Viewing file:  apr_atomic.h (12.5 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* Portions of this software are based upon public domain software
* originally written at the National Center for Supercomputing Applications,
* University of Illinois, Urbana-Champaign.
*/
#ifndef APR_ATOMIC_H
#define APR_ATOMIC_H
/**
* @file apr_atomic.h
* @brief APR Atomic Operations
*/
#include "apr.h"
#include "apr_pools.h"
/* Platform includes for atomics */
#if defined(NETWARE) || defined(__MVS__) /* OS/390 */
#include <stdlib.h>
#elif defined(__FreeBSD__)
#include <machine/atomic.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup apr_atomic Atomic Operations
* @ingroup APR
* @{
*/
/* easiest way to get these documented for the moment */
#if defined(DOXYGEN)
/**
* structure for holding a atomic value.
* this number >only< has a 24 bit size on some platforms
*/
typedef apr_atomic_t;
/**
* this function is required on some platforms to initialize the
* atomic operation's internal structures
* @param p pool
* @return APR_SUCCESS on successful completion
*/
apr_status_t apr_atomic_init(apr_pool_t *p);
/**
* read the value stored in a atomic variable
* @param mem the pointer
* @warning on certain platforms this number is not stored
* directly in the pointer. in others it is
*/
apr_uint32_t apr_atomic_read(volatile apr_atomic_t *mem);
/**
* set the value for atomic.
* @param mem the pointer
* @param val the value
*/
void apr_atomic_set(volatile apr_atomic_t *mem, apr_uint32_t val);
/**
* Add 'val' to the atomic variable
* @param mem pointer to the atomic value
* @param val the addition
*/
void apr_atomic_add(volatile apr_atomic_t *mem, apr_uint32_t val);
/**
* increment the atomic variable by 1
* @param mem pointer to the atomic value
*/
void apr_atomic_inc(volatile apr_atomic_t *mem);
/**
* decrement the atomic variable by 1
* @param mem pointer to the atomic value
* @return zero if the value is zero, otherwise non-zero
*/
int apr_atomic_dec(volatile apr_atomic_t *mem);
/**
* compare the atomic's value with cmp.
* If they are the same swap the value with 'with'
* @param mem pointer to the atomic value
* @param with what to swap it with
* @param cmp the value to compare it to
* @return the old value of the atomic
* @warning do not mix apr_atomic's with the CAS function.
* on some platforms they may be implemented by different mechanisms
*/
apr_uint32_t apr_atomic_cas(volatile apr_uint32_t *mem, long with, long cmp);
/**
* compare the pointer's value with cmp.
* If they are the same swap the value with 'with'
* @param mem pointer to the pointer
* @param with what to swap it with
* @param cmp the value to compare it to
* @return the old value of the pointer
*/
void *apr_atomic_casptr(volatile void **mem, void *with, const void *cmp);
#else /* !DOXYGEN */
/* The following definitions provide optimized, OS-specific
* implementations of the APR atomic functions on various
* platforms. Any atomic operation that isn't redefined as
* a macro here will be declared as a function later, and
* apr_atomic.c will provide a mutex-based default implementation.
*/
#if defined(WIN32)
typedef LONG apr_atomic_t;
#define apr_atomic_add(mem, val) InterlockedExchangeAdd(mem,val)
#define apr_atomic_dec(mem) InterlockedDecrement(mem)
#define apr_atomic_inc(mem) InterlockedIncrement(mem)
#define apr_atomic_set(mem, val) InterlockedExchange(mem, val)
#define apr_atomic_read(mem) (*mem)
#define apr_atomic_cas(mem,with,cmp) InterlockedCompareExchange(mem,with,cmp)
#define apr_atomic_init(pool) APR_SUCCESS
#define apr_atomic_casptr(mem,with,cmp) InterlockedCompareExchangePointer(mem,with,cmp)
#elif defined(NETWARE)
#define apr_atomic_t unsigned long
#define apr_atomic_add(mem, val) atomic_add(mem,val)
#define apr_atomic_inc(mem) atomic_inc(mem)
#define apr_atomic_set(mem, val) (*mem = val)
#define apr_atomic_read(mem) (*mem)
#define apr_atomic_init(pool) APR_SUCCESS
#define apr_atomic_cas(mem,with,cmp) atomic_cmpxchg((unsigned long *)(mem),(unsigned long)(cmp),(unsigned long)(with))
int apr_atomic_dec(apr_atomic_t *mem);
void *apr_atomic_casptr(void **mem, void *with, const void *cmp);
#define APR_OVERRIDE_ATOMIC_DEC 1
#define APR_OVERRIDE_ATOMIC_CASPTR 1
inline int apr_atomic_dec(apr_atomic_t *mem)
{
atomic_dec(mem);
return *mem;
}
inline void *apr_atomic_casptr(void **mem, void *with, const void *cmp)
{
return (void*)atomic_cmpxchg((unsigned long *)mem,(unsigned long)cmp,(unsigned long)with);
}
#elif defined(__FreeBSD__)
#define apr_atomic_t apr_uint32_t
#define apr_atomic_add(mem, val) atomic_add_int(mem,val)
#define apr_atomic_dec(mem) atomic_subtract_int(mem,1)
#define apr_atomic_inc(mem) atomic_add_int(mem,1)
#define apr_atomic_set(mem, val) atomic_set_int(mem, val)
#define apr_atomic_read(mem) (*mem)
#elif (defined(__linux__) || defined(__EMX__)) && defined(__i386__) && !APR_FORCE_ATOMIC_GENERIC
#define apr_atomic_t apr_uint32_t
#define apr_atomic_cas(mem,with,cmp) \
({ apr_atomic_t prev; \
asm volatile ("lock; cmpxchgl %1, %2" \
: "=a" (prev) \
: "r" (with), "m" (*(mem)), "0"(cmp) \
: "memory"); \
prev;})
#define apr_atomic_add(mem, val) \
({ register apr_atomic_t last; \
do { \
last = *(mem); \
} while (apr_atomic_cas((mem), last + (val), last) != last); \
})
#define apr_atomic_dec(mem) \
({ register apr_atomic_t last; \
do { \
last = *(mem); \
} while (apr_atomic_cas((mem), last - 1, last) != last); \
(--last != 0); })
#define apr_atomic_inc(mem) \
({ register apr_atomic_t last; \
do { \
last = *(mem); \
} while (apr_atomic_cas((mem), last + 1, last) != last); \
})
#define apr_atomic_set(mem, val) (*(mem) = val)
#define apr_atomic_read(mem) (*(mem))
#define apr_atomic_init(pool) APR_SUCCESS
#elif defined(__MVS__) /* OS/390 */
#define apr_atomic_t cs_t
apr_int32_t apr_atomic_add(volatile apr_atomic_t *mem, apr_int32_t val);
apr_uint32_t apr_atomic_cas(volatile apr_atomic_t *mem, apr_uint32_t swap,
apr_uint32_t cmp);
#define APR_OVERRIDE_ATOMIC_ADD 1
#define APR_OVERRIDE_ATOMIC_CAS 1
#define apr_atomic_inc(mem) apr_atomic_add(mem, 1)
#define apr_atomic_dec(mem) apr_atomic_add(mem, -1)
#define apr_atomic_init(pool) APR_SUCCESS
/* warning: the following two operations, _read and _set, are atomic
* if the memory variables are aligned (the usual case).
*
* If you try really hard and manage to mis-align them, they are not
* guaranteed to be atomic on S/390. But then your program will blow up
* with SIGBUS on a sparc, or with a S0C6 abend if you use the mis-aligned
* variables with other apr_atomic_* operations on OS/390.
*/
#define apr_atomic_read(p) (*p)
#define apr_atomic_set(mem, val) (*mem = val)
#endif /* end big if-elseif switch for platform-specifics */
/* Default implementation of the atomic API
* The definitions above may override some or all of the
* atomic functions with optimized, platform-specific versions.
* Any operation that hasn't been overridden as a macro above
* is declared as a function here, unless APR_OVERRIDE_ATOMIC_[OPERATION]
* is defined. (The purpose of the APR_OVERRIDE_ATOMIC_* is
* to allow a platform to declare an apr_atomic_*() function
* with a different signature than the default.)
*/
#if !defined(apr_atomic_t)
#define apr_atomic_t apr_uint32_t
#endif
#if !defined(apr_atomic_init) && !defined(APR_OVERRIDE_ATOMIC_INIT)
apr_status_t apr_atomic_init(apr_pool_t *p);
#endif
#if !defined(apr_atomic_read) && !defined(APR_OVERRIDE_ATOMIC_READ)
#define apr_atomic_read(p) *p
#endif
#if !defined(apr_atomic_set) && !defined(APR_OVERRIDE_ATOMIC_SET)
void apr_atomic_set(volatile apr_atomic_t *mem, apr_uint32_t val);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#if !defined(apr_atomic_add) && !defined(APR_OVERRIDE_ATOMIC_ADD)
void apr_atomic_add(volatile apr_atomic_t *mem, apr_uint32_t val);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#if !defined(apr_atomic_inc) && !defined(APR_OVERRIDE_ATOMIC_INC)
void apr_atomic_inc(volatile apr_atomic_t *mem);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#if !defined(apr_atomic_dec) && !defined(APR_OVERRIDE_ATOMIC_DEC)
int apr_atomic_dec(volatile apr_atomic_t *mem);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#if !defined(apr_atomic_cas) && !defined(APR_OVERRIDE_ATOMIC_CAS)
apr_uint32_t apr_atomic_cas(volatile apr_uint32_t *mem,long with,long cmp);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#if !defined(apr_atomic_casptr) && !defined(APR_OVERRIDE_ATOMIC_CASPTR)
#if APR_SIZEOF_VOIDP == 4
#define apr_atomic_casptr(mem, with, cmp) (void *)apr_atomic_cas((apr_uint32_t *)(mem), (long)(with), (long)cmp)
#else
void *apr_atomic_casptr(volatile void **mem, void *with, const void *cmp);
#define APR_ATOMIC_NEED_DEFAULT_INIT 1
#endif
#endif
#ifndef APR_ATOMIC_NEED_DEFAULT_INIT
#define APR_ATOMIC_NEED_DEFAULT_INIT 0
#endif
/* If we're using the default versions of any of the atomic functions,
* we'll need the atomic init to set up mutexes. If a platform-specific
* override above has replaced the atomic_init with a macro, it's an error.
*/
#if APR_ATOMIC_NEED_DEFAULT_INIT
#if defined(apr_atomic_init) || defined(APR_OVERRIDE_ATOMIC_INIT)
#error Platform has redefined apr_atomic_init, but other default default atomics require a default apr_atomic_init
#endif
#endif /* APR_ATOMIC_NEED_DEFAULT_INIT */
#endif /* !DOXYGEN */
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* !APR_ATOMIC_H */
|