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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 ***** */
+
+/*
+** File: prrwlock.h
+** Description: API to basic reader-writer lock functions of NSPR.
+**
+**/
+
+#ifndef prrwlock_h___
+#define prrwlock_h___
+
+#include "prtypes.h"
+
+PR_BEGIN_EXTERN_C
+
+/*
+ * PRRWLock --
+ *
+ * The reader writer lock, PRRWLock, is an opaque object to the clients
+ * of NSPR. All routines operate on a pointer to this opaque entity.
+ */
+
+
+typedef struct PRRWLock PRRWLock;
+
+#define PR_RWLOCK_RANK_NONE 0
+
+
+/***********************************************************************
+** FUNCTION: PR_NewRWLock
+** DESCRIPTION:
+** Returns a pointer to a newly created reader-writer lock object.
+** INPUTS: Lock rank
+** Lock name
+** OUTPUTS: void
+** RETURN: PRRWLock*
+** If the lock cannot be created because of resource constraints, NULL
+** is returned.
+**
+***********************************************************************/
+NSPR_API(PRRWLock*) PR_NewRWLock(PRUint32 lock_rank, const char *lock_name);
+
+/***********************************************************************
+** FUNCTION: PR_DestroyRWLock
+** DESCRIPTION:
+** Destroys a given RW lock object.
+** INPUTS: PRRWLock *lock - Lock to be freed.
+** OUTPUTS: void
+** RETURN: None
+***********************************************************************/
+NSPR_API(void) PR_DestroyRWLock(PRRWLock *lock);
+
+/***********************************************************************
+** FUNCTION: PR_RWLock_Rlock
+** DESCRIPTION:
+** Apply a read lock (non-exclusive) on a RWLock
+** INPUTS: PRRWLock *lock - Lock to be read-locked.
+** OUTPUTS: void
+** RETURN: None
+***********************************************************************/
+NSPR_API(void) PR_RWLock_Rlock(PRRWLock *lock);
+
+/***********************************************************************
+** FUNCTION: PR_RWLock_Wlock
+** DESCRIPTION:
+** Apply a write lock (exclusive) on a RWLock
+** INPUTS: PRRWLock *lock - Lock to write-locked.
+** OUTPUTS: void
+** RETURN: None
+***********************************************************************/
+NSPR_API(void) PR_RWLock_Wlock(PRRWLock *lock);
+
+/***********************************************************************
+** FUNCTION: PR_RWLock_Unlock
+** DESCRIPTION:
+** Release a RW lock. Unlocking an unlocked lock has undefined results.
+** INPUTS: PRRWLock *lock - Lock to unlocked.
+** OUTPUTS: void
+** RETURN: void
+***********************************************************************/
+NSPR_API(void) PR_RWLock_Unlock(PRRWLock *lock);
+
+PR_END_EXTERN_C
+
+#endif /* prrwlock_h___ */