1 /*
2 * Copyright 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "os/handler.h"
18
19 #include <sys/eventfd.h>
20 #include <cstring>
21 #include <unistd.h>
22
23 #include "os/log.h"
24 #include "os/reactor.h"
25 #include "os/utils.h"
26
27 #ifndef EFD_SEMAPHORE
28 #define EFD_SEMAPHORE 1
29 #endif
30
31 namespace bluetooth {
32 namespace os {
33
Handler(Thread * thread)34 Handler::Handler(Thread* thread)
35 : thread_(thread),
36 fd_(eventfd(0, EFD_SEMAPHORE | EFD_NONBLOCK)) {
37 ASSERT(fd_ != -1);
38
39 reactable_ = thread_->GetReactor()->Register(fd_, [this] { this->handle_next_event(); }, nullptr);
40 }
41
~Handler()42 Handler::~Handler() {
43 thread_->GetReactor()->Unregister(reactable_);
44 reactable_ = nullptr;
45
46 int close_status;
47 RUN_NO_INTR(close_status = close(fd_));
48 ASSERT(close_status != -1);
49 }
50
Post(Closure closure)51 void Handler::Post(Closure closure) {
52 {
53 std::lock_guard<std::mutex> lock(mutex_);
54 tasks_.emplace(std::move(closure));
55 }
56 uint64_t val = 1;
57 auto write_result = eventfd_write(fd_, val);
58 ASSERT(write_result != -1);
59 }
60
Clear()61 void Handler::Clear() {
62 std::lock_guard<std::mutex> lock(mutex_);
63
64 std::queue<Closure> empty;
65 std::swap(tasks_, empty);
66
67 uint64_t val;
68 while (eventfd_read(fd_, &val) == 0) {
69 }
70 }
71
handle_next_event()72 void Handler::handle_next_event() {
73 Closure closure;
74 uint64_t val = 0;
75 auto read_result = eventfd_read(fd_, &val);
76 if (read_result == -1 && errno == EAGAIN) {
77 // We were told there was an item, but it was removed before we got there
78 // (aka the queue was cleared). Not a fatal error, so just bail.
79 return;
80 }
81
82 ASSERT(read_result != -1);
83
84 {
85 std::lock_guard<std::mutex> lock(mutex_);
86 closure = std::move(tasks_.front());
87 tasks_.pop();
88 }
89 closure();
90 }
91
92 } // namespace os
93 } // namespace bluetooth
94