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/Singleton.h>
26 #include <folly/portability/Sockets.h>
32 folly::Singleton<folly::ShutdownSocketSet, PrivateTag> singleton;
35 ShutdownSocketSet::ShutdownSocketSet(int maxFd)
37 data_(static_cast<std::atomic<uint8_t>*>(
38 folly::checkedCalloc(size_t(maxFd), sizeof(std::atomic<uint8_t>)))),
39 nullFile_("/dev/null", O_RDWR) {}
41 std::shared_ptr<ShutdownSocketSet> ShutdownSocketSet::getInstance() {
42 return singleton.try_get();
45 void ShutdownSocketSet::add(int fd) {
46 // Silently ignore any fds >= maxFd_, very unlikely
52 auto& sref = data_[size_t(fd)];
53 uint8_t prevState = FREE;
54 CHECK(sref.compare_exchange_strong(prevState,
56 std::memory_order_acq_rel))
57 << "Invalid prev state for fd " << fd << ": " << int(prevState);
60 void ShutdownSocketSet::remove(int fd) {
66 auto& sref = data_[size_t(fd)];
67 uint8_t prevState = 0;
70 prevState = sref.load(std::memory_order_relaxed);
75 std::this_thread::sleep_for(std::chrono::milliseconds(1));
78 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
81 if (!sref.compare_exchange_weak(prevState,
83 std::memory_order_acq_rel)) {
88 int ShutdownSocketSet::close(int fd) {
91 return folly::closeNoInt(fd);
94 auto& sref = data_[size_t(fd)];
95 uint8_t prevState = sref.load(std::memory_order_relaxed);
105 newState = MUST_CLOSE;
108 LOG(FATAL) << "Invalid prev state for fd " << fd << ": " << int(prevState);
111 if (!sref.compare_exchange_weak(prevState,
113 std::memory_order_acq_rel)) {
117 return newState == FREE ? folly::closeNoInt(fd) : 0;
120 void ShutdownSocketSet::shutdown(int fd, bool abortive) {
123 doShutdown(fd, abortive);
127 auto& sref = data_[size_t(fd)];
128 uint8_t prevState = IN_USE;
129 if (!sref.compare_exchange_strong(prevState,
131 std::memory_order_acq_rel)) {
135 doShutdown(fd, abortive);
137 prevState = IN_SHUTDOWN;
138 if (sref.compare_exchange_strong(prevState,
140 std::memory_order_acq_rel)) {
144 CHECK_EQ(prevState, MUST_CLOSE)
145 << "Invalid prev state for fd " << fd << ": " << int(prevState);
147 folly::closeNoInt(fd); // ignore errors, nothing to do
149 CHECK(sref.compare_exchange_strong(prevState,
151 std::memory_order_acq_rel))
152 << "Invalid prev state for fd " << fd << ": " << int(prevState);
155 void ShutdownSocketSet::shutdownAll(bool abortive) {
156 for (int i = 0; i < maxFd_; ++i) {
157 auto& sref = data_[size_t(i)];
158 if (sref.load(std::memory_order_acquire) == IN_USE) {
159 shutdown(i, abortive);
164 void ShutdownSocketSet::doShutdown(int fd, bool abortive) {
165 // shutdown() the socket first, to awaken any threads blocked on the fd
166 // (subsequent IO will fail because it's been shutdown); close()ing the
167 // socket does not wake up blockers, see
168 // http://stackoverflow.com/a/3624545/1736339
169 folly::shutdownNoInt(fd, SHUT_RDWR);
171 // If abortive shutdown is desired, we'll set the SO_LINGER option on
172 // the socket with a timeout of 0; this will cause RST to be sent on
175 struct linger l = {1, 0};
176 if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &l, sizeof(l)) != 0) {
177 // Probably not a socket, ignore.
182 // We can't close() the socket, as that would be dangerous; a new file
183 // could be opened and get the same file descriptor, and then code assuming
184 // the old fd would do IO in the wrong place. We'll (atomically) dup2
185 // /dev/null onto the fd instead.
186 folly::dup2NoInt(nullFile_.fd(), fd);