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(maxFd, sizeof(std::atomic<uint8_t>)))),
33 nullFile_("/dev/null", O_RDWR) {
36 void ShutdownSocketSet::add(int fd) {
37 // Silently ignore any fds >= maxFd_, very unlikely
43 auto& sref = data_[fd];
44 uint8_t prevState = FREE;
45 CHECK(sref.compare_exchange_strong(prevState,
47 std::memory_order_acq_rel))
48 << "Invalid prev state for fd " << fd << ": " << int(prevState);
51 void ShutdownSocketSet::remove(int fd) {
57 auto& sref = data_[fd];
58 uint8_t prevState = 0;
61 prevState = sref.load(std::memory_order_relaxed);
66 std::this_thread::sleep_for(std::chrono::milliseconds(1));
69 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
72 if (!sref.compare_exchange_weak(prevState,
74 std::memory_order_acq_rel)) {
79 int ShutdownSocketSet::close(int fd) {
82 return folly::closeNoInt(fd);
85 auto& sref = data_[fd];
86 uint8_t prevState = sref.load(std::memory_order_relaxed);
96 newState = MUST_CLOSE;
99 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
102 if (!sref.compare_exchange_weak(prevState,
104 std::memory_order_acq_rel)) {
108 return newState == FREE ? folly::closeNoInt(fd) : 0;
111 void ShutdownSocketSet::shutdown(int fd, bool abortive) {
114 doShutdown(fd, abortive);
118 auto& sref = data_[fd];
119 uint8_t prevState = IN_USE;
120 if (!sref.compare_exchange_strong(prevState,
122 std::memory_order_acq_rel)) {
126 doShutdown(fd, abortive);
128 prevState = IN_SHUTDOWN;
129 if (sref.compare_exchange_strong(prevState,
131 std::memory_order_acq_rel)) {
135 CHECK_EQ(prevState, MUST_CLOSE)
136 << "Invalid prev state for fd " << fd << ": " << int(prevState);
138 folly::closeNoInt(fd); // ignore errors, nothing to do
140 CHECK(sref.compare_exchange_strong(prevState,
142 std::memory_order_acq_rel))
143 << "Invalid prev state for fd " << fd << ": " << int(prevState);
146 void ShutdownSocketSet::shutdownAll(bool abortive) {
147 for (int i = 0; i < maxFd_; ++i) {
148 auto& sref = data_[i];
149 if (sref.load(std::memory_order_acquire) == IN_USE) {
150 shutdown(i, abortive);
155 void ShutdownSocketSet::doShutdown(int fd, bool abortive) {
156 // shutdown() the socket first, to awaken any threads blocked on the fd
157 // (subsequent IO will fail because it's been shutdown); close()ing the
158 // socket does not wake up blockers, see
159 // http://stackoverflow.com/a/3624545/1736339
160 folly::shutdownNoInt(fd, SHUT_RDWR);
162 // If abortive shutdown is desired, we'll set the SO_LINGER option on
163 // the socket with a timeout of 0; this will cause RST to be sent on
166 struct linger l = {1, 0};
167 if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &l, sizeof(l)) != 0) {
168 // Probably not a socket, ignore.
173 // We can't close() the socket, as that would be dangerous; a new file
174 // could be opened and get the same file descriptor, and then code assuming
175 // the old fd would do IO in the wrong place. We'll (atomically) dup2
176 // /dev/null onto the fd instead.
177 folly::dup2NoInt(nullFile_.fd(), fd);