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/*
* 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.
*/
#include "git2_util.h"
#include "runtime.h"
static git_runtime_shutdown_fn shutdown_callback[32];
static git_atomic32 shutdown_callback_count;
static git_atomic32 init_count;
static int init_common(git_runtime_init_fn init_fns[], size_t cnt)
{
size_t i;
int ret;
/* Initialize subsystems that have global state */
for (i = 0; i < cnt; i++) {
if ((ret = init_fns[i]()) != 0)
break;
}
GIT_MEMORY_BARRIER;
return ret;
}
static void shutdown_common(void)
{
git_runtime_shutdown_fn cb;
int pos;
for (pos = git_atomic32_get(&shutdown_callback_count);
pos > 0;
pos = git_atomic32_dec(&shutdown_callback_count)) {
cb = git_atomic_swap(shutdown_callback[pos - 1], NULL);
if (cb != NULL)
cb();
}
}
int git_runtime_shutdown_register(git_runtime_shutdown_fn callback)
{
int count = git_atomic32_inc(&shutdown_callback_count);
if (count > (int)ARRAY_SIZE(shutdown_callback) || count == 0) {
git_error_set(GIT_ERROR_INVALID,
"too many shutdown callbacks registered");
git_atomic32_dec(&shutdown_callback_count);
return -1;
}
shutdown_callback[count - 1] = callback;
return 0;
}
#if defined(GIT_THREADS) && defined(GIT_WIN32)
/*
* On Win32, we use a spinlock to provide locking semantics. This is
* lighter-weight than a proper critical section.
*/
static volatile LONG init_spinlock = 0;
GIT_INLINE(int) init_lock(void)
{
while (InterlockedCompareExchange(&init_spinlock, 1, 0)) { Sleep(0); }
return 0;
}
GIT_INLINE(int) init_unlock(void)
{
InterlockedExchange(&init_spinlock, 0);
return 0;
}
#elif defined(GIT_THREADS) && defined(_POSIX_THREADS)
/*
* On POSIX, we need to use a proper mutex for locking. We might prefer
* a spinlock here, too, but there's no static initializer for a
* pthread_spinlock_t.
*/
static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER;
GIT_INLINE(int) init_lock(void)
{
return pthread_mutex_lock(&init_mutex) == 0 ? 0 : -1;
}
GIT_INLINE(int) init_unlock(void)
{
return pthread_mutex_unlock(&init_mutex) == 0 ? 0 : -1;
}
#elif defined(GIT_THREADS)
# error unknown threading model
#else
# define init_lock() git__noop()
# define init_unlock() git__noop()
#endif
int git_runtime_init(git_runtime_init_fn init_fns[], size_t cnt)
{
int ret;
if (init_lock() < 0)
return -1;
/* Only do work on a 0 -> 1 transition of the refcount */
if ((ret = git_atomic32_inc(&init_count)) == 1) {
if (init_common(init_fns, cnt) < 0)
ret = -1;
}
if (init_unlock() < 0)
return -1;
return ret;
}
int git_runtime_init_count(void)
{
int ret;
if (init_lock() < 0)
return -1;
ret = git_atomic32_get(&init_count);
if (init_unlock() < 0)
return -1;
return ret;
}
int git_runtime_shutdown(void)
{
int ret;
/* Enter the lock */
if (init_lock() < 0)
return -1;
/* Only do work on a 1 -> 0 transition of the refcount */
if ((ret = git_atomic32_dec(&init_count)) == 0)
shutdown_common();
/* Exit the lock */
if (init_unlock() < 0)
return -1;
return ret;
}
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