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diff --git a/nsprpub/pr/include/prrwlock.h b/nsprpub/pr/include/prrwlock.h
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+** 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___ */