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
future_new(void)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
future_new_immediate(void * value)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
future_ready(future_t * future,void * value)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
future_await(future_t * future)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
future_free(future_t * future)83 static void future_free(future_t* future) {
84 if (!future) return;
85
86 semaphore_free(future->semaphore);
87 osi_free(future);
88 }
89