1 files changed, 98 insertions, 0 deletions
diff --git a/distbuild/jm.py b/distbuild/jm.py
new file mode 100644
index 00000000..ae222c00
--- /dev/null
+++ b/distbuild/jm.py
@@ -0,0 +1,98 @@
+# mainloop/jm.py -- state machine for JSON communication between nodes
+#
+# Copyright 2012 Codethink Limited.
+# All rights reserved.
+
+
+import fcntl
+import json
+import logging
+import os
+import socket
+import sys
+
+from sm import StateMachine 
+from stringbuffer import StringBuffer
+from sockbuf import (SocketBuffer, SocketBufferNewData, 
+                     SocketBufferEof, SocketError)
+
+
+class JsonNewMessage(object):
+
+    def __init__(self, msg):
+        self.msg = msg
+
+        
+class JsonEof(object):
+
+    pass
+    
+    
+class _Close2(object):
+
+    pass
+
+
+class JsonMachine(StateMachine):
+
+    '''A state machine for sending/receiving JSON messages across TCP.'''
+
+    max_buffer = 16 * 1024
+
+    def __init__(self, conn):
+        StateMachine.__init__(self, 'rw')
+        self.conn = conn
+        self.debug_json = False
+        
+    def setup(self):
+        sockbuf = self.sockbuf = SocketBuffer(self.conn, self.max_buffer)
+        self.mainloop.add_state_machine(sockbuf)
+
+        self._eof = False
+        self.receive_buf = StringBuffer()
+
+        spec = [
+            ('rw', sockbuf, SocketBufferNewData, 'rw', self._parse),
+            ('rw', sockbuf, SocketBufferEof, 'w', self._send_eof),
+            ('rw', self, _Close2, None, self._really_close),
+            
+            ('w', self, _Close2, None, self._really_close),
+        ]
+        self.add_transitions(spec)
+        
+    def send(self, msg):
+        '''Send a message to the other side.'''
+        self.sockbuf.write('%s\n' % json.dumps(msg))
+    
+    def close(self):
+        '''Tell state machine it should shut down.
+        
+        The state machine will vanish once it has flushed any pending
+        writes.
+        
+        '''
+        
+        self.mainloop.queue_event(self, _Close2())
+        
+    def _parse(self, event_source, event):
+        data = event.data
+        self.receive_buf.add(data)
+        if self.debug_json:
+            logging.debug('JsonMachine: Received: %s' % repr(data))
+        while True:
+            line = self.receive_buf.readline()
+            if line is None:
+                break
+            line = line.rstrip()
+            if self.debug_json:
+                logging.debug('JsonMachine: line: %s' % repr(line))
+            msg = json.loads(line)
+            self.mainloop.queue_event(self, JsonNewMessage(msg))
+
+    def _send_eof(self, event_source, event):
+        self.mainloop.queue_event(self, JsonEof())
+
+    def _really_close(self, event_source, event):
+        self.sockbuf.close()
+        self._send_eof(event_source, event)
+