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- /* Copyright (c) 2003-2004, Roger Dingledine
- * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2018, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file compat_mutex_pthreads.c
- *
- * \brief Implement the tor_mutex API using pthread_mutex_t.
- **/
- #include "lib/lock/compat_mutex.h"
- #include "lib/cc/compat_compiler.h"
- #include "lib/err/torerr.h"
- /** A mutex attribute that we're going to use to tell pthreads that we want
- * "recursive" mutexes (i.e., once we can re-lock if we're already holding
- * them.) */
- static pthread_mutexattr_t attr_recursive;
- static int attr_initialized = 0;
- void
- tor_locking_init(void)
- {
- if (!attr_initialized) {
- pthread_mutexattr_init(&attr_recursive);
- pthread_mutexattr_settype(&attr_recursive, PTHREAD_MUTEX_RECURSIVE);
- attr_initialized = 1;
- }
- }
- /** Initialize <b>mutex</b> so it can be locked. Every mutex must be set
- * up with tor_mutex_init() or tor_mutex_new(); not both. */
- void
- tor_mutex_init(tor_mutex_t *mutex)
- {
- if (PREDICT_UNLIKELY(!attr_initialized))
- tor_locking_init(); // LCOV_EXCL_LINE
- const int err = pthread_mutex_init(&mutex->mutex, &attr_recursive);
- if (PREDICT_UNLIKELY(err)) {
- // LCOV_EXCL_START
- raw_assert_unreached_msg("Error creating a mutex.");
- // LCOV_EXCL_STOP
- }
- }
- /** As tor_mutex_init, but initialize a mutex suitable that may be
- * non-recursive, if the OS supports that. */
- void
- tor_mutex_init_nonrecursive(tor_mutex_t *mutex)
- {
- int err;
- if (!attr_initialized)
- tor_locking_init(); // LCOV_EXCL_LINE
- err = pthread_mutex_init(&mutex->mutex, NULL);
- if (PREDICT_UNLIKELY(err)) {
- // LCOV_EXCL_START
- raw_assert_unreached_msg("Error creating a mutex.");
- // LCOV_EXCL_STOP
- }
- }
- /** Wait until <b>m</b> is free, then acquire it. */
- void
- tor_mutex_acquire(tor_mutex_t *m)
- {
- int err;
- raw_assert(m);
- err = pthread_mutex_lock(&m->mutex);
- if (PREDICT_UNLIKELY(err)) {
- // LCOV_EXCL_START
- raw_assert_unreached_msg("Error locking a mutex.");
- // LCOV_EXCL_STOP
- }
- }
- /** Release the lock <b>m</b> so another thread can have it. */
- void
- tor_mutex_release(tor_mutex_t *m)
- {
- int err;
- raw_assert(m);
- err = pthread_mutex_unlock(&m->mutex);
- if (PREDICT_UNLIKELY(err)) {
- // LCOV_EXCL_START
- raw_assert_unreached_msg("Error unlocking a mutex.");
- // LCOV_EXCL_STOP
- }
- }
- /** Clean up the mutex <b>m</b> so that it no longer uses any system
- * resources. Does not free <b>m</b>. This function must only be called on
- * mutexes from tor_mutex_init(). */
- void
- tor_mutex_uninit(tor_mutex_t *m)
- {
- int err;
- raw_assert(m);
- err = pthread_mutex_destroy(&m->mutex);
- if (PREDICT_UNLIKELY(err)) {
- // LCOV_EXCL_START
- raw_assert_unreached_msg("Error destroying a mutex.");
- // LCOV_EXCL_STOP
- }
- }
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