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3e0fb8fb56
In particular, in standard C, a struct or union must have at least one member declared (ie. structs and unions cannot be empty). Some compilers allow empty structs as an extension and won't even issue a warning unless asked for it (eg, gcc requires -pedantic). Some compilers allow empty structs as an extension and will only treat it as an error if asked for strict checking (eg Digital-Mars with -A). Some compilers simply treat it as an error (eg MS Visual C/C++). Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Signed-off-by: Andreas Ericsson <ae@op5.se>
90 lines
2.2 KiB
C
90 lines
2.2 KiB
C
#ifndef INCLUDE_thread_utils_h__
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#define INCLUDE_thread_utils_h__
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#if defined(GIT_HAS_PTHREAD)
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typedef pthread_mutex_t git_lck;
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# define GITLCK_INIT PTHREAD_MUTEX_INITIALIZER
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# define gitlck_init(a) pthread_mutex_init(a, NULL)
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# define gitlck_lock(a) pthread_mutex_lock(a)
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# define gitlck_unlock(a) pthread_mutex_unlock(a)
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# define gitlck_free(a) pthread_mutex_destroy(a)
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# if defined(GIT_HAS_ASM_ATOMIC)
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# include <asm/atomic.h>
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typedef atomic_t git_refcnt;
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# define gitrc_init(a) atomic_set(a, 0)
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# define gitrc_inc(a) atomic_inc_return(a)
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# define gitrc_dec(a) atomic_dec_and_test(a)
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# define gitrc_free(a) (void)0
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# else
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typedef struct { git_lck lock; int counter; } git_refcnt;
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/** Initialize to 0. No memory barrier is issued. */
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GIT_INLINE(void) gitrc_init(git_refcnt *p)
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{
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gitlck_init(&p->lock);
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p->counter = 0;
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}
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/**
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* Increment.
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*
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* Atomically increments @p by 1. A memory barrier is also
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* issued before and after the operation.
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*
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* @param p pointer of type git_refcnt
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*/
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GIT_INLINE(void) gitrc_inc(git_refcnt *p)
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{
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gitlck_lock(&p->lock);
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p->counter++;
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gitlck_unlock(&p->lock);
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}
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/**
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* Decrement and test.
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*
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* Atomically decrements @p by 1 and returns true if the
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* result is 0, or false for all other cases. A memory
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* barrier is also issued before and after the operation.
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*
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* @param p pointer of type git_refcnt
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*/
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GIT_INLINE(int) gitrc_dec(git_refcnt *p)
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{
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int c;
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gitlck_lock(&p->lock);
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c = --p->counter;
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gitlck_unlock(&p->lock);
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return !c;
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}
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/** Free any resources associated with the counter. */
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# define gitrc_free(p) gitlck_free(&(p)->lock)
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# endif
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#elif defined(GIT_THREADS)
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# error GIT_THREADS but no git_lck implementation
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#else
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typedef struct { int dummy; } git_lck;
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# define GIT_MUTEX_INIT {}
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# define gitlck_init(a) (void)0
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# define gitlck_lock(a) (void)0
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# define gitlck_unlock(a) (void)0
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# define gitlck_free(a) (void)0
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typedef struct { int counter; } git_refcnt;
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# define gitrc_init(a) ((a)->counter = 0)
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# define gitrc_inc(a) ((a)->counter++)
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# define gitrc_dec(a) (--(a)->counter == 0)
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# define gitrc_free(a) (void)0
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#endif
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extern int git_online_cpus(void);
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#endif /* INCLUDE_thread_utils_h__ */
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