/usr/include/dispatch/semaphore.h is in libdispatch-dev 0~svn197-3.3ubuntu2.
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* Copyright (c) 2008-2009 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
/*!
* @typedef dispatch_semaphore_t
*
* @abstract
* A counting semaphore.
*/
DISPATCH_DECL(dispatch_semaphore);
__DISPATCH_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 greather 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.
*/
__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_4_0)
DISPATCH_EXPORT DISPATCH_MALLOC 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 in FIFO order 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.
*/
__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_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.
*/
__OSX_AVAILABLE_STARTING(__MAC_10_6,__IPHONE_4_0)
DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW
long
dispatch_semaphore_signal(dispatch_semaphore_t dsema);
__DISPATCH_END_DECLS
#endif /* __DISPATCH_SEMAPHORE__ */
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