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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";
}
Info info;
info.events = events;
info.handler = std::make_shared<decltype(handler)>(std::move(handler));
auto [it, inserted] = epoll_handlers_.emplace(fd, std::move(info));
if (!inserted) {
return Error() << "Cannot specify two epoll handlers for a given FD";
}
epoll_event ev;
ev.events = events;
// std::map's iterators do not get invalidated until erased, so we use the
// pointer to the std::function in the map directly for epoll_ctl.
ev.data.ptr = reinterpret_cast<void*>(&it->second);
if (epoll_ctl(epoll_fd_, 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_, EPOLL_CTL_DEL, fd, nullptr) == -1) {
return ErrnoError() << "epoll_ctl failed to remove fd";
}
if (epoll_handlers_.erase(fd) != 1) {
return Error() << "Attempting to remove epoll handler for FD without an existing handler";
}
return {};
}
Result<std::vector<std::shared_ptr<Epoll::Handler>>> 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_, ev, max_events, timeout_ms));
if (num_events == -1) {
return ErrnoError() << "epoll_wait failed";
}
std::vector<std::shared_ptr<Handler>> pending_functions;
for (int i = 0; i < num_events; ++i) {
auto& info = *reinterpret_cast<Info*>(ev[i].data.ptr);
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;
}
pending_functions.emplace_back(info.handler);
}
return pending_functions;
}
} // namespace init
} // namespace android
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