| /* |
| * 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@ |
| */ |
| |
| #ifndef __DISPATCH_SEMAPHORE__ |
| #define __DISPATCH_SEMAPHORE__ |
| |
| #ifndef __DISPATCH_INDIRECT__ |
| #error "Please #include <dispatch/dispatch.h> instead of this file directly." |
| #include <dispatch/base.h> // for HeaderDoc |
| #endif |
| |
| DISPATCH_ASSUME_NONNULL_BEGIN |
| |
| /*! |
| * @typedef dispatch_semaphore_t |
| * |
| * @abstract |
| * A counting semaphore. |
| */ |
| DISPATCH_DECL(dispatch_semaphore); |
| |
| __BEGIN_DECLS |
| |
| /*! |
| * @function dispatch_semaphore_create |
| * |
| * @abstract |
| * Creates new counting semaphore with an initial value. |
| * |
| * @discussion |
| * Passing zero for the value is useful for when two threads need to reconcile |
| * the completion of a particular event. Passing a value greater than zero is |
| * useful for managing a finite pool of resources, where the pool size is equal |
| * to the value. |
| * |
| * @param value |
| * The starting value for the semaphore. Passing a value less than zero will |
| * cause NULL to be returned. |
| * |
| * @result |
| * The newly created semaphore, or NULL on failure. |
| */ |
| API_AVAILABLE(macos(10.6), ios(4.0)) |
| DISPATCH_EXPORT DISPATCH_MALLOC DISPATCH_RETURNS_RETAINED DISPATCH_WARN_RESULT |
| DISPATCH_NOTHROW |
| dispatch_semaphore_t |
| dispatch_semaphore_create(long value); |
| |
| /*! |
| * @function dispatch_semaphore_wait |
| * |
| * @abstract |
| * Wait (decrement) for a semaphore. |
| * |
| * @discussion |
| * Decrement the counting semaphore. If the resulting value is less than zero, |
| * this function waits for a signal to occur before returning. |
| * |
| * @param dsema |
| * The semaphore. The result of passing NULL in this parameter is undefined. |
| * |
| * @param timeout |
| * When to timeout (see dispatch_time). As a convenience, there are the |
| * DISPATCH_TIME_NOW and DISPATCH_TIME_FOREVER constants. |
| * |
| * @result |
| * Returns zero on success, or non-zero if the timeout occurred. |
| */ |
| API_AVAILABLE(macos(10.6), ios(4.0)) |
| DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW |
| long |
| dispatch_semaphore_wait(dispatch_semaphore_t dsema, dispatch_time_t timeout); |
| |
| /*! |
| * @function dispatch_semaphore_signal |
| * |
| * @abstract |
| * Signal (increment) a semaphore. |
| * |
| * @discussion |
| * Increment the counting semaphore. If the previous value was less than zero, |
| * this function wakes a waiting thread before returning. |
| * |
| * @param dsema The counting semaphore. |
| * The result of passing NULL in this parameter is undefined. |
| * |
| * @result |
| * This function returns non-zero if a thread is woken. Otherwise, zero is |
| * returned. |
| */ |
| API_AVAILABLE(macos(10.6), ios(4.0)) |
| DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW |
| long |
| dispatch_semaphore_signal(dispatch_semaphore_t dsema); |
| |
| __END_DECLS |
| |
| DISPATCH_ASSUME_NONNULL_END |
| |
| #endif /* __DISPATCH_SEMAPHORE__ */ |