1 /****************************************************************************** 2 * 3 * Copyright (C) 2014 Google, Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19 #define LOG_TAG "bt_osi_future" 20 21 #include <assert.h> 22 23 #include "osi/include/allocator.h" 24 #include "osi/include/future.h" 25 #include "osi/include/osi.h" 26 #include "osi/include/log.h" 27 #include "osi/include/semaphore.h" 28 29 struct future_t { 30 bool ready_can_be_called; 31 semaphore_t *semaphore; // NULL semaphore means immediate future 32 void *result; 33 }; 34 35 static void future_free(future_t *future); 36 37 future_t *future_new(void) { 38 future_t *ret = osi_calloc(sizeof(future_t)); 39 if (!ret) { 40 LOG_ERROR("%s unable to allocate memory for return value.", __func__); 41 goto error; 42 } 43 44 ret->semaphore = semaphore_new(0); 45 if (!ret->semaphore) { 46 LOG_ERROR("%s unable to allocate memory for the semaphore.", __func__); 47 goto error; 48 } 49 50 ret->ready_can_be_called = true; 51 return ret; 52 error:; 53 future_free(ret); 54 return NULL; 55 } 56 57 future_t *future_new_immediate(void *value) { 58 future_t *ret = osi_calloc(sizeof(future_t)); 59 if (!ret) { 60 LOG_ERROR("%s unable to allocate memory for return value.", __func__); 61 goto error; 62 } 63 64 ret->result = value; 65 ret->ready_can_be_called = false; 66 return ret; 67 error:; 68 future_free(ret); 69 return NULL; 70 } 71 72 void future_ready(future_t *future, void *value) { 73 assert(future != NULL); 74 assert(future->ready_can_be_called); 75 76 future->ready_can_be_called = false; 77 future->result = value; 78 semaphore_post(future->semaphore); 79 } 80 81 void *future_await(future_t *future) { 82 assert(future != NULL); 83 84 // If the future is immediate, it will not have a semaphore 85 if (future->semaphore) 86 semaphore_wait(future->semaphore); 87 88 void *result = future->result; 89 future_free(future); 90 return result; 91 } 92 93 static void future_free(future_t *future) { 94 if (!future) 95 return; 96 97 semaphore_free(future->semaphore); 98 osi_free(future); 99 } 100
