diff options
Diffstat (limited to 'erts/lib_src/pthread/ethr_event.c')
| -rw-r--r-- | erts/lib_src/pthread/ethr_event.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/erts/lib_src/pthread/ethr_event.c b/erts/lib_src/pthread/ethr_event.c new file mode 100644 index 0000000000..6731c0eb46 --- /dev/null +++ b/erts/lib_src/pthread/ethr_event.c @@ -0,0 +1,219 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2009-2010. All Rights Reserved. + * + * The contents of this file are subject to the Erlang Public License, + * Version 1.1, (the "License"); you may not use this file except in + * compliance with the License. You should have received a copy of the + * Erlang Public License along with this software. If not, it can be + * retrieved online at http://www.erlang.org/. + * + * Software distributed under the License is distributed on an "AS IS" + * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + * the License for the specific language governing rights and limitations + * under the License. + * + * %CopyrightEnd% + */ + +/* + * Author: Rickard Green + */ + +#define ETHR_INLINE_FUNC_NAME_(X) X ## __ +#define ETHR_EVENT_IMPL__ + +#include "ethread.h" + +#if defined(ETHR_LINUX_FUTEX_IMPL__) +/* --- Linux futex implementation of ethread events ------------------------- */ + +#include <sched.h> +#include <errno.h> + +#define ETHR_YIELD_AFTER_BUSY_LOOPS 50 + +int +ethr_event_init(ethr_event *e) +{ + ethr_atomic_init(&e->futex, ETHR_EVENT_OFF__); + return 0; +} + +int +ethr_event_destroy(ethr_event *e) +{ + return 0; +} + +static ETHR_INLINE int +wait__(ethr_event *e, int spincount) +{ + unsigned sc = spincount; + int res; + long val; + int until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS; + + if (spincount < 0) + ETHR_FATAL_ERROR__(EINVAL); + + while (1) { + while (1) { + val = ethr_atomic_read(&e->futex); + if (val == ETHR_EVENT_ON__) + return 0; + if (sc == 0) + break; + sc--; + ETHR_SPIN_BODY; + if (--until_yield == 0) { + until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS; + res = ETHR_YIELD(); + if (res != 0) + ETHR_FATAL_ERROR__(res); + } + } + + if (val != ETHR_EVENT_OFF_WAITER__) { + val = ethr_atomic_cmpxchg(&e->futex, + ETHR_EVENT_OFF_WAITER__, + ETHR_EVENT_OFF__); + + if (val == ETHR_EVENT_ON__) + return 0; + ETHR_ASSERT(val == ETHR_EVENT_OFF__); + } + + res = ETHR_FUTEX__(&e->futex, ETHR_FUTEX_WAIT__, ETHR_EVENT_OFF_WAITER__); + if (res == EINTR) + break; + if (res != 0 && res != EWOULDBLOCK) + ETHR_FATAL_ERROR__(res); + } + + return res; +} + +#elif defined(ETHR_PTHREADS) +/* --- Posix mutex/cond implementation of events ---------------------------- */ + +int +ethr_event_init(ethr_event *e) +{ + int res; + ethr_atomic_init(&e->state, ETHR_EVENT_OFF__); + res = pthread_mutex_init(&e->mtx, NULL); + if (res != 0) + return res; + res = pthread_cond_init(&e->cnd, NULL); + if (res != 0) { + pthread_mutex_destroy(&e->mtx); + return res; + } + return 0; +} + +int +ethr_event_destroy(ethr_event *e) +{ + int res; + res = pthread_mutex_destroy(&e->mtx); + if (res != 0) + return res; + res = pthread_cond_destroy(&e->cnd); + if (res != 0) + return res; + return 0; +} + +static ETHR_INLINE int +wait__(ethr_event *e, int spincount) +{ + int sc = spincount; + long val; + int res, ulres; + int until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS; + + if (spincount < 0) + ETHR_FATAL_ERROR__(EINVAL); + + while (1) { + val = ethr_atomic_read(&e->state); + if (val == ETHR_EVENT_ON__) + return 0; + if (sc == 0) + break; + sc--; + ETHR_SPIN_BODY; + if (--until_yield == 0) { + until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS; + res = ETHR_YIELD(); + if (res != 0) + ETHR_FATAL_ERROR__(res); + } + } + + if (val != ETHR_EVENT_OFF_WAITER__) { + val = ethr_atomic_cmpxchg(&e->state, + ETHR_EVENT_OFF_WAITER__, + ETHR_EVENT_OFF__); + if (val == ETHR_EVENT_ON__) + return 0; + ETHR_ASSERT(val == ETHR_EVENT_OFF__); + } + + ETHR_ASSERT(val == ETHR_EVENT_OFF_WAITER__ + || val == ETHR_EVENT_OFF__); + + res = pthread_mutex_lock(&e->mtx); + if (res != 0) + ETHR_FATAL_ERROR__(res); + + while (1) { + + val = ethr_atomic_read(&e->state); + if (val == ETHR_EVENT_ON__) + break; + + res = pthread_cond_wait(&e->cnd, &e->mtx); + if (res == EINTR) + break; + if (res != 0) + ETHR_FATAL_ERROR__(res); + } + + ulres = pthread_mutex_unlock(&e->mtx); + if (ulres != 0) + ETHR_FATAL_ERROR__(ulres); + + return res; /* 0 || EINTR */ +} + +#else +#error No ethread event implementation +#endif + +void +ethr_event_reset(ethr_event *e) +{ + ethr_event_reset__(e); +} + +void +ethr_event_set(ethr_event *e) +{ + ethr_event_set__(e); +} + +int +ethr_event_wait(ethr_event *e) +{ + return wait__(e, 0); +} + +int +ethr_event_swait(ethr_event *e, int spincount) +{ + return wait__(e, spincount); +} |