thodg/libgit2/src/thread-utils.h

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• Hash : 1a42dd17
  Author :
  Date : 2013-05-31T14:13:11
  

  Mutex init can fail It is obviously quite a serious problem if this happens, but mutex initialization can fail and we should detect it. It's a bit like a memory allocation failure, in that you're probably pretty screwed if this occurs, but at least we'll catch it.

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• src/thread-utils.h

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  #ifndef INCLUDE_thread_utils_h__
  #define INCLUDE_thread_utils_h__
  
  #include "common.h"
  
  /* Common operations even if threading has been disabled */
  typedef struct {
  #if defined(GIT_WIN32)
  	volatile long val;
  #else
  	volatile int val;
  #endif
  } git_atomic;
  
  #ifdef GIT_ARCH_64
  
  typedef struct {
  #if defined(GIT_WIN32)
  	__int64 val;
  #else
  	int64_t val;
  #endif
  } git_atomic64;
  
  typedef git_atomic64 git_atomic_ssize;
  
  #define git_atomic_ssize_add git_atomic64_add
  
  #else
  
  typedef git_atomic git_atomic_ssize;
  
  #define git_atomic_ssize_add git_atomic_add
  
  #endif
  
  GIT_INLINE(void) git_atomic_set(git_atomic *a, int val)
  {
  	a->val = val;
  }
  
  #ifdef GIT_THREADS
  
  #define git_thread pthread_t
  #define git_thread_create(thread, attr, start_routine, arg) pthread_create(thread, attr, start_routine, arg)
  #define git_thread_kill(thread) pthread_cancel(thread)
  #define git_thread_exit(status)	pthread_exit(status)
  #define git_thread_join(id, status) pthread_join(id, status)
  
  /* Pthreads Mutex */
  #define git_mutex pthread_mutex_t
  #define git_mutex_init(a)	pthread_mutex_init(a, NULL)
  #define git_mutex_lock(a)	pthread_mutex_lock(a)
  #define git_mutex_unlock(a) pthread_mutex_unlock(a)
  #define git_mutex_free(a)	pthread_mutex_destroy(a)
  
  /* Pthreads condition vars */
  #define git_cond pthread_cond_t
  #define git_cond_init(c)	pthread_cond_init(c, NULL)
  #define git_cond_free(c) 	pthread_cond_destroy(c)
  #define git_cond_wait(c, l)	pthread_cond_wait(c, l)
  #define git_cond_signal(c)	pthread_cond_signal(c)
  #define git_cond_broadcast(c)	pthread_cond_broadcast(c)
  
  GIT_INLINE(int) git_atomic_inc(git_atomic *a)
  {
  #if defined(GIT_WIN32)
  	return InterlockedIncrement(&a->val);
  #elif defined(__GNUC__)
  	return __sync_add_and_fetch(&a->val, 1);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(int) git_atomic_add(git_atomic *a, int32_t addend)
  {
  #if defined(GIT_WIN32)
  	return InterlockedExchangeAdd(&a->val, addend);
  #elif defined(__GNUC__)
  	return __sync_add_and_fetch(&a->val, addend);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(int) git_atomic_dec(git_atomic *a)
  {
  #if defined(GIT_WIN32)
  	return InterlockedDecrement(&a->val);
  #elif defined(__GNUC__)
  	return __sync_sub_and_fetch(&a->val, 1);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(void *) git___compare_and_swap(
  	volatile void **ptr, void *oldval, void *newval)
  {
  	volatile void *foundval;
  #if defined(GIT_WIN32)
  	foundval = InterlockedCompareExchangePointer(ptr, newval, oldval);
  #elif defined(__GNUC__)
  	foundval = __sync_val_compare_and_swap(ptr, oldval, newval);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  	return (foundval == oldval) ? oldval : newval;
  }
  
  #ifdef GIT_ARCH_64
  
  GIT_INLINE(int64_t) git_atomic64_add(git_atomic64 *a, int64_t addend)
  {
  #if defined(GIT_WIN32)
  	return InterlockedExchangeAdd64(&a->val, addend);
  #elif defined(__GNUC__)
  	return __sync_add_and_fetch(&a->val, addend);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  #endif
  
  #else
  
  #define git_thread unsigned int
  #define git_thread_create(thread, attr, start_routine, arg) (void)0
  #define git_thread_kill(thread) (void)0
  #define git_thread_exit(status) (void)0
  #define git_thread_join(id, status) (void)0
  
  /* Pthreads Mutex */
  #define git_mutex unsigned int
  #define git_mutex_init(a) 0
  #define git_mutex_lock(a) 0
  #define git_mutex_unlock(a) (void)0
  #define git_mutex_free(a) (void)0
  
  /* Pthreads condition vars */
  #define git_cond unsigned int
  #define git_cond_init(c, a)	(void)0
  #define git_cond_free(c) (void)0
  #define git_cond_wait(c, l)	(void)0
  #define git_cond_signal(c) (void)0
  #define git_cond_broadcast(c) (void)0
  
  GIT_INLINE(int) git_atomic_inc(git_atomic *a)
  {
  	return ++a->val;
  }
  
  GIT_INLINE(int) git_atomic_add(git_atomic *a, int32_t addend)
  {
  	a->val += addend;
  	return a->val;
  }
  
  GIT_INLINE(int) git_atomic_dec(git_atomic *a)
  {
  	return --a->val;
  }
  
  GIT_INLINE(void *) git___compare_and_swap(
  	volatile void **ptr, void *oldval, void *newval)
  {
  	if (*ptr == oldval)
  		*ptr = newval;
  	else
  		oldval = newval;
  	return oldval;
  }
  
  #ifdef GIT_ARCH_64
  
  GIT_INLINE(int64_t) git_atomic64_add(git_atomic64 *a, int64_t addend)
  {
  	a->val += addend;
  	return a->val;
  }
  
  #endif
  
  #endif
  
  /* Atomically replace oldval with newval
   * @return oldval if it was replaced or newval if it was not
   */
  #define git__compare_and_swap(P,O,N) \
  	git___compare_and_swap((volatile void **)P, O, N)
  
  #define git__swap(ptr, val) git__compare_and_swap(&ptr, ptr, val)
  
  extern int git_online_cpus(void);
  
  #if defined(GIT_THREADS) && defined(GIT_WIN32)
  # define GIT_MEMORY_BARRIER MemoryBarrier()
  #elif defined(GIT_THREADS)
  # define GIT_MEMORY_BARRIER __sync_synchronize()
  #else
  # define GIT_MEMORY_BARRIER /* noop */
  #endif
  
  #endif /* INCLUDE_thread_utils_h__ */
  

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