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/*
* Copyright 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <folly/io/async/AsyncServerSocket.h>
#include <folly/FileUtil.h>
#include <folly/Portability.h>
#include <folly/SocketAddress.h>
#include <folly/String.h>
#include <folly/detail/SocketFastOpen.h>
#include <folly/io/async/EventBase.h>
#include <folly/io/async/NotificationQueue.h>
#include <folly/portability/Fcntl.h>
#include <folly/portability/Sockets.h>
#include <folly/portability/Unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
namespace fsp = folly::portability::sockets;
namespace folly {
const uint32_t AsyncServerSocket::kDefaultMaxAcceptAtOnce;
const uint32_t AsyncServerSocket::kDefaultCallbackAcceptAtOnce;
const uint32_t AsyncServerSocket::kDefaultMaxMessagesInQueue;
int setCloseOnExec(int fd, int value) {
// Read the current flags
int old_flags = fcntl(fd, F_GETFD, 0);
// If reading the flags failed, return error indication now
if (old_flags < 0)
return -1;
// Set just the flag we want to set
int new_flags;
if (value != 0)
new_flags = old_flags | FD_CLOEXEC;
else
new_flags = old_flags & ~FD_CLOEXEC;
// Store modified flag word in the descriptor
return fcntl(fd, F_SETFD, new_flags);
}
void AsyncServerSocket::RemoteAcceptor::start(
EventBase* eventBase, uint32_t maxAtOnce, uint32_t maxInQueue) {
setMaxReadAtOnce(maxAtOnce);
queue_.setMaxQueueSize(maxInQueue);
if (!eventBase->runInEventBaseThread([=](){
callback_->acceptStarted();
this->startConsuming(eventBase, &queue_);
})) {
throw std::invalid_argument("unable to start waiting on accept "
"notification queue in the specified "
"EventBase thread");
}
}
void AsyncServerSocket::RemoteAcceptor::stop(
EventBase* eventBase, AcceptCallback* callback) {
if (!eventBase->runInEventBaseThread([=](){
callback->acceptStopped();
delete this;
})) {
throw std::invalid_argument("unable to start waiting on accept "
"notification queue in the specified "
"EventBase thread");
}
}
void AsyncServerSocket::RemoteAcceptor::messageAvailable(
QueueMessage&& msg) {
switch (msg.type) {
case MessageType::MSG_NEW_CONN:
{
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionDequeuedByAcceptorCallback(
msg.fd, msg.address);
}
callback_->connectionAccepted(msg.fd, msg.address);
break;
}
case MessageType::MSG_ERROR:
{
std::runtime_error ex(msg.msg);
callback_->acceptError(ex);
break;
}
default:
{
LOG(ERROR) << "invalid accept notification message type "
<< int(msg.type);
std::runtime_error ex(
"received invalid accept notification message type");
callback_->acceptError(ex);
}
}
}
/*
* AsyncServerSocket::BackoffTimeout
*/
class AsyncServerSocket::BackoffTimeout : public AsyncTimeout {
public:
// Disallow copy, move, and default constructors.
BackoffTimeout(BackoffTimeout&&) = delete;
explicit BackoffTimeout(AsyncServerSocket* socket)
: AsyncTimeout(socket->getEventBase()), socket_(socket) {}
void timeoutExpired() noexcept override { socket_->backoffTimeoutExpired(); }
private:
AsyncServerSocket* socket_;
};
/*
* AsyncServerSocket methods
*/
AsyncServerSocket::AsyncServerSocket(EventBase* eventBase)
: eventBase_(eventBase),
accepting_(false),
maxAcceptAtOnce_(kDefaultMaxAcceptAtOnce),
maxNumMsgsInQueue_(kDefaultMaxMessagesInQueue),
acceptRateAdjustSpeed_(0),
acceptRate_(1),
lastAccepTimestamp_(std::chrono::steady_clock::now()),
numDroppedConnections_(0),
callbackIndex_(0),
backoffTimeout_(nullptr),
callbacks_(),
keepAliveEnabled_(true),
closeOnExec_(true),
shutdownSocketSet_(nullptr) {
}
void AsyncServerSocket::setShutdownSocketSet(ShutdownSocketSet* newSS) {
if (shutdownSocketSet_ == newSS) {
return;
}
if (shutdownSocketSet_) {
for (auto& h : sockets_) {
shutdownSocketSet_->remove(h.socket_);
}
}
shutdownSocketSet_ = newSS;
if (shutdownSocketSet_) {
for (auto& h : sockets_) {
shutdownSocketSet_->add(h.socket_);
}
}
}
AsyncServerSocket::~AsyncServerSocket() {
assert(callbacks_.empty());
}
int AsyncServerSocket::stopAccepting(int shutdownFlags) {
int result = 0;
for (auto& handler : sockets_) {
VLOG(10) << "AsyncServerSocket::stopAccepting " << this <<
handler.socket_;
}
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
// When destroy is called, unregister and close the socket immediately.
accepting_ = false;
// Close the sockets in reverse order as they were opened to avoid
// the condition where another process concurrently tries to open
// the same port, succeed to bind the first socket but fails on the
// second because it hasn't been closed yet.
for (; !sockets_.empty(); sockets_.pop_back()) {
auto& handler = sockets_.back();
handler.unregisterHandler();
if (shutdownSocketSet_) {
shutdownSocketSet_->close(handler.socket_);
} else if (shutdownFlags >= 0) {
result = shutdownNoInt(handler.socket_, shutdownFlags);
pendingCloseSockets_.push_back(handler.socket_);
} else {
closeNoInt(handler.socket_);
}
}
// Destroy the backoff timout. This will cancel it if it is running.
delete backoffTimeout_;
backoffTimeout_ = nullptr;
// Close all of the callback queues to notify them that they are being
// destroyed. No one should access the AsyncServerSocket any more once
// destroy() is called. However, clear out callbacks_ before invoking the
// accept callbacks just in case. This will potentially help us detect the
// bug if one of the callbacks calls addAcceptCallback() or
// removeAcceptCallback().
std::vector<CallbackInfo> callbacksCopy;
callbacks_.swap(callbacksCopy);
for (std::vector<CallbackInfo>::iterator it = callbacksCopy.begin();
it != callbacksCopy.end();
++it) {
// consumer may not be set if we are running in primary event base
if (it->consumer) {
DCHECK(it->eventBase);
it->consumer->stop(it->eventBase, it->callback);
} else {
DCHECK(it->callback);
it->callback->acceptStopped();
}
}
return result;
}
void AsyncServerSocket::destroy() {
stopAccepting();
for (auto s : pendingCloseSockets_) {
closeNoInt(s);
}
// Then call DelayedDestruction::destroy() to take care of
// whether or not we need immediate or delayed destruction
DelayedDestruction::destroy();
}
void AsyncServerSocket::attachEventBase(EventBase *eventBase) {
assert(eventBase_ == nullptr);
assert(eventBase->isInEventBaseThread());
eventBase_ = eventBase;
for (auto& handler : sockets_) {
handler.attachEventBase(eventBase);
}
}
void AsyncServerSocket::detachEventBase() {
assert(eventBase_ != nullptr);
assert(eventBase_->isInEventBaseThread());
assert(!accepting_);
eventBase_ = nullptr;
for (auto& handler : sockets_) {
handler.detachEventBase();
}
}
void AsyncServerSocket::useExistingSockets(const std::vector<int>& fds) {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
if (sockets_.size() > 0) {
throw std::invalid_argument(
"cannot call useExistingSocket() on a "
"AsyncServerSocket that already has a socket");
}
for (auto fd: fds) {
// Set addressFamily_ from this socket.
// Note that the socket may not have been bound yet, but
// setFromLocalAddress() will still work and get the correct address family.
// We will update addressFamily_ again anyway if bind() is called later.
SocketAddress address;
address.setFromLocalAddress(fd);
setupSocket(fd, address.getFamily());
sockets_.emplace_back(eventBase_, fd, this, address.getFamily());
sockets_.back().changeHandlerFD(fd);
}
}
void AsyncServerSocket::useExistingSocket(int fd) {
useExistingSockets({fd});
}
void AsyncServerSocket::bindSocket(
int fd,
const SocketAddress& address,
bool isExistingSocket) {
sockaddr_storage addrStorage;
address.getAddress(&addrStorage);
sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
if (fsp::bind(fd, saddr, address.getActualSize()) != 0) {
if (!isExistingSocket) {
closeNoInt(fd);
}
folly::throwSystemError(errno,
"failed to bind to async server socket: " +
address.describe());
}
// If we just created this socket, update the EventHandler and set socket_
if (!isExistingSocket) {
sockets_.emplace_back(eventBase_, fd, this, address.getFamily());
}
}
void AsyncServerSocket::bind(const SocketAddress& address) {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
// useExistingSocket() may have been called to initialize socket_ already.
// However, in the normal case we need to create a new socket now.
// Don't set socket_ yet, so that socket_ will remain uninitialized if an
// error occurs.
int fd;
if (sockets_.size() == 0) {
fd = createSocket(address.getFamily());
} else if (sockets_.size() == 1) {
if (address.getFamily() != sockets_[0].addressFamily_) {
throw std::invalid_argument(
"Attempted to bind address to socket with "
"different address family");
}
fd = sockets_[0].socket_;
} else {
throw std::invalid_argument(
"Attempted to bind to multiple fds");
}
bindSocket(fd, address, !sockets_.empty());
}
void AsyncServerSocket::bind(
const std::vector<IPAddress>& ipAddresses,
uint16_t port) {
if (ipAddresses.empty()) {
throw std::invalid_argument("No ip addresses were provided");
}
if (!sockets_.empty()) {
throw std::invalid_argument("Cannot call bind on a AsyncServerSocket "
"that already has a socket.");
}
for (const IPAddress& ipAddress : ipAddresses) {
SocketAddress address(ipAddress.toFullyQualified(), port);
int fd = createSocket(address.getFamily());
bindSocket(fd, address, false);
}
if (sockets_.size() == 0) {
throw std::runtime_error(
"did not bind any async server socket for port and addresses");
}
}
void AsyncServerSocket::bind(uint16_t port) {
struct addrinfo hints, *res0;
char sport[sizeof("65536")];
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV;
snprintf(sport, sizeof(sport), "%u", port);
// On Windows the value we need to pass to bind to all available
// addresses is an empty string. Everywhere else, it's nullptr.
constexpr const char* kWildcardNode = kIsWindows ? "" : nullptr;
if (getaddrinfo(kWildcardNode, sport, &hints, &res0)) {
throw std::invalid_argument(
"Attempted to bind address to socket with "
"bad getaddrinfo");
}
SCOPE_EXIT { freeaddrinfo(res0); };
auto setupAddress = [&] (struct addrinfo* res) {
int s = fsp::socket(res->ai_family, res->ai_socktype, res->ai_protocol);
// IPv6/IPv4 may not be supported by the kernel
if (s < 0 && errno == EAFNOSUPPORT) {
return;
}
CHECK_GE(s, 0);
try {
setupSocket(s, res->ai_family);
} catch (...) {
closeNoInt(s);
throw;
}
if (res->ai_family == AF_INET6) {
int v6only = 1;
CHECK(0 == setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
&v6only, sizeof(v6only)));
}
// Bind to the socket
if (fsp::bind(s, res->ai_addr, socklen_t(res->ai_addrlen)) != 0) {
folly::throwSystemError(
errno,
"failed to bind to async server socket for port ",
SocketAddress::getPortFrom(res->ai_addr),
" family ",
SocketAddress::getFamilyNameFrom(res->ai_addr, "<unknown>"));
}
SocketAddress address;
address.setFromLocalAddress(s);
sockets_.emplace_back(eventBase_, s, this, address.getFamily());
};
const int kNumTries = 25;
for (int tries = 1; true; tries++) {
// Prefer AF_INET6 addresses. RFC 3484 mandates that getaddrinfo
// should return IPv6 first and then IPv4 addresses, but glibc's
// getaddrinfo(nullptr) with AI_PASSIVE returns:
// - 0.0.0.0 (IPv4-only)
// - :: (IPv6+IPv4) in this order
// See: https://sourceware.org/bugzilla/show_bug.cgi?id=9981
for (struct addrinfo* res = res0; res; res = res->ai_next) {
if (res->ai_family == AF_INET6) {
setupAddress(res);
}
}
// If port == 0, then we should try to bind to the same port on ipv4 and
// ipv6. So if we did bind to ipv6, figure out that port and use it.
if (sockets_.size() == 1 && port == 0) {
SocketAddress address;
address.setFromLocalAddress(sockets_.back().socket_);
snprintf(sport, sizeof(sport), "%u", address.getPort());
freeaddrinfo(res0);
CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
}
try {
for (struct addrinfo* res = res0; res; res = res->ai_next) {
if (res->ai_family != AF_INET6) {
setupAddress(res);
}
}
} catch (const std::system_error&) {
// If we can't bind to the same port on ipv4 as ipv6 when using
// port=0 then we will retry again before giving up after
// kNumTries attempts. We do this by closing the sockets that
// were opened, then restarting from scratch.
if (port == 0 && !sockets_.empty() && tries != kNumTries) {
for (const auto& socket : sockets_) {
if (socket.socket_ <= 0) {
continue;
} else if (shutdownSocketSet_) {
shutdownSocketSet_->close(socket.socket_);
} else {
closeNoInt(socket.socket_);
}
}
sockets_.clear();
snprintf(sport, sizeof(sport), "%u", port);
freeaddrinfo(res0);
CHECK_EQ(0, getaddrinfo(nullptr, sport, &hints, &res0));
continue;
}
throw;
}
break;
}
if (sockets_.size() == 0) {
throw std::runtime_error(
"did not bind any async server socket for port");
}
}
void AsyncServerSocket::listen(int backlog) {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
// Start listening
for (auto& handler : sockets_) {
if (fsp::listen(handler.socket_, backlog) == -1) {
folly::throwSystemError(errno,
"failed to listen on async server socket");
}
}
}
void AsyncServerSocket::getAddress(SocketAddress* addressReturn) const {
CHECK(sockets_.size() >= 1);
VLOG_IF(2, sockets_.size() > 1)
<< "Warning: getAddress() called and multiple addresses available ("
<< sockets_.size() << "). Returning only the first one.";
addressReturn->setFromLocalAddress(sockets_[0].socket_);
}
std::vector<SocketAddress> AsyncServerSocket::getAddresses()
const {
CHECK(sockets_.size() >= 1);
auto tsaVec = std::vector<SocketAddress>(sockets_.size());
auto tsaIter = tsaVec.begin();
for (const auto& socket : sockets_) {
(tsaIter++)->setFromLocalAddress(socket.socket_);
};
return tsaVec;
}
void AsyncServerSocket::addAcceptCallback(AcceptCallback *callback,
EventBase *eventBase,
uint32_t maxAtOnce) {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
// If this is the first accept callback and we are supposed to be accepting,
// start accepting once the callback is installed.
bool runStartAccepting = accepting_ && callbacks_.empty();
callbacks_.emplace_back(callback, eventBase);
SCOPE_SUCCESS {
// If this is the first accept callback and we are supposed to be accepting,
// start accepting.
if (runStartAccepting) {
startAccepting();
}
};
if (!eventBase) {
// Run in AsyncServerSocket's eventbase; notify that we are
// starting to accept connections
callback->acceptStarted();
return;
}
// Start the remote acceptor.
//
// It would be nice if we could avoid starting the remote acceptor if
// eventBase == eventBase_. However, that would cause issues if
// detachEventBase() and attachEventBase() were ever used to change the
// primary EventBase for the server socket. Therefore we require the caller
// to specify a nullptr EventBase if they want to ensure that the callback is
// always invoked in the primary EventBase, and to be able to invoke that
// callback more efficiently without having to use a notification queue.
RemoteAcceptor* acceptor = nullptr;
try {
acceptor = new RemoteAcceptor(callback, connectionEventCallback_);
acceptor->start(eventBase, maxAtOnce, maxNumMsgsInQueue_);
} catch (...) {
callbacks_.pop_back();
delete acceptor;
throw;
}
callbacks_.back().consumer = acceptor;
}
void AsyncServerSocket::removeAcceptCallback(AcceptCallback *callback,
EventBase *eventBase) {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
// Find the matching AcceptCallback.
// We just do a simple linear search; we don't expect removeAcceptCallback()
// to be called frequently, and we expect there to only be a small number of
// callbacks anyway.
std::vector<CallbackInfo>::iterator it = callbacks_.begin();
uint32_t n = 0;
while (true) {
if (it == callbacks_.end()) {
throw std::runtime_error("AsyncServerSocket::removeAcceptCallback(): "
"accept callback not found");
}
if (it->callback == callback &&
(it->eventBase == eventBase || eventBase == nullptr)) {
break;
}
++it;
++n;
}
// Remove this callback from callbacks_.
//
// Do this before invoking the acceptStopped() callback, in case
// acceptStopped() invokes one of our methods that examines callbacks_.
//
// Save a copy of the CallbackInfo first.
CallbackInfo info(*it);
callbacks_.erase(it);
if (n < callbackIndex_) {
// We removed an element before callbackIndex_. Move callbackIndex_ back
// one step, since things after n have been shifted back by 1.
--callbackIndex_;
} else {
// We removed something at or after callbackIndex_.
// If we removed the last element and callbackIndex_ was pointing at it,
// we need to reset callbackIndex_ to 0.
if (callbackIndex_ >= callbacks_.size()) {
callbackIndex_ = 0;
}
}
if (info.consumer) {
// consumer could be nullptr is we run callbacks in primary event
// base
DCHECK(info.eventBase);
info.consumer->stop(info.eventBase, info.callback);
} else {
// callback invoked in the primary event base, just call directly
DCHECK(info.callback);
callback->acceptStopped();
}
// If we are supposed to be accepting but the last accept callback
// was removed, unregister for events until a callback is added.
if (accepting_ && callbacks_.empty()) {
for (auto& handler : sockets_) {
handler.unregisterHandler();
}
}
}
void AsyncServerSocket::startAccepting() {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
accepting_ = true;
if (callbacks_.empty()) {
// We can't actually begin accepting if no callbacks are defined.
// Wait until a callback is added to start accepting.
return;
}
for (auto& handler : sockets_) {
if (!handler.registerHandler(
EventHandler::READ | EventHandler::PERSIST)) {
throw std::runtime_error("failed to register for accept events");
}
}
}
void AsyncServerSocket::pauseAccepting() {
assert(eventBase_ == nullptr || eventBase_->isInEventBaseThread());
accepting_ = false;
for (auto& handler : sockets_) {
handler. unregisterHandler();
}
// If we were in the accept backoff state, disable the backoff timeout
if (backoffTimeout_) {
backoffTimeout_->cancelTimeout();
}
}
int AsyncServerSocket::createSocket(int family) {
int fd = fsp::socket(family, SOCK_STREAM, 0);
if (fd == -1) {
folly::throwSystemError(errno, "error creating async server socket");
}
try {
setupSocket(fd, family);
} catch (...) {
closeNoInt(fd);
throw;
}
return fd;
}
void AsyncServerSocket::setupSocket(int fd, int family) {
// Put the socket in non-blocking mode
if (fcntl(fd, F_SETFL, O_NONBLOCK) != 0) {
folly::throwSystemError(errno,
"failed to put socket in non-blocking mode");
}
// Set reuseaddr to avoid 2MSL delay on server restart
int one = 1;
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) != 0) {
// This isn't a fatal error; just log an error message and continue
LOG(ERROR) << "failed to set SO_REUSEADDR on async server socket " << errno;
}
// Set reuseport to support multiple accept threads
int zero = 0;
if (reusePortEnabled_ &&
setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(int)) != 0) {
LOG(ERROR) << "failed to set SO_REUSEPORT on async server socket "
<< strerror(errno);
#ifdef WIN32
folly::throwSystemError(errno, "failed to bind to the async server socket");
#else
SocketAddress address;
address.setFromLocalAddress(fd);
folly::throwSystemError(errno,
"failed to bind to async server socket: " +
address.describe());
#endif
}
// Set keepalive as desired
if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE,
(keepAliveEnabled_) ? &one : &zero, sizeof(int)) != 0) {
LOG(ERROR) << "failed to set SO_KEEPALIVE on async server socket: " <<
strerror(errno);
}
// Setup FD_CLOEXEC flag
if (closeOnExec_ &&
(-1 == folly::setCloseOnExec(fd, closeOnExec_))) {
LOG(ERROR) << "failed to set FD_CLOEXEC on async server socket: " <<
strerror(errno);
}
// Set TCP nodelay if available, MAC OS X Hack
// See http://lists.danga.com/pipermail/memcached/2005-March/001240.html
#ifndef TCP_NOPUSH
if (family != AF_UNIX) {
if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) != 0) {
// This isn't a fatal error; just log an error message and continue
LOG(ERROR) << "failed to set TCP_NODELAY on async server socket: " <<
strerror(errno);
}
}
#endif
#if FOLLY_ALLOW_TFO
if (tfo_ && detail::tfo_enable(fd, tfoMaxQueueSize_) != 0) {
// This isn't a fatal error; just log an error message and continue
LOG(WARNING) << "failed to set TCP_FASTOPEN on async server socket: "
<< folly::errnoStr(errno);
}
#endif
if (shutdownSocketSet_) {
shutdownSocketSet_->add(fd);
}
}
void AsyncServerSocket::handlerReady(uint16_t /* events */,
int fd,
sa_family_t addressFamily) noexcept {
assert(!callbacks_.empty());
DestructorGuard dg(this);
// Only accept up to maxAcceptAtOnce_ connections at a time,
// to avoid starving other I/O handlers using this EventBase.
for (uint32_t n = 0; n < maxAcceptAtOnce_; ++n) {
SocketAddress address;
sockaddr_storage addrStorage;
socklen_t addrLen = sizeof(addrStorage);
sockaddr* saddr = reinterpret_cast<sockaddr*>(&addrStorage);
// In some cases, accept() doesn't seem to update these correctly.
saddr->sa_family = addressFamily;
if (addressFamily == AF_UNIX) {
addrLen = sizeof(struct sockaddr_un);
}
// Accept a new client socket
#ifdef SOCK_NONBLOCK
int clientSocket = accept4(fd, saddr, &addrLen, SOCK_NONBLOCK);
#else
int clientSocket = accept(fd, saddr, &addrLen);
#endif
address.setFromSockaddr(saddr, addrLen);
if (clientSocket >= 0 && connectionEventCallback_) {
connectionEventCallback_->onConnectionAccepted(clientSocket, address);
}
std::chrono::time_point<std::chrono::steady_clock> nowMs =
std::chrono::steady_clock::now();
auto timeSinceLastAccept = std::max<int64_t>(
0,
nowMs.time_since_epoch().count() -
lastAccepTimestamp_.time_since_epoch().count());
lastAccepTimestamp_ = nowMs;
if (acceptRate_ < 1) {
acceptRate_ *= 1 + acceptRateAdjustSpeed_ * timeSinceLastAccept;
if (acceptRate_ >= 1) {
acceptRate_ = 1;
} else if (rand() > acceptRate_ * RAND_MAX) {
++numDroppedConnections_;
if (clientSocket >= 0) {
closeNoInt(clientSocket);
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionDropped(clientSocket,
address);
}
}
continue;
}
}
if (clientSocket < 0) {
if (errno == EAGAIN) {
// No more sockets to accept right now.
// Check for this code first, since it's the most common.
return;
} else if (errno == EMFILE || errno == ENFILE) {
// We're out of file descriptors. Perhaps we're accepting connections
// too quickly. Pause accepting briefly to back off and give the server
// a chance to recover.
LOG(ERROR) << "accept failed: out of file descriptors; entering accept "
"back-off state";
enterBackoff();
// Dispatch the error message
dispatchError("accept() failed", errno);
} else {
dispatchError("accept() failed", errno);
}
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionAcceptError(errno);
}
return;
}
#ifndef SOCK_NONBLOCK
// Explicitly set the new connection to non-blocking mode
if (fcntl(clientSocket, F_SETFL, O_NONBLOCK) != 0) {
closeNoInt(clientSocket);
dispatchError("failed to set accepted socket to non-blocking mode",
errno);
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionDropped(clientSocket, address);
}
return;
}
#endif
// Inform the callback about the new connection
dispatchSocket(clientSocket, std::move(address));
// If we aren't accepting any more, break out of the loop
if (!accepting_ || callbacks_.empty()) {
break;
}
}
}
void AsyncServerSocket::dispatchSocket(int socket,
SocketAddress&& address) {
uint32_t startingIndex = callbackIndex_;
// Short circuit if the callback is in the primary EventBase thread
CallbackInfo *info = nextCallback();
if (info->eventBase == nullptr) {
info->callback->connectionAccepted(socket, address);
return;
}
const SocketAddress addr(address);
// Create a message to send over the notification queue
QueueMessage msg;
msg.type = MessageType::MSG_NEW_CONN;
msg.address = std::move(address);
msg.fd = socket;
// Loop until we find a free queue to write to
while (true) {
if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionEnqueuedForAcceptorCallback(
socket,
addr);
}
// Success! return.
return;
}
// We couldn't add to queue. Fall through to below
++numDroppedConnections_;
if (acceptRateAdjustSpeed_ > 0) {
// aggressively decrease accept rate when in trouble
static const double kAcceptRateDecreaseSpeed = 0.1;
acceptRate_ *= 1 - kAcceptRateDecreaseSpeed;
}
if (callbackIndex_ == startingIndex) {
// The notification queue was full
// We can't really do anything at this point other than close the socket.
//
// This should only happen if a user's service is behaving extremely
// badly and none of the EventBase threads are looping fast enough to
// process the incoming connections. If the service is overloaded, it
// should use pauseAccepting() to temporarily back off accepting new
// connections, before they reach the point where their threads can't
// even accept new messages.
LOG(ERROR) << "failed to dispatch newly accepted socket:"
<< " all accept callback queues are full";
closeNoInt(socket);
if (connectionEventCallback_) {
connectionEventCallback_->onConnectionDropped(socket, addr);
}
return;
}
info = nextCallback();
}
}
void AsyncServerSocket::dispatchError(const char *msgstr, int errnoValue) {
uint32_t startingIndex = callbackIndex_;
CallbackInfo *info = nextCallback();
// Create a message to send over the notification queue
QueueMessage msg;
msg.type = MessageType::MSG_ERROR;
msg.err = errnoValue;
msg.msg = std::move(msgstr);
while (true) {
// Short circuit if the callback is in the primary EventBase thread
if (info->eventBase == nullptr) {
std::runtime_error ex(
std::string(msgstr) + folly::to<std::string>(errnoValue));
info->callback->acceptError(ex);
return;
}
if (info->consumer->getQueue()->tryPutMessageNoThrow(std::move(msg))) {
return;
}
// Fall through and try another callback
if (callbackIndex_ == startingIndex) {
// The notification queues for all of the callbacks were full.
// We can't really do anything at this point.
LOG(ERROR) << "failed to dispatch accept error: all accept callback "
"queues are full: error msg: " <<
msg.msg.c_str() << errnoValue;
return;
}
info = nextCallback();
}
}
void AsyncServerSocket::enterBackoff() {
// If this is the first time we have entered the backoff state,
// allocate backoffTimeout_.
if (backoffTimeout_ == nullptr) {
try {
backoffTimeout_ = new BackoffTimeout(this);
} catch (const std::bad_alloc&) {
// Man, we couldn't even allocate the timer to re-enable accepts.
// We must be in pretty bad shape. Don't pause accepting for now,
// since we won't be able to re-enable ourselves later.
LOG(ERROR) << "failed to allocate AsyncServerSocket backoff"
<< " timer; unable to temporarly pause accepting";
if (connectionEventCallback_) {
connectionEventCallback_->onBackoffError();
}
return;
}
}
// For now, we simply pause accepting for 1 second.
//
// We could add some smarter backoff calculation here in the future. (e.g.,
// start sleeping for longer if we keep hitting the backoff frequently.)
// Typically the user needs to figure out why the server is overloaded and
// fix it in some other way, though. The backoff timer is just a simple
// mechanism to try and give the connection processing code a little bit of
// breathing room to catch up, and to avoid just spinning and failing to
// accept over and over again.
const uint32_t timeoutMS = 1000;
if (!backoffTimeout_->scheduleTimeout(timeoutMS)) {
LOG(ERROR) << "failed to schedule AsyncServerSocket backoff timer;"
<< "unable to temporarly pause accepting";
if (connectionEventCallback_) {
connectionEventCallback_->onBackoffError();
}
return;
}
// The backoff timer is scheduled to re-enable accepts.
// Go ahead and disable accepts for now. We leave accepting_ set to true,
// since that tracks the desired state requested by the user.
for (auto& handler : sockets_) {
handler.unregisterHandler();
}
if (connectionEventCallback_) {
connectionEventCallback_->onBackoffStarted();
}
}
void AsyncServerSocket::backoffTimeoutExpired() {
// accepting_ should still be true.
// If pauseAccepting() was called while in the backoff state it will cancel
// the backoff timeout.
assert(accepting_);
// We can't be detached from the EventBase without being paused
assert(eventBase_ != nullptr && eventBase_->isInEventBaseThread());
// If all of the callbacks were removed, we shouldn't re-enable accepts
if (callbacks_.empty()) {
if (connectionEventCallback_) {
connectionEventCallback_->onBackoffEnded();
}
return;
}
// Register the handler.
for (auto& handler : sockets_) {
if (!handler.registerHandler(
EventHandler::READ | EventHandler::PERSIST)) {
// We're hosed. We could just re-schedule backoffTimeout_ to
// re-try again after a little bit. However, we don't want to
// loop retrying forever if we can't re-enable accepts. Just
// abort the entire program in this state; things are really bad
// and restarting the entire server is probably the best remedy.
LOG(ERROR)
<< "failed to re-enable AsyncServerSocket accepts after backoff; "
<< "crashing now";
abort();
}
}
if (connectionEventCallback_) {
connectionEventCallback_->onBackoffEnded();
}
}
} // folly