Home | History | Annotate | Download | only in unix 
      1 /*-------------------------------------------------------------------------
      2  * drawElements Thread Library
      3  * ---------------------------
      4  *
      5  * Copyright 2014 The Android Open Source Project
      6  *
      7  * Licensed under the Apache License, Version 2.0 (the "License");
      8  * you may not use this file except in compliance with the License.
      9  * You may obtain a copy of the License at
     10  *
     11  *      http://www.apache.org/licenses/LICENSE-2.0
     12  *
     13  * Unless required by applicable law or agreed to in writing, software
     14  * distributed under the License is distributed on an "AS IS" BASIS,
     15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     16  * See the License for the specific language governing permissions and
     17  * limitations under the License.
     18  *
     19  *//*!
     20  * \file
     21  * \brief Unix implementation of semaphore using named semaphores.
     22  *//*--------------------------------------------------------------------*/
     23 
     24 #include "deSemaphore.h"
     25 
     26 #if (DE_OS == DE_OS_IOS || DE_OS == DE_OS_OSX)
     27 
     28 #include "deMemory.h"
     29 #include "deString.h"
     30 
     31 #include <semaphore.h>
     32 #include <unistd.h>
     33 
     34 typedef struct NamedSemaphore_s
     35 {
     36 	sem_t*	semaphore;
     37 } NamedSemaphore;
     38 
     39 static void NamedSemaphore_getName (const NamedSemaphore* sem, char* buf, int bufSize)
     40 {
     41 	deSprintf(buf, bufSize, "/desem-%d-%p", getpid(), (void*)sem);
     42 }
     43 
     44 DE_STATIC_ASSERT(sizeof(deSemaphore) >= sizeof(NamedSemaphore*));
     45 
     46 deSemaphore deSemaphore_create (int initialValue, const deSemaphoreAttributes* attributes)
     47 {
     48 	NamedSemaphore*	sem		= (NamedSemaphore*)deCalloc(sizeof(NamedSemaphore));
     49 	char			name[128];
     50 	deUint32		mode	= 0700;
     51 
     52 	DE_UNREF(attributes);
     53 
     54 	if (!sem)
     55 		return 0;
     56 
     57 	NamedSemaphore_getName(sem, name, DE_LENGTH_OF_ARRAY(name));
     58 
     59 	sem->semaphore = sem_open(name, O_CREAT|O_EXCL, mode, initialValue);
     60 
     61 	if (sem->semaphore == SEM_FAILED)
     62 	{
     63 		deFree(sem);
     64 		return 0;
     65 	}
     66 
     67 	return (deSemaphore)sem;
     68 }
     69 
     70 void deSemaphore_destroy (deSemaphore semaphore)
     71 {
     72 	NamedSemaphore* sem			= (NamedSemaphore*)semaphore;
     73 	char			name[128];
     74 	int				res;
     75 
     76 	NamedSemaphore_getName(sem, name, DE_LENGTH_OF_ARRAY(name));
     77 
     78 	res = sem_close(sem->semaphore);
     79 	DE_ASSERT(res == 0);
     80 	res = sem_unlink(name);
     81 	DE_ASSERT(res == 0);
     82 	DE_UNREF(res);
     83 	deFree(sem);
     84 }
     85 
     86 void deSemaphore_increment (deSemaphore semaphore)
     87 {
     88 	sem_t*	sem		= ((NamedSemaphore*)semaphore)->semaphore;
     89 	int		res		= sem_post(sem);
     90 	DE_ASSERT(res == 0);
     91 	DE_UNREF(res);
     92 }
     93 
     94 void deSemaphore_decrement (deSemaphore semaphore)
     95 {
     96 	sem_t*	sem		= ((NamedSemaphore*)semaphore)->semaphore;
     97 	int		res		= sem_wait(sem);
     98 	DE_ASSERT(res == 0);
     99 	DE_UNREF(res);
    100 }
    101 
    102 deBool deSemaphore_tryDecrement (deSemaphore semaphore)
    103 {
    104 	sem_t* sem = ((NamedSemaphore*)semaphore)->semaphore;
    105 	return (sem_trywait(sem) == 0);
    106 }
    107 
    108 #endif /* DE_OS */
    109