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