prcvar.h
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- /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
- /* ***** 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 the Netscape Portable Runtime (NSPR).
- *
- * The Initial Developer of the Original Code is
- * Netscape Communications Corporation.
- * Portions created by the Initial Developer are Copyright (C) 1998-2000
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *
- * 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
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * 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 ***** */
- #ifndef prcvar_h___
- #define prcvar_h___
- #include "prlock.h"
- #include "prinrval.h"
- PR_BEGIN_EXTERN_C
- typedef struct PRCondVar PRCondVar;
- /*
- ** Create a new condition variable.
- **
- ** "lock" is the lock used to protect the condition variable.
- **
- ** Condition variables are synchronization objects that threads can use
- ** to wait for some condition to occur.
- **
- ** This may fail if memory is tight or if some operating system resource
- ** is low. In such cases, a NULL will be returned.
- */
- NSPR_API(PRCondVar*) PR_NewCondVar(PRLock *lock);
- /*
- ** Destroy a condition variable. There must be no thread
- ** waiting on the condvar. The caller is responsible for guaranteeing
- ** that the condvar is no longer in use.
- **
- */
- NSPR_API(void) PR_DestroyCondVar(PRCondVar *cvar);
- /*
- ** The thread that waits on a condition is blocked in a "waiting on
- ** condition" state until another thread notifies the condition or a
- ** caller specified amount of time expires. The lock associated with
- ** the condition variable will be released, which must have be held
- ** prior to the call to wait.
- **
- ** Logically a notified thread is moved from the "waiting on condition"
- ** state and made "ready." When scheduled, it will attempt to reacquire
- ** the lock that it held when wait was called.
- **
- ** The timeout has two well known values, PR_INTERVAL_NO_TIMEOUT and
- ** PR_INTERVAL_NO_WAIT. The former value requires that a condition be
- ** notified (or the thread interrupted) before it will resume from the
- ** wait. If the timeout has a value of PR_INTERVAL_NO_WAIT, the effect
- ** is to release the lock, possibly causing a rescheduling within the
- ** runtime, then immediately attempting to reacquire the lock and resume.
- **
- ** Any other value for timeout will cause the thread to be rescheduled
- ** either due to explicit notification or an expired interval. The latter
- ** must be determined by treating time as one part of the monitored data
- ** being protected by the lock and tested explicitly for an expired
- ** interval.
- **
- ** Returns PR_FAILURE if the caller has not locked the lock associated
- ** with the condition variable or the thread was interrupted (PR_Interrupt()).
- ** The particular reason can be extracted with PR_GetError().
- */
- NSPR_API(PRStatus) PR_WaitCondVar(PRCondVar *cvar, PRIntervalTime timeout);
- /*
- ** Notify ONE thread that is currently waiting on 'cvar'. Which thread is
- ** dependent on the implementation of the runtime. Common sense would dictate
- ** that all threads waiting on a single condition have identical semantics,
- ** therefore which one gets notified is not significant.
- **
- ** The calling thead must hold the lock that protects the condition, as
- ** well as the invariants that are tightly bound to the condition, when
- ** notify is called.
- **
- ** Returns PR_FAILURE if the caller has not locked the lock associated
- ** with the condition variable.
- */
- NSPR_API(PRStatus) PR_NotifyCondVar(PRCondVar *cvar);
- /*
- ** Notify all of the threads waiting on the condition variable. The order
- ** that the threads are notified is indeterminant. The lock that protects
- ** the condition must be held.
- **
- ** Returns PR_FAILURE if the caller has not locked the lock associated
- ** with the condition variable.
- */
- NSPR_API(PRStatus) PR_NotifyAllCondVar(PRCondVar *cvar);
- PR_END_EXTERN_C
- #endif /* prcvar_h___ */