From ce0aad4337ca4567cb9fa7557f5d7f502a4e7333 Mon Sep 17 00:00:00 2001
From: Antoine Millet <antoine.millet@smartjog.com>
Date: Thu, 29 Sep 2011 15:19:39 +0200
Subject: [PATCH] Implementation of sjRpc tunnel protocol.

---
 sjrpc/core/protocols/tunnel.py | 96 ++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 sjrpc/core/protocols/tunnel.py

diff --git a/sjrpc/core/protocols/tunnel.py b/sjrpc/core/protocols/tunnel.py
new file mode 100644
index 0000000..a759a4a
--- /dev/null
+++ b/sjrpc/core/protocols/tunnel.py
@@ -0,0 +1,96 @@
+from __future__ import absolute_import
+
+import socket
+
+from sjrpc.core.protocols import Protocol
+
+import pyev
+
+class TunnelProtocol(Protocol):
+
+    '''
+    A Tunneling protocol used to 
+    '''
+
+    GET_SIZE = 1024 * 1024 # 1MB
+    DEFAULT_GET_SIZE = GET_SIZE
+
+    def __init__(self, *args, **kwargs):
+        endpoint = kwargs.pop('endpoint', None)
+        super(TunnelProtocol, self).__init__(*args, **kwargs)
+
+        if endpoint is None:
+            self._endpoint, self._socket = socket.socketpair()
+        else:
+            self._endpoint = endpoint
+
+        self._from_tun_to_endpoint_buf = ''
+        self._asked = 0 # Data asked to the peer
+        self._ok_to_send = 0 # Data I can send to the peer
+
+        # Set the endpoint as non-blocking socket:
+        self._endpoint.setblocking(False)
+
+        # Create watcher to handle data coming from the endpoint:
+        props = dict(fd=self._endpoint, events=pyev.EV_READ,
+                     callback=self._handle_from_endpoint)
+        self._endpoint_reader = self._connection.create_watcher(pyev.Io, **props)
+
+        # Create watcher to handle data going to the endpoint:
+        props = dict(fd=self._endpoint, events=pyev.EV_WRITE,
+                     callback=self._handle_from_tunnel)
+        self._endpoint_writer = self._connection.create_watcher(pyev.Io, **props)
+
+        # Ask some data to the peer:
+        self._send_get(TunnelProtocol.GET_SIZE)
+
+    def _handle_from_endpoint(self, watcher, revents):
+        '''
+        Handle data coming from the endpoint socket and push it through the
+        sjRpc tunnel.
+        '''
+        read = self._endpoint.recv(self._ok_to_send)
+        self._ok_to_send -= len(read)
+        self.send(read)
+        if not self._ok_to_send:
+            watcher.stop()
+
+    def _handle_from_tunnel(self, watcher, revent):
+        '''
+        Handle writing of the data already received from the tunnel and stored
+        into the incoming buffer. Data are writed only when the endpoint socket
+        is ready to write.
+
+        This method is also responsible of asking more data to the peer when
+        the incoming buffer is empty.
+        '''
+        sent = self._endpoint.send(self._from_tun_to_endpoint_buf)
+        self._from_tun_to_endpoint_buf = self._from_tun_to_endpoint_buf[sent:]
+        self._asked -= sent
+        if self._asked < TunnelProtocol.GET_SIZE * 2:
+            self._send_get(TunnelProtocol.GET_SIZE)
+        if not self._from_tun_to_endpoint_buf:
+            watcher.stop()
+
+    def _send_get(self, size):
+        self._connection.rpc.send_special('protoctl', label=self._label,
+                                          type='get', payload=dict(size=size))
+        self._asked += size
+
+#
+# Public methods:
+#
+
+    def end_of_message(self):
+        '''
+        Handle inbound data from the :class:`RpcConnection` peer and place it
+        on the incoming buffer.
+        '''
+        self._from_tun_to_endpoint_buf += self._incoming_buf
+        self._endpoint_writer.start()
+
+    def handle_control(self, control_type, payload):
+        if control_type == 'get':
+            size = payload.get('size', TunnelProtocol.DEFAULT_GET_SIZE)
+            self._ok_to_send += size
+            self._endpoint_reader.start()
-- 
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