php5-apc retained as dummy package.

[php5-apc.git] / apc_futex.c

diff --git a/apc_futex.c b/apc_futex.c
deleted file mode 100644 (file)
index 61ccc76..0000000
--- a/apc_futex.c
+++ /dev/null
@@ -1,116 +0,0 @@
-/*
-  +----------------------------------------------------------------------+
-  | APC                                                                  |
-  +----------------------------------------------------------------------+
-  | Copyright (c) 2008 The PHP Group                                     |
-  +----------------------------------------------------------------------+
-  | This source file is subject to version 3.01 of the PHP license,      |
-  | that is bundled with this package in the file LICENSE, and is        |
-  | available through the world-wide-web at the following url:           |
-  | http://www.php.net/license/3_01.txt                                  |
-  | If you did not receive a copy of the PHP license and are unable to   |
-  | obtain it through the world-wide-web, please send a note to          |
-  | license@php.net so we can mail you a copy immediately.               |
-  +----------------------------------------------------------------------+
-  | Authors: Brian Shire <shire@php.net>                                 |
-  +----------------------------------------------------------------------+
-
- */
-
-/* $Id: apc_futex.c,v 3.2.2.1 2008/05/11 18:57:00 rasmus Exp $ */
-
-/***************************************************************************
-* Futex (Fast Userspace Mutex) support for APC
-* 
-* Futex support provides user space locking with system calls only
-* for the contended cases.  Some required reading for this functionality is:
-*
-* 'Fuss, Futexes and Furwocks: Fast Userlevel Locking in Linux' 
-*  by Hubertus Franke, Rusty Russell, and Matthew Kirkwood
-*   http://www.realitydiluted.com/nptl-uclibc/docs/futex.pdf
-*
-* 'Futexes are Tricky' by Ulrich Drepper 
-*    http://people.redhat.com/drepper/futex.pdf
-*
-* 
-* This implementation is optimized and designed for the i386 and x86_64 
-* architectures.  Other architectures may require additional design 
-* to efficiently and safely implement this functionality. 
-*
-* Lock values are:
-* 0 = Unlocked
-* 1 = Locked without any waiting processes
-* 2 = Locked with an unknown number of waiting processes
-*
-***************************************************************************/
-
-#include "apc.h"
-#include "apc_futex.h"
-
-#ifdef APC_FUTEX_LOCKS
-
-
-inline int apc_futex_create()
-{
-    return 0;
-}
-
-inline void apc_futex_destroy(volatile int* lock)
-{
-    return;
-}
-
-void apc_futex_lock(volatile int* lock)
-{
-    int c;
-  
-    /*  Attempt to obtain a lock if not currently locked.  If the previous
-     *  value was not 0 then we did not obtain the lock, and must wait.
-     *  If the previous value was 1 (has no waiting processes) then we
-     *  set the lock to 2 before blocking on the futex wait operation.  
-     *  This implementation suffers from the possible difficulty of 
-     *  efficently implementing the atomic xchg operation on some
-     *  architectures, and could also cause unecessary wake operations by
-     *  setting the lock to 2 when there are no additional waiters.
-     */ 
-    if((c = apc_cmpxchg(lock, 0, 1)) != 0) {
-        if(c != 2) {
-            c = apc_xchg(lock, 2);
-        }
-        while(c != 0) {
-            apc_futex_wait(lock, 2);
-            c = apc_xchg(lock, 2);
-        }
-    }
-    
-}
-
-/* non-blocking lock returns 1 when the lock has been obtained, 0 if it would block */
-inline zend_bool apc_futex_nonblocking_lock(volatile int* lock)
-{
-    return apc_cmpxchg(lock, 0, 1) == 0;
-}
-
-
-inline void apc_futex_unlock(volatile int* lock)
-{
-    /* set the lock to 0, if it's previous values was not 1 (no waiters)
-     * then perform a wake operation on one process letting it know the lock 
-     * is available.  This is an optimization to save wake calls if there
-     * are no waiting processes for the lock 
-     */
-    if(apc_xchg(lock,0) != 1) {
-        apc_futex_wake(lock, 1);
-    }
-}
-
-#endif
-
-/*
- * Local variables:
- * tab-width: 4
- * c-basic-offset: 4
- * End:
- * vim600: expandtab sw=4 ts=4 sts=4 fdm=marker
- * vim<600: expandtab sw=4 ts=4 sts=4
- */