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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 "epoll.h"
#include <stdint.h>
#include <sys/epoll.h>
#include <chrono>
#include <functional>
#include <map>
#include <android-base/logging.h>
namespace android {
namespace init {
Epoll::Epoll() {}
Result<void> Epoll::Open() {
if (epoll_fd_ >= 0) return {};
epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
if (epoll_fd_ == -1) {
return ErrnoError() << "epoll_create1 failed";
}
return {};
}
Result<void> Epoll::RegisterHandler(int fd, Handler handler, uint32_t events) {
if (!events) {
return Error() << "Must specify events";
}
auto [it, inserted] = epoll_handlers_.emplace(
fd, Info{
.events = events,
.handler = std::move(handler),
});
if (!inserted) {
return Error() << "Cannot specify two epoll handlers for a given FD";
}
epoll_event ev = {
.events = events,
.data.fd = fd,
};
if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, fd, &ev) == -1) {
Result<void> result = ErrnoError() << "epoll_ctl failed to add fd";
epoll_handlers_.erase(fd);
return result;
}
return {};
}
Result<void> Epoll::UnregisterHandler(int fd) {
if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_DEL, fd, nullptr) == -1) {
return ErrnoError() << "epoll_ctl failed to remove fd";
}
auto it = epoll_handlers_.find(fd);
if (it == epoll_handlers_.end()) {
return Error() << "Attempting to remove epoll handler for FD without an existing handler";
}
to_remove_.insert(it->first);
return {};
}
void Epoll::SetFirstCallback(std::function<void()> first_callback) {
first_callback_ = std::move(first_callback);
}
Result<int> Epoll::Wait(std::optional<std::chrono::milliseconds> timeout) {
int timeout_ms = -1;
if (timeout && timeout->count() < INT_MAX) {
timeout_ms = timeout->count();
}
const auto max_events = epoll_handlers_.size();
epoll_event ev[max_events];
auto num_events = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_.get(), ev, max_events, timeout_ms));
if (num_events == -1) {
return ErrnoError() << "epoll_wait failed";
}
if (num_events > 0 && first_callback_) {
first_callback_();
}
for (int i = 0; i < num_events; ++i) {
const auto it = epoll_handlers_.find(ev[i].data.fd);
if (it == epoll_handlers_.end()) {
continue;
}
const Info& info = it->second;
if ((info.events & (EPOLLIN | EPOLLPRI)) == (EPOLLIN | EPOLLPRI) &&
(ev[i].events & EPOLLIN) != ev[i].events) {
// This handler wants to know about exception events, and just got one.
// Log something informational.
LOG(ERROR) << "Received unexpected epoll event set: " << ev[i].events;
}
info.handler();
for (auto fd : to_remove_) {
epoll_handlers_.erase(fd);
}
to_remove_.clear();
}
return num_events;
}
} // namespace init
} // namespace android
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