server: fix do_read() enough to run bench_sendall() PY3

gevent/_socket3.py

@@ -125,6 +125,7 @@ class socket(_socket.socket):
         # Python Issue #7995: if no default timeout is set and the listening
         # socket had a (non-zero) timeout, force the new socket in blocking
         # mode to override platform-specific socket flags inheritance.
+        # XXX do we need to do this?
         if getdefaulttimeout() is None and self.gettimeout():
             sock.setblocking(True)
         return sock, addr

gevent/server.py

@@ -4,7 +4,9 @@ import sys
 import _socket
 from gevent.baseserver import BaseServer
 from gevent.socket import EWOULDBLOCK, socket
-from gevent.hub import PYPY
+from gevent.hub import PYPY, PY3
+if PY3:
+    from io import BlockingIOError
 
 
 __all__ = ['StreamServer', 'DatagramServer']
@@ -89,6 +91,22 @@ class StreamServer(BaseServer):
             backlog = self.backlog
         return _tcp_listener(address, backlog=backlog, reuse_addr=self.reuse_addr, family=family)
 
+    if PY3:
+
+        def do_read(self):
+            sock = self.socket
+            try:
+                fd, address = sock._accept()
+            except BlockingIOError:
+                if sock.timeout == 0.0:
+                    return
+                raise
+            sock = socket(sock.family, sock.type, sock.proto, fileno=fd)
+            # XXX Python issue #7995?
+            return sock, address
+
+    else:
+
         def do_read(self):
             try:
                 client_socket, address = self.socket.accept()