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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_threads.c
- *
- * \brief Cross-platform threading and inter-thread communication logic.
- * (Platform-specific parts are written in the other compat_*threads
- * modules.)
- */
- #include "orconfig.h"
- #include <stdlib.h>
- #include "lib/thread/threads.h"
- #include "lib/log/log.h"
- #include "lib/log/util_bug.h"
- #include <string.h>
- /** Allocate and return a new condition variable. */
- tor_cond_t *
- tor_cond_new(void)
- {
- tor_cond_t *cond = tor_malloc(sizeof(tor_cond_t));
- if (BUG(tor_cond_init(cond)<0))
- tor_free(cond); // LCOV_EXCL_LINE
- return cond;
- }
- /** Free all storage held in <b>c</b>. */
- void
- tor_cond_free_(tor_cond_t *c)
- {
- if (!c)
- return;
- tor_cond_uninit(c);
- tor_free(c);
- }
- /** Identity of the "main" thread */
- static unsigned long main_thread_id = -1;
- /** Start considering the current thread to be the 'main thread'. This has
- * no effect on anything besides in_main_thread(). */
- void
- set_main_thread(void)
- {
- main_thread_id = tor_get_thread_id();
- }
- /** Return true iff called from the main thread. */
- int
- in_main_thread(void)
- {
- return main_thread_id == tor_get_thread_id();
- }
- #ifndef HAVE_WORKING_STDATOMIC
- /** Initialize a new atomic counter with the value 0 */
- void
- atomic_counter_init(atomic_counter_t *counter)
- {
- memset(counter, 0, sizeof(*counter));
- tor_mutex_init_nonrecursive(&counter->mutex);
- }
- /** Clean up all resources held by an atomic counter. */
- void
- atomic_counter_destroy(atomic_counter_t *counter)
- {
- tor_mutex_uninit(&counter->mutex);
- memset(counter, 0, sizeof(*counter));
- }
- /** Add a value to an atomic counter. */
- void
- atomic_counter_add(atomic_counter_t *counter, size_t add)
- {
- tor_mutex_acquire(&counter->mutex);
- counter->val += add;
- tor_mutex_release(&counter->mutex);
- }
- /** Subtract a value from an atomic counter. */
- void
- atomic_counter_sub(atomic_counter_t *counter, size_t sub)
- {
- // this relies on unsigned overflow, but that's fine.
- atomic_counter_add(counter, -sub);
- }
- /** Return the current value of an atomic counter */
- size_t
- atomic_counter_get(atomic_counter_t *counter)
- {
- size_t val;
- tor_mutex_acquire(&counter->mutex);
- val = counter->val;
- tor_mutex_release(&counter->mutex);
- return val;
- }
- /** Replace the value of an atomic counter; return the old one. */
- size_t
- atomic_counter_exchange(atomic_counter_t *counter, size_t newval)
- {
- size_t oldval;
- tor_mutex_acquire(&counter->mutex);
- oldval = counter->val;
- counter->val = newval;
- tor_mutex_release(&counter->mutex);
- return oldval;
- }
- #endif /* !defined(HAVE_WORKING_STDATOMIC) */
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