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 // Disallow copy, move, and default constructors.
120 BackoffTimeout(BackoffTimeout&&) = delete;
121 BackoffTimeout(AsyncServerSocket* socket)
122 : AsyncTimeout(socket->getEventBase()), socket_(socket) {}
124 virtual void timeoutExpired() noexcept {
125 socket_->backoffTimeoutExpired();
129 AsyncServerSocket* socket_;
133 * AsyncServerSocket methods
136 AsyncServerSocket::AsyncServerSocket(EventBase* eventBase)
137 : eventBase_(eventBase),
139 maxAcceptAtOnce_(kDefaultMaxAcceptAtOnce),
140 maxNumMsgsInQueue_(kDefaultMaxMessagesInQueue),
141 acceptRateAdjustSpeed_(0),
143 lastAccepTimestamp_(std::chrono::steady_clock::now()),
144 numDroppedConnections_(0),
146 backoffTimeout_(nullptr),
148 keepAliveEnabled_(true),
150 shutdownSocketSet_(nullptr) {
153 void AsyncServerSocket::setShutdownSocketSet(ShutdownSocketSet* newSS) {
154 if (shutdownSocketSet_ == newSS) {
157 if (shutdownSocketSet_) {
158 for (auto& h : sockets_) {
159 shutdownSocketSet_->remove(h.socket_);
162 shutdownSocketSet_ = newSS;
163 if (shutdownSocketSet_) {
164 for (auto& h : sockets_) {
165 shutdownSocketSet_->add(h.socket_);
170 AsyncServerSocket::~AsyncServerSocket() {
171 assert(callbacks_.empty());
174 int AsyncServerSocket::stopAccepting(int shutdownFlags) {
176 for (auto& handler : sockets_) {
177 VLOG(10) << "AsyncServerSocket::stopAccepting " << this <<
180 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
182 // When destroy is called, unregister and close the socket immediately
185 for (auto& handler : sockets_) {
186 handler.unregisterHandler();
187 if (shutdownSocketSet_) {
188 shutdownSocketSet_->close(handler.socket_);
189 } else if (shutdownFlags >= 0) {
190 result = shutdownNoInt(handler.socket_, shutdownFlags);
191 pendingCloseSockets_.push_back(handler.socket_);
193 closeNoInt(handler.socket_);
198 // Destroy the backoff timout. This will cancel it if it is running.
199 delete backoffTimeout_;
200 backoffTimeout_ = nullptr;
202 // Close all of the callback queues to notify them that they are being
203 // destroyed. No one should access the AsyncServerSocket any more once
204 // destroy() is called. However, clear out callbacks_ before invoking the
205 // accept callbacks just in case. This will potentially help us detect the
206 // bug if one of the callbacks calls addAcceptCallback() or
207 // removeAcceptCallback().
208 std::vector<CallbackInfo> callbacksCopy;
209 callbacks_.swap(callbacksCopy);
210 for (std::vector<CallbackInfo>::iterator it = callbacksCopy.begin();
211 it != callbacksCopy.end();
213 it->consumer->stop(it->eventBase, it->callback);
219 void AsyncServerSocket::destroy() {
221 for (auto s : pendingCloseSockets_) {
224 // Then call DelayedDestruction::destroy() to take care of
225 // whether or not we need immediate or delayed destruction
226 DelayedDestruction::destroy();
229 void AsyncServerSocket::attachEventBase(EventBase *eventBase) {
230 assert(eventBase_ == nullptr);
231 assert(eventBase->isInEventBaseThread());
233 eventBase_ = eventBase;
234 for (auto& handler : sockets_) {
235 handler.attachEventBase(eventBase);
239 void AsyncServerSocket::detachEventBase() {
240 assert(eventBase_ != nullptr);
241 assert(eventBase_->isInEventBaseThread());
244 eventBase_ = nullptr;
245 for (auto& handler : sockets_) {
246 handler.detachEventBase();
250 void AsyncServerSocket::useExistingSockets(const std::vector<int>& fds) {
251 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
253 if (sockets_.size() > 0) {
254 throw std::invalid_argument(
255 "cannot call useExistingSocket() on a "
256 "AsyncServerSocket that already has a socket");
260 // Set addressFamily_ from this socket.
261 // Note that the socket may not have been bound yet, but
262 // setFromLocalAddress() will still work and get the correct address family.
263 // We will update addressFamily_ again anyway if bind() is called later.
264 SocketAddress address;
265 address.setFromLocalAddress(fd);
268 sockets_.emplace_back(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) {
295 sockets_.emplace_back(eventBase_, fd, this, address.getFamily());
299 void AsyncServerSocket::bind(const SocketAddress& address) {
300 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
302 // useExistingSocket() may have been called to initialize socket_ already.
303 // However, in the normal case we need to create a new socket now.
304 // Don't set socket_ yet, so that socket_ will remain uninitialized if an
307 if (sockets_.size() == 0) {
308 fd = createSocket(address.getFamily());
309 } else if (sockets_.size() == 1) {
310 if (address.getFamily() != sockets_[0].addressFamily_) {
311 throw std::invalid_argument(
312 "Attempted to bind address to socket with "
313 "different address family");
315 fd = sockets_[0].socket_;
317 throw std::invalid_argument(
318 "Attempted to bind to multiple fds");
321 bindSocket(fd, address, !sockets_.empty());
324 void AsyncServerSocket::bind(
325 const std::vector<IPAddress>& ipAddresses,
327 if (ipAddresses.empty()) {
328 throw std::invalid_argument("No ip addresses were provided");
330 if (!sockets_.empty()) {
331 throw std::invalid_argument("Cannot call bind on a AsyncServerSocket "
332 "that already has a socket.");
335 for (const IPAddress& ipAddress : ipAddresses) {
336 SocketAddress address(ipAddress.toFullyQualified(), port);
337 int fd = createSocket(address.getFamily());
339 bindSocket(fd, address, false);
341 if (sockets_.size() == 0) {
342 throw std::runtime_error(
343 "did not bind any async server socket for port and addresses");
347 void AsyncServerSocket::bind(uint16_t port) {
348 struct addrinfo hints, *res, *res0;
349 char sport[sizeof("65536")];
351 memset(&hints, 0, sizeof(hints));
352 hints.ai_family = AF_UNSPEC;
353 hints.ai_socktype = SOCK_STREAM;
354 hints.ai_flags = AI_PASSIVE;
355 snprintf(sport, sizeof(sport), "%u", port);
357 if (getaddrinfo(nullptr, sport, &hints, &res0)) {
358 throw std::invalid_argument(
359 "Attempted to bind address to socket with "
363 SCOPE_EXIT { freeaddrinfo(res0); };
365 auto setupAddress = [&] (struct addrinfo* res) {
366 int s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
367 // IPv6/IPv4 may not be supported by the kernel
368 if (s < 0 && errno == EAFNOSUPPORT) {
380 if (res->ai_family == AF_INET6) {
382 CHECK(0 == setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
383 &v6only, sizeof(v6only)));
386 SocketAddress address;
387 address.setFromLocalAddress(s);
389 sockets_.emplace_back(eventBase_, s, this, address.getFamily());
391 // Bind to the socket
392 if (::bind(s, res->ai_addr, res->ai_addrlen) != 0) {
393 folly::throwSystemError(
395 "failed to bind to async server socket for port");
399 const int kNumTries = 5;
400 for (int tries = 1; true; tries++) {
401 // Prefer AF_INET6 addresses. RFC 3484 mandates that getaddrinfo
402 // should return IPv6 first and then IPv4 addresses, but glibc's
403 // getaddrinfo(nullptr) with AI_PASSIVE returns:
404 // - 0.0.0.0 (IPv4-only)
405 // - :: (IPv6+IPv4) in this order
406 // See: https://sourceware.org/bugzilla/show_bug.cgi?id=9981
407 for (res = res0; res; res = res->ai_next) {
408 if (res->ai_family == AF_INET6) {
413 // If port == 0, then we should try to bind to the same port on ipv4 and
414 // ipv6. So if we did bind to ipv6, figure out that port and use it,
415 // except for the last attempt when we just use any port available.
416 if (sockets_.size() == 1 && port == 0) {
417 SocketAddress address;
418 address.setFromLocalAddress(sockets_.back().socket_);
419 snprintf(sport, sizeof(sport), "%u", address.getPort());
421 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
425 for (res = res0; res; res = res->ai_next) {
426 if (res->ai_family != AF_INET6) {
430 } catch (const std::system_error& e) {
431 // if we can't bind to the same port on ipv4 as ipv6 when using port=0
432 // then we will try again another 2 times before giving up. We do this
433 // by closing the sockets that were opened, then redoing the whole thing
434 if (port == 0 && !sockets_.empty() && tries != kNumTries) {
435 for (const auto& socket : sockets_) {
436 if (socket.socket_ <= 0) {
438 } else if (shutdownSocketSet_) {
439 shutdownSocketSet_->close(socket.socket_);
441 closeNoInt(socket.socket_);
445 snprintf(sport, sizeof(sport), "%u", port);
447 CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
456 if (sockets_.size() == 0) {
457 throw std::runtime_error(
458 "did not bind any async server socket for port");
462 void AsyncServerSocket::listen(int backlog) {
463 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
466 for (auto& handler : sockets_) {
467 if (::listen(handler.socket_, backlog) == -1) {
468 folly::throwSystemError(errno,
469 "failed to listen on async server socket");
474 void AsyncServerSocket::getAddress(SocketAddress* addressReturn) const {
475 CHECK(sockets_.size() >= 1);
476 VLOG_IF(2, sockets_.size() > 1)
477 << "Warning: getAddress() called and multiple addresses available ("
478 << sockets_.size() << "). Returning only the first one.";
480 addressReturn->setFromLocalAddress(sockets_[0].socket_);
483 std::vector<SocketAddress> AsyncServerSocket::getAddresses()
485 CHECK(sockets_.size() >= 1);
486 auto tsaVec = std::vector<SocketAddress>(sockets_.size());
487 auto tsaIter = tsaVec.begin();
488 for (const auto& socket : sockets_) {
489 (tsaIter++)->setFromLocalAddress(socket.socket_);
494 void AsyncServerSocket::addAcceptCallback(AcceptCallback *callback,
495 EventBase *eventBase,
496 uint32_t maxAtOnce) {
497 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
499 // If this is the first accept callback and we are supposed to be accepting,
500 // start accepting once the callback is installed.
501 bool runStartAccepting = accepting_ && callbacks_.empty();
504 eventBase = eventBase_; // Run in AsyncServerSocket's eventbase
507 callbacks_.emplace_back(callback, eventBase);
509 // Start the remote acceptor.
511 // It would be nice if we could avoid starting the remote acceptor if
512 // eventBase == eventBase_. However, that would cause issues if
513 // detachEventBase() and attachEventBase() were ever used to change the
514 // primary EventBase for the server socket. Therefore we require the caller
515 // to specify a nullptr EventBase if they want to ensure that the callback is
516 // always invoked in the primary EventBase, and to be able to invoke that
517 // callback more efficiently without having to use a notification queue.
518 RemoteAcceptor* acceptor = nullptr;
520 acceptor = new RemoteAcceptor(callback);
521 acceptor->start(eventBase, maxAtOnce, maxNumMsgsInQueue_);
523 callbacks_.pop_back();
527 callbacks_.back().consumer = acceptor;
529 // If this is the first accept callback and we are supposed to be accepting,
531 if (runStartAccepting) {
536 void AsyncServerSocket::removeAcceptCallback(AcceptCallback *callback,
537 EventBase *eventBase) {
538 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
540 // Find the matching AcceptCallback.
541 // We just do a simple linear search; we don't expect removeAcceptCallback()
542 // to be called frequently, and we expect there to only be a small number of
544 std::vector<CallbackInfo>::iterator it = callbacks_.begin();
547 if (it == callbacks_.end()) {
548 throw std::runtime_error("AsyncServerSocket::removeAcceptCallback(): "
549 "accept callback not found");
551 if (it->callback == callback &&
552 (it->eventBase == eventBase || eventBase == nullptr)) {
559 // Remove this callback from callbacks_.
561 // Do this before invoking the acceptStopped() callback, in case
562 // acceptStopped() invokes one of our methods that examines callbacks_.
564 // Save a copy of the CallbackInfo first.
565 CallbackInfo info(*it);
566 callbacks_.erase(it);
567 if (n < callbackIndex_) {
568 // We removed an element before callbackIndex_. Move callbackIndex_ back
569 // one step, since things after n have been shifted back by 1.
572 // We removed something at or after callbackIndex_.
573 // If we removed the last element and callbackIndex_ was pointing at it,
574 // we need to reset callbackIndex_ to 0.
575 if (callbackIndex_ >= callbacks_.size()) {
580 info.consumer->stop(info.eventBase, info.callback);
582 // If we are supposed to be accepting but the last accept callback
583 // was removed, unregister for events until a callback is added.
584 if (accepting_ && callbacks_.empty()) {
585 for (auto& handler : sockets_) {
586 handler.unregisterHandler();
591 void AsyncServerSocket::startAccepting() {
592 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
595 if (callbacks_.empty()) {
596 // We can't actually begin accepting if no callbacks are defined.
597 // Wait until a callback is added to start accepting.
601 for (auto& handler : sockets_) {
602 if (!handler.registerHandler(
603 EventHandler::READ | EventHandler::PERSIST)) {
604 throw std::runtime_error("failed to register for accept events");
609 void AsyncServerSocket::pauseAccepting() {
610 assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
612 for (auto& handler : sockets_) {
613 handler. unregisterHandler();
616 // If we were in the accept backoff state, disable the backoff timeout
617 if (backoffTimeout_) {
618 backoffTimeout_->cancelTimeout();
622 int AsyncServerSocket::createSocket(int family) {
623 int fd = socket(family, SOCK_STREAM, 0);
625 folly::throwSystemError(errno, "error creating async server socket");
637 void AsyncServerSocket::setupSocket(int fd) {
638 // Get the address family
639 SocketAddress address;
640 address.setFromLocalAddress(fd);
641 auto family = address.getFamily();
643 // Put the socket in non-blocking mode
644 if (fcntl(fd, F_SETFL, O_NONBLOCK) != 0) {
645 folly::throwSystemError(errno,
646 "failed to put socket in non-blocking mode");
649 // Set reuseaddr to avoid 2MSL delay on server restart
651 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) != 0) {
652 // This isn't a fatal error; just log an error message and continue
653 LOG(ERROR) << "failed to set SO_REUSEADDR on async server socket " << errno;
656 // Set reuseport to support multiple accept threads
658 if (reusePortEnabled_ &&
659 setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(int)) != 0) {
660 LOG(ERROR) << "failed to set SO_REUSEPORT on async server socket "
662 folly::throwSystemError(errno,
663 "failed to bind to async server socket: " +
667 // Set keepalive as desired
668 if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE,
669 (keepAliveEnabled_) ? &one : &zero, sizeof(int)) != 0) {
670 LOG(ERROR) << "failed to set SO_KEEPALIVE on async server socket: " <<
674 // Setup FD_CLOEXEC flag
676 (-1 == folly::setCloseOnExec(fd, closeOnExec_))) {
677 LOG(ERROR) << "failed to set FD_CLOEXEC on async server socket: " <<
681 // Set TCP nodelay if available, MAC OS X Hack
682 // See http://lists.danga.com/pipermail/memcached/2005-March/001240.html
684 if (family != AF_UNIX) {
685 if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) != 0) {
686 // This isn't a fatal error; just log an error message and continue
687 LOG(ERROR) << "failed to set TCP_NODELAY on async server socket: " <<
693 if (shutdownSocketSet_) {
694 shutdownSocketSet_->add(fd);
698 void AsyncServerSocket::handlerReady(
699 uint16_t events, int fd, sa_family_t addressFamily) noexcept {
700 assert(!callbacks_.empty());
701 DestructorGuard dg(this);
703 // Only accept up to maxAcceptAtOnce_ connections at a time,
704 // to avoid starving other I/O handlers using this EventBase.
705 for (uint32_t n = 0; n < maxAcceptAtOnce_; ++n) {
706 SocketAddress address;
708 sockaddr_storage addrStorage;
709 socklen_t addrLen = sizeof(addrStorage);
710 sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
712 // In some cases, accept() doesn't seem to update these correctly.
713 saddr->sa_family = addressFamily;
714 if (addressFamily == AF_UNIX) {
715 addrLen = sizeof(struct sockaddr_un);
718 // Accept a new client socket
720 int clientSocket = accept4(fd, saddr, &addrLen, SOCK_NONBLOCK);
722 int clientSocket = accept(fd, saddr, &addrLen);
725 address.setFromSockaddr(saddr, addrLen);
727 std::chrono::time_point<std::chrono::steady_clock> nowMs =
728 std::chrono::steady_clock::now();
729 int64_t timeSinceLastAccept = std::max(
731 nowMs.time_since_epoch().count() -
732 lastAccepTimestamp_.time_since_epoch().count());
733 lastAccepTimestamp_ = nowMs;
734 if (acceptRate_ < 1) {
735 acceptRate_ *= 1 + acceptRateAdjustSpeed_ * timeSinceLastAccept;
736 if (acceptRate_ >= 1) {
738 } else if (rand() > acceptRate_ * RAND_MAX) {
739 ++numDroppedConnections_;
740 if (clientSocket >= 0) {
741 closeNoInt(clientSocket);
747 if (clientSocket < 0) {
748 if (errno == EAGAIN) {
749 // No more sockets to accept right now.
750 // Check for this code first, since it's the most common.
752 } else if (errno == EMFILE || errno == ENFILE) {
753 // We're out of file descriptors. Perhaps we're accepting connections
754 // too quickly. Pause accepting briefly to back off and give the server
755 // a chance to recover.
756 LOG(ERROR) << "accept failed: out of file descriptors; entering accept "
760 // Dispatch the error message
761 dispatchError("accept() failed", errno);
763 dispatchError("accept() failed", errno);
768 #ifndef SOCK_NONBLOCK
769 // Explicitly set the new connection to non-blocking mode
770 if (fcntl(clientSocket, F_SETFL, O_NONBLOCK) != 0) {
771 closeNoInt(clientSocket);
772 dispatchError("failed to set accepted socket to non-blocking mode",
778 // Inform the callback about the new connection
779 dispatchSocket(clientSocket, std::move(address));
781 // If we aren't accepting any more, break out of the loop
782 if (!accepting_ || callbacks_.empty()) {
788 void AsyncServerSocket::dispatchSocket(int socket,
789 SocketAddress&& address) {
790 uint32_t startingIndex = callbackIndex_;
792 // Short circuit if the callback is in the primary EventBase thread
794 CallbackInfo *info = nextCallback();
795 if (info->eventBase == nullptr) {
796 info->callback->connectionAccepted(socket, address);
800 // Create a message to send over the notification queue
802 msg.type = MessageType::MSG_NEW_CONN;
803 msg.address = std::move(address);
806 // Loop until we find a free queue to write to
808 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
813 // We couldn't add to queue. Fall through to below
815 ++numDroppedConnections_;
816 if (acceptRateAdjustSpeed_ > 0) {
817 // aggressively decrease accept rate when in trouble
818 static const double kAcceptRateDecreaseSpeed = 0.1;
819 acceptRate_ *= 1 - kAcceptRateDecreaseSpeed;
823 if (callbackIndex_ == startingIndex) {
824 // The notification queue was full
825 // We can't really do anything at this point other than close the socket.
827 // This should only happen if a user's service is behaving extremely
828 // badly and none of the EventBase threads are looping fast enough to
829 // process the incoming connections. If the service is overloaded, it
830 // should use pauseAccepting() to temporarily back off accepting new
831 // connections, before they reach the point where their threads can't
832 // even accept new messages.
833 LOG(ERROR) << "failed to dispatch newly accepted socket:"
834 << " all accept callback queues are full";
839 info = nextCallback();
843 void AsyncServerSocket::dispatchError(const char *msgstr, int errnoValue) {
844 uint32_t startingIndex = callbackIndex_;
845 CallbackInfo *info = nextCallback();
847 // Create a message to send over the notification queue
849 msg.type = MessageType::MSG_ERROR;
850 msg.err = errnoValue;
851 msg.msg = std::move(msgstr);
854 // Short circuit if the callback is in the primary EventBase thread
855 if (info->eventBase == nullptr) {
856 std::runtime_error ex(
857 std::string(msgstr) + folly::to<std::string>(errnoValue));
858 info->callback->acceptError(ex);
862 if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
865 // Fall through and try another callback
867 if (callbackIndex_ == startingIndex) {
868 // The notification queues for all of the callbacks were full.
869 // We can't really do anything at this point.
870 LOG(ERROR) << "failed to dispatch accept error: all accept callback "
871 "queues are full: error msg: " <<
872 msg.msg.c_str() << errnoValue;
875 info = nextCallback();
879 void AsyncServerSocket::enterBackoff() {
880 // If this is the first time we have entered the backoff state,
881 // allocate backoffTimeout_.
882 if (backoffTimeout_ == nullptr) {
884 backoffTimeout_ = new BackoffTimeout(this);
885 } catch (const std::bad_alloc& ex) {
886 // Man, we couldn't even allocate the timer to re-enable accepts.
887 // We must be in pretty bad shape. Don't pause accepting for now,
888 // since we won't be able to re-enable ourselves later.
889 LOG(ERROR) << "failed to allocate AsyncServerSocket backoff"
890 << " timer; unable to temporarly pause accepting";
895 // For now, we simply pause accepting for 1 second.
897 // We could add some smarter backoff calculation here in the future. (e.g.,
898 // start sleeping for longer if we keep hitting the backoff frequently.)
899 // Typically the user needs to figure out why the server is overloaded and
900 // fix it in some other way, though. The backoff timer is just a simple
901 // mechanism to try and give the connection processing code a little bit of
902 // breathing room to catch up, and to avoid just spinning and failing to
903 // accept over and over again.
904 const uint32_t timeoutMS = 1000;
905 if (!backoffTimeout_->scheduleTimeout(timeoutMS)) {
906 LOG(ERROR) << "failed to schedule AsyncServerSocket backoff timer;"
907 << "unable to temporarly pause accepting";
911 // The backoff timer is scheduled to re-enable accepts.
912 // Go ahead and disable accepts for now. We leave accepting_ set to true,
913 // since that tracks the desired state requested by the user.
914 for (auto& handler : sockets_) {
915 handler.unregisterHandler();
919 void AsyncServerSocket::backoffTimeoutExpired() {
920 // accepting_ should still be true.
921 // If pauseAccepting() was called while in the backoff state it will cancel
922 // the backoff timeout.
924 // We can't be detached from the EventBase without being paused
925 assert(eventBase_ != nullptr && eventBase_->isInEventBaseThread());
927 // If all of the callbacks were removed, we shouldn't re-enable accepts
928 if (callbacks_.empty()) {
932 // Register the handler.
933 for (auto& handler : sockets_) {
934 if (!handler.registerHandler(
935 EventHandler::READ | EventHandler::PERSIST)) {
936 // We're hosed. We could just re-schedule backoffTimeout_ to
937 // re-try again after a little bit. However, we don't want to
938 // loop retrying forever if we can't re-enable accepts. Just
939 // abort the entire program in this state; things are really bad
940 // and restarting the entire server is probably the best remedy.
942 << "failed to re-enable AsyncServerSocket accepts after backoff; "