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 "osi/include/future.h"
22
23 #include <assert.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 = 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.", __func__);
44 goto error;
45 }
46
47 ret->ready_can_be_called = true;
48 return ret;
49 error:;
50 future_free(ret);
51 return NULL;
52 }
53
future_new_immediate(void * value)54 future_t *future_new_immediate(void *value) {
55 future_t *ret = osi_calloc(sizeof(future_t));
56
57 ret->result = value;
58 ret->ready_can_be_called = false;
59 return ret;
60 }
61
future_ready(future_t * future,void * value)62 void future_ready(future_t *future, void *value) {
63 assert(future != NULL);
64 assert(future->ready_can_be_called);
65
66 future->ready_can_be_called = false;
67 future->result = value;
68 semaphore_post(future->semaphore);
69 }
70
future_await(future_t * future)71 void *future_await(future_t *future) {
72 assert(future != NULL);
73
74 // If the future is immediate, it will not have a semaphore
75 if (future->semaphore)
76 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)
85 return;
86
87 semaphore_free(future->semaphore);
88 osi_free(future);
89 }
90