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 <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
30struct future_t {
31  bool ready_can_be_called;
32  semaphore_t* semaphore;  // NULL semaphore means immediate future
33  void* result;
34};
35
36static void future_free(future_t* future);
37
38future_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;
50error:;
51  future_free(ret);
52  return NULL;
53}
54
55future_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
63void 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
72void* 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
83static void future_free(future_t* future) {
84  if (!future) return;
85
86  semaphore_free(future->semaphore);
87  osi_free(future);
88}
89