X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=5514b278e4322b0f600a6d3427eab700057dc573;hp=b8c80ab39ab3daf54a9f25d6ce3bd004a312c5e3;hb=4917a879125c1fca08ccb4328104701e83108556;hpb=27b012e271a82b9a0d94543688904f207cd154ea diff --git a/urcu.c b/urcu.c index b8c80ab..5514b27 100644 --- a/urcu.c +++ b/urcu.c @@ -1,75 +1,117 @@ +/* + * urcu.c + * + * Userspace RCU library + * + * Copyright February 2009 - Mathieu Desnoyers + * + * Distributed under GPLv2 + */ + #include #include #include #include +#include +#include #include "urcu.h" pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER; -/* Global quiescent period parity */ -int urcu_qparity; +/* Global grace period counter */ +int urcu_gp_ctr; -int __thread urcu_active_readers[2]; +int __thread urcu_active_readers; /* Thread IDs of registered readers */ #define INIT_NUM_THREADS 4 struct reader_data { pthread_t tid; - int **urcu_active_readers; + int *urcu_active_readers; }; +#ifdef DEBUG_YIELD +unsigned int yield_active; +unsigned int __thread rand_yield; +#endif + static struct reader_data *reader_data; static int num_readers, alloc_readers; static int sig_done; +void internal_urcu_lock(void) +{ + int ret; + ret = pthread_mutex_lock(&urcu_mutex); + if (ret) { + perror("Error in pthread mutex lock"); + exit(-1); + } +} + +void internal_urcu_unlock(void) +{ + int ret; + + ret = pthread_mutex_unlock(&urcu_mutex); + if (ret) { + perror("Error in pthread mutex unlock"); + exit(-1); + } +} + /* * called with urcu_mutex held. */ -static int switch_next_urcu_qparity(void) +static void switch_next_urcu_qparity(void) { - int old_parity = urcu_qparity; - urcu_qparity = 1 - old_parity; - return old_parity; + urcu_gp_ctr ^= RCU_GP_CTR_BIT; } static void force_mb_all_threads(void) { - pthread_t *index; + struct reader_data *index; /* * Ask for each threads to execute a mb() so we can consider the * compiler barriers around rcu read lock as real memory barriers. */ if (!reader_data) return; - sigtask = TASK_FORCE_MB; + debug_yield_write(); sig_done = 0; - mb(); /* write sig_done and sigtask before sending the signals */ - for (index = reader_data; index < reader_data + num_readers; index++) - pthread_kill(*index, SIGURCU); + debug_yield_write(); + mb(); /* write sig_done before sending the signals */ + debug_yield_write(); + for (index = reader_data; index < reader_data + num_readers; index++) { + pthread_kill(index->tid, SIGURCU); + debug_yield_write(); + } /* * Wait for sighandler (and thus mb()) to execute on every thread. * BUSY-LOOP. */ while (sig_done < num_readers) barrier(); - mb(); /* read sig_done before writing sigtask */ - sigtask = TASK_NONE; + debug_yield_write(); + mb(); /* read sig_done before ending the barrier */ + debug_yield_write(); } -void wait_for_quiescent_state(int parity) +void wait_for_quiescent_state(void) { + struct reader_data *index; if (!reader_data) return; /* Wait for each thread urcu_active_readers count to become 0. */ - for (index = readers_data; index < reader_data + num_readers; index++) { + for (index = reader_data; index < reader_data + num_readers; index++) { /* * BUSY-LOOP. */ - while (*index->urcu_active_readers != 0) + while (rcu_old_gp_ongoing(index->urcu_active_readers)) barrier(); } /* @@ -81,64 +123,45 @@ void wait_for_quiescent_state(int parity) force_mb_all_threads(); } -/* - * Return old pointer, OK to free, no more reference exist. - */ -void *urcu_publish_content(void **ptr, void *new) +static void switch_qparity(void) { - int ret, prev_parity; - void *oldptr; - - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex lock", __func__); - exit(-1); - } - - /* - * We can publish the new pointer before we change the current qparity. - * Readers seeing the new pointer while being in the previous qparity - * window will make us wait until the end of the quiescent state before - * we release the unrelated memory area. However, given we hold the - * urcu_mutex, we are making sure that no further garbage collection can - * occur until we release the mutex, therefore we guarantee that this - * given reader will have completed its execution using the new pointer - * when the next quiescent state window will be over. - */ - oldptr = *ptr; - *ptr = new; - wmb(); /* Write ptr before changing the qparity */ - /* All threads should read qparity before ptr */ - force_rmb_all_threads(); - prev_parity = switch_next_urcu_qparity(); + /* All threads should read qparity before accessing data structure. */ + /* Write ptr before changing the qparity */ + force_mb_all_threads(); + debug_yield_write(); + switch_next_urcu_qparity(); + debug_yield_write(); /* * Wait for previous parity to be empty of readers. */ - wait_for_quiescent_state(prev_parity); - /* - * Deleting old data is ok ! - */ - - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex lock", __func__); - exit(-1); - } - return oldptr; + wait_for_quiescent_state(); +} + +void synchronize_rcu(void) +{ + debug_yield_write(); + internal_urcu_lock(); + debug_yield_write(); + switch_qparity(); + debug_yield_write(); + switch_qparity(); + debug_yield_write(); + internal_urcu_unlock(); + debug_yield_write(); } void urcu_add_reader(pthread_t id) { + struct reader_data *oldarray; + if (!reader_data) { alloc_readers = INIT_NUM_THREADS; - num_readers = 1; + num_readers = 0; reader_data = malloc(sizeof(struct reader_data) * alloc_readers); - return; } if (alloc_readers < num_readers + 1) { - pthread_t *oldarray; oldarray = reader_data; reader_data = malloc(sizeof(struct reader_data) * (alloc_readers << 1)); @@ -149,7 +172,7 @@ void urcu_add_reader(pthread_t id) } reader_data[num_readers].tid = id; /* reference to the TLS of _this_ reader thread. */ - reader_data[num_readers].urcu_active_readers = urcu_active_readers; + reader_data[num_readers].urcu_active_readers = &urcu_active_readers; num_readers++; } @@ -163,7 +186,7 @@ void urcu_remove_reader(pthread_t id) assert(reader_data != NULL); for (index = reader_data; index < reader_data + num_readers; index++) { - if (index->tid == id) { + if (pthread_equal(index->tid, id)) { memcpy(index, &reader_data[num_readers - 1], sizeof(struct reader_data)); reader_data[num_readers - 1].tid = 0; @@ -178,45 +201,19 @@ void urcu_remove_reader(pthread_t id) void urcu_register_thread(void) { - pthread_t self = pthread_self(); - - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex lock", __func__); - exit(-1); - } - - urcu_add_reader(self); - - - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex unlock", __func__); - exit(-1); - } + internal_urcu_lock(); + urcu_add_reader(pthread_self()); + internal_urcu_unlock(); } -void urcu_register_thread(void) +void urcu_unregister_thread(void) { - pthread_t self = pthread_self(); - - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex lock", __func__); - exit(-1); - } - - urcu_remove_reader(self); - - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in %s pthread mutex unlock", __func__); - exit(-1); - } - + internal_urcu_lock(); + urcu_remove_reader(pthread_self()); + internal_urcu_unlock(); } -void handler(int signo, siginfo_t *siginfo, void *context) +void sigurcu_handler(int signo, siginfo_t *siginfo, void *context) { mb(); atomic_inc(&sig_done); @@ -229,8 +226,8 @@ void __attribute__((constructor)) urcu_init(void) act.sa_sigaction = sigurcu_handler; ret = sigaction(SIGURCU, &act, NULL); - if (!ret) { - perror("Error in %s sigaction", __func__); + if (ret) { + perror("Error in sigaction"); exit(-1); } } @@ -241,8 +238,8 @@ void __attribute__((destructor)) urcu_exit(void) int ret; ret = sigaction(SIGURCU, NULL, &act); - if (!ret) { - perror("Error in %s sigaction", __func__); + if (ret) { + perror("Error in sigaction"); exit(-1); } assert(act.sa_sigaction == sigurcu_handler);