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.
19 #include <sys/types.h>
20 #include <sys/socket.h>
21 #include <glog/logging.h>
22 #include <folly/SocketAddress.h>
23 #include <folly/io/ShutdownSocketSet.h>
24 #include <folly/io/IOBuf.h>
25 #include <folly/io/async/AsyncTimeout.h>
26 #include <folly/io/async/AsyncSocketException.h>
27 #include <folly/io/async/AsyncTransport.h>
28 #include <folly/io/async/EventHandler.h>
29 #include <folly/io/async/DelayedDestruction.h>
37 * A class for performing asynchronous I/O on a socket.
39 * AsyncSocket allows users to asynchronously wait for data on a socket, and
40 * to asynchronously send data.
42 * The APIs for reading and writing are intentionally asymmetric. Waiting for
43 * data to read is a persistent API: a callback is installed, and is notified
44 * whenever new data is available. It continues to be notified of new events
45 * until it is uninstalled.
47 * AsyncSocket does not provide read timeout functionality, because it
48 * typically cannot determine when the timeout should be active. Generally, a
49 * timeout should only be enabled when processing is blocked waiting on data
50 * from the remote endpoint. For server sockets, the timeout should not be
51 * active if the server is currently processing one or more outstanding
52 * requests for this socket. For client sockets, the timeout should not be
53 * active if there are no requests pending on the socket. Additionally, if a
54 * client has multiple pending requests, it will ususally want a separate
55 * timeout for each request, rather than a single read timeout.
57 * The write API is fairly intuitive: a user can request to send a block of
58 * data, and a callback will be informed once the entire block has been
59 * transferred to the kernel, or on error. AsyncSocket does provide a send
60 * timeout, since most callers want to give up if the remote end stops
61 * responding and no further progress can be made sending the data.
64 class AsyncSocket : virtual public AsyncTransportWrapper {
66 typedef std::unique_ptr<AsyncSocket, Destructor> UniquePtr;
68 class ConnectCallback {
70 virtual ~ConnectCallback() {}
73 * connectSuccess() will be invoked when the connection has been
74 * successfully established.
76 virtual void connectSuccess() noexcept = 0;
79 * connectErr() will be invoked if the connection attempt fails.
81 * @param ex An exception describing the error that occurred.
83 virtual void connectErr(const AsyncSocketException& ex)
87 explicit AsyncSocket();
89 * Create a new unconnected AsyncSocket.
91 * connect() must later be called on this socket to establish a connection.
93 explicit AsyncSocket(EventBase* evb);
95 void setShutdownSocketSet(ShutdownSocketSet* ss);
98 * Create a new AsyncSocket and begin the connection process.
100 * @param evb EventBase that will manage this socket.
101 * @param address The address to connect to.
102 * @param connectTimeout Optional timeout in milliseconds for the connection
105 AsyncSocket(EventBase* evb,
106 const folly::SocketAddress& address,
107 uint32_t connectTimeout = 0);
110 * Create a new AsyncSocket and begin the connection process.
112 * @param evb EventBase that will manage this socket.
113 * @param ip IP address to connect to (dotted-quad).
114 * @param port Destination port in host byte order.
115 * @param connectTimeout Optional timeout in milliseconds for the connection
118 AsyncSocket(EventBase* evb,
119 const std::string& ip,
121 uint32_t connectTimeout = 0);
124 * Create a AsyncSocket from an already connected socket file descriptor.
126 * Note that while AsyncSocket enables TCP_NODELAY for sockets it creates
127 * when connecting, it does not change the socket options when given an
128 * existing file descriptor. If callers want TCP_NODELAY enabled when using
129 * this version of the constructor, they need to explicitly call
130 * setNoDelay(true) after the constructor returns.
132 * @param evb EventBase that will manage this socket.
133 * @param fd File descriptor to take over (should be a connected socket).
135 AsyncSocket(EventBase* evb, int fd);
138 * Helper function to create a shared_ptr<AsyncSocket>.
140 * This passes in the correct destructor object, since AsyncSocket's
141 * destructor is protected and cannot be invoked directly.
143 static std::shared_ptr<AsyncSocket> newSocket(EventBase* evb) {
144 return std::shared_ptr<AsyncSocket>(new AsyncSocket(evb),
149 * Helper function to create a shared_ptr<AsyncSocket>.
151 static std::shared_ptr<AsyncSocket> newSocket(
153 const folly::SocketAddress& address,
154 uint32_t connectTimeout = 0) {
155 return std::shared_ptr<AsyncSocket>(
156 new AsyncSocket(evb, address, connectTimeout),
161 * Helper function to create a shared_ptr<AsyncSocket>.
163 static std::shared_ptr<AsyncSocket> newSocket(
165 const std::string& ip,
167 uint32_t connectTimeout = 0) {
168 return std::shared_ptr<AsyncSocket>(
169 new AsyncSocket(evb, ip, port, connectTimeout),
174 * Helper function to create a shared_ptr<AsyncSocket>.
176 static std::shared_ptr<AsyncSocket> newSocket(EventBase* evb, int fd) {
177 return std::shared_ptr<AsyncSocket>(new AsyncSocket(evb, fd),
182 * Destroy the socket.
184 * AsyncSocket::destroy() must be called to destroy the socket.
185 * The normal destructor is private, and should not be invoked directly.
186 * This prevents callers from deleting a AsyncSocket while it is invoking a
189 virtual void destroy() override;
192 * Get the EventBase used by this socket.
194 EventBase* getEventBase() const override {
199 * Get the file descriptor used by the AsyncSocket.
201 virtual int getFd() const {
206 * Extract the file descriptor from the AsyncSocket.
208 * This will immediately cause any installed callbacks to be invoked with an
209 * error. The AsyncSocket may no longer be used after the file descriptor
210 * has been extracted.
212 * Returns the file descriptor. The caller assumes ownership of the
213 * descriptor, and it will not be closed when the AsyncSocket is destroyed.
215 virtual int detachFd();
218 * Uniquely identifies a handle to a socket option value. Each
219 * combination of level and option name corresponds to one socket
224 bool operator<(const OptionKey& other) const {
225 if (level == other.level) {
226 return optname < other.optname;
228 return level < other.level;
230 int apply(int fd, int val) const {
231 return setsockopt(fd, level, optname, &val, sizeof(val));
237 // Maps from a socket option key to its value
238 typedef std::map<OptionKey, int> OptionMap;
240 static const OptionMap emptyOptionMap;
241 static const folly::SocketAddress& anyAddress();
244 * Initiate a connection.
246 * @param callback The callback to inform when the connection attempt
248 * @param address The address to connect to.
249 * @param timeout A timeout value, in milliseconds. If the connection
250 * does not succeed within this period,
251 * callback->connectError() will be invoked.
253 virtual void connect(ConnectCallback* callback,
254 const folly::SocketAddress& address,
256 const OptionMap &options = emptyOptionMap,
257 const folly::SocketAddress& bindAddr = anyAddress()
259 void connect(ConnectCallback* callback, const std::string& ip, uint16_t port,
261 const OptionMap &options = emptyOptionMap) noexcept;
264 * If a connect request is in-flight, cancels it and closes the socket
265 * immediately. Otherwise, this is a no-op.
267 * This does not invoke any connection related callbacks. Call this to
268 * prevent any connect callback while cleaning up, etc.
270 void cancelConnect();
273 * Set the send timeout.
275 * If write requests do not make any progress for more than the specified
276 * number of milliseconds, fail all pending writes and close the socket.
278 * If write requests are currently pending when setSendTimeout() is called,
279 * the timeout interval is immediately restarted using the new value.
281 * (See the comments for AsyncSocket for an explanation of why AsyncSocket
282 * provides setSendTimeout() but not setRecvTimeout().)
284 * @param milliseconds The timeout duration, in milliseconds. If 0, no
285 * timeout will be used.
287 void setSendTimeout(uint32_t milliseconds) override;
290 * Get the send timeout.
292 * @return Returns the current send timeout, in milliseconds. A return value
293 * of 0 indicates that no timeout is set.
295 uint32_t getSendTimeout() const override {
300 * Set the maximum number of reads to execute from the underlying
301 * socket each time the EventBase detects that new ingress data is
302 * available. The default is unlimited, but callers can use this method
303 * to limit the amount of data read from the socket per event loop
306 * @param maxReads Maximum number of reads per data-available event;
307 * a value of zero means unlimited.
309 void setMaxReadsPerEvent(uint16_t maxReads) {
310 maxReadsPerEvent_ = maxReads;
314 * Get the maximum number of reads this object will execute from
315 * the underlying socket each time the EventBase detects that new
316 * ingress data is available.
318 * @returns Maximum number of reads per data-available event; a value
319 * of zero means unlimited.
321 uint16_t getMaxReadsPerEvent() const {
322 return maxReadsPerEvent_;
325 // Read and write methods
326 void setReadCB(ReadCallback* callback) override;
327 ReadCallback* getReadCallback() const override;
329 void write(WriteCallback* callback, const void* buf, size_t bytes,
330 WriteFlags flags = WriteFlags::NONE) override;
331 void writev(WriteCallback* callback, const iovec* vec, size_t count,
332 WriteFlags flags = WriteFlags::NONE) override;
333 void writeChain(WriteCallback* callback,
334 std::unique_ptr<folly::IOBuf>&& buf,
335 WriteFlags flags = WriteFlags::NONE) override;
337 // Methods inherited from AsyncTransport
338 void close() override;
339 void closeNow() override;
340 void closeWithReset() override;
341 void shutdownWrite() override;
342 void shutdownWriteNow() override;
344 bool readable() const override;
345 bool isPending() const override;
346 virtual bool hangup() const;
347 bool good() const override;
348 bool error() const override;
349 void attachEventBase(EventBase* eventBase) override;
350 void detachEventBase() override;
351 bool isDetachable() const override;
353 void getLocalAddress(
354 folly::SocketAddress* address) const override;
356 folly::SocketAddress* address) const override;
358 bool isEorTrackingEnabled() const override { return false; }
360 void setEorTracking(bool track) override {}
362 bool connecting() const override {
363 return (state_ == StateEnum::CONNECTING);
366 size_t getAppBytesWritten() const override {
367 return appBytesWritten_;
370 size_t getRawBytesWritten() const override {
371 return getAppBytesWritten();
374 size_t getAppBytesReceived() const override {
375 return appBytesReceived_;
378 size_t getRawBytesReceived() const override {
379 return getAppBytesReceived();
382 // Methods controlling socket options
385 * Force writes to be transmitted immediately.
387 * This controls the TCP_NODELAY socket option. When enabled, TCP segments
388 * are sent as soon as possible, even if it is not a full frame of data.
389 * When disabled, the data may be buffered briefly to try and wait for a full
392 * By default, TCP_NODELAY is enabled for AsyncSocket objects.
394 * This method will fail if the socket is not currently open.
396 * @return Returns 0 if the TCP_NODELAY flag was successfully updated,
397 * or a non-zero errno value on error.
399 int setNoDelay(bool noDelay);
403 * Set the FD_CLOEXEC flag so that the socket will be closed if the program
404 * later forks and execs.
406 void setCloseOnExec();
409 * Set the Flavor of Congestion Control to be used for this Socket
410 * Please check '/lib/modules/<kernel>/kernel/net/ipv4' for tcp_*.ko
411 * first to make sure the module is available for plugging in
412 * Alternatively you can choose from net.ipv4.tcp_allowed_congestion_control
414 int setCongestionFlavor(const std::string &cname);
417 * Forces ACKs to be sent immediately
419 * @return Returns 0 if the TCP_QUICKACK flag was successfully updated,
420 * or a non-zero errno value on error.
422 int setQuickAck(bool quickack);
425 * Set the send bufsize
427 int setSendBufSize(size_t bufsize);
430 * Set the recv bufsize
432 int setRecvBufSize(size_t bufsize);
435 * Sets a specific tcp personality
436 * Available only on kernels 3.2 and greater
438 #define SO_SET_NAMESPACE 41
439 int setTCPProfile(int profd);
443 * Generic API for reading a socket option.
445 * @param level same as the "level" parameter in getsockopt().
446 * @param optname same as the "optname" parameter in getsockopt().
447 * @param optval pointer to the variable in which the option value should
449 * @param optlen value-result argument, initially containing the size of
450 * the buffer pointed to by optval, and modified on return
451 * to indicate the actual size of the value returned.
452 * @return same as the return value of getsockopt().
454 template <typename T>
455 int getSockOpt(int level, int optname, T* optval, socklen_t* optlen) {
456 return getsockopt(fd_, level, optname, (void*) optval, optlen);
460 * Generic API for setting a socket option.
462 * @param level same as the "level" parameter in getsockopt().
463 * @param optname same as the "optname" parameter in getsockopt().
464 * @param optval the option value to set.
465 * @return same as the return value of setsockopt().
467 template <typename T>
468 int setSockOpt(int level, int optname, const T *optval) {
469 return setsockopt(fd_, level, optname, optval, sizeof(T));
472 enum class StateEnum : uint8_t {
481 enum ReadResultEnum {
488 * Protected destructor.
490 * Users of AsyncSocket must never delete it directly. Instead, invoke
491 * destroy() instead. (See the documentation in DelayedDestruction.h for
496 friend std::ostream& operator << (std::ostream& os, const StateEnum& state);
499 /// shutdownWrite() called, but we are still waiting on writes to drain
500 SHUT_WRITE_PENDING = 0x01,
501 /// writes have been completely shut down
504 * Reads have been shutdown.
506 * At the moment we don't distinguish between remote read shutdown
507 * (received EOF from the remote end) and local read shutdown. We can
508 * only receive EOF when a read callback is set, and we immediately inform
509 * it of the EOF. Therefore there doesn't seem to be any reason to have a
510 * separate state of "received EOF but the local side may still want to
513 * We also don't currently provide any API for only shutting down the read
514 * side of a socket. (This is a no-op as far as TCP is concerned, anyway.)
520 class BytesWriteRequest;
522 class WriteTimeout : public AsyncTimeout {
524 WriteTimeout(AsyncSocket* socket, EventBase* eventBase)
525 : AsyncTimeout(eventBase)
528 virtual void timeoutExpired() noexcept {
529 socket_->timeoutExpired();
533 AsyncSocket* socket_;
536 class IoHandler : public EventHandler {
538 IoHandler(AsyncSocket* socket, EventBase* eventBase)
539 : EventHandler(eventBase, -1)
541 IoHandler(AsyncSocket* socket, EventBase* eventBase, int fd)
542 : EventHandler(eventBase, fd)
545 virtual void handlerReady(uint16_t events) noexcept {
546 socket_->ioReady(events);
550 AsyncSocket* socket_;
555 // event notification methods
556 void ioReady(uint16_t events) noexcept;
557 virtual void checkForImmediateRead() noexcept;
558 virtual void handleInitialReadWrite() noexcept;
559 virtual void handleRead() noexcept;
560 virtual void handleWrite() noexcept;
561 virtual void handleConnect() noexcept;
562 void timeoutExpired() noexcept;
565 * Attempt to read from the socket.
567 * @param buf The buffer to read data into.
568 * @param buflen The length of the buffer.
570 * @return Returns the number of bytes read, or READ_EOF on EOF, or
571 * READ_ERROR on error, or READ_BLOCKING if the operation will
574 virtual ssize_t performRead(void* buf, size_t buflen);
577 * Populate an iovec array from an IOBuf and attempt to write it.
579 * @param callback Write completion/error callback.
580 * @param vec Target iovec array; caller retains ownership.
581 * @param count Number of IOBufs to write, beginning at start of buf.
582 * @param buf Chain of iovecs.
583 * @param flags set of flags for the underlying write calls, like cork
585 void writeChainImpl(WriteCallback* callback, iovec* vec,
586 size_t count, std::unique_ptr<folly::IOBuf>&& buf,
590 * Write as much data as possible to the socket without blocking,
591 * and queue up any leftover data to send when the socket can
592 * handle writes again.
594 * @param callback The callback to invoke when the write is completed.
595 * @param vec Array of buffers to write; this method will make a
596 * copy of the vector (but not the buffers themselves)
597 * if the write has to be completed asynchronously.
598 * @param count Number of elements in vec.
599 * @param buf The IOBuf that manages the buffers referenced by
600 * vec, or a pointer to nullptr if the buffers are not
601 * associated with an IOBuf. Note that ownership of
602 * the IOBuf is transferred here; upon completion of
603 * the write, the AsyncSocket deletes the IOBuf.
604 * @param flags Set of write flags.
606 void writeImpl(WriteCallback* callback, const iovec* vec, size_t count,
607 std::unique_ptr<folly::IOBuf>&& buf,
608 WriteFlags flags = WriteFlags::NONE);
611 * Attempt to write to the socket.
613 * @param vec The iovec array pointing to the buffers to write.
614 * @param count The length of the iovec array.
615 * @param flags Set of write flags.
616 * @param countWritten On return, the value pointed to by this parameter
617 * will contain the number of iovec entries that were
619 * @param partialWritten On return, the value pointed to by this parameter
620 * will contain the number of bytes written in the
621 * partially written iovec entry.
623 * @return Returns the total number of bytes written, or -1 on error. If no
624 * data can be written immediately, 0 is returned.
626 virtual ssize_t performWrite(const iovec* vec, uint32_t count,
627 WriteFlags flags, uint32_t* countWritten,
628 uint32_t* partialWritten);
630 bool updateEventRegistration();
633 * Update event registration.
635 * @param enable Flags of events to enable. Set it to 0 if no events
636 * need to be enabled in this call.
637 * @param disable Flags of events
638 * to disable. Set it to 0 if no events need to be disabled in this
641 * @return true iff the update is successful.
643 bool updateEventRegistration(uint16_t enable, uint16_t disable);
645 // Actually close the file descriptor and set it to -1 so we don't
646 // accidentally close it again.
649 // error handling methods
652 void fail(const char* fn, const AsyncSocketException& ex);
653 void failConnect(const char* fn, const AsyncSocketException& ex);
654 void failRead(const char* fn, const AsyncSocketException& ex);
655 void failWrite(const char* fn, WriteCallback* callback, size_t bytesWritten,
656 const AsyncSocketException& ex);
657 void failWrite(const char* fn, const AsyncSocketException& ex);
658 void failAllWrites(const AsyncSocketException& ex);
659 void invalidState(ConnectCallback* callback);
660 void invalidState(ReadCallback* callback);
661 void invalidState(WriteCallback* callback);
663 std::string withAddr(const std::string& s);
665 StateEnum state_; ///< StateEnum describing current state
666 uint8_t shutdownFlags_; ///< Shutdown state (ShutdownFlags)
667 uint16_t eventFlags_; ///< EventBase::HandlerFlags settings
668 int fd_; ///< The socket file descriptor
670 folly::SocketAddress addr_; ///< The address we tried to connect to
671 uint32_t sendTimeout_; ///< The send timeout, in milliseconds
672 uint16_t maxReadsPerEvent_; ///< Max reads per event loop iteration
673 EventBase* eventBase_; ///< The EventBase
674 WriteTimeout writeTimeout_; ///< A timeout for connect and write
675 IoHandler ioHandler_; ///< A EventHandler to monitor the fd
677 ConnectCallback* connectCallback_; ///< ConnectCallback
678 ReadCallback* readCallback_; ///< ReadCallback
679 WriteRequest* writeReqHead_; ///< Chain of WriteRequests
680 WriteRequest* writeReqTail_; ///< End of WriteRequest chain
681 ShutdownSocketSet* shutdownSocketSet_;
682 size_t appBytesReceived_; ///< Num of bytes received from socket
683 size_t appBytesWritten_; ///< Num of bytes written to socket