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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "perfetto/base/build_config.h"
#if !PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
#include <stdint.h>
#include <unistd.h>
#include "perfetto/base/logging.h"
#include "perfetto/ext/base/event_fd.h"
#include "perfetto/ext/base/pipe.h"
#include "perfetto/ext/base/utils.h"
#if PERFETTO_USE_EVENTFD()
#include <sys/eventfd.h>
#endif
namespace perfetto {
namespace base {
EventFd::EventFd() {
#if PERFETTO_USE_EVENTFD()
fd_.reset(eventfd(/* start value */ 0, EFD_CLOEXEC | EFD_NONBLOCK));
PERFETTO_CHECK(fd_);
#else
// Make the pipe non-blocking so that we never block the waking thread (either
// the main thread or another one) when scheduling a wake-up.
Pipe pipe = Pipe::Create(Pipe::kBothNonBlock);
fd_ = std::move(pipe.rd);
write_fd_ = std::move(pipe.wr);
#endif // !PERFETTO_USE_EVENTFD()
}
EventFd::~EventFd() = default;
void EventFd::Notify() {
const uint64_t value = 1;
#if PERFETTO_USE_EVENTFD()
ssize_t ret = write(fd_.get(), &value, sizeof(value));
#else
ssize_t ret = write(write_fd_.get(), &value, sizeof(uint8_t));
#endif
if (ret <= 0 && errno != EAGAIN) {
PERFETTO_DFATAL("write()");
}
}
void EventFd::Clear() {
#if PERFETTO_USE_EVENTFD()
uint64_t value;
ssize_t ret = read(fd_.get(), &value, sizeof(value));
#else
// Drain the byte(s) written to the wake-up pipe. We can potentially read
// more than one byte if several wake-ups have been scheduled.
char buffer[16];
ssize_t ret = read(fd_.get(), &buffer[0], sizeof(buffer));
#endif
if (ret <= 0 && errno != EAGAIN)
PERFETTO_DPLOG("read()");
}
} // namespace base
} // namespace perfetto
#endif // !PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
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