thodg/libgit2/src/thread-utils.h

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• Hash : aa532e29
  Author :
  Date : 2020-10-31T07:51:03
  

  Fix the `-DTHREADSAFE=OFF` build This change avoids using the `(void)0` construct for some of the mutex `#define`s, since that makes the "return type" of those "functions" to be `void` instead of `int`.

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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__
  
  #if defined(GIT_THREADS)
  
  #if defined(__clang__)
  
  # if (__clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 1))
  #  error Atomic primitives do not exist on this version of clang; configure libgit2 with -DTHREADSAFE=OFF
  # else
  #  define GIT_BUILTIN_ATOMIC
  # endif
  
  #elif defined(__GNUC__)
  
  # if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1))
  #  error Atomic primitives do not exist on this version of gcc; configure libgit2 with -DTHREADSAFE=OFF
  # elif (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
  #  define GIT_BUILTIN_ATOMIC
  # else
  #  define GIT_BUILTIN_SYNC
  # endif
  
  #endif
  
  #endif /* GIT_THREADS */
  
  /* 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)
  	volatile __int64 val;
  #else
  	volatile int64_t val;
  #endif
  } git_atomic64;
  
  typedef git_atomic64 git_atomic_ssize;
  
  #define git_atomic_ssize_set git_atomic64_set
  #define git_atomic_ssize_add git_atomic64_add
  #define git_atomic_ssize_get git_atomic64_get
  
  #else
  
  typedef git_atomic git_atomic_ssize;
  
  #define git_atomic_ssize_set git_atomic_set
  #define git_atomic_ssize_add git_atomic_add
  #define git_atomic_ssize_get git_atomic_get
  
  #endif
  
  #ifdef GIT_THREADS
  
  #ifdef GIT_WIN32
  #   include "win32/thread.h"
  #else
  #   include "unix/pthread.h"
  #endif
  
  GIT_INLINE(void) git_atomic_set(git_atomic *a, int val)
  {
  #if defined(GIT_WIN32)
  	InterlockedExchange(&a->val, (LONG)val);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	__atomic_store_n(&a->val, val, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	__sync_lock_test_and_set(&a->val, val);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(int) git_atomic_inc(git_atomic *a)
  {
  #if defined(GIT_WIN32)
  	return InterlockedIncrement(&a->val);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	return __atomic_add_fetch(&a->val, 1, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	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(GIT_BUILTIN_ATOMIC)
  	return __atomic_add_fetch(&a->val, addend, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	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(GIT_BUILTIN_ATOMIC)
  	return __atomic_sub_fetch(&a->val, 1, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	return __sync_sub_and_fetch(&a->val, 1);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(int) git_atomic_get(git_atomic *a)
  {
  #if defined(GIT_WIN32)
  	return (int)InterlockedCompareExchange(&a->val, 0, 0);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	return __atomic_load_n(&a->val, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	return __sync_val_compare_and_swap(&a->val, 0, 0);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(void *) git___compare_and_swap(
  	void * volatile *ptr, void *oldval, void *newval)
  {
  #if defined(GIT_WIN32)
  	volatile void *foundval;
  	foundval = InterlockedCompareExchangePointer((volatile PVOID *)ptr, newval, oldval);
  	return (foundval == oldval) ? oldval : newval;
  #elif defined(GIT_BUILTIN_ATOMIC)
  	bool success = __atomic_compare_exchange(ptr, &oldval, &newval, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
  	return success ? oldval : newval;
  #elif defined(GIT_BUILTIN_SYNC)
  	volatile void *foundval;
  	foundval = __sync_val_compare_and_swap(ptr, oldval, newval);
  	return (foundval == oldval) ? oldval : newval;
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(volatile void *) git___swap(
  	void * volatile *ptr, void *newval)
  {
  #if defined(GIT_WIN32)
  	return InterlockedExchangePointer(ptr, newval);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	void * volatile foundval;
  	__atomic_exchange(ptr, &newval, &foundval, __ATOMIC_SEQ_CST);
  	return foundval;
  #elif defined(GIT_BUILTIN_SYNC)
  	return __sync_lock_test_and_set(ptr, newval);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(volatile void *) git___load(void * volatile *ptr)
  {
  #if defined(GIT_WIN32)
  	void *newval = NULL, *oldval = NULL;
  	volatile void *foundval = NULL;
  	foundval = InterlockedCompareExchangePointer((volatile PVOID *)ptr, newval, oldval);
  	return foundval;
  #elif defined(GIT_BUILTIN_ATOMIC)
  	return (volatile void *)__atomic_load_n(ptr, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	return (volatile void *)__sync_val_compare_and_swap(ptr, 0, 0);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  #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(GIT_BUILTIN_ATOMIC)
  	return __atomic_add_fetch(&a->val, addend, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	return __sync_add_and_fetch(&a->val, addend);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(void) git_atomic64_set(git_atomic64 *a, int64_t val)
  {
  #if defined(GIT_WIN32)
  	InterlockedExchange64(&a->val, val);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	__atomic_store_n(&a->val, val, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	__sync_lock_test_and_set(&a->val, val);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  GIT_INLINE(int64_t) git_atomic64_get(git_atomic64 *a)
  {
  #if defined(GIT_WIN32)
  	return (int64_t)InterlockedCompareExchange64(&a->val, 0, 0);
  #elif defined(GIT_BUILTIN_ATOMIC)
  	return __atomic_load_n(&a->val, __ATOMIC_SEQ_CST);
  #elif defined(GIT_BUILTIN_SYNC)
  	return __sync_val_compare_and_swap(&a->val, 0, 0);
  #else
  #	error "Unsupported architecture for atomic operations"
  #endif
  }
  
  #endif
  
  #else
  
  GIT_INLINE(int) git___noop(void) { return 0; }
  
  #define git_threads_global_init git___noop
  
  #define git_thread unsigned int
  #define git_thread_create(thread, start_routine, arg) git___noop()
  #define git_thread_join(id, status) git___noop()
  
  /* Pthreads Mutex */
  #define git_mutex unsigned int
  #define git_mutex_init(a)	git___noop()
  #define git_mutex_init(a)	git___noop()
  #define git_mutex_lock(a)	git___noop()
  #define git_mutex_unlock(a)	git___noop()
  #define git_mutex_free(a)	git___noop()
  
  /* Pthreads condition vars */
  #define git_cond unsigned int
  #define git_cond_init(c)	git___noop()
  #define git_cond_free(c)	git___noop()
  #define git_cond_wait(c, l)	git___noop()
  #define git_cond_signal(c)	git___noop()
  #define git_cond_broadcast(c)	git___noop()
  
  /* Pthreads rwlock */
  #define git_rwlock unsigned int
  #define git_rwlock_init(a)	git___noop()
  #define git_rwlock_rdlock(a)	git___noop()
  #define git_rwlock_rdunlock(a)	git___noop()
  #define git_rwlock_wrlock(a)	git___noop()
  #define git_rwlock_wrunlock(a)	git___noop()
  #define git_rwlock_free(a)	git___noop()
  #define GIT_RWLOCK_STATIC_INIT	0
  
  
  GIT_INLINE(void) git_atomic_set(git_atomic *a, int val)
  {
  	a->val = val;
  }
  
  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(int) git_atomic_get(git_atomic *a)
  {
  	return (int)a->val;
  }
  
  GIT_INLINE(void *) git___compare_and_swap(
  	void * volatile *ptr, void *oldval, void *newval)
  {
  	if (*ptr == oldval)
  		*ptr = newval;
  	else
  		oldval = newval;
  	return oldval;
  }
  
  GIT_INLINE(volatile void *) git___swap(
  	void * volatile *ptr, void *newval)
  {
  	volatile void *old = *ptr;
  	*ptr = newval;
  	return old;
  }
  
  GIT_INLINE(volatile void *) git___load(void * volatile *ptr)
  {
  	return *ptr;
  }
  
  #ifdef GIT_ARCH_64
  
  GIT_INLINE(int64_t) git_atomic64_add(git_atomic64 *a, int64_t addend)
  {
  	a->val += addend;
  	return a->val;
  }
  
  GIT_INLINE(void) git_atomic64_set(git_atomic64 *a, int64_t val)
  {
  	a->val = val;
  }
  
  GIT_INLINE(int64_t) git_atomic64_get(git_atomic64 *a)
  {
  	return (int64_t)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((void * volatile *)P, O, N)
  
  #define git__swap(ptr, val) (void *)git___swap((void * volatile *)&ptr, val)
  
  #define git__load(ptr) (void *)git___load((void * volatile *)&ptr)
  
  extern int git_online_cpus(void);
  
  #if defined(GIT_THREADS)
  
  # if defined(GIT_WIN32)
  #  define GIT_MEMORY_BARRIER MemoryBarrier()
  # elif defined(GIT_BUILTIN_ATOMIC)
  #  define GIT_MEMORY_BARRIER __atomic_thread_fence(__ATOMIC_SEQ_CST)
  # elif defined(GIT_BUILTIN_SYNC)
  #  define GIT_MEMORY_BARRIER __sync_synchronize()
  # endif
  
  #else
  
  # define GIT_MEMORY_BARRIER /* noop */
  
  #endif
  
  #endif
  

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