2 * Copyright 2016 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 <folly/Optional.h>
20 #include <folly/SocketAddress.h>
21 #include <folly/detail/SocketFastOpen.h>
22 #include <folly/io/IOBuf.h>
23 #include <folly/io/ShutdownSocketSet.h>
24 #include <folly/io/async/AsyncSocketException.h>
25 #include <folly/io/async/AsyncTimeout.h>
26 #include <folly/io/async/AsyncTransport.h>
27 #include <folly/io/async/DelayedDestruction.h>
28 #include <folly/io/async/EventHandler.h>
29 #include <folly/portability/Sockets.h>
31 #include <sys/types.h>
40 * A class for performing asynchronous I/O on a socket.
42 * AsyncSocket allows users to asynchronously wait for data on a socket, and
43 * to asynchronously send data.
45 * The APIs for reading and writing are intentionally asymmetric. Waiting for
46 * data to read is a persistent API: a callback is installed, and is notified
47 * whenever new data is available. It continues to be notified of new events
48 * until it is uninstalled.
50 * AsyncSocket does not provide read timeout functionality, because it
51 * typically cannot determine when the timeout should be active. Generally, a
52 * timeout should only be enabled when processing is blocked waiting on data
53 * from the remote endpoint. For server sockets, the timeout should not be
54 * active if the server is currently processing one or more outstanding
55 * requests for this socket. For client sockets, the timeout should not be
56 * active if there are no requests pending on the socket. Additionally, if a
57 * client has multiple pending requests, it will ususally want a separate
58 * timeout for each request, rather than a single read timeout.
60 * The write API is fairly intuitive: a user can request to send a block of
61 * data, and a callback will be informed once the entire block has been
62 * transferred to the kernel, or on error. AsyncSocket does provide a send
63 * timeout, since most callers want to give up if the remote end stops
64 * responding and no further progress can be made sending the data.
68 // We do a dynamic_cast on this, in
69 // AsyncTransportWrapper::getUnderlyingTransport so be safe and
70 // force displacements for it. See:
71 // https://msdn.microsoft.com/en-us/library/7sf3txa8.aspx
72 #pragma vtordisp(push, 2)
74 class AsyncSocket : virtual public AsyncTransportWrapper {
76 typedef std::unique_ptr<AsyncSocket, Destructor> UniquePtr;
78 class ConnectCallback {
80 virtual ~ConnectCallback() = default;
83 * connectSuccess() will be invoked when the connection has been
84 * successfully established.
86 virtual void connectSuccess() noexcept = 0;
89 * connectErr() will be invoked if the connection attempt fails.
91 * @param ex An exception describing the error that occurred.
93 virtual void connectErr(const AsyncSocketException& ex)
97 explicit AsyncSocket();
99 * Create a new unconnected AsyncSocket.
101 * connect() must later be called on this socket to establish a connection.
103 explicit AsyncSocket(EventBase* evb);
105 void setShutdownSocketSet(ShutdownSocketSet* ss);
108 * Create a new AsyncSocket and begin the connection process.
110 * @param evb EventBase that will manage this socket.
111 * @param address The address to connect to.
112 * @param connectTimeout Optional timeout in milliseconds for the connection
115 AsyncSocket(EventBase* evb,
116 const folly::SocketAddress& address,
117 uint32_t connectTimeout = 0);
120 * Create a new AsyncSocket and begin the connection process.
122 * @param evb EventBase that will manage this socket.
123 * @param ip IP address to connect to (dotted-quad).
124 * @param port Destination port in host byte order.
125 * @param connectTimeout Optional timeout in milliseconds for the connection
128 AsyncSocket(EventBase* evb,
129 const std::string& ip,
131 uint32_t connectTimeout = 0);
134 * Create a AsyncSocket from an already connected socket file descriptor.
136 * Note that while AsyncSocket enables TCP_NODELAY for sockets it creates
137 * when connecting, it does not change the socket options when given an
138 * existing file descriptor. If callers want TCP_NODELAY enabled when using
139 * this version of the constructor, they need to explicitly call
140 * setNoDelay(true) after the constructor returns.
142 * @param evb EventBase that will manage this socket.
143 * @param fd File descriptor to take over (should be a connected socket).
145 AsyncSocket(EventBase* evb, int fd);
148 * Helper function to create a shared_ptr<AsyncSocket>.
150 * This passes in the correct destructor object, since AsyncSocket's
151 * destructor is protected and cannot be invoked directly.
153 static std::shared_ptr<AsyncSocket> newSocket(EventBase* evb) {
154 return std::shared_ptr<AsyncSocket>(new AsyncSocket(evb),
159 * Helper function to create a shared_ptr<AsyncSocket>.
161 static std::shared_ptr<AsyncSocket> newSocket(
163 const folly::SocketAddress& address,
164 uint32_t connectTimeout = 0) {
165 return std::shared_ptr<AsyncSocket>(
166 new AsyncSocket(evb, address, connectTimeout),
171 * Helper function to create a shared_ptr<AsyncSocket>.
173 static std::shared_ptr<AsyncSocket> newSocket(
175 const std::string& ip,
177 uint32_t connectTimeout = 0) {
178 return std::shared_ptr<AsyncSocket>(
179 new AsyncSocket(evb, ip, port, connectTimeout),
184 * Helper function to create a shared_ptr<AsyncSocket>.
186 static std::shared_ptr<AsyncSocket> newSocket(EventBase* evb, int fd) {
187 return std::shared_ptr<AsyncSocket>(new AsyncSocket(evb, fd),
192 * Destroy the socket.
194 * AsyncSocket::destroy() must be called to destroy the socket.
195 * The normal destructor is private, and should not be invoked directly.
196 * This prevents callers from deleting a AsyncSocket while it is invoking a
199 virtual void destroy() override;
202 * Get the EventBase used by this socket.
204 EventBase* getEventBase() const override {
209 * Get the file descriptor used by the AsyncSocket.
211 virtual int getFd() const {
216 * Extract the file descriptor from the AsyncSocket.
218 * This will immediately cause any installed callbacks to be invoked with an
219 * error. The AsyncSocket may no longer be used after the file descriptor
220 * has been extracted.
222 * Returns the file descriptor. The caller assumes ownership of the
223 * descriptor, and it will not be closed when the AsyncSocket is destroyed.
225 virtual int detachFd();
228 * Uniquely identifies a handle to a socket option value. Each
229 * combination of level and option name corresponds to one socket
234 bool operator<(const OptionKey& other) const {
235 if (level == other.level) {
236 return optname < other.optname;
238 return level < other.level;
240 int apply(int fd, int val) const {
241 return setsockopt(fd, level, optname, &val, sizeof(val));
247 // Maps from a socket option key to its value
248 typedef std::map<OptionKey, int> OptionMap;
250 static const OptionMap emptyOptionMap;
251 static const folly::SocketAddress& anyAddress();
254 * Initiate a connection.
256 * @param callback The callback to inform when the connection attempt
258 * @param address The address to connect to.
259 * @param timeout A timeout value, in milliseconds. If the connection
260 * does not succeed within this period,
261 * callback->connectError() will be invoked.
263 virtual void connect(
264 ConnectCallback* callback,
265 const folly::SocketAddress& address,
267 const OptionMap& options = emptyOptionMap,
268 const folly::SocketAddress& bindAddr = anyAddress()) noexcept;
271 ConnectCallback* callback,
272 const std::string& ip,
275 const OptionMap& options = emptyOptionMap) noexcept;
278 * If a connect request is in-flight, cancels it and closes the socket
279 * immediately. Otherwise, this is a no-op.
281 * This does not invoke any connection related callbacks. Call this to
282 * prevent any connect callback while cleaning up, etc.
284 void cancelConnect();
287 * Set the send timeout.
289 * If write requests do not make any progress for more than the specified
290 * number of milliseconds, fail all pending writes and close the socket.
292 * If write requests are currently pending when setSendTimeout() is called,
293 * the timeout interval is immediately restarted using the new value.
295 * (See the comments for AsyncSocket for an explanation of why AsyncSocket
296 * provides setSendTimeout() but not setRecvTimeout().)
298 * @param milliseconds The timeout duration, in milliseconds. If 0, no
299 * timeout will be used.
301 void setSendTimeout(uint32_t milliseconds) override;
304 * Get the send timeout.
306 * @return Returns the current send timeout, in milliseconds. A return value
307 * of 0 indicates that no timeout is set.
309 uint32_t getSendTimeout() const override {
314 * Set the maximum number of reads to execute from the underlying
315 * socket each time the EventBase detects that new ingress data is
316 * available. The default is unlimited, but callers can use this method
317 * to limit the amount of data read from the socket per event loop
320 * @param maxReads Maximum number of reads per data-available event;
321 * a value of zero means unlimited.
323 void setMaxReadsPerEvent(uint16_t maxReads) {
324 maxReadsPerEvent_ = maxReads;
328 * Get the maximum number of reads this object will execute from
329 * the underlying socket each time the EventBase detects that new
330 * ingress data is available.
332 * @returns Maximum number of reads per data-available event; a value
333 * of zero means unlimited.
335 uint16_t getMaxReadsPerEvent() const {
336 return maxReadsPerEvent_;
339 // Read and write methods
340 void setReadCB(ReadCallback* callback) override;
341 ReadCallback* getReadCallback() const override;
343 void write(WriteCallback* callback, const void* buf, size_t bytes,
344 WriteFlags flags = WriteFlags::NONE) override;
345 void writev(WriteCallback* callback, const iovec* vec, size_t count,
346 WriteFlags flags = WriteFlags::NONE) override;
347 void writeChain(WriteCallback* callback,
348 std::unique_ptr<folly::IOBuf>&& buf,
349 WriteFlags flags = WriteFlags::NONE) override;
352 virtual void writeRequest(WriteRequest* req);
353 void writeRequestReady() {
357 // Methods inherited from AsyncTransport
358 void close() override;
359 void closeNow() override;
360 void closeWithReset() override;
361 void shutdownWrite() override;
362 void shutdownWriteNow() override;
364 bool readable() const override;
365 bool isPending() const override;
366 virtual bool hangup() const;
367 bool good() const override;
368 bool error() const override;
369 void attachEventBase(EventBase* eventBase) override;
370 void detachEventBase() override;
371 bool isDetachable() const override;
373 void getLocalAddress(
374 folly::SocketAddress* address) const override;
376 folly::SocketAddress* address) const override;
378 bool isEorTrackingEnabled() const override { return false; }
380 void setEorTracking(bool /*track*/) override {}
382 bool connecting() const override {
383 return (state_ == StateEnum::CONNECTING);
386 virtual bool isClosedByPeer() const {
387 return (state_ == StateEnum::CLOSED &&
388 (readErr_ == READ_EOF || readErr_ == READ_ERROR));
391 virtual bool isClosedBySelf() const {
392 return (state_ == StateEnum::CLOSED &&
393 (readErr_ != READ_EOF && readErr_ != READ_ERROR));
396 size_t getAppBytesWritten() const override {
397 return appBytesWritten_;
400 size_t getRawBytesWritten() const override {
401 return getAppBytesWritten();
404 size_t getAppBytesReceived() const override {
405 return appBytesReceived_;
408 size_t getRawBytesReceived() const override {
409 return getAppBytesReceived();
412 std::chrono::nanoseconds getConnectTime() const {
413 return connectEndTime_ - connectStartTime_;
416 std::chrono::milliseconds getConnectTimeout() const {
417 return connectTimeout_;
420 bool getTFOAttempted() const {
421 return tfoAttempted_;
425 * Returns whether or not the attempt to use TFO
426 * finished successfully. This does not necessarily
427 * mean TFO worked, just that trying to use TFO
430 bool getTFOFinished() const {
435 * Returns whether or not TFO attempt succeded on this
437 * For servers this is pretty straightforward API and can
438 * be invoked right after the connection is accepted. This API
439 * will perform one syscall.
440 * This API is a bit tricky to use for clients, since clients
441 * only know this for sure after the SYN-ACK is returned. So it's
442 * appropriate to call this only after the first application
443 * data is read from the socket when the caller knows that
444 * the SYN has been ACKed by the server.
446 bool getTFOSucceded() const;
448 // Methods controlling socket options
451 * Force writes to be transmitted immediately.
453 * This controls the TCP_NODELAY socket option. When enabled, TCP segments
454 * are sent as soon as possible, even if it is not a full frame of data.
455 * When disabled, the data may be buffered briefly to try and wait for a full
458 * By default, TCP_NODELAY is enabled for AsyncSocket objects.
460 * This method will fail if the socket is not currently open.
462 * @return Returns 0 if the TCP_NODELAY flag was successfully updated,
463 * or a non-zero errno value on error.
465 int setNoDelay(bool noDelay);
469 * Set the FD_CLOEXEC flag so that the socket will be closed if the program
470 * later forks and execs.
472 void setCloseOnExec();
475 * Set the Flavor of Congestion Control to be used for this Socket
476 * Please check '/lib/modules/<kernel>/kernel/net/ipv4' for tcp_*.ko
477 * first to make sure the module is available for plugging in
478 * Alternatively you can choose from net.ipv4.tcp_allowed_congestion_control
480 int setCongestionFlavor(const std::string &cname);
483 * Forces ACKs to be sent immediately
485 * @return Returns 0 if the TCP_QUICKACK flag was successfully updated,
486 * or a non-zero errno value on error.
488 int setQuickAck(bool quickack);
491 * Set the send bufsize
493 int setSendBufSize(size_t bufsize);
496 * Set the recv bufsize
498 int setRecvBufSize(size_t bufsize);
501 * Sets a specific tcp personality
502 * Available only on kernels 3.2 and greater
504 #define SO_SET_NAMESPACE 41
505 int setTCPProfile(int profd);
508 * Generic API for reading a socket option.
510 * @param level same as the "level" parameter in getsockopt().
511 * @param optname same as the "optname" parameter in getsockopt().
512 * @param optval pointer to the variable in which the option value should
514 * @param optlen value-result argument, initially containing the size of
515 * the buffer pointed to by optval, and modified on return
516 * to indicate the actual size of the value returned.
517 * @return same as the return value of getsockopt().
519 template <typename T>
520 int getSockOpt(int level, int optname, T* optval, socklen_t* optlen) {
521 return getsockopt(fd_, level, optname, (void*) optval, optlen);
525 * Generic API for setting a socket option.
527 * @param level same as the "level" parameter in getsockopt().
528 * @param optname same as the "optname" parameter in getsockopt().
529 * @param optval the option value to set.
530 * @return same as the return value of setsockopt().
532 template <typename T>
533 int setSockOpt(int level, int optname, const T *optval) {
534 return setsockopt(fd_, level, optname, optval, sizeof(T));
537 virtual void setPeek(bool peek) {
542 * Enables TFO behavior on the AsyncSocket if FOLLY_ALLOW_TFO
546 // No-op if folly does not allow tfo
552 enum class StateEnum : uint8_t {
561 void setBufferCallback(BufferCallback* cb);
564 * writeReturn is the total number of bytes written, or WRITE_ERROR on error.
565 * If no data has been written, 0 is returned.
566 * exception is a more specific exception that cause a write error.
567 * Not all writes have exceptions associated with them thus writeReturn
568 * should be checked to determine whether the operation resulted in an error.
571 explicit WriteResult(ssize_t ret) : writeReturn(ret) {}
573 WriteResult(ssize_t ret, std::unique_ptr<const AsyncSocketException> e)
574 : writeReturn(ret), exception(std::move(e)) {}
577 std::unique_ptr<const AsyncSocketException> exception;
581 * readReturn is the number of bytes read, or READ_EOF on EOF, or
582 * READ_ERROR on error, or READ_BLOCKING if the operation will
584 * exception is a more specific exception that may have caused a read error.
585 * Not all read errors have exceptions associated with them thus readReturn
586 * should be checked to determine whether the operation resulted in an error.
589 explicit ReadResult(ssize_t ret) : readReturn(ret) {}
591 ReadResult(ssize_t ret, std::unique_ptr<const AsyncSocketException> e)
592 : readReturn(ret), exception(std::move(e)) {}
595 std::unique_ptr<const AsyncSocketException> exception;
599 * A WriteRequest object tracks information about a pending write operation.
603 WriteRequest(AsyncSocket* socket, WriteCallback* callback) :
604 socket_(socket), callback_(callback) {}
606 virtual void start() {};
608 virtual void destroy() = 0;
610 virtual WriteResult performWrite() = 0;
612 virtual void consume() = 0;
614 virtual bool isComplete() = 0;
616 WriteRequest* getNext() const {
620 WriteCallback* getCallback() const {
624 uint32_t getTotalBytesWritten() const {
625 return totalBytesWritten_;
628 void append(WriteRequest* next) {
629 assert(next_ == nullptr);
633 void fail(const char* fn, const AsyncSocketException& ex) {
634 socket_->failWrite(fn, ex);
637 void bytesWritten(size_t count) {
638 totalBytesWritten_ += count;
639 socket_->appBytesWritten_ += count;
643 // protected destructor, to ensure callers use destroy()
644 virtual ~WriteRequest() {}
646 AsyncSocket* socket_; ///< parent socket
647 WriteRequest* next_{nullptr}; ///< pointer to next WriteRequest
648 WriteCallback* callback_; ///< completion callback
649 uint32_t totalBytesWritten_{0}; ///< total bytes written
653 enum ReadResultEnum {
660 enum WriteResultEnum {
665 * Protected destructor.
667 * Users of AsyncSocket must never delete it directly. Instead, invoke
668 * destroy() instead. (See the documentation in DelayedDestruction.h for
673 friend std::ostream& operator << (std::ostream& os, const StateEnum& state);
676 /// shutdownWrite() called, but we are still waiting on writes to drain
677 SHUT_WRITE_PENDING = 0x01,
678 /// writes have been completely shut down
681 * Reads have been shutdown.
683 * At the moment we don't distinguish between remote read shutdown
684 * (received EOF from the remote end) and local read shutdown. We can
685 * only receive EOF when a read callback is set, and we immediately inform
686 * it of the EOF. Therefore there doesn't seem to be any reason to have a
687 * separate state of "received EOF but the local side may still want to
690 * We also don't currently provide any API for only shutting down the read
691 * side of a socket. (This is a no-op as far as TCP is concerned, anyway.)
696 class BytesWriteRequest;
698 class WriteTimeout : public AsyncTimeout {
700 WriteTimeout(AsyncSocket* socket, EventBase* eventBase)
701 : AsyncTimeout(eventBase)
704 virtual void timeoutExpired() noexcept {
705 socket_->timeoutExpired();
709 AsyncSocket* socket_;
712 class IoHandler : public EventHandler {
714 IoHandler(AsyncSocket* socket, EventBase* eventBase)
715 : EventHandler(eventBase, -1)
717 IoHandler(AsyncSocket* socket, EventBase* eventBase, int fd)
718 : EventHandler(eventBase, fd)
721 virtual void handlerReady(uint16_t events) noexcept {
722 socket_->ioReady(events);
726 AsyncSocket* socket_;
731 class ImmediateReadCB : public folly::EventBase::LoopCallback {
733 explicit ImmediateReadCB(AsyncSocket* socket) : socket_(socket) {}
734 void runLoopCallback() noexcept override {
735 DestructorGuard dg(socket_);
736 socket_->checkForImmediateRead();
739 AsyncSocket* socket_;
743 * Schedule checkForImmediateRead to be executed in the next loop
746 void scheduleImmediateRead() noexcept {
748 eventBase_->runInLoop(&immediateReadHandler_);
753 * Schedule handleInitalReadWrite to run in the next iteration.
755 void scheduleInitialReadWrite() noexcept {
757 DestructorGuard dg(this);
758 eventBase_->runInLoop([this, dg] {
760 handleInitialReadWrite();
766 // event notification methods
767 void ioReady(uint16_t events) noexcept;
768 virtual void checkForImmediateRead() noexcept;
769 virtual void handleInitialReadWrite() noexcept;
770 virtual void prepareReadBuffer(void** buf, size_t* buflen) noexcept;
771 virtual void handleRead() noexcept;
772 virtual void handleWrite() noexcept;
773 virtual void handleConnect() noexcept;
774 void timeoutExpired() noexcept;
777 * Attempt to read from the socket.
779 * @param buf The buffer to read data into.
780 * @param buflen The length of the buffer.
782 * @return Returns a read result. See read result for details.
784 virtual ReadResult performRead(void** buf, size_t* buflen, size_t* offset);
787 * Populate an iovec array from an IOBuf and attempt to write it.
789 * @param callback Write completion/error callback.
790 * @param vec Target iovec array; caller retains ownership.
791 * @param count Number of IOBufs to write, beginning at start of buf.
792 * @param buf Chain of iovecs.
793 * @param flags set of flags for the underlying write calls, like cork
795 void writeChainImpl(WriteCallback* callback, iovec* vec,
796 size_t count, std::unique_ptr<folly::IOBuf>&& buf,
800 * Write as much data as possible to the socket without blocking,
801 * and queue up any leftover data to send when the socket can
802 * handle writes again.
804 * @param callback The callback to invoke when the write is completed.
805 * @param vec Array of buffers to write; this method will make a
806 * copy of the vector (but not the buffers themselves)
807 * if the write has to be completed asynchronously.
808 * @param count Number of elements in vec.
809 * @param buf The IOBuf that manages the buffers referenced by
810 * vec, or a pointer to nullptr if the buffers are not
811 * associated with an IOBuf. Note that ownership of
812 * the IOBuf is transferred here; upon completion of
813 * the write, the AsyncSocket deletes the IOBuf.
814 * @param flags Set of write flags.
816 void writeImpl(WriteCallback* callback, const iovec* vec, size_t count,
817 std::unique_ptr<folly::IOBuf>&& buf,
818 WriteFlags flags = WriteFlags::NONE);
821 * Attempt to write to the socket.
823 * @param vec The iovec array pointing to the buffers to write.
824 * @param count The length of the iovec array.
825 * @param flags Set of write flags.
826 * @param countWritten On return, the value pointed to by this parameter
827 * will contain the number of iovec entries that were
829 * @param partialWritten On return, the value pointed to by this parameter
830 * will contain the number of bytes written in the
831 * partially written iovec entry.
833 * @return Returns a WriteResult. See WriteResult for more details.
835 virtual WriteResult performWrite(
839 uint32_t* countWritten,
840 uint32_t* partialWritten);
843 * Sends the message over the socket using sendmsg
845 * @param msg Message to send
846 * @param msg_flags Flags to pass to sendmsg
848 AsyncSocket::WriteResult
849 sendSocketMessage(int fd, struct msghdr* msg, int msg_flags);
851 virtual ssize_t tfoSendMsg(int fd, struct msghdr* msg, int msg_flags);
853 int socketConnect(const struct sockaddr* addr, socklen_t len);
855 virtual void scheduleConnectTimeout();
856 void registerForConnectEvents();
858 bool updateEventRegistration();
861 * Update event registration.
863 * @param enable Flags of events to enable. Set it to 0 if no events
864 * need to be enabled in this call.
865 * @param disable Flags of events
866 * to disable. Set it to 0 if no events need to be disabled in this
869 * @return true iff the update is successful.
871 bool updateEventRegistration(uint16_t enable, uint16_t disable);
873 // Actually close the file descriptor and set it to -1 so we don't
874 // accidentally close it again.
877 // error handling methods
880 void fail(const char* fn, const AsyncSocketException& ex);
881 void failConnect(const char* fn, const AsyncSocketException& ex);
882 void failRead(const char* fn, const AsyncSocketException& ex);
883 void failWrite(const char* fn, WriteCallback* callback, size_t bytesWritten,
884 const AsyncSocketException& ex);
885 void failWrite(const char* fn, const AsyncSocketException& ex);
886 void failAllWrites(const AsyncSocketException& ex);
887 virtual void invokeConnectErr(const AsyncSocketException& ex);
888 virtual void invokeConnectSuccess();
889 void invalidState(ConnectCallback* callback);
890 void invalidState(ReadCallback* callback);
891 void invalidState(WriteCallback* callback);
893 std::string withAddr(const std::string& s);
895 StateEnum state_; ///< StateEnum describing current state
896 uint8_t shutdownFlags_; ///< Shutdown state (ShutdownFlags)
897 uint16_t eventFlags_; ///< EventBase::HandlerFlags settings
898 int fd_; ///< The socket file descriptor
899 mutable folly::SocketAddress addr_; ///< The address we tried to connect to
900 mutable folly::SocketAddress localAddr_;
901 ///< The address we are connecting from
902 uint32_t sendTimeout_; ///< The send timeout, in milliseconds
903 uint16_t maxReadsPerEvent_; ///< Max reads per event loop iteration
904 EventBase* eventBase_; ///< The EventBase
905 WriteTimeout writeTimeout_; ///< A timeout for connect and write
906 IoHandler ioHandler_; ///< A EventHandler to monitor the fd
907 ImmediateReadCB immediateReadHandler_; ///< LoopCallback for checking read
909 ConnectCallback* connectCallback_; ///< ConnectCallback
910 ReadCallback* readCallback_; ///< ReadCallback
911 WriteRequest* writeReqHead_; ///< Chain of WriteRequests
912 WriteRequest* writeReqTail_; ///< End of WriteRequest chain
913 ShutdownSocketSet* shutdownSocketSet_;
914 size_t appBytesReceived_; ///< Num of bytes received from socket
915 size_t appBytesWritten_; ///< Num of bytes written to socket
916 bool isBufferMovable_{false};
918 bool peek_{false}; // Peek bytes.
920 int8_t readErr_{READ_NO_ERROR}; ///< The read error encountered, if any.
922 std::chrono::steady_clock::time_point connectStartTime_;
923 std::chrono::steady_clock::time_point connectEndTime_;
925 std::chrono::milliseconds connectTimeout_{0};
927 BufferCallback* bufferCallback_{nullptr};
928 bool tfoEnabled_{false};
929 bool tfoAttempted_{false};
930 bool tfoFinished_{false};
933 #pragma vtordisp(pop)