When sending large buffers to a socket, use MSG_MORE.

contrib/sb-bsd-sockets/sockets.lisp

@@ -286,6 +286,7 @@ request an input stream and get an output stream in response\)."
                     :name (format nil "socket~@[ ~A~]~@[, peer: ~A~]"
                                   (socket-namestring socket)
                                   (socket-peerstring socket))
+                    :class 'sb-sys:socket-stream
                     :dual-channel-p t
                     :input input
                     :output output

src/code/fd-stream.lisp

@@ -162,6 +162,10 @@
   (char-size 1 :type (or fixnum function))
   (output-bytes #'ill-out :type function))
 
+(defstruct (socket-stream
+             (:constructor %make-socket-stream)
+             (:include fd-stream)))
+
 (defun fd-stream-bivalent-p (stream)
   (eq (fd-stream-element-mode stream) :bivalent))
 
@@ -264,7 +268,7 @@
                 (length (- end start)))
            (cond ((and (not (fd-stream-serve-events stream))
                        (>= length buffer-length))
-                  (flush-output-buffer stream)
+                  (flush-output-buffer stream t)
                   (finish-writing-sequence thing stream start end)
                   (return-from buffer-output))
                  ((plusp space)
@@ -284,12 +288,23 @@
 
 (define-symbol-macro +write-failed+ "Couldn't write to ~S")
 
+(declaim (inline fd-stream-write))
+(defun fd-stream-write (stream sap offset len &optional more?)
+  (if (typep stream 'socket-stream)
+      (sb-unix:unix-sendto (fd-stream-fd stream) sap
+                           offset len
+                           (if more?
+                               sb-unix:msg-more
+                               0))
+      (sb-unix:unix-write (fd-stream-fd stream) sap
+                          offset len)))
+
 ;;; Flush the current output buffer of the stream, ensuring that the
 ;;; new buffer is empty. Returns (for convenience) the new output
 ;;; buffer -- which may or may not be EQ to the old one. If the is no
 ;;; queued output we try to write the buffer immediately -- otherwise
 ;;; we queue it for later.
-(defun flush-output-buffer (stream)
+(defun flush-output-buffer (stream &optional more?)
   (let ((obuf (fd-stream-obuf stream)))
     (when obuf
       (let ((head (buffer-head obuf))
@@ -311,8 +326,8 @@
                (loop
                  (let ((length (- tail head)))
                    (multiple-value-bind (count errno)
-                       (sb-unix:unix-write (fd-stream-fd stream) (buffer-sap obuf)
-                                           head length)
+                       (fd-stream-write stream (buffer-sap obuf)
+                                        head length more?)
                      (flet ((queue-or-wait ()
                               (if (fd-stream-serve-events stream)
                                   (return (%queue-and-replace-output-buffer stream))
@@ -347,7 +362,7 @@
   (loop
    (let ((length (- end start)))
      (multiple-value-bind (count errno)
-         (sb-unix:unix-write (fd-stream-fd stream) sequence start length)
+         (fd-stream-write stream sequence start length)
        (flet ((wait ()
                 (or (wait-until-fd-usable (fd-stream-fd stream) :output
                                           (fd-stream-timeout stream)
@@ -408,7 +423,7 @@
          (declare (index head length))
          (aver (>= length 0))
          (multiple-value-bind (count errno)
-             (sb-unix:unix-write (fd-stream-fd stream) (buffer-sap buffer)
+             (fd-stream-write stream (buffer-sap buffer)
                                  head length)
            (cond ((eql count length)
                   ;; Complete write, see if we can do another right
@@ -455,7 +470,7 @@
          (let ((length (- end start)))
            (synchronize-stream-output stream)
            (multiple-value-bind (count errno)
-               (sb-unix:unix-write (fd-stream-fd stream) thing start length)
+               (fd-stream-write stream thing start length)
              (cond ((eql count length)
                     ;; Complete write -- done!
                     )
@@ -2270,6 +2285,7 @@
          (error "File descriptor must be opened either for input or output.")))
   (let* ((constructor (ecase class
                         (fd-stream '%make-fd-stream)
+                        (socket-stream '%make-socket-stream)
                         (form-tracking-stream '%make-form-tracking-stream)))
          (element-mode (stream-element-type-stream-element-mode element-type))
          (stream (funcall constructor

src/code/unix.lisp

@@ -350,6 +350,38 @@ corresponds to NAME, or NIL if there is none."
       (system-area-pointer
        (%write buf)))))
 
+
+(defconstant msg-more (+ 0 #+linux #x8000)) ; will send more data
+
+;;; UNIX-SENDTO accepts a file descriptor, a buffer, an offset, the
+;;; length to write, and a bitmask for flags.
+;;; It attempts to write len bytes to the device
+;;; associated with fd from the buffer starting at offset. It returns
+;;; the actual number of bytes written.
+;;; The sockaddr argument allowed by unix "sendto" is currently not available.
+#-win32
+(defun unix-sendto (fd buf offset len flags)
+  (declare (optimize (debug 1)))
+  (declare (type unix-fd fd)
+           (type (unsigned-byte 32) offset len flags))
+  (flet ((%sendto (sap)
+           (declare (system-area-pointer sap))
+           (int-syscall ("sendto"
+                         int (* char) int int (* char) int)
+                        fd
+                        (with-alien ((ptr (* char) sap))
+                          (addr (deref ptr offset)))
+                        len
+                        flags
+                        (int-sap 0) 0)))
+    (etypecase buf
+      ((simple-array * (*))
+       (with-pinned-objects (buf)
+         (%sendto (vector-sap buf))))
+      (system-area-pointer
+       (%sendto buf)))))
+
+
 ;;; Set up a unix-piping mechanism consisting of an input pipe and an
 ;;; output pipe. Return two values: if no error occurred the first
 ;;; value is the pipe to be read from and the second is can be written

src/cold/exports.lisp

@@ -98,7 +98,7 @@ interface stability.")
    "UNIX-OPEN" "UNIX-OPENDIR" "UNIX-PATHNAME" "UNIX-PID"
    "UNIX-PIPE" "UNIX-POLL" "UNIX-SIMPLE-POLL"
    "UNIX-READ" "UNIX-READDIR" "UNIX-READLINK" "UNIX-REALPATH"
-   "UNIX-RENAME" "UNIX-STAT" "UNIX-UID"
+   "UNIX-RENAME" "UNIX-SENDTO" "UNIX-STAT" "UNIX-UID"
    "UNIX-UNLINK" "UNIX-WRITE"
    "WCONTINUED" "WNOHANG" "WUNTRACED"
    "W_OK" "X_OK"
@@ -107,6 +107,7 @@ interface stability.")
    "CLOCK-THREAD-CPUTIME-ID"
    "CLOCK-PROCESS-CPUTIME-ID"
    "CLOCK-REALTIME"
+   "MSG-MORE"
 
    ;; signals
 
@@ -1603,6 +1604,7 @@ SB-KERNEL) have been undone, but probably more remain.")
    "EXTERN-ALIEN-NAME"
    "EXIT-CODE"
    "FD-STREAM" "FD-STREAM-FD" "FD-STREAM-P"
+   "SOCKET-STREAM" "SOCKET-STREAM-P"
    "FIND-DYNAMIC-FOREIGN-SYMBOL-ADDRESS"
    "FIND-FOREIGN-SYMBOL-ADDRESS"
    #+(and win32 x86-64) "FOREIGN-HEAP-CORRUPTION"