| /* |
| * Copyright (c) 2008-2013 Apple Inc. All rights reserved. |
| * |
| * @APPLE_APACHE_LICENSE_HEADER_START@ |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| * @APPLE_APACHE_LICENSE_HEADER_END@ |
| */ |
| |
| #include "internal.h" |
| |
| DISPATCH_WEAK // rdar://problem/8503746 |
| long _dispatch_semaphore_signal_slow(dispatch_semaphore_t dsema); |
| |
| #pragma mark - |
| #pragma mark dispatch_semaphore_class_t |
| |
| static void |
| _dispatch_semaphore_class_init(long value, dispatch_semaphore_class_t dsemau) |
| { |
| struct dispatch_semaphore_header_s *dsema = dsemau._dsema_hdr; |
| |
| dsema->do_next = DISPATCH_OBJECT_LISTLESS; |
| dsema->do_targetq = _dispatch_get_root_queue(DISPATCH_QOS_DEFAULT, false); |
| dsema->dsema_value = value; |
| _dispatch_sema4_init(&dsema->dsema_sema, _DSEMA4_POLICY_FIFO); |
| } |
| |
| #pragma mark - |
| #pragma mark dispatch_semaphore_t |
| |
| dispatch_semaphore_t |
| dispatch_semaphore_create(long value) |
| { |
| dispatch_semaphore_t dsema; |
| |
| // If the internal value is negative, then the absolute of the value is |
| // equal to the number of waiting threads. Therefore it is bogus to |
| // initialize the semaphore with a negative value. |
| if (value < 0) { |
| return DISPATCH_BAD_INPUT; |
| } |
| |
| dsema = (dispatch_semaphore_t)_dispatch_alloc(DISPATCH_VTABLE(semaphore), |
| sizeof(struct dispatch_semaphore_s)); |
| _dispatch_semaphore_class_init(value, dsema); |
| dsema->dsema_orig = value; |
| return dsema; |
| } |
| |
| void |
| _dispatch_semaphore_dispose(dispatch_object_t dou) |
| { |
| dispatch_semaphore_t dsema = dou._dsema; |
| |
| if (dsema->dsema_value < dsema->dsema_orig) { |
| DISPATCH_CLIENT_CRASH(dsema->dsema_orig - dsema->dsema_value, |
| "Semaphore object deallocated while in use"); |
| } |
| |
| _dispatch_sema4_dispose(&dsema->dsema_sema, _DSEMA4_POLICY_FIFO); |
| } |
| |
| size_t |
| _dispatch_semaphore_debug(dispatch_object_t dou, char *buf, size_t bufsiz) |
| { |
| dispatch_semaphore_t dsema = dou._dsema; |
| |
| size_t offset = 0; |
| offset += dsnprintf(&buf[offset], bufsiz - offset, "%s[%p] = { ", |
| dx_kind(dsema), dsema); |
| offset += _dispatch_object_debug_attr(dsema, &buf[offset], bufsiz - offset); |
| #if USE_MACH_SEM |
| offset += dsnprintf(&buf[offset], bufsiz - offset, "port = 0x%u, ", |
| dsema->dsema_sema); |
| #endif |
| offset += dsnprintf(&buf[offset], bufsiz - offset, |
| "value = %ld, orig = %ld }", dsema->dsema_value, dsema->dsema_orig); |
| return offset; |
| } |
| |
| DISPATCH_NOINLINE |
| long |
| _dispatch_semaphore_signal_slow(dispatch_semaphore_t dsema) |
| { |
| _dispatch_sema4_create(&dsema->dsema_sema, _DSEMA4_POLICY_FIFO); |
| _dispatch_sema4_signal(&dsema->dsema_sema, 1); |
| return 1; |
| } |
| |
| long |
| dispatch_semaphore_signal(dispatch_semaphore_t dsema) |
| { |
| long value = os_atomic_inc2o(dsema, dsema_value, release); |
| if (fastpath(value > 0)) { |
| return 0; |
| } |
| if (slowpath(value == LONG_MIN)) { |
| DISPATCH_CLIENT_CRASH(value, |
| "Unbalanced call to dispatch_semaphore_signal()"); |
| } |
| return _dispatch_semaphore_signal_slow(dsema); |
| } |
| |
| DISPATCH_NOINLINE |
| static long |
| _dispatch_semaphore_wait_slow(dispatch_semaphore_t dsema, |
| dispatch_time_t timeout) |
| { |
| long orig; |
| |
| _dispatch_sema4_create(&dsema->dsema_sema, _DSEMA4_POLICY_FIFO); |
| switch (timeout) { |
| default: |
| if (!_dispatch_sema4_timedwait(&dsema->dsema_sema, timeout)) { |
| break; |
| } |
| // Fall through and try to undo what the fast path did to |
| // dsema->dsema_value |
| case DISPATCH_TIME_NOW: |
| orig = dsema->dsema_value; |
| while (orig < 0) { |
| if (os_atomic_cmpxchgvw2o(dsema, dsema_value, orig, orig + 1, |
| &orig, relaxed)) { |
| return _DSEMA4_TIMEOUT(); |
| } |
| } |
| // Another thread called semaphore_signal(). |
| // Fall through and drain the wakeup. |
| case DISPATCH_TIME_FOREVER: |
| _dispatch_sema4_wait(&dsema->dsema_sema); |
| break; |
| } |
| return 0; |
| } |
| |
| long |
| dispatch_semaphore_wait(dispatch_semaphore_t dsema, dispatch_time_t timeout) |
| { |
| long value = os_atomic_dec2o(dsema, dsema_value, acquire); |
| if (fastpath(value >= 0)) { |
| return 0; |
| } |
| return _dispatch_semaphore_wait_slow(dsema, timeout); |
| } |
| |
| #pragma mark - |
| #pragma mark dispatch_group_t |
| |
| DISPATCH_ALWAYS_INLINE |
| static inline dispatch_group_t |
| _dispatch_group_create_with_count(long count) |
| { |
| dispatch_group_t dg = (dispatch_group_t)_dispatch_alloc( |
| DISPATCH_VTABLE(group), sizeof(struct dispatch_group_s)); |
| _dispatch_semaphore_class_init(count, dg); |
| if (count) { |
| os_atomic_store2o(dg, do_ref_cnt, 1, relaxed); // <rdar://problem/22318411> |
| } |
| return dg; |
| } |
| |
| dispatch_group_t |
| dispatch_group_create(void) |
| { |
| return _dispatch_group_create_with_count(0); |
| } |
| |
| dispatch_group_t |
| _dispatch_group_create_and_enter(void) |
| { |
| return _dispatch_group_create_with_count(1); |
| } |
| |
| void |
| dispatch_group_enter(dispatch_group_t dg) |
| { |
| long value = os_atomic_inc_orig2o(dg, dg_value, acquire); |
| if (slowpath((unsigned long)value >= (unsigned long)LONG_MAX)) { |
| DISPATCH_CLIENT_CRASH(value, |
| "Too many nested calls to dispatch_group_enter()"); |
| } |
| if (value == 0) { |
| _dispatch_retain(dg); // <rdar://problem/22318411> |
| } |
| } |
| |
| DISPATCH_NOINLINE |
| static long |
| _dispatch_group_wake(dispatch_group_t dg, bool needs_release) |
| { |
| dispatch_continuation_t next, head, tail = NULL; |
| long rval; |
| |
| // cannot use os_mpsc_capture_snapshot() because we can have concurrent |
| // _dispatch_group_wake() calls |
| head = os_atomic_xchg2o(dg, dg_notify_head, NULL, relaxed); |
| if (head) { |
| // snapshot before anything is notified/woken <rdar://problem/8554546> |
| tail = os_atomic_xchg2o(dg, dg_notify_tail, NULL, release); |
| } |
| rval = (long)os_atomic_xchg2o(dg, dg_waiters, 0, relaxed); |
| if (rval) { |
| // wake group waiters |
| _dispatch_sema4_create(&dg->dg_sema, _DSEMA4_POLICY_FIFO); |
| _dispatch_sema4_signal(&dg->dg_sema, rval); |
| } |
| if (head) { |
| // async group notify blocks |
| do { |
| next = os_mpsc_pop_snapshot_head(head, tail, do_next); |
| dispatch_queue_t dsn_queue = (dispatch_queue_t)head->dc_data; |
| _dispatch_continuation_async(dsn_queue, head); |
| _dispatch_release(dsn_queue); |
| } while ((head = next)); |
| _dispatch_release(dg); |
| } |
| if (needs_release) { |
| _dispatch_release(dg); // <rdar://problem/22318411> |
| } |
| return 0; |
| } |
| |
| void |
| dispatch_group_leave(dispatch_group_t dg) |
| { |
| long value = os_atomic_dec2o(dg, dg_value, release); |
| if (slowpath(value == 0)) { |
| return (void)_dispatch_group_wake(dg, true); |
| } |
| if (slowpath(value < 0)) { |
| DISPATCH_CLIENT_CRASH(value, |
| "Unbalanced call to dispatch_group_leave()"); |
| } |
| } |
| |
| void |
| _dispatch_group_dispose(dispatch_object_t dou) |
| { |
| dispatch_group_t dg = dou._dg; |
| |
| if (dg->dg_value) { |
| DISPATCH_CLIENT_CRASH(dg->dg_value, |
| "Group object deallocated while in use"); |
| } |
| |
| _dispatch_sema4_dispose(&dg->dg_sema, _DSEMA4_POLICY_FIFO); |
| } |
| |
| size_t |
| _dispatch_group_debug(dispatch_object_t dou, char *buf, size_t bufsiz) |
| { |
| dispatch_group_t dg = dou._dg; |
| |
| size_t offset = 0; |
| offset += dsnprintf(&buf[offset], bufsiz - offset, "%s[%p] = { ", |
| dx_kind(dg), dg); |
| offset += _dispatch_object_debug_attr(dg, &buf[offset], bufsiz - offset); |
| #if USE_MACH_SEM |
| offset += dsnprintf(&buf[offset], bufsiz - offset, "port = 0x%u, ", |
| dg->dg_sema); |
| #endif |
| offset += dsnprintf(&buf[offset], bufsiz - offset, |
| "count = %ld, waiters = %d }", dg->dg_value, dg->dg_waiters); |
| return offset; |
| } |
| |
| DISPATCH_NOINLINE |
| static long |
| _dispatch_group_wait_slow(dispatch_group_t dg, dispatch_time_t timeout) |
| { |
| long value; |
| int orig_waiters; |
| |
| // check before we cause another signal to be sent by incrementing |
| // dg->dg_waiters |
| value = os_atomic_load2o(dg, dg_value, ordered); // 19296565 |
| if (value == 0) { |
| return _dispatch_group_wake(dg, false); |
| } |
| |
| (void)os_atomic_inc2o(dg, dg_waiters, relaxed); |
| // check the values again in case we need to wake any threads |
| value = os_atomic_load2o(dg, dg_value, ordered); // 19296565 |
| if (value == 0) { |
| _dispatch_group_wake(dg, false); |
| // Fall through to consume the extra signal, forcing timeout to avoid |
| // useless setups as it won't block |
| timeout = DISPATCH_TIME_FOREVER; |
| } |
| |
| _dispatch_sema4_create(&dg->dg_sema, _DSEMA4_POLICY_FIFO); |
| switch (timeout) { |
| default: |
| if (!_dispatch_sema4_timedwait(&dg->dg_sema, timeout)) { |
| break; |
| } |
| // Fall through and try to undo the earlier change to |
| // dg->dg_waiters |
| case DISPATCH_TIME_NOW: |
| orig_waiters = dg->dg_waiters; |
| while (orig_waiters) { |
| if (os_atomic_cmpxchgvw2o(dg, dg_waiters, orig_waiters, |
| orig_waiters - 1, &orig_waiters, relaxed)) { |
| return _DSEMA4_TIMEOUT(); |
| } |
| } |
| // Another thread is running _dispatch_group_wake() |
| // Fall through and drain the wakeup. |
| case DISPATCH_TIME_FOREVER: |
| _dispatch_sema4_wait(&dg->dg_sema); |
| break; |
| } |
| return 0; |
| } |
| |
| long |
| dispatch_group_wait(dispatch_group_t dg, dispatch_time_t timeout) |
| { |
| if (dg->dg_value == 0) { |
| return 0; |
| } |
| if (timeout == 0) { |
| return _DSEMA4_TIMEOUT(); |
| } |
| return _dispatch_group_wait_slow(dg, timeout); |
| } |
| |
| DISPATCH_ALWAYS_INLINE |
| static inline void |
| _dispatch_group_notify(dispatch_group_t dg, dispatch_queue_t dq, |
| dispatch_continuation_t dsn) |
| { |
| dsn->dc_data = dq; |
| dsn->do_next = NULL; |
| _dispatch_retain(dq); |
| if (os_mpsc_push_update_tail(dg, dg_notify, dsn, do_next)) { |
| _dispatch_retain(dg); |
| os_atomic_store2o(dg, dg_notify_head, dsn, ordered); |
| // seq_cst with atomic store to notify_head <rdar://problem/11750916> |
| if (os_atomic_load2o(dg, dg_value, ordered) == 0) { |
| _dispatch_group_wake(dg, false); |
| } |
| } |
| } |
| |
| DISPATCH_NOINLINE |
| void |
| dispatch_group_notify_f(dispatch_group_t dg, dispatch_queue_t dq, void *ctxt, |
| dispatch_function_t func) |
| { |
| dispatch_continuation_t dsn = _dispatch_continuation_alloc(); |
| _dispatch_continuation_init_f(dsn, dq, ctxt, func, 0, 0, |
| DISPATCH_OBJ_CONSUME_BIT); |
| _dispatch_group_notify(dg, dq, dsn); |
| } |
| |
| #ifdef __BLOCKS__ |
| void |
| dispatch_group_notify(dispatch_group_t dg, dispatch_queue_t dq, |
| dispatch_block_t db) |
| { |
| dispatch_continuation_t dsn = _dispatch_continuation_alloc(); |
| _dispatch_continuation_init(dsn, dq, db, 0, 0, DISPATCH_OBJ_CONSUME_BIT); |
| _dispatch_group_notify(dg, dq, dsn); |
| } |
| #endif |