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nsslocks.c
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00001 /* ***** BEGIN LICENSE BLOCK *****
00002  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00003  *
00004  * The contents of this file are subject to the Mozilla Public License Version
00005  * 1.1 (the "License"); you may not use this file except in compliance with
00006  * the License. You may obtain a copy of the License at
00007  * http://www.mozilla.org/MPL/
00008  *
00009  * Software distributed under the License is distributed on an "AS IS" basis,
00010  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00011  * for the specific language governing rights and limitations under the
00012  * License.
00013  *
00014  * The Original Code is the Netscape security libraries.
00015  *
00016  * The Initial Developer of the Original Code is
00017  * Netscape Communications Corporation.
00018  * Portions created by the Initial Developer are Copyright (C) 1994-2000
00019  * the Initial Developer. All Rights Reserved.
00020  *
00021  * Contributor(s):
00022  *
00023  * Alternatively, the contents of this file may be used under the terms of
00024  * either the GNU General Public License Version 2 or later (the "GPL"), or
00025  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00026  * in which case the provisions of the GPL or the LGPL are applicable instead
00027  * of those above. If you wish to allow use of your version of this file only
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00030  * decision by deleting the provisions above and replace them with the notice
00031  * and other provisions required by the GPL or the LGPL. If you do not delete
00032  * the provisions above, a recipient may use your version of this file under
00033  * the terms of any one of the MPL, the GPL or the LGPL.
00034  *
00035  * ***** END LICENSE BLOCK ***** */
00036 
00037 /*
00038  * nsslocks.h - threadsafe functions to initialize lock pointers.
00039  *
00040  * NOTE - These are not public interfaces
00041  *
00042  * $Id: nsslocks.c,v 1.5 2004/04/25 15:03:17 gerv%gerv.net Exp $
00043  */
00044 
00045 #include "seccomon.h"
00046 #include "nsslocks.h"
00047 #include "pratom.h"
00048 #include "prthread.h"
00049 
00050 /* Given the address of a (global) pointer to a PZLock, 
00051  * atomicly create the lock and initialize the (global) pointer, 
00052  * if it is not already created/initialized.
00053  */
00054 
00055 SECStatus 
00056 __nss_InitLock(   PZLock    **ppLock, nssILockType ltype )
00057 {
00058     static PRInt32  initializers;
00059 
00060     PORT_Assert( ppLock != NULL);
00061 
00062     /* atomically initialize the lock */
00063     while (!*ppLock) {
00064         PRInt32 myAttempt = PR_AtomicIncrement(&initializers);
00065         if (myAttempt == 1) {
00066             if (!*ppLock) {
00067                 *ppLock = PZ_NewLock(ltype);
00068             }
00069             (void) PR_AtomicDecrement(&initializers);
00070             break;
00071         }
00072         PR_Sleep(PR_INTERVAL_NO_WAIT);          /* PR_Yield() */
00073         (void) PR_AtomicDecrement(&initializers);
00074     }
00075 
00076     return (*ppLock != NULL) ? SECSuccess : SECFailure;
00077 }
00078 
00079 SECStatus 
00080 nss_InitLock(   PZLock    **ppLock, nssILockType ltype )
00081 {
00082     return __nss_InitLock(ppLock, ltype);
00083 }
00084 
00085 /* Given the address of a (global) pointer to a PZMonitor, 
00086  * atomicly create the monitor and initialize the (global) pointer, 
00087  * if it is not already created/initialized.
00088  */
00089 
00090 SECStatus 
00091 nss_InitMonitor(PZMonitor **ppMonitor, nssILockType ltype )
00092 {
00093     static PRInt32  initializers;
00094 
00095     PORT_Assert( ppMonitor != NULL);
00096 
00097     /* atomically initialize the lock */
00098     while (!*ppMonitor) {
00099         PRInt32 myAttempt = PR_AtomicIncrement(&initializers);
00100         if (myAttempt == 1) {
00101             if (!*ppMonitor) {
00102                 *ppMonitor = PZ_NewMonitor(ltype);
00103             }
00104             (void) PR_AtomicDecrement(&initializers);
00105             break;
00106         }
00107         PR_Sleep(PR_INTERVAL_NO_WAIT);          /* PR_Yield() */
00108         (void) PR_AtomicDecrement(&initializers);
00109     }
00110 
00111     return (*ppMonitor != NULL) ? SECSuccess : SECFailure;
00112 }