Optimize stream send op -- try to send the data right away, w/o libuv

Author: 1st1

uvloop/handles/stream.pxd

@@ -20,6 +20,7 @@ cdef class UVStream(UVBaseTransport):
     cdef inline __reading_stopped(self)
 
     cdef inline _write(self, object data)
+    cdef inline _try_write(self, object data)
 
     cdef _close(self)
 

uvloop/handles/stream.pyx

@@ -157,13 +157,50 @@ cdef class UVStream(UVBaseTransport):
         else:
             self.__reading_stopped()
 
+    cdef inline _try_write(self, object data):
+        if self._get_write_buffer_size():
+            # Don't try to write anything as we already have some
+            # data in the write buffers.
+            return
+
+        cdef:
+            ssize_t written
+            int fd
+            Py_buffer py_buf
+
+        # Let's try to send the data right away.
+
+        fd = self._fileno()
+        PyObject_GetBuffer(data, &py_buf, PyBUF_SIMPLE)
+        written = system.send(fd, <char*>py_buf.buf, py_buf.len, 0)
+        PyBuffer_Release(&py_buf)
+        if written < 0:
+            if errno.errno not in (system.EINTR, system.EAGAIN,
+                                   system.EWOULDBLOCK, system.EINPROGRESS,
+                                   system.EALREADY,
+                                   # If it's a wrong type of FD - let libuv
+                                   # handle it, ignore the error:
+                                   system.ENOTSOCK, system.EBADF,
+                                   system.ENOSYS):
+                exc = convert_error(-errno.errno)
+                self._fatal_error(exc, True)
+
+        return written
+
     cdef inline _write(self, object data):
         cdef:
             int err
+            int sent
             _StreamWriteContext ctx
 
         self._ensure_alive()
 
+        sent = self._try_write(data)
+        if sent > 0:
+            if sent == len(data):
+                return
+            data = data[sent:]
+
         ctx = _StreamWriteContext.new(self, data)
 
         err = uv.uv_write(&ctx.req,

uvloop/includes/system.pxd

@@ -40,3 +40,19 @@ cdef extern from "sys/socket.h" nogil:
     const char *gai_strerror(int errcode)
 
     int socketpair(int domain, int type, int protocol, int socket_vector[2])
+
+    ssize_t send(int sockfd, const void *buf, size_t len, int flags);
+
+
+cdef extern from "errno.h" nogil:
+
+    cdef:
+        # cython.errno doesn't have EWOULDBLOCK defined.
+        int EINTR
+        int EAGAIN
+        int EWOULDBLOCK
+        int EINPROGRESS
+        int EALREADY
+        int ENOTSOCK
+        int EBADF
+        int ENOSYS