2 * Copyright 2014 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);
268 ServerEventHandler(eventBase_, fd, this, address.getFamily()));
269 sockets_.back().changeHandlerFD(fd);
273 void AsyncServerSocket::useExistingSocket(int fd) {
274 useExistingSockets({fd});
277 void AsyncServerSocket::bindSocket(
279 const SocketAddress& address,
280 bool isExistingSocket) {
281 sockaddr_storage addrStorage;
282 address.getAddress(&addrStorage);
283 sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
284 if (::bind(fd, saddr, address.getActualSize()) != 0) {
285 if (!isExistingSocket) {
288 folly::throwSystemError(errno,
289 "failed to bind to async server socket: " +
293 // If we just created this socket, update the EventHandler and set socket_
294 if (!isExistingSocket) {
296 ServerEventHandler(eventBase_, fd, this, address.getFamily()));
300 void AsyncServerSocket::bind(const SocketAddress& address) {
301 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
303 // useExistingSocket() may have been called to initialize socket_ already.
304 // However, in the normal case we need to create a new socket now.
305 // Don't set socket_ yet, so that socket_ will remain uninitialized if an
308 if (sockets_.size() == 0) {
309 fd = createSocket(address.getFamily());
310 } else if (sockets_.size() == 1) {
311 if (address.getFamily() != sockets_[0].addressFamily_) {
312 throw std::invalid_argument(
313 "Attempted to bind address to socket with "
314 "different address family");
316 fd = sockets_[0].socket_;
318 throw std::invalid_argument(
319 "Attempted to bind to multiple fds");
322 bindSocket(fd, address, !sockets_.empty());
325 void AsyncServerSocket::bind(
326 const std::vector<IPAddress>& ipAddresses,
328 if (ipAddresses.empty()) {
329 throw std::invalid_argument("No ip addresses were provided");
331 if (!sockets_.empty()) {
332 throw std::invalid_argument("Cannot call bind on a AsyncServerSocket "
333 "that already has a socket.");
336 for (const IPAddress& ipAddress : ipAddresses) {
337 SocketAddress address(ipAddress.toFullyQualified(), port);
338 int fd = createSocket(address.getFamily());
340 bindSocket(fd, address, false);
342 if (sockets_.size() == 0) {
343 throw std::runtime_error(
344 "did not bind any async server socket for port and addresses");
348 void AsyncServerSocket::bind(uint16_t port) {
349 struct addrinfo hints, *res, *res0;
350 char sport[sizeof("65536")];
352 memset(&hints, 0, sizeof(hints));
353 hints.ai_family = AF_UNSPEC;
354 hints.ai_socktype = SOCK_STREAM;
355 hints.ai_flags = AI_PASSIVE;
356 snprintf(sport, sizeof(sport), "%u", port);
358 if (getaddrinfo(nullptr, sport, &hints, &res0)) {
359 throw std::invalid_argument(
360 "Attempted to bind address to socket with "
364 SCOPE_EXIT { freeaddrinfo(res0); };
366 auto setupAddress = [&] (struct addrinfo* res) {
367 int s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
368 // IPv6/IPv4 may not be supported by the kernel
369 if (s < 0 && errno == EAFNOSUPPORT) {
381 if (res->ai_family == AF_INET6) {
383 CHECK(0 == setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
384 &v6only, sizeof(v6only)));
387 SocketAddress address;
388 address.setFromLocalAddress(s);
391 ServerEventHandler(eventBase_, s, this, address.getFamily()));
393 // Bind to the socket
394 if (::bind(s, res->ai_addr, res->ai_addrlen) != 0) {
395 folly::throwSystemError(
397 "failed to bind to async server socket for port");
401 const int kNumTries = 5;
402 for (int tries = 1; true; tries++) {
403 // Prefer AF_INET6 addresses. RFC 3484 mandates that getaddrinfo
404 // should return IPv6 first and then IPv4 addresses, but glibc's
405 // getaddrinfo(nullptr) with AI_PASSIVE returns:
406 // - 0.0.0.0 (IPv4-only)
407 // - :: (IPv6+IPv4) in this order
408 // See: https://sourceware.org/bugzilla/show_bug.cgi?id=9981
409 for (res = res0; res; res = res->ai_next) {
410 if (res->ai_family == AF_INET6) {
415 // If port == 0, then we should try to bind to the same port on ipv4 and
416 // ipv6. So if we did bind to ipv6, figure out that port and use it,
417 // except for the last attempt when we just use any port available.
418 if (sockets_.size() == 1 && port == 0) {
419 SocketAddress address;
420 address.setFromLocalAddress(sockets_.back().socket_);
421 snprintf(sport, sizeof(sport), "%u", address.getPort());
423 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
427 for (res = res0; res; res = res->ai_next) {
428 if (res->ai_family != AF_INET6) {
432 } catch (const std::system_error& e) {
433 // if we can't bind to the same port on ipv4 as ipv6 when using port=0
434 // then we will try again another 2 times before giving up. We do this
435 // by closing the sockets that were opened, then redoing the whole thing
436 if (port == 0 && !sockets_.empty() && tries != kNumTries) {
437 for (const auto& socket : sockets_) {
438 if (socket.socket_ <= 0) {
440 } else if (shutdownSocketSet_) {
441 shutdownSocketSet_->close(socket.socket_);
443 closeNoInt(socket.socket_);
447 snprintf(sport, sizeof(sport), "%u", port);
449 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
458 if (sockets_.size() == 0) {
459 throw std::runtime_error(
460 "did not bind any async server socket for port");
464 void AsyncServerSocket::listen(int backlog) {
465 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
468 for (auto& handler : sockets_) {
469 if (::listen(handler.socket_, backlog) == -1) {
470 folly::throwSystemError(errno,
471 "failed to listen on async server socket");
476 void AsyncServerSocket::getAddress(SocketAddress* addressReturn) const {
477 CHECK(sockets_.size() >= 1);
478 VLOG_IF(2, sockets_.size() > 1)
479 << "Warning: getAddress() called and multiple addresses available ("
480 << sockets_.size() << "). Returning only the first one.";
482 addressReturn->setFromLocalAddress(sockets_[0].socket_);
485 std::vector<SocketAddress> AsyncServerSocket::getAddresses()
487 CHECK(sockets_.size() >= 1);
488 auto tsaVec = std::vector<SocketAddress>(sockets_.size());
489 auto tsaIter = tsaVec.begin();
490 for (const auto& socket : sockets_) {
491 (tsaIter++)->setFromLocalAddress(socket.socket_);
496 void AsyncServerSocket::addAcceptCallback(AcceptCallback *callback,
497 EventBase *eventBase,
498 uint32_t maxAtOnce) {
499 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
501 // If this is the first accept callback and we are supposed to be accepting,
502 // start accepting once the callback is installed.
503 bool runStartAccepting = accepting_ && callbacks_.empty();
506 eventBase = eventBase_; // Run in AsyncServerSocket's eventbase
509 callbacks_.push_back(CallbackInfo(callback, eventBase));
511 // Start the remote acceptor.
513 // It would be nice if we could avoid starting the remote acceptor if
514 // eventBase == eventBase_. However, that would cause issues if
515 // detachEventBase() and attachEventBase() were ever used to change the
516 // primary EventBase for the server socket. Therefore we require the caller
517 // to specify a nullptr EventBase if they want to ensure that the callback is
518 // always invoked in the primary EventBase, and to be able to invoke that
519 // callback more efficiently without having to use a notification queue.
520 RemoteAcceptor* acceptor = nullptr;
522 acceptor = new RemoteAcceptor(callback);
523 acceptor->start(eventBase, maxAtOnce, maxNumMsgsInQueue_);
525 callbacks_.pop_back();
529 callbacks_.back().consumer = acceptor;
531 // If this is the first accept callback and we are supposed to be accepting,
533 if (runStartAccepting) {
538 void AsyncServerSocket::removeAcceptCallback(AcceptCallback *callback,
539 EventBase *eventBase) {
540 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
542 // Find the matching AcceptCallback.
543 // We just do a simple linear search; we don't expect removeAcceptCallback()
544 // to be called frequently, and we expect there to only be a small number of
546 std::vector<CallbackInfo>::iterator it = callbacks_.begin();
549 if (it == callbacks_.end()) {
550 throw std::runtime_error("AsyncServerSocket::removeAcceptCallback(): "
551 "accept callback not found");
553 if (it->callback == callback &&
554 (it->eventBase == eventBase || eventBase == nullptr)) {
561 // Remove this callback from callbacks_.
563 // Do this before invoking the acceptStopped() callback, in case
564 // acceptStopped() invokes one of our methods that examines callbacks_.
566 // Save a copy of the CallbackInfo first.
567 CallbackInfo info(*it);
568 callbacks_.erase(it);
569 if (n < callbackIndex_) {
570 // We removed an element before callbackIndex_. Move callbackIndex_ back
571 // one step, since things after n have been shifted back by 1.
574 // We removed something at or after callbackIndex_.
575 // If we removed the last element and callbackIndex_ was pointing at it,
576 // we need to reset callbackIndex_ to 0.
577 if (callbackIndex_ >= callbacks_.size()) {
582 info.consumer->stop(info.eventBase, info.callback);
584 // If we are supposed to be accepting but the last accept callback
585 // was removed, unregister for events until a callback is added.
586 if (accepting_ && callbacks_.empty()) {
587 for (auto& handler : sockets_) {
588 handler.unregisterHandler();
593 void AsyncServerSocket::startAccepting() {
594 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
597 if (callbacks_.empty()) {
598 // We can't actually begin accepting if no callbacks are defined.
599 // Wait until a callback is added to start accepting.
603 for (auto& handler : sockets_) {
604 if (!handler.registerHandler(
605 EventHandler::READ | EventHandler::PERSIST)) {
606 throw std::runtime_error("failed to register for accept events");
611 void AsyncServerSocket::pauseAccepting() {
612 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
614 for (auto& handler : sockets_) {
615 handler. unregisterHandler();
618 // If we were in the accept backoff state, disable the backoff timeout
619 if (backoffTimeout_) {
620 backoffTimeout_->cancelTimeout();
624 int AsyncServerSocket::createSocket(int family) {
625 int fd = socket(family, SOCK_STREAM, 0);
627 folly::throwSystemError(errno, "error creating async server socket");
639 void AsyncServerSocket::setupSocket(int fd) {
640 // Get the address family
641 SocketAddress address;
642 address.setFromLocalAddress(fd);
643 auto family = address.getFamily();
645 // Put the socket in non-blocking mode
646 if (fcntl(fd, F_SETFL, O_NONBLOCK) != 0) {
647 folly::throwSystemError(errno,
648 "failed to put socket in non-blocking mode");
651 // Set reuseaddr to avoid 2MSL delay on server restart
653 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) != 0) {
654 // This isn't a fatal error; just log an error message and continue
655 LOG(ERROR) << "failed to set SO_REUSEADDR on async server socket " << errno;
658 // Set reuseport to support multiple accept threads
660 if (reusePortEnabled_ &&
661 setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(int)) != 0) {
662 LOG(ERROR) << "failed to set SO_REUSEPORT on async server socket "
664 folly::throwSystemError(errno,
665 "failed to bind to async server socket: " +
669 // Set keepalive as desired
670 if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE,
671 (keepAliveEnabled_) ? &one : &zero, sizeof(int)) != 0) {
672 LOG(ERROR) << "failed to set SO_KEEPALIVE on async server socket: " <<
676 // Setup FD_CLOEXEC flag
678 (-1 == folly::setCloseOnExec(fd, closeOnExec_))) {
679 LOG(ERROR) << "failed to set FD_CLOEXEC on async server socket: " <<
683 // Set TCP nodelay if available, MAC OS X Hack
684 // See http://lists.danga.com/pipermail/memcached/2005-March/001240.html
686 if (family != AF_UNIX) {
687 if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) != 0) {
688 // This isn't a fatal error; just log an error message and continue
689 LOG(ERROR) << "failed to set TCP_NODELAY on async server socket: " <<
695 if (shutdownSocketSet_) {
696 shutdownSocketSet_->add(fd);
700 void AsyncServerSocket::handlerReady(
701 uint16_t events, int fd, sa_family_t addressFamily) noexcept {
702 assert(!callbacks_.empty());
703 DestructorGuard dg(this);
705 // Only accept up to maxAcceptAtOnce_ connections at a time,
706 // to avoid starving other I/O handlers using this EventBase.
707 for (uint32_t n = 0; n < maxAcceptAtOnce_; ++n) {
708 SocketAddress address;
710 sockaddr_storage addrStorage;
711 socklen_t addrLen = sizeof(addrStorage);
712 sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
714 // In some cases, accept() doesn't seem to update these correctly.
715 saddr->sa_family = addressFamily;
716 if (addressFamily == AF_UNIX) {
717 addrLen = sizeof(struct sockaddr_un);
720 // Accept a new client socket
722 int clientSocket = accept4(fd, saddr, &addrLen, SOCK_NONBLOCK);
724 int clientSocket = accept(fd, saddr, &addrLen);
727 address.setFromSockaddr(saddr, addrLen);
729 std::chrono::time_point<std::chrono::steady_clock> nowMs =
730 std::chrono::steady_clock::now();
731 int64_t timeSinceLastAccept = std::max(
733 nowMs.time_since_epoch().count() -
734 lastAccepTimestamp_.time_since_epoch().count());
735 lastAccepTimestamp_ = nowMs;
736 if (acceptRate_ < 1) {
737 acceptRate_ *= 1 + acceptRateAdjustSpeed_ * timeSinceLastAccept;
738 if (acceptRate_ >= 1) {
740 } else if (rand() > acceptRate_ * RAND_MAX) {
741 ++numDroppedConnections_;
742 if (clientSocket >= 0) {
743 closeNoInt(clientSocket);
749 if (clientSocket < 0) {
750 if (errno == EAGAIN) {
751 // No more sockets to accept right now.
752 // Check for this code first, since it's the most common.
754 } else if (errno == EMFILE || errno == ENFILE) {
755 // We're out of file descriptors. Perhaps we're accepting connections
756 // too quickly. Pause accepting briefly to back off and give the server
757 // a chance to recover.
758 LOG(ERROR) << "accept failed: out of file descriptors; entering accept "
762 // Dispatch the error message
763 dispatchError("accept() failed", errno);
765 dispatchError("accept() failed", errno);
770 #ifndef SOCK_NONBLOCK
771 // Explicitly set the new connection to non-blocking mode
772 if (fcntl(clientSocket, F_SETFL, O_NONBLOCK) != 0) {
773 closeNoInt(clientSocket);
774 dispatchError("failed to set accepted socket to non-blocking mode",
780 // Inform the callback about the new connection
781 dispatchSocket(clientSocket, std::move(address));
783 // If we aren't accepting any more, break out of the loop
784 if (!accepting_ || callbacks_.empty()) {
790 void AsyncServerSocket::dispatchSocket(int socket,
791 SocketAddress&& address) {
792 uint32_t startingIndex = callbackIndex_;
794 // Short circuit if the callback is in the primary EventBase thread
796 CallbackInfo *info = nextCallback();
797 if (info->eventBase == nullptr) {
798 info->callback->connectionAccepted(socket, address);
802 // Create a message to send over the notification queue
804 msg.type = MessageType::MSG_NEW_CONN;
805 msg.address = std::move(address);
808 // Loop until we find a free queue to write to
810 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
815 // We couldn't add to queue. Fall through to below
817 ++numDroppedConnections_;
818 if (acceptRateAdjustSpeed_ > 0) {
819 // aggressively decrease accept rate when in trouble
820 static const double kAcceptRateDecreaseSpeed = 0.1;
821 acceptRate_ *= 1 - kAcceptRateDecreaseSpeed;
825 if (callbackIndex_ == startingIndex) {
826 // The notification queue was full
827 // We can't really do anything at this point other than close the socket.
829 // This should only happen if a user's service is behaving extremely
830 // badly and none of the EventBase threads are looping fast enough to
831 // process the incoming connections. If the service is overloaded, it
832 // should use pauseAccepting() to temporarily back off accepting new
833 // connections, before they reach the point where their threads can't
834 // even accept new messages.
835 LOG(ERROR) << "failed to dispatch newly accepted socket:"
836 << " all accept callback queues are full";
841 info = nextCallback();
845 void AsyncServerSocket::dispatchError(const char *msgstr, int errnoValue) {
846 uint32_t startingIndex = callbackIndex_;
847 CallbackInfo *info = nextCallback();
849 // Create a message to send over the notification queue
851 msg.type = MessageType::MSG_ERROR;
852 msg.err = errnoValue;
853 msg.msg = std::move(msgstr);
856 // Short circuit if the callback is in the primary EventBase thread
857 if (info->eventBase == nullptr) {
858 std::runtime_error ex(
859 std::string(msgstr) + folly::to<std::string>(errnoValue));
860 info->callback->acceptError(ex);
864 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
867 // Fall through and try another callback
869 if (callbackIndex_ == startingIndex) {
870 // The notification queues for all of the callbacks were full.
871 // We can't really do anything at this point.
872 LOG(ERROR) << "failed to dispatch accept error: all accept callback "
873 "queues are full: error msg: " <<
874 msg.msg.c_str() << errnoValue;
877 info = nextCallback();
881 void AsyncServerSocket::enterBackoff() {
882 // If this is the first time we have entered the backoff state,
883 // allocate backoffTimeout_.
884 if (backoffTimeout_ == nullptr) {
886 backoffTimeout_ = new BackoffTimeout(this);
887 } catch (const std::bad_alloc& ex) {
888 // Man, we couldn't even allocate the timer to re-enable accepts.
889 // We must be in pretty bad shape. Don't pause accepting for now,
890 // since we won't be able to re-enable ourselves later.
891 LOG(ERROR) << "failed to allocate AsyncServerSocket backoff"
892 << " timer; unable to temporarly pause accepting";
897 // For now, we simply pause accepting for 1 second.
899 // We could add some smarter backoff calculation here in the future. (e.g.,
900 // start sleeping for longer if we keep hitting the backoff frequently.)
901 // Typically the user needs to figure out why the server is overloaded and
902 // fix it in some other way, though. The backoff timer is just a simple
903 // mechanism to try and give the connection processing code a little bit of
904 // breathing room to catch up, and to avoid just spinning and failing to
905 // accept over and over again.
906 const uint32_t timeoutMS = 1000;
907 if (!backoffTimeout_->scheduleTimeout(timeoutMS)) {
908 LOG(ERROR) << "failed to schedule AsyncServerSocket backoff timer;"
909 << "unable to temporarly pause accepting";
913 // The backoff timer is scheduled to re-enable accepts.
914 // Go ahead and disable accepts for now. We leave accepting_ set to true,
915 // since that tracks the desired state requested by the user.
916 for (auto& handler : sockets_) {
917 handler.unregisterHandler();
921 void AsyncServerSocket::backoffTimeoutExpired() {
922 // accepting_ should still be true.
923 // If pauseAccepting() was called while in the backoff state it will cancel
924 // the backoff timeout.
926 // We can't be detached from the EventBase without being paused
927 assert(eventBase_ != nullptr && eventBase_->isInEventBaseThread());
929 // If all of the callbacks were removed, we shouldn't re-enable accepts
930 if (callbacks_.empty()) {
934 // Register the handler.
935 for (auto& handler : sockets_) {
936 if (!handler.registerHandler(
937 EventHandler::READ | EventHandler::PERSIST)) {
938 // We're hosed. We could just re-schedule backoffTimeout_ to
939 // re-try again after a little bit. However, we don't want to
940 // loop retrying forever if we can't re-enable accepts. Just
941 // abort the entire program in this state; things are really bad
942 // and restarting the entire server is probably the best remedy.
944 << "failed to re-enable AsyncServerSocket accepts after backoff; "