2 * Copyright 2015 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 #ifndef __STDC_FORMAT_MACROS
18 #define __STDC_FORMAT_MACROS
21 #include <folly/io/async/AsyncServerSocket.h>
23 #include <folly/FileUtil.h>
24 #include <folly/SocketAddress.h>
25 #include <folly/io/async/EventBase.h>
26 #include <folly/io/async/NotificationQueue.h>
30 #include <netinet/tcp.h>
32 #include <sys/socket.h>
33 #include <sys/types.h>
38 const uint32_t AsyncServerSocket::kDefaultMaxAcceptAtOnce;
39 const uint32_t AsyncServerSocket::kDefaultCallbackAcceptAtOnce;
40 const uint32_t AsyncServerSocket::kDefaultMaxMessagesInQueue;
42 int setCloseOnExec(int fd, int value) {
43 // Read the current flags
44 int old_flags = fcntl(fd, F_GETFD, 0);
46 // If reading the flags failed, return error indication now
50 // Set just the flag we want to set
53 new_flags = old_flags | FD_CLOEXEC;
55 new_flags = old_flags & ~FD_CLOEXEC;
57 // Store modified flag word in the descriptor
58 return fcntl(fd, F_SETFD, new_flags);
61 void AsyncServerSocket::RemoteAcceptor::start(
62 EventBase* eventBase, uint32_t maxAtOnce, uint32_t maxInQueue) {
63 setMaxReadAtOnce(maxAtOnce);
64 queue_.setMaxQueueSize(maxInQueue);
66 if (!eventBase->runInEventBaseThread([=](){
67 callback_->acceptStarted();
68 this->startConsuming(eventBase, &queue_);
70 throw std::invalid_argument("unable to start waiting on accept "
71 "notification queue in the specified "
76 void AsyncServerSocket::RemoteAcceptor::stop(
77 EventBase* eventBase, AcceptCallback* callback) {
78 if (!eventBase->runInEventBaseThread([=](){
79 callback->acceptStopped();
82 throw std::invalid_argument("unable to start waiting on accept "
83 "notification queue in the specified "
88 void AsyncServerSocket::RemoteAcceptor::messageAvailable(
92 case MessageType::MSG_NEW_CONN:
94 callback_->connectionAccepted(msg.fd, msg.address);
97 case MessageType::MSG_ERROR:
99 std::runtime_error ex(msg.msg);
100 callback_->acceptError(ex);
105 LOG(ERROR) << "invalid accept notification message type "
107 std::runtime_error ex(
108 "received invalid accept notification message type");
109 callback_->acceptError(ex);
115 * AsyncServerSocket::BackoffTimeout
117 class AsyncServerSocket::BackoffTimeout : public AsyncTimeout {
119 BackoffTimeout(AsyncServerSocket* socket)
120 : AsyncTimeout(socket->getEventBase()),
123 virtual void timeoutExpired() noexcept {
124 socket_->backoffTimeoutExpired();
128 AsyncServerSocket* socket_;
132 * AsyncServerSocket methods
135 AsyncServerSocket::AsyncServerSocket(EventBase* eventBase)
136 : eventBase_(eventBase),
138 maxAcceptAtOnce_(kDefaultMaxAcceptAtOnce),
139 maxNumMsgsInQueue_(kDefaultMaxMessagesInQueue),
140 acceptRateAdjustSpeed_(0),
142 lastAccepTimestamp_(std::chrono::steady_clock::now()),
143 numDroppedConnections_(0),
145 backoffTimeout_(nullptr),
147 keepAliveEnabled_(true),
149 shutdownSocketSet_(nullptr) {
152 void AsyncServerSocket::setShutdownSocketSet(ShutdownSocketSet* newSS) {
153 if (shutdownSocketSet_ == newSS) {
156 if (shutdownSocketSet_) {
157 for (auto& h : sockets_) {
158 shutdownSocketSet_->remove(h.socket_);
161 shutdownSocketSet_ = newSS;
162 if (shutdownSocketSet_) {
163 for (auto& h : sockets_) {
164 shutdownSocketSet_->add(h.socket_);
169 AsyncServerSocket::~AsyncServerSocket() {
170 assert(callbacks_.empty());
173 int AsyncServerSocket::stopAccepting(int shutdownFlags) {
175 for (auto& handler : sockets_) {
176 VLOG(10) << "AsyncServerSocket::stopAccepting " << this <<
179 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
181 // When destroy is called, unregister and close the socket immediately
184 for (auto& handler : sockets_) {
185 handler.unregisterHandler();
186 if (shutdownSocketSet_) {
187 shutdownSocketSet_->close(handler.socket_);
188 } else if (shutdownFlags >= 0) {
189 result = shutdownNoInt(handler.socket_, shutdownFlags);
190 pendingCloseSockets_.push_back(handler.socket_);
192 closeNoInt(handler.socket_);
197 // Destroy the backoff timout. This will cancel it if it is running.
198 delete backoffTimeout_;
199 backoffTimeout_ = nullptr;
201 // Close all of the callback queues to notify them that they are being
202 // destroyed. No one should access the AsyncServerSocket any more once
203 // destroy() is called. However, clear out callbacks_ before invoking the
204 // accept callbacks just in case. This will potentially help us detect the
205 // bug if one of the callbacks calls addAcceptCallback() or
206 // removeAcceptCallback().
207 std::vector<CallbackInfo> callbacksCopy;
208 callbacks_.swap(callbacksCopy);
209 for (std::vector<CallbackInfo>::iterator it = callbacksCopy.begin();
210 it != callbacksCopy.end();
212 it->consumer->stop(it->eventBase, it->callback);
218 void AsyncServerSocket::destroy() {
220 for (auto s : pendingCloseSockets_) {
223 // Then call DelayedDestruction::destroy() to take care of
224 // whether or not we need immediate or delayed destruction
225 DelayedDestruction::destroy();
228 void AsyncServerSocket::attachEventBase(EventBase *eventBase) {
229 assert(eventBase_ == nullptr);
230 assert(eventBase->isInEventBaseThread());
232 eventBase_ = eventBase;
233 for (auto& handler : sockets_) {
234 handler.attachEventBase(eventBase);
238 void AsyncServerSocket::detachEventBase() {
239 assert(eventBase_ != nullptr);
240 assert(eventBase_->isInEventBaseThread());
243 eventBase_ = nullptr;
244 for (auto& handler : sockets_) {
245 handler.detachEventBase();
249 void AsyncServerSocket::useExistingSockets(const std::vector<int>& fds) {
250 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
252 if (sockets_.size() > 0) {
253 throw std::invalid_argument(
254 "cannot call useExistingSocket() on a "
255 "AsyncServerSocket that already has a socket");
259 // Set addressFamily_ from this socket.
260 // Note that the socket may not have been bound yet, but
261 // setFromLocalAddress() will still work and get the correct address family.
262 // We will update addressFamily_ again anyway if bind() is called later.
263 SocketAddress address;
264 address.setFromLocalAddress(fd);
267 sockets_.emplace_back(eventBase_, fd, this, address.getFamily());
268 sockets_.back().changeHandlerFD(fd);
272 void AsyncServerSocket::useExistingSocket(int fd) {
273 useExistingSockets({fd});
276 void AsyncServerSocket::bindSocket(
278 const SocketAddress& address,
279 bool isExistingSocket) {
280 sockaddr_storage addrStorage;
281 address.getAddress(&addrStorage);
282 sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
283 if (::bind(fd, saddr, address.getActualSize()) != 0) {
284 if (!isExistingSocket) {
287 folly::throwSystemError(errno,
288 "failed to bind to async server socket: " +
292 // If we just created this socket, update the EventHandler and set socket_
293 if (!isExistingSocket) {
294 sockets_.emplace_back(eventBase_, fd, this, address.getFamily());
298 void AsyncServerSocket::bind(const SocketAddress& address) {
299 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
301 // useExistingSocket() may have been called to initialize socket_ already.
302 // However, in the normal case we need to create a new socket now.
303 // Don't set socket_ yet, so that socket_ will remain uninitialized if an
306 if (sockets_.size() == 0) {
307 fd = createSocket(address.getFamily());
308 } else if (sockets_.size() == 1) {
309 if (address.getFamily() != sockets_[0].addressFamily_) {
310 throw std::invalid_argument(
311 "Attempted to bind address to socket with "
312 "different address family");
314 fd = sockets_[0].socket_;
316 throw std::invalid_argument(
317 "Attempted to bind to multiple fds");
320 bindSocket(fd, address, !sockets_.empty());
323 void AsyncServerSocket::bind(
324 const std::vector<IPAddress>& ipAddresses,
326 if (ipAddresses.empty()) {
327 throw std::invalid_argument("No ip addresses were provided");
329 if (!sockets_.empty()) {
330 throw std::invalid_argument("Cannot call bind on a AsyncServerSocket "
331 "that already has a socket.");
334 for (const IPAddress& ipAddress : ipAddresses) {
335 SocketAddress address(ipAddress.toFullyQualified(), port);
336 int fd = createSocket(address.getFamily());
338 bindSocket(fd, address, false);
340 if (sockets_.size() == 0) {
341 throw std::runtime_error(
342 "did not bind any async server socket for port and addresses");
346 void AsyncServerSocket::bind(uint16_t port) {
347 struct addrinfo hints, *res, *res0;
348 char sport[sizeof("65536")];
350 memset(&hints, 0, sizeof(hints));
351 hints.ai_family = AF_UNSPEC;
352 hints.ai_socktype = SOCK_STREAM;
353 hints.ai_flags = AI_PASSIVE;
354 snprintf(sport, sizeof(sport), "%u", port);
356 if (getaddrinfo(nullptr, sport, &hints, &res0)) {
357 throw std::invalid_argument(
358 "Attempted to bind address to socket with "
362 SCOPE_EXIT { freeaddrinfo(res0); };
364 auto setupAddress = [&] (struct addrinfo* res) {
365 int s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
366 // IPv6/IPv4 may not be supported by the kernel
367 if (s < 0 && errno == EAFNOSUPPORT) {
379 if (res->ai_family == AF_INET6) {
381 CHECK(0 == setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
382 &v6only, sizeof(v6only)));
385 SocketAddress address;
386 address.setFromLocalAddress(s);
388 sockets_.emplace_back(eventBase_, s, this, address.getFamily());
390 // Bind to the socket
391 if (::bind(s, res->ai_addr, res->ai_addrlen) != 0) {
392 folly::throwSystemError(
394 "failed to bind to async server socket for port");
398 const int kNumTries = 5;
399 for (int tries = 1; true; tries++) {
400 // Prefer AF_INET6 addresses. RFC 3484 mandates that getaddrinfo
401 // should return IPv6 first and then IPv4 addresses, but glibc's
402 // getaddrinfo(nullptr) with AI_PASSIVE returns:
403 // - 0.0.0.0 (IPv4-only)
404 // - :: (IPv6+IPv4) in this order
405 // See: https://sourceware.org/bugzilla/show_bug.cgi?id=9981
406 for (res = res0; res; res = res->ai_next) {
407 if (res->ai_family == AF_INET6) {
412 // If port == 0, then we should try to bind to the same port on ipv4 and
413 // ipv6. So if we did bind to ipv6, figure out that port and use it,
414 // except for the last attempt when we just use any port available.
415 if (sockets_.size() == 1 && port == 0) {
416 SocketAddress address;
417 address.setFromLocalAddress(sockets_.back().socket_);
418 snprintf(sport, sizeof(sport), "%u", address.getPort());
420 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
424 for (res = res0; res; res = res->ai_next) {
425 if (res->ai_family != AF_INET6) {
429 } catch (const std::system_error& e) {
430 // if we can't bind to the same port on ipv4 as ipv6 when using port=0
431 // then we will try again another 2 times before giving up. We do this
432 // by closing the sockets that were opened, then redoing the whole thing
433 if (port == 0 && !sockets_.empty() && tries != kNumTries) {
434 for (const auto& socket : sockets_) {
435 if (socket.socket_ <= 0) {
437 } else if (shutdownSocketSet_) {
438 shutdownSocketSet_->close(socket.socket_);
440 closeNoInt(socket.socket_);
444 snprintf(sport, sizeof(sport), "%u", port);
446 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
455 if (sockets_.size() == 0) {
456 throw std::runtime_error(
457 "did not bind any async server socket for port");
461 void AsyncServerSocket::listen(int backlog) {
462 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
465 for (auto& handler : sockets_) {
466 if (::listen(handler.socket_, backlog) == -1) {
467 folly::throwSystemError(errno,
468 "failed to listen on async server socket");
473 void AsyncServerSocket::getAddress(SocketAddress* addressReturn) const {
474 CHECK(sockets_.size() >= 1);
475 VLOG_IF(2, sockets_.size() > 1)
476 << "Warning: getAddress() called and multiple addresses available ("
477 << sockets_.size() << "). Returning only the first one.";
479 addressReturn->setFromLocalAddress(sockets_[0].socket_);
482 std::vector<SocketAddress> AsyncServerSocket::getAddresses()
484 CHECK(sockets_.size() >= 1);
485 auto tsaVec = std::vector<SocketAddress>(sockets_.size());
486 auto tsaIter = tsaVec.begin();
487 for (const auto& socket : sockets_) {
488 (tsaIter++)->setFromLocalAddress(socket.socket_);
493 void AsyncServerSocket::addAcceptCallback(AcceptCallback *callback,
494 EventBase *eventBase,
495 uint32_t maxAtOnce) {
496 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
498 // If this is the first accept callback and we are supposed to be accepting,
499 // start accepting once the callback is installed.
500 bool runStartAccepting = accepting_ && callbacks_.empty();
503 eventBase = eventBase_; // Run in AsyncServerSocket's eventbase
506 callbacks_.emplace_back(callback, eventBase);
508 // Start the remote acceptor.
510 // It would be nice if we could avoid starting the remote acceptor if
511 // eventBase == eventBase_. However, that would cause issues if
512 // detachEventBase() and attachEventBase() were ever used to change the
513 // primary EventBase for the server socket. Therefore we require the caller
514 // to specify a nullptr EventBase if they want to ensure that the callback is
515 // always invoked in the primary EventBase, and to be able to invoke that
516 // callback more efficiently without having to use a notification queue.
517 RemoteAcceptor* acceptor = nullptr;
519 acceptor = new RemoteAcceptor(callback);
520 acceptor->start(eventBase, maxAtOnce, maxNumMsgsInQueue_);
522 callbacks_.pop_back();
526 callbacks_.back().consumer = acceptor;
528 // If this is the first accept callback and we are supposed to be accepting,
530 if (runStartAccepting) {
535 void AsyncServerSocket::removeAcceptCallback(AcceptCallback *callback,
536 EventBase *eventBase) {
537 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
539 // Find the matching AcceptCallback.
540 // We just do a simple linear search; we don't expect removeAcceptCallback()
541 // to be called frequently, and we expect there to only be a small number of
543 std::vector<CallbackInfo>::iterator it = callbacks_.begin();
546 if (it == callbacks_.end()) {
547 throw std::runtime_error("AsyncServerSocket::removeAcceptCallback(): "
548 "accept callback not found");
550 if (it->callback == callback &&
551 (it->eventBase == eventBase || eventBase == nullptr)) {
558 // Remove this callback from callbacks_.
560 // Do this before invoking the acceptStopped() callback, in case
561 // acceptStopped() invokes one of our methods that examines callbacks_.
563 // Save a copy of the CallbackInfo first.
564 CallbackInfo info(*it);
565 callbacks_.erase(it);
566 if (n < callbackIndex_) {
567 // We removed an element before callbackIndex_. Move callbackIndex_ back
568 // one step, since things after n have been shifted back by 1.
571 // We removed something at or after callbackIndex_.
572 // If we removed the last element and callbackIndex_ was pointing at it,
573 // we need to reset callbackIndex_ to 0.
574 if (callbackIndex_ >= callbacks_.size()) {
579 info.consumer->stop(info.eventBase, info.callback);
581 // If we are supposed to be accepting but the last accept callback
582 // was removed, unregister for events until a callback is added.
583 if (accepting_ && callbacks_.empty()) {
584 for (auto& handler : sockets_) {
585 handler.unregisterHandler();
590 void AsyncServerSocket::startAccepting() {
591 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
594 if (callbacks_.empty()) {
595 // We can't actually begin accepting if no callbacks are defined.
596 // Wait until a callback is added to start accepting.
600 for (auto& handler : sockets_) {
601 if (!handler.registerHandler(
602 EventHandler::READ | EventHandler::PERSIST)) {
603 throw std::runtime_error("failed to register for accept events");
608 void AsyncServerSocket::pauseAccepting() {
609 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
611 for (auto& handler : sockets_) {
612 handler. unregisterHandler();
615 // If we were in the accept backoff state, disable the backoff timeout
616 if (backoffTimeout_) {
617 backoffTimeout_->cancelTimeout();
621 int AsyncServerSocket::createSocket(int family) {
622 int fd = socket(family, SOCK_STREAM, 0);
624 folly::throwSystemError(errno, "error creating async server socket");
636 void AsyncServerSocket::setupSocket(int fd) {
637 // Get the address family
638 SocketAddress address;
639 address.setFromLocalAddress(fd);
640 auto family = address.getFamily();
642 // Put the socket in non-blocking mode
643 if (fcntl(fd, F_SETFL, O_NONBLOCK) != 0) {
644 folly::throwSystemError(errno,
645 "failed to put socket in non-blocking mode");
648 // Set reuseaddr to avoid 2MSL delay on server restart
650 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) != 0) {
651 // This isn't a fatal error; just log an error message and continue
652 LOG(ERROR) << "failed to set SO_REUSEADDR on async server socket " << errno;
655 // Set reuseport to support multiple accept threads
657 if (reusePortEnabled_ &&
658 setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(int)) != 0) {
659 LOG(ERROR) << "failed to set SO_REUSEPORT on async server socket "
661 folly::throwSystemError(errno,
662 "failed to bind to async server socket: " +
666 // Set keepalive as desired
667 if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE,
668 (keepAliveEnabled_) ? &one : &zero, sizeof(int)) != 0) {
669 LOG(ERROR) << "failed to set SO_KEEPALIVE on async server socket: " <<
673 // Setup FD_CLOEXEC flag
675 (-1 == folly::setCloseOnExec(fd, closeOnExec_))) {
676 LOG(ERROR) << "failed to set FD_CLOEXEC on async server socket: " <<
680 // Set TCP nodelay if available, MAC OS X Hack
681 // See http://lists.danga.com/pipermail/memcached/2005-March/001240.html
683 if (family != AF_UNIX) {
684 if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) != 0) {
685 // This isn't a fatal error; just log an error message and continue
686 LOG(ERROR) << "failed to set TCP_NODELAY on async server socket: " <<
692 if (shutdownSocketSet_) {
693 shutdownSocketSet_->add(fd);
697 void AsyncServerSocket::handlerReady(
698 uint16_t events, int fd, sa_family_t addressFamily) noexcept {
699 assert(!callbacks_.empty());
700 DestructorGuard dg(this);
702 // Only accept up to maxAcceptAtOnce_ connections at a time,
703 // to avoid starving other I/O handlers using this EventBase.
704 for (uint32_t n = 0; n < maxAcceptAtOnce_; ++n) {
705 SocketAddress address;
707 sockaddr_storage addrStorage;
708 socklen_t addrLen = sizeof(addrStorage);
709 sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
711 // In some cases, accept() doesn't seem to update these correctly.
712 saddr->sa_family = addressFamily;
713 if (addressFamily == AF_UNIX) {
714 addrLen = sizeof(struct sockaddr_un);
717 // Accept a new client socket
719 int clientSocket = accept4(fd, saddr, &addrLen, SOCK_NONBLOCK);
721 int clientSocket = accept(fd, saddr, &addrLen);
724 address.setFromSockaddr(saddr, addrLen);
726 std::chrono::time_point<std::chrono::steady_clock> nowMs =
727 std::chrono::steady_clock::now();
728 int64_t timeSinceLastAccept = std::max(
730 nowMs.time_since_epoch().count() -
731 lastAccepTimestamp_.time_since_epoch().count());
732 lastAccepTimestamp_ = nowMs;
733 if (acceptRate_ < 1) {
734 acceptRate_ *= 1 + acceptRateAdjustSpeed_ * timeSinceLastAccept;
735 if (acceptRate_ >= 1) {
737 } else if (rand() > acceptRate_ * RAND_MAX) {
738 ++numDroppedConnections_;
739 if (clientSocket >= 0) {
740 closeNoInt(clientSocket);
746 if (clientSocket < 0) {
747 if (errno == EAGAIN) {
748 // No more sockets to accept right now.
749 // Check for this code first, since it's the most common.
751 } else if (errno == EMFILE || errno == ENFILE) {
752 // We're out of file descriptors. Perhaps we're accepting connections
753 // too quickly. Pause accepting briefly to back off and give the server
754 // a chance to recover.
755 LOG(ERROR) << "accept failed: out of file descriptors; entering accept "
759 // Dispatch the error message
760 dispatchError("accept() failed", errno);
762 dispatchError("accept() failed", errno);
767 #ifndef SOCK_NONBLOCK
768 // Explicitly set the new connection to non-blocking mode
769 if (fcntl(clientSocket, F_SETFL, O_NONBLOCK) != 0) {
770 closeNoInt(clientSocket);
771 dispatchError("failed to set accepted socket to non-blocking mode",
777 // Inform the callback about the new connection
778 dispatchSocket(clientSocket, std::move(address));
780 // If we aren't accepting any more, break out of the loop
781 if (!accepting_ || callbacks_.empty()) {
787 void AsyncServerSocket::dispatchSocket(int socket,
788 SocketAddress&& address) {
789 uint32_t startingIndex = callbackIndex_;
791 // Short circuit if the callback is in the primary EventBase thread
793 CallbackInfo *info = nextCallback();
794 if (info->eventBase == nullptr) {
795 info->callback->connectionAccepted(socket, address);
799 // Create a message to send over the notification queue
801 msg.type = MessageType::MSG_NEW_CONN;
802 msg.address = std::move(address);
805 // Loop until we find a free queue to write to
807 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
812 // We couldn't add to queue. Fall through to below
814 ++numDroppedConnections_;
815 if (acceptRateAdjustSpeed_ > 0) {
816 // aggressively decrease accept rate when in trouble
817 static const double kAcceptRateDecreaseSpeed = 0.1;
818 acceptRate_ *= 1 - kAcceptRateDecreaseSpeed;
822 if (callbackIndex_ == startingIndex) {
823 // The notification queue was full
824 // We can't really do anything at this point other than close the socket.
826 // This should only happen if a user's service is behaving extremely
827 // badly and none of the EventBase threads are looping fast enough to
828 // process the incoming connections. If the service is overloaded, it
829 // should use pauseAccepting() to temporarily back off accepting new
830 // connections, before they reach the point where their threads can't
831 // even accept new messages.
832 LOG(ERROR) << "failed to dispatch newly accepted socket:"
833 << " all accept callback queues are full";
838 info = nextCallback();
842 void AsyncServerSocket::dispatchError(const char *msgstr, int errnoValue) {
843 uint32_t startingIndex = callbackIndex_;
844 CallbackInfo *info = nextCallback();
846 // Create a message to send over the notification queue
848 msg.type = MessageType::MSG_ERROR;
849 msg.err = errnoValue;
850 msg.msg = std::move(msgstr);
853 // Short circuit if the callback is in the primary EventBase thread
854 if (info->eventBase == nullptr) {
855 std::runtime_error ex(
856 std::string(msgstr) + folly::to<std::string>(errnoValue));
857 info->callback->acceptError(ex);
861 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
864 // Fall through and try another callback
866 if (callbackIndex_ == startingIndex) {
867 // The notification queues for all of the callbacks were full.
868 // We can't really do anything at this point.
869 LOG(ERROR) << "failed to dispatch accept error: all accept callback "
870 "queues are full: error msg: " <<
871 msg.msg.c_str() << errnoValue;
874 info = nextCallback();
878 void AsyncServerSocket::enterBackoff() {
879 // If this is the first time we have entered the backoff state,
880 // allocate backoffTimeout_.
881 if (backoffTimeout_ == nullptr) {
883 backoffTimeout_ = new BackoffTimeout(this);
884 } catch (const std::bad_alloc& ex) {
885 // Man, we couldn't even allocate the timer to re-enable accepts.
886 // We must be in pretty bad shape. Don't pause accepting for now,
887 // since we won't be able to re-enable ourselves later.
888 LOG(ERROR) << "failed to allocate AsyncServerSocket backoff"
889 << " timer; unable to temporarly pause accepting";
894 // For now, we simply pause accepting for 1 second.
896 // We could add some smarter backoff calculation here in the future. (e.g.,
897 // start sleeping for longer if we keep hitting the backoff frequently.)
898 // Typically the user needs to figure out why the server is overloaded and
899 // fix it in some other way, though. The backoff timer is just a simple
900 // mechanism to try and give the connection processing code a little bit of
901 // breathing room to catch up, and to avoid just spinning and failing to
902 // accept over and over again.
903 const uint32_t timeoutMS = 1000;
904 if (!backoffTimeout_->scheduleTimeout(timeoutMS)) {
905 LOG(ERROR) << "failed to schedule AsyncServerSocket backoff timer;"
906 << "unable to temporarly pause accepting";
910 // The backoff timer is scheduled to re-enable accepts.
911 // Go ahead and disable accepts for now. We leave accepting_ set to true,
912 // since that tracks the desired state requested by the user.
913 for (auto& handler : sockets_) {
914 handler.unregisterHandler();
918 void AsyncServerSocket::backoffTimeoutExpired() {
919 // accepting_ should still be true.
920 // If pauseAccepting() was called while in the backoff state it will cancel
921 // the backoff timeout.
923 // We can't be detached from the EventBase without being paused
924 assert(eventBase_ != nullptr && eventBase_->isInEventBaseThread());
926 // If all of the callbacks were removed, we shouldn't re-enable accepts
927 if (callbacks_.empty()) {
931 // Register the handler.
932 for (auto& handler : sockets_) {
933 if (!handler.registerHandler(
934 EventHandler::READ | EventHandler::PERSIST)) {
935 // We're hosed. We could just re-schedule backoffTimeout_ to
936 // re-try again after a little bit. However, we don't want to
937 // loop retrying forever if we can't re-enable accepts. Just
938 // abort the entire program in this state; things are really bad
939 // and restarting the entire server is probably the best remedy.
941 << "failed to re-enable AsyncServerSocket accepts after backoff; "