1 /*
2 * Copyright (C) 2018 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 "perfetto/base/build_config.h"
18
19 #include <errno.h>
20 #include <stdint.h>
21
22 #if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
23 #include <Windows.h>
24 #include <synchapi.h>
25 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_QNX)
26 #include <unistd.h>
27 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
28 PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
29 #include <sys/eventfd.h>
30 #include <unistd.h>
31 #else // Mac, Fuchsia and other non-Linux UNIXes
32 #include <unistd.h>
33 #endif
34
35 #include "perfetto/base/logging.h"
36 #include "perfetto/ext/base/event_fd.h"
37 #include "perfetto/ext/base/pipe.h"
38 #include "perfetto/ext/base/utils.h"
39
40 namespace perfetto {
41 namespace base {
42
43 EventFd::~EventFd() = default;
44
45 #if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
EventFd()46 EventFd::EventFd() {
47 event_handle_.reset(
48 CreateEventA(/*lpEventAttributes=*/nullptr, /*bManualReset=*/true,
49 /*bInitialState=*/false, /*bInitialState=*/nullptr));
50 }
51
Notify()52 void EventFd::Notify() {
53 if (!SetEvent(event_handle_.get())) // 0: fail, !0: success, unlike UNIX.
54 PERFETTO_DFATAL("EventFd::Notify()");
55 }
56
Clear()57 void EventFd::Clear() {
58 if (!ResetEvent(event_handle_.get())) // 0: fail, !0: success, unlike UNIX.
59 PERFETTO_DFATAL("EventFd::Clear()");
60 }
61
62 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX_BUT_NOT_QNX) || \
63 PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
64
EventFd()65 EventFd::EventFd() {
66 event_handle_.reset(eventfd(/*initval=*/0, EFD_CLOEXEC | EFD_NONBLOCK));
67 PERFETTO_CHECK(event_handle_);
68 }
69
Notify()70 void EventFd::Notify() {
71 const uint64_t value = 1;
72 ssize_t ret = write(event_handle_.get(), &value, sizeof(value));
73 if (ret <= 0 && errno != EAGAIN)
74 PERFETTO_DFATAL("EventFd::Notify()");
75 }
76
Clear()77 void EventFd::Clear() {
78 uint64_t value;
79 ssize_t ret =
80 PERFETTO_EINTR(read(event_handle_.get(), &value, sizeof(value)));
81 if (ret <= 0 && errno != EAGAIN)
82 PERFETTO_DFATAL("EventFd::Clear()");
83 }
84
85 #else
86
EventFd()87 EventFd::EventFd() {
88 // Make the pipe non-blocking so that we never block the waking thread (either
89 // the main thread or another one) when scheduling a wake-up.
90 Pipe pipe = Pipe::Create(Pipe::kBothNonBlock);
91 event_handle_ = ScopedPlatformHandle(std::move(pipe.rd).release());
92 write_fd_ = std::move(pipe.wr);
93 }
94
Notify()95 void EventFd::Notify() {
96 const uint64_t value = 1;
97 ssize_t ret = write(write_fd_.get(), &value, sizeof(uint8_t));
98 if (ret <= 0 && errno != EAGAIN)
99 PERFETTO_DFATAL("EventFd::Notify()");
100 }
101
Clear()102 void EventFd::Clear() {
103 // Drain the byte(s) written to the wake-up pipe. We can potentially read
104 // more than one byte if several wake-ups have been scheduled.
105 char buffer[16];
106 ssize_t ret =
107 PERFETTO_EINTR(read(event_handle_.get(), &buffer[0], sizeof(buffer)));
108 if (ret <= 0 && errno != EAGAIN)
109 PERFETTO_DFATAL("EventFd::Clear()");
110 }
111 #endif
112
113 } // namespace base
114 } // namespace perfetto
115