127 lines
5.0 KiB
C
127 lines
5.0 KiB
C
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the Netscape Portable Runtime (NSPR).
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998-2000
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef prcvar_h___
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#define prcvar_h___
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#include "prlock.h"
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#include "prinrval.h"
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PR_BEGIN_EXTERN_C
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typedef struct PRCondVar PRCondVar;
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/*
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** Create a new condition variable.
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**
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** "lock" is the lock used to protect the condition variable.
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**
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** Condition variables are synchronization objects that threads can use
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** to wait for some condition to occur.
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**
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** This may fail if memory is tight or if some operating system resource
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** is low. In such cases, a NULL will be returned.
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*/
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NSPR_API(PRCondVar*) PR_NewCondVar(PRLock *lock);
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/*
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** Destroy a condition variable. There must be no thread
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** waiting on the condvar. The caller is responsible for guaranteeing
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** that the condvar is no longer in use.
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**
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*/
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NSPR_API(void) PR_DestroyCondVar(PRCondVar *cvar);
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/*
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** The thread that waits on a condition is blocked in a "waiting on
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** condition" state until another thread notifies the condition or a
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** caller specified amount of time expires. The lock associated with
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** the condition variable will be released, which must have be held
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** prior to the call to wait.
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**
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** Logically a notified thread is moved from the "waiting on condition"
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** state and made "ready." When scheduled, it will attempt to reacquire
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** the lock that it held when wait was called.
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**
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** The timeout has two well known values, PR_INTERVAL_NO_TIMEOUT and
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** PR_INTERVAL_NO_WAIT. The former value requires that a condition be
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** notified (or the thread interrupted) before it will resume from the
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** wait. If the timeout has a value of PR_INTERVAL_NO_WAIT, the effect
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** is to release the lock, possibly causing a rescheduling within the
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** runtime, then immediately attempting to reacquire the lock and resume.
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**
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** Any other value for timeout will cause the thread to be rescheduled
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** either due to explicit notification or an expired interval. The latter
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** must be determined by treating time as one part of the monitored data
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** being protected by the lock and tested explicitly for an expired
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** interval.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable or the thread was interrupted (PR_Interrupt()).
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** The particular reason can be extracted with PR_GetError().
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*/
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NSPR_API(PRStatus) PR_WaitCondVar(PRCondVar *cvar, PRIntervalTime timeout);
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/*
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** Notify ONE thread that is currently waiting on 'cvar'. Which thread is
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** dependent on the implementation of the runtime. Common sense would dictate
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** that all threads waiting on a single condition have identical semantics,
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** therefore which one gets notified is not significant.
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**
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** The calling thead must hold the lock that protects the condition, as
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** well as the invariants that are tightly bound to the condition, when
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** notify is called.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable.
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*/
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NSPR_API(PRStatus) PR_NotifyCondVar(PRCondVar *cvar);
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/*
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** Notify all of the threads waiting on the condition variable. The order
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** that the threads are notified is indeterminant. The lock that protects
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** the condition must be held.
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**
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** Returns PR_FAILURE if the caller has not locked the lock associated
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** with the condition variable.
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*/
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NSPR_API(PRStatus) PR_NotifyAllCondVar(PRCondVar *cvar);
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PR_END_EXTERN_C
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#endif /* prcvar_h___ */
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