PR_TRUE) {
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PR_ASSERT(mLock);
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// This will assert deep in the bowels of NSPR if you attempt
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// to re-enter the lock.
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PR_Lock(mLock);
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}
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~nsAutoLock(void) {
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if (mLocked)
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PR_Unlock(mLock);
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}
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void lock() {
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PR_ASSERT(!mLocked);
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PR_Lock(mLock);
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mLocked = PR_TRUE;
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}
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void unlock() {
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PR_ASSERT(mLocked);
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PR_Unlock(mLock);
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mLocked = PR_FALSE;
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}
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};
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////////////////////////////////////////////////////////////////////////////////
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// Same sort of shit here. Imagine if you will:
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//
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// nsresult MyClass::MyMethod(...) {
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// nsAutoMonitor mon(this); // or some random object as a monitor
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// ...
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// // go ahead and do deeply nested returns...
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// return NS_ERROR_FAILURE;
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// ...
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// // or call Wait or Notify...
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// mon.Wait();
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// ...
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// // cleanup is automatic
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// }
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#include "prcmon.h"
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#include "nsError.h"
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class NS_COM nsAutoMonitor : public nsAutoLockBase {
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public:
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static PRMonitor* NewMonitor(const char* name);
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static void DestroyMonitor(PRMonitor* mon);
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nsAutoMonitor(PRMonitor* mon)
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: nsAutoLockBase((void*)mon, eAutoMonitor),
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mMonitor(mon)
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{
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NS_ASSERTION(mMonitor, "null monitor");
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PR_EnterMonitor(mMonitor);
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}
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~nsAutoMonitor() {
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#ifdef DEBUG
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PRStatus status =
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#endif
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PR_ExitMonitor(mMonitor);
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NS_ASSERTION(status == PR_SUCCESS, "PR_ExitMonitor failed");
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}
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void Enter();
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void Exit();
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nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
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return PR_Wait(mMonitor, interval) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult Notify() {
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return PR_Notify(mMonitor) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult NotifyAll() {
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return PR_NotifyAll(mMonitor) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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private:
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PRMonitor* mMonitor;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoMonitor(void) {}
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nsAutoMonitor(nsAutoMonitor& /*aMon*/) {}
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nsAutoMonitor& operator =(nsAutoMonitor& /*aMon*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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#if (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95))
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static void* operator new(size_t /*size*/) throw () {
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#else
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static void* operator new(size_t /*size*/) {
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#endif
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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};
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////////////////////////////////////////////////////////////////////////////////
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// Once again, this time with a cache...
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// (Using this avoids the need to allocate a PRMonitor, which may be useful when
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// a large number of objects of the same class need associated monitors.)
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#include "prcmon.h"
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#include "nsError.h"
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class NS_COM nsAutoCMonitor : public nsAutoLockBase {
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public:
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nsAutoCMonitor(void* lockObject)
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: nsAutoLockBase(lockObject, eAutoCMonitor),
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mLockObject(lockObject)
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{
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NS_ASSERTION(lockObject, "null lock object");
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PR_CEnterMonitor(mLockObject);
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}
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~nsAutoCMonitor() {
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#ifdef DEBUG
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PRStatus status =
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#endif
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PR_CExitMonitor(mLockObject);
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NS_ASSERTION(status == PR_SUCCESS, "PR_CExitMonitor failed");
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}
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void Enter();
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void Exit();
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nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
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return PR_CWait(mLockObject, interval) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult Notify() {
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return PR_CNotify(mLockObject) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult NotifyAll() {
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return PR_CNotifyAll(mLockObject) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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private:
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void* mLockObject;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoCMonitor(void) {}
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nsAutoCMonitor(nsAutoCMonitor& /*aMon*/) {}
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nsAutoCMonitor& operator =(nsAutoCMonitor& /*aMon*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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#if (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95))
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static void* operator new(size_t /*size*/) throw() {
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#else
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static void* operator new(size_t /*size*/) {
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#endif
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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};
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#endif // nsAutoLock_h__
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