gecko-dev/xpcom/threads/nsAutoLock.h
sspitzer%netscape.com 9bef23e66b fix warnings
1999-06-26 04:17:58 +00:00

239 lines
6.4 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
/*
A stack-based lock object that makes using PRLock a bit more
convenient. It acquires the monitor when constructed, and releases
it when it goes out of scope.
For example,
class Foo {
private:
PRLock* mLock;
public:
Foo(void) {
mLock = PR_NewLock();
}
virtual ~Foo(void) {
PR_DestroyLock(mLock);
}
void ThreadSafeMethod(void) {
// we're don't hold the lock yet...
nsAutoLock lock(mLock);
// ...but now we do.
// we even can do wacky stuff like return from arbitrary places w/o
// worrying about forgetting to release the lock
if (some_weird_condition)
return;
// otherwise do some other stuff
}
void ThreadSafeBlockScope(void) {
// we're not in the lock here...
{
nsAutoLock lock(mLock);
// but we are now, at least until the block scope closes
}
// ...now we're not in the lock anymore
}
};
*/
#ifndef nsAutoLock_h__
#define nsAutoLock_h__
#include "nscore.h"
#include "prlock.h"
#include "prlog.h"
// If you ever decide that you need to add a non-inline method to this
// class, be sure to change the class declaration to "class NS_COM
// nsAutoLock".
class nsAutoLock {
private:
PRLock* mLock;
// Not meant to be implemented. This makes it a compiler error to
// construct or assign an nsAutoLock object incorrectly.
nsAutoLock(void) {}
nsAutoLock(nsAutoLock& aLock) {}
nsAutoLock& operator =(nsAutoLock& aLock) {
return *this;
}
// Not meant to be implemented. This makes it a compiler error to
// attempt to create an nsAutoLock object on the heap.
static void* operator new(size_t size) {
return nsnull;
}
static void operator delete(void* memory) {}
public:
nsAutoLock(PRLock* aLock) : mLock(aLock) {
PR_ASSERT(mLock);
// This will assert deep in the bowels of NSPR if you attempt
// to re-enter the lock.
PR_Lock(mLock);
}
~nsAutoLock(void) {
PR_Unlock(mLock);
}
};
////////////////////////////////////////////////////////////////////////////////
// Same sort of shit here. Imagine if you will:
//
// nsresult MyClass::MyMethod(...) {
// nsAutoMonitor mon(this); // or some random object as a monitor
// ...
// // go ahead and do deeply nested returns...
// return NS_ERROR_FAILURE;
// ...
// // or call Wait or Notify...
// mon.Wait();
// ...
// // cleanup is automatic
// }
#include "prcmon.h"
#include "nsError.h"
class nsAutoMonitor {
public:
nsAutoMonitor(PRMonitor* mon)
: mMonitor(mon)
{
NS_ASSERTION(mMonitor, "null lock object");
PR_EnterMonitor(mMonitor);
}
~nsAutoMonitor() {
PRStatus status;
status = PR_ExitMonitor(mMonitor);
NS_ASSERTION(status == PR_SUCCESS, "PR_CExitMonitor failed");
}
nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
return PR_Wait(mMonitor, interval) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
nsresult Notify() {
return PR_Notify(mMonitor) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
nsresult NotifyAll() {
return PR_NotifyAll(mMonitor) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
private:
PRMonitor* mMonitor;
// Not meant to be implemented. This makes it a compiler error to
// construct or assign an nsAutoLock object incorrectly.
nsAutoMonitor(void) {}
nsAutoMonitor(nsAutoMonitor& aMon) {}
nsAutoMonitor& operator =(nsAutoMonitor& aMon) {
return *this;
}
// Not meant to be implemented. This makes it a compiler error to
// attempt to create an nsAutoLock object on the heap.
static void* operator new(size_t size) {
return nsnull;
}
static void operator delete(void* memory) {}
};
////////////////////////////////////////////////////////////////////////////////
// Once again, this time with a cache...
// (Using this avoids the need to allocate a PRMonitor, which may be useful when
// a large number of objects of the same class need associated monitors.)
#include "prcmon.h"
#include "nsError.h"
class nsAutoCMonitor {
public:
nsAutoCMonitor(void* lockObject)
: mLockObject(lockObject)
{
NS_ASSERTION(lockObject, "null lock object");
PR_CEnterMonitor(mLockObject);
}
~nsAutoCMonitor() {
PRStatus status;
status = PR_CExitMonitor(mLockObject);
NS_ASSERTION(status == PR_SUCCESS, "PR_CExitMonitor failed");
}
nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
return PR_CWait(mLockObject, interval) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
nsresult Notify() {
return PR_CNotify(mLockObject) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
nsresult NotifyAll() {
return PR_CNotifyAll(mLockObject) == PR_SUCCESS
? NS_OK : NS_ERROR_FAILURE;
}
private:
void* mLockObject;
// Not meant to be implemented. This makes it a compiler error to
// construct or assign an nsAutoLock object incorrectly.
nsAutoCMonitor(void) {}
nsAutoCMonitor(nsAutoCMonitor& aMon) {}
nsAutoCMonitor& operator =(nsAutoCMonitor& aMon) {
return *this;
}
// Not meant to be implemented. This makes it a compiler error to
// attempt to create an nsAutoLock object on the heap.
static void* operator new(size_t size) {
return nsnull;
}
static void operator delete(void* memory) {}
};
#endif // nsAutoLock_h__