1 /****************************************************************************** 2 * 3 * Copyright 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 "osi/include/future.h" 22 23 #include <base/logging.h> 24 25 #include "osi/include/allocator.h" 26 #include "osi/include/log.h" 27 #include "osi/include/osi.h" 28 #include "osi/include/semaphore.h" 29 30 struct future_t { 31 bool ready_can_be_called; 32 semaphore_t* semaphore; // NULL semaphore means immediate future 33 void* result; 34 }; 35 36 static void future_free(future_t* future); 37 38 future_t* future_new(void) { 39 future_t* ret = static_cast<future_t*>(osi_calloc(sizeof(future_t))); 40 41 ret->semaphore = semaphore_new(0); 42 if (!ret->semaphore) { 43 LOG_ERROR(LOG_TAG, "%s unable to allocate memory for the semaphore.", 44 __func__); 45 goto error; 46 } 47 48 ret->ready_can_be_called = true; 49 return ret; 50 error:; 51 future_free(ret); 52 return NULL; 53 } 54 55 future_t* future_new_immediate(void* value) { 56 future_t* ret = static_cast<future_t*>(osi_calloc(sizeof(future_t))); 57 58 ret->result = value; 59 ret->ready_can_be_called = false; 60 return ret; 61 } 62 63 void future_ready(future_t* future, void* value) { 64 CHECK(future != NULL); 65 CHECK(future->ready_can_be_called); 66 67 future->ready_can_be_called = false; 68 future->result = value; 69 semaphore_post(future->semaphore); 70 } 71 72 void* future_await(future_t* future) { 73 CHECK(future != NULL); 74 75 // If the future is immediate, it will not have a semaphore 76 if (future->semaphore) semaphore_wait(future->semaphore); 77 78 void* result = future->result; 79 future_free(future); 80 return result; 81 } 82 83 static void future_free(future_t* future) { 84 if (!future) return; 85 86 semaphore_free(future->semaphore); 87 osi_free(future); 88 } 89
