2 * Copyright 2017 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #include <folly/io/ShutdownSocketSet.h>
22 #include <glog/logging.h>
24 #include <folly/FileUtil.h>
25 #include <folly/portability/Sockets.h>
29 ShutdownSocketSet::ShutdownSocketSet(int maxFd)
31 data_(static_cast<std::atomic<uint8_t>*>(
32 folly::checkedCalloc(size_t(maxFd), sizeof(std::atomic<uint8_t>)))),
33 nullFile_("/dev/null", O_RDWR) {}
35 void ShutdownSocketSet::add(int fd) {
36 // Silently ignore any fds >= maxFd_, very unlikely
42 auto& sref = data_[size_t(fd)];
43 uint8_t prevState = FREE;
44 CHECK(sref.compare_exchange_strong(prevState,
46 std::memory_order_acq_rel))
47 << "Invalid prev state for fd " << fd << ": " << int(prevState);
50 void ShutdownSocketSet::remove(int fd) {
56 auto& sref = data_[size_t(fd)];
57 uint8_t prevState = 0;
60 prevState = sref.load(std::memory_order_relaxed);
65 std::this_thread::sleep_for(std::chrono::milliseconds(1));
68 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
71 if (!sref.compare_exchange_weak(prevState,
73 std::memory_order_acq_rel)) {
78 int ShutdownSocketSet::close(int fd) {
81 return folly::closeNoInt(fd);
84 auto& sref = data_[size_t(fd)];
85 uint8_t prevState = sref.load(std::memory_order_relaxed);
95 newState = MUST_CLOSE;
98 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
101 if (!sref.compare_exchange_weak(prevState,
103 std::memory_order_acq_rel)) {
107 return newState == FREE ? folly::closeNoInt(fd) : 0;
110 void ShutdownSocketSet::shutdown(int fd, bool abortive) {
113 doShutdown(fd, abortive);
117 auto& sref = data_[size_t(fd)];
118 uint8_t prevState = IN_USE;
119 if (!sref.compare_exchange_strong(prevState,
121 std::memory_order_acq_rel)) {
125 doShutdown(fd, abortive);
127 prevState = IN_SHUTDOWN;
128 if (sref.compare_exchange_strong(prevState,
130 std::memory_order_acq_rel)) {
134 CHECK_EQ(prevState, MUST_CLOSE)
135 << "Invalid prev state for fd " << fd << ": " << int(prevState);
137 folly::closeNoInt(fd); // ignore errors, nothing to do
139 CHECK(sref.compare_exchange_strong(prevState,
141 std::memory_order_acq_rel))
142 << "Invalid prev state for fd " << fd << ": " << int(prevState);
145 void ShutdownSocketSet::shutdownAll(bool abortive) {
146 for (int i = 0; i < maxFd_; ++i) {
147 auto& sref = data_[size_t(i)];
148 if (sref.load(std::memory_order_acquire) == IN_USE) {
149 shutdown(i, abortive);
154 void ShutdownSocketSet::doShutdown(int fd, bool abortive) {
155 // shutdown() the socket first, to awaken any threads blocked on the fd
156 // (subsequent IO will fail because it's been shutdown); close()ing the
157 // socket does not wake up blockers, see
158 // http://stackoverflow.com/a/3624545/1736339
159 folly::shutdownNoInt(fd, SHUT_RDWR);
161 // If abortive shutdown is desired, we'll set the SO_LINGER option on
162 // the socket with a timeout of 0; this will cause RST to be sent on
165 struct linger l = {1, 0};
166 if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &l, sizeof(l)) != 0) {
167 // Probably not a socket, ignore.
172 // We can't close() the socket, as that would be dangerous; a new file
173 // could be opened and get the same file descriptor, and then code assuming
174 // the old fd would do IO in the wrong place. We'll (atomically) dup2
175 // /dev/null onto the fd instead.
176 folly::dup2NoInt(nullFile_.fd(), fd);