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atomics: Move atomics/recounting support to separate files

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This commit is contained in:
Martin Willi
2015-04-16 14:49:19 +02:00
parent 31a171f5c4
commit 717313c542
6 changed files with 251 additions and 183 deletions
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src/libstrongswan/utils/utils.h
+1 -95
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@@ -96,6 +96,7 @@
#endif /* TRUE */
#include "enum.h"
#include "utils/atomics.h"
#include "utils/strerror.h"
#ifdef __APPLE__
# include "compat/apple.h"
@@ -968,101 +969,6 @@ static inline size_t round_down(size_t size, size_t alignment)
return size - (size % alignment);
}
/**
* Special type to count references
*/
typedef u_int refcount_t;
/* use __atomic* built-ins with GCC 4.7 and newer */
#ifdef __GNUC__
# if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 6))
# define HAVE_GCC_ATOMIC_OPERATIONS
# endif
#endif
#ifdef HAVE_GCC_ATOMIC_OPERATIONS
#define ref_get(ref) __atomic_add_fetch(ref, 1, __ATOMIC_RELAXED)
/* The relaxed memory model works fine for increments as these (usually) don't
* change the state of refcounted objects. But here we have to ensure that we
* free the right stuff if ref counted objects are mutable. So we have to sync
* with other threads that call ref_put(). It would be sufficient to use
* __ATOMIC_RELEASE here and then call __atomic_thread_fence() with
* __ATOMIC_ACQUIRE if we reach 0, but since we don't have control over the use
* of ref_put() we have to make sure. */
#define ref_put(ref) (!__atomic_sub_fetch(ref, 1, __ATOMIC_ACQ_REL))
#define ref_cur(ref) __atomic_load_n(ref, __ATOMIC_RELAXED)
#define _cas_impl(ptr, oldval, newval) ({ typeof(oldval) _old = oldval; \
__atomic_compare_exchange_n(ptr, &_old, newval, FALSE, \
__ATOMIC_SEQ_CST, __ATOMIC_RELAXED); })
#define cas_bool(ptr, oldval, newval) _cas_impl(ptr, oldval, newval)
#define cas_ptr(ptr, oldval, newval) _cas_impl(ptr, oldval, newval)
#elif defined(HAVE_GCC_SYNC_OPERATIONS)
#define ref_get(ref) __sync_add_and_fetch(ref, 1)
#define ref_put(ref) (!__sync_sub_and_fetch(ref, 1))
#define ref_cur(ref) __sync_fetch_and_add(ref, 0)
#define cas_bool(ptr, oldval, newval) \
(__sync_bool_compare_and_swap(ptr, oldval, newval))
#define cas_ptr(ptr, oldval, newval) \
(__sync_bool_compare_and_swap(ptr, oldval, newval))
#else /* !HAVE_GCC_ATOMIC_OPERATIONS && !HAVE_GCC_SYNC_OPERATIONS */
/**
* Get a new reference.
*
* Increments the reference counter atomically.
*
* @param ref pointer to ref counter
* @return new value of ref
*/
refcount_t ref_get(refcount_t *ref);
/**
* Put back a unused reference.
*
* Decrements the reference counter atomically and
* says if more references available.
*
* @param ref pointer to ref counter
* @return TRUE if no more references counted
*/
bool ref_put(refcount_t *ref);
/**
* Get the current value of the reference counter.
*
* @param ref pointer to ref counter
* @return current value of ref
*/
refcount_t ref_cur(refcount_t *ref);
/**
* Atomically replace value of ptr with newval if it currently equals oldval.
*
* @param ptr pointer to variable
* @param oldval old value of the variable
* @param newval new value set if possible
* @return TRUE if value equaled oldval and newval was written
*/
bool cas_bool(bool *ptr, bool oldval, bool newval);
/**
* Atomically replace value of ptr with newval if it currently equals oldval.
*
* @param ptr pointer to variable
* @param oldval old value of the variable
* @param newval new value set if possible
* @return TRUE if value equaled oldval and newval was written
*/
bool cas_ptr(void **ptr, void *oldval, void *newval);
#endif /* HAVE_GCC_ATOMIC_OPERATIONS */
#ifndef HAVE_FMEMOPEN
# ifdef HAVE_FUNOPEN
# define HAVE_FMEMOPEN