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::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>"));
}
#if __linux__
if (noTransparentTls_) {
// Ignore return value, errors are ok
setsockopt(s, SOL_SOCKET, SO_NO_TRANSPARENT_TLS, nullptr, 0);
}
#endif
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");
}
}
Symbolizer::Symbolizer(ElfCacheBase* cache)
: cache_(cache ?: defaultElfCache()) {
}
void Symbolizer::symbolize(const uintptr_t* addresses,
SymbolizedFrame* frames,
size_t addressCount) {
size_t remaining = 0;
for (size_t i = 0; i < addressCount; ++i) {
auto& frame = frames[i];
if (!frame.found) {
++remaining;
frame.clear();
}
}
if (remaining == 0) { // we're done
return;
}
int fd = openNoInt("/proc/self/maps", O_RDONLY);
if (fd == -1) {
return;
}
char buf[PATH_MAX + 100]; // Long enough for any line
LineReader reader(fd, buf, sizeof(buf));
while (remaining != 0) {
StringPiece line;
if (reader.readLine(line) != LineReader::kReading) {
break;
}
// Parse line
uintptr_t from;
uintptr_t to;
StringPiece fileName;
if (!parseProcMapsLine(line, from, to, fileName)) {
continue;
}
bool first = true;
std::shared_ptr<ElfFile> elfFile;
// See if any addresses are here
for (size_t i = 0; i < addressCount; ++i) {
auto& frame = frames[i];
if (frame.found) {
continue;
}
uintptr_t address = addresses[i];
if (from > address || address >= to) {
continue;
}
// Found
frame.found = true;
--remaining;
// Open the file on first use
if (first) {
first = false;
elfFile = cache_->getFile(fileName);
}
if (!elfFile) {
continue;
}
// Undo relocation
frame.set(elfFile, address - from);
}
}
closeNoInt(fd);
}
void Symbolizer::symbolize(const uintptr_t* addresses,
SymbolizedFrame* frames,
size_t addressCount) {
size_t remaining = 0;
for (size_t i = 0; i < addressCount; ++i) {
auto& frame = frames[i];
if (!frame.found) {
++remaining;
frame.name.clear();
frame.location = Dwarf::LocationInfo();
}
}
if (remaining == 0) { // we're done
return;
}
int fd = openNoInt("/proc/self/maps", O_RDONLY);
if (fd == -1) {
return;
}
char buf[PATH_MAX + 100]; // Long enough for any line
LineReader reader(fd, buf, sizeof(buf));
char fileNameBuf[PATH_MAX];
while (remaining != 0) {
StringPiece line;
if (reader.readLine(line) != LineReader::kReading) {
break;
}
// Parse line
uintptr_t from;
uintptr_t to;
StringPiece fileName;
if (!parseProcMapsLine(line, from, to, fileName)) {
continue;
}
bool first = true;
ElfFile* elfFile = nullptr;
// See if any addresses are here
for (size_t i = 0; i < addressCount; ++i) {
auto& frame = frames[i];
if (frame.found) {
continue;
}
uintptr_t address = addresses[i];
if (from > address || address >= to) {
continue;
}
// Found
frame.found = true;
--remaining;
// Open the file on first use
if (first) {
first = false;
if (fileCount_ < kMaxFiles &&
!fileName.empty() &&
fileName.size() < sizeof(fileNameBuf)) {
memcpy(fileNameBuf, fileName.data(), fileName.size());
fileNameBuf[fileName.size()] = '\0';
auto& f = files_[fileCount_++];
if (f.openNoThrow(fileNameBuf) != -1) {
elfFile = &f;
}
}
}
if (!elfFile) {
continue;
}
// Undo relocation
uintptr_t fileAddress = address - from + elfFile->getBaseAddress();
auto sym = elfFile->getDefinitionByAddress(fileAddress);
if (!sym.first) {
continue;
}
auto name = elfFile->getSymbolName(sym);
if (name) {
frame.name = name;
}
Dwarf(elfFile).findAddress(fileAddress, frame.location);
}
}
closeNoInt(fd);
}
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::bind(uint16_t port) {
struct addrinfo hints, *res, *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;
snprintf(sport, sizeof(sport), "%u", port);
if (getaddrinfo(nullptr, 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 = 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);
} catch (...) {
closeNoInt(s);
throw;
}
if (res->ai_family == AF_INET6) {
int v6only = 1;
CHECK(0 == setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY,
&v6only, sizeof(v6only)));
}
SocketAddress address;
address.setFromLocalAddress(s);
sockets_.emplace_back(eventBase_, s, this, address.getFamily());
// Bind to the socket
if (::bind(s, res->ai_addr, res->ai_addrlen) != 0) {
folly::throwSystemError(
errno,
"failed to bind to async server socket for port");
}
};
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 (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,
// except for the last attempt when we just use any port available.
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 (res = res0; res; res = res->ai_next) {
if (res->ai_family != AF_INET6) {
setupAddress(res);
}
}
} catch (const std::system_error& e) {
// if we can't bind to the same port on ipv4 as ipv6 when using port=0
// then we will try again another 2 times before giving up. We do this
// by closing the sockets that were opened, then redoing the whole thing
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");
}
}
