michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * File: pripcsem.h
michael@0:  *
michael@0:  * Description: named semaphores for interprocess
michael@0:  * synchronization
michael@0:  *
michael@0:  * Unrelated processes obtain access to a shared semaphore
michael@0:  * by specifying its name.
michael@0:  *
michael@0:  * Our goal is to support named semaphores on at least
michael@0:  * Unix and Win32 platforms.  The implementation will use
michael@0:  * one of the three native semaphore APIs: POSIX, System V,
michael@0:  * and Win32.
michael@0:  *
michael@0:  * Because POSIX named semaphores have kernel persistence,
michael@0:  * we are forced to have a delete function in this API.
michael@0:  */
michael@0: 
michael@0: #ifndef pripcsem_h___
michael@0: #define pripcsem_h___
michael@0: 
michael@0: #include "prtypes.h"
michael@0: #include "prio.h"
michael@0: 
michael@0: PR_BEGIN_EXTERN_C
michael@0: 
michael@0: /*
michael@0:  * PRSem is an opaque structure that represents a named
michael@0:  * semaphore.
michael@0:  */
michael@0: typedef struct PRSem PRSem;
michael@0: 
michael@0: /*
michael@0:  * PR_OpenSemaphore --
michael@0:  *
michael@0:  * Create or open a named semaphore with the specified name.
michael@0:  * A handle to the semaphore is returned.
michael@0:  *
michael@0:  * If the named semaphore doesn't exist and the PR_SEM_CREATE
michael@0:  * flag is specified, the named semaphore is created.  The
michael@0:  * created semaphore needs to be removed from the system with
michael@0:  * a PR_DeleteSemaphore call.
michael@0:  *
michael@0:  * If PR_SEM_CREATE is specified, the third argument is the
michael@0:  * access permission bits of the new semaphore (same
michael@0:  * interpretation as the mode argument to PR_Open) and the
michael@0:  * fourth argument is the initial value of the new semaphore.
michael@0:  * If PR_SEM_CREATE is not specified, the third and fourth
michael@0:  * arguments are ignored.
michael@0:  */
michael@0: 
michael@0: #define PR_SEM_CREATE 0x1  /* create if not exist */
michael@0: #define PR_SEM_EXCL   0x2  /* fail if already exists */
michael@0: 
michael@0: NSPR_API(PRSem *) PR_OpenSemaphore(
michael@0:     const char *name, PRIntn flags, PRIntn mode, PRUintn value);
michael@0: 
michael@0: /*
michael@0:  * PR_WaitSemaphore --
michael@0:  *
michael@0:  * If the value of the semaphore is > 0, decrement the value and return.
michael@0:  * If the value is 0, sleep until the value becomes > 0, then decrement
michael@0:  * the value and return.
michael@0:  *
michael@0:  * The "test and decrement" operation is performed atomically.
michael@0:  */
michael@0: 
michael@0: NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
michael@0: 
michael@0: /*
michael@0:  * PR_PostSemaphore --
michael@0:  *
michael@0:  * Increment the value of the named semaphore by 1.
michael@0:  */
michael@0: 
michael@0: NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);
michael@0: 
michael@0: /*
michael@0:  * PR_CloseSemaphore --
michael@0:  *
michael@0:  * Close a named semaphore handle.
michael@0:  */
michael@0: 
michael@0: NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);
michael@0: 
michael@0: /*
michael@0:  * PR_DeleteSemaphore --
michael@0:  *
michael@0:  * Remove a named semaphore from the system.
michael@0:  */
michael@0: 
michael@0: NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);
michael@0: 
michael@0: PR_END_EXTERN_C
michael@0: 
michael@0: #endif /* pripcsem_h___ */