Objects to be downloaded fixes

- tries to avoid calling senddata it it would block receiveDataThread,
  allowing fore more asynchronous operation
- request objects in chunks of 100 (CPU performance optimisation)

src/class_receiveDataThread.py

@@ -217,9 +217,9 @@ class receiveDataThread(threading.Thread):
         self.data = self.data[payloadLength + protocol.Header.size:] # take this message out and then process the next message
 
         if self.data == '': # if there are no more messages
-            while Missing().len() > 0 and not self.sendDataThreadQueue.full():
-                objectHash = Missing().pull()
-                if objectHash is None:
+            if Missing().len() > 0 and self.sendDataThreadQueue.qsize() < 10:
+                for objectHash in Missing().pull(100):
+                    if self.sendDataThreadQueue.full():
                         break
                     if objectHash in Inventory():
                         logger.debug('Inventory already has object listed in inv message.')

src/inventory.py

@@ -101,14 +101,20 @@ class Missing(object):
         with self.lock:
             return len(self.hashes)
 
-    def pull(self):
+    def pull(self, count=1):
+        if count < 1:
+            raise ValueError("Must be at least one")
         with self.lock:
             now = time.time()
             since = now - 300 # once every 5 minutes
             try:
-                objectHash = random.choice({k:v for k, v in self.hashes.iteritems() if current_thread().peer in self.hashes[k]['peers'] and self.hashes[k]['requested'] < since}.keys())
+                matchingHashes = {k:v for k, v in self.hashes.iteritems() if current_thread().peer in self.hashes[k]['peers'] and self.hashes[k]['requested'] < since}
+                if count > len(matchingHashes):
+                    count = len(matchingHashes)
+                objectHashes = random.sample(matchingHashes, count)
             except (IndexError, KeyError): # list is empty
                 return None
+            for objectHash in objectHashes:
                 try:
                     self.hashes[objectHash]['peers'].remove(current_thread().peer)
                 except ValueError:
@@ -117,7 +123,7 @@ class Missing(object):
                     self.delete(objectHash)
                 else:
                     self.hashes[objectHash]['requested'] = now
-            return objectHash
+            return objectHashes
 
     def delete(self, objectHash):
         with self.lock: