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Diffstat (limited to 'src/common/compat_pthreads.c')
| -rw-r--r-- | src/common/compat_pthreads.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/src/common/compat_pthreads.c b/src/common/compat_pthreads.c new file mode 100644 index 0000000000..246076b276 --- /dev/null +++ b/src/common/compat_pthreads.c @@ -0,0 +1,291 @@ +/* Copyright (c) 2003-2004, Roger Dingledine + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2015, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#define _GNU_SOURCE + +#include "orconfig.h" +#include <pthread.h> +#include <signal.h> +#include <time.h> + +#include "compat.h" +#include "torlog.h" +#include "util.h" + +/** Wraps a void (*)(void*) function and its argument so we can + * invoke them in a way pthreads would expect. + */ +typedef struct tor_pthread_data_t { + void (*func)(void *); + void *data; +} tor_pthread_data_t; +/** Given a tor_pthread_data_t <b>_data</b>, call _data->func(d->data) + * and free _data. Used to make sure we can call functions the way pthread + * expects. */ +static void * +tor_pthread_helper_fn(void *_data) +{ + tor_pthread_data_t *data = _data; + void (*func)(void*); + void *arg; + /* mask signals to worker threads to avoid SIGPIPE, etc */ + sigset_t sigs; + /* We're in a subthread; don't handle any signals here. */ + sigfillset(&sigs); + pthread_sigmask(SIG_SETMASK, &sigs, NULL); + + func = data->func; + arg = data->data; + tor_free(_data); + func(arg); + return NULL; +} +/** + * A pthread attribute to make threads start detached. + */ +static pthread_attr_t attr_detached; +/** True iff we've called tor_threads_init() */ +static int threads_initialized = 0; + +/** Minimalist interface to run a void function in the background. On + * Unix calls fork, on win32 calls beginthread. Returns -1 on failure. + * func should not return, but rather should call spawn_exit. + * + * NOTE: if <b>data</b> is used, it should not be allocated on the stack, + * since in a multithreaded environment, there is no way to be sure that + * the caller's stack will still be around when the called function is + * running. + */ +int +spawn_func(void (*func)(void *), void *data) +{ + pthread_t thread; + tor_pthread_data_t *d; + if (PREDICT_UNLIKELY(!threads_initialized)) + tor_threads_init(); + d = tor_malloc(sizeof(tor_pthread_data_t)); + d->data = data; + d->func = func; + if (pthread_create(&thread,&attr_detached,tor_pthread_helper_fn,d)) + return -1; + return 0; +} + +/** End the current thread/process. + */ +void +spawn_exit(void) +{ + pthread_exit(NULL); +} + +/** 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; + +/** 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) +{ + int err; + if (PREDICT_UNLIKELY(!threads_initialized)) + tor_threads_init(); + err = pthread_mutex_init(&mutex->mutex, &attr_recursive); + if (PREDICT_UNLIKELY(err)) { + log_err(LD_GENERAL, "Error %d creating a mutex.", err); + tor_fragile_assert(); + } +} + +/** 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 (PREDICT_UNLIKELY(!threads_initialized)) + tor_threads_init(); + err = pthread_mutex_init(&mutex->mutex, NULL); + if (PREDICT_UNLIKELY(err)) { + log_err(LD_GENERAL, "Error %d creating a mutex.", err); + tor_fragile_assert(); + } +} + +/** Wait until <b>m</b> is free, then acquire it. */ +void +tor_mutex_acquire(tor_mutex_t *m) +{ + int err; + tor_assert(m); + err = pthread_mutex_lock(&m->mutex); + if (PREDICT_UNLIKELY(err)) { + log_err(LD_GENERAL, "Error %d locking a mutex.", err); + tor_fragile_assert(); + } +} +/** Release the lock <b>m</b> so another thread can have it. */ +void +tor_mutex_release(tor_mutex_t *m) +{ + int err; + tor_assert(m); + err = pthread_mutex_unlock(&m->mutex); + if (PREDICT_UNLIKELY(err)) { + log_err(LD_GENERAL, "Error %d unlocking a mutex.", err); + tor_fragile_assert(); + } +} +/** 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; + tor_assert(m); + err = pthread_mutex_destroy(&m->mutex); + if (PREDICT_UNLIKELY(err)) { + log_err(LD_GENERAL, "Error %d destroying a mutex.", err); + tor_fragile_assert(); + } +} +/** Return an integer representing this thread. */ +unsigned long +tor_get_thread_id(void) +{ + union { + pthread_t thr; + unsigned long id; + } r; + r.thr = pthread_self(); + return r.id; +} + +/* Conditions. */ + +/** Initialize an already-allocated condition variable. */ +int +tor_cond_init(tor_cond_t *cond) +{ + pthread_condattr_t condattr; + + memset(cond, 0, sizeof(tor_cond_t)); + /* Default condition attribute. Might be used if clock monotonic is + * available else this won't affect anything. */ + if (pthread_condattr_init(&condattr)) { + return -1; + } + +#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC) + /* Use monotonic time so when we timedwait() on it, any clock adjustment + * won't affect the timeout value. */ + if (pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC)) { + return -1; + } +#endif + if (pthread_cond_init(&cond->cond, &condattr)) { + return -1; + } + return 0; +} + +/** Release all resources held by <b>cond</b>, but do not free <b>cond</b> + * itself. */ +void +tor_cond_uninit(tor_cond_t *cond) +{ + if (pthread_cond_destroy(&cond->cond)) { + log_warn(LD_GENERAL,"Error freeing condition: %s", strerror(errno)); + return; + } +} +/** Wait until one of the tor_cond_signal functions is called on <b>cond</b>. + * (If <b>tv</b> is set, and that amount of time passes with no signal to + * <b>cond</b>, return anyway. All waiters on the condition must wait holding + * the same <b>mutex</b>. All signallers should hold that mutex. The mutex + * needs to have been allocated with tor_mutex_init_for_cond(). + * + * Returns 0 on success, -1 on failure, 1 on timeout. */ +int +tor_cond_wait(tor_cond_t *cond, tor_mutex_t *mutex, const struct timeval *tv) +{ + int r; + if (tv == NULL) { + while (1) { + r = pthread_cond_wait(&cond->cond, &mutex->mutex); + if (r == EINTR) { + /* EINTR should be impossible according to POSIX, but POSIX, like the + * Pirate's Code, is apparently treated "more like what you'd call + * guidelines than actual rules." */ + continue; + } + return r ? -1 : 0; + } + } else { + struct timeval tvnow, tvsum; + struct timespec ts; + while (1) { +#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC) + if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) { + return -1; + } + tvnow.tv_sec = ts.tv_sec; + tvnow.tv_usec = ts.tv_nsec / 1000; + timeradd(tv, &tvnow, &tvsum); +#else + if (gettimeofday(&tvnow, NULL) < 0) + return -1; + timeradd(tv, &tvnow, &tvsum); +#endif /* HAVE_CLOCK_GETTIME, CLOCK_MONOTONIC */ + + ts.tv_sec = tvsum.tv_sec; + ts.tv_nsec = tvsum.tv_usec * 1000; + + r = pthread_cond_timedwait(&cond->cond, &mutex->mutex, &ts); + if (r == 0) + return 0; + else if (r == ETIMEDOUT) + return 1; + else if (r == EINTR) + continue; + else + return -1; + } + } +} +/** Wake up one of the waiters on <b>cond</b>. */ +void +tor_cond_signal_one(tor_cond_t *cond) +{ + pthread_cond_signal(&cond->cond); +} +/** Wake up all of the waiters on <b>cond</b>. */ +void +tor_cond_signal_all(tor_cond_t *cond) +{ + pthread_cond_broadcast(&cond->cond); +} + +/** Set up common structures for use by threading. */ +void +tor_threads_init(void) +{ + if (!threads_initialized) { + pthread_mutexattr_init(&attr_recursive); + pthread_mutexattr_settype(&attr_recursive, PTHREAD_MUTEX_RECURSIVE); + tor_assert(0==pthread_attr_init(&attr_detached)); +#ifndef PTHREAD_CREATE_DETACHED +#define PTHREAD_CREATE_DETACHED 1 +#endif + tor_assert(0==pthread_attr_setdetachstate(&attr_detached, + PTHREAD_CREATE_DETACHED)); + threads_initialized = 1; + set_main_thread(); + } +} + |