Asyncore performance optimisation

- don't transfer unnecessary amount of bytes from network buffers
- slice buffer more efficiently if it results in an empty buffer

src/network/advanceddispatcher.py

@@ -36,11 +36,17 @@ class AdvancedDispatcher(asyncore.dispatcher):
     def slice_write_buf(self, length=0):
         if length > 0:
             with self.writeLock:
+                if length >= len(self.write_buf):
+                    del self.write_buf[:]
+                else:
                     del self.write_buf[0:length]
 
     def slice_read_buf(self, length=0):
         if length > 0:
             with self.readLock:
+                if length >= len(self.read_buf):
+                    del self.read_buf[:]
+                else:
                     del self.read_buf[0:length]
 
     def process(self):
@@ -77,7 +83,7 @@ class AdvancedDispatcher(asyncore.dispatcher):
         if asyncore.maxDownloadRate > 0:
             self.downloadChunk = asyncore.downloadBucket
         try:
-            if self.expectBytes > 0 and not self.fullyEstablished:
+            if self.expectBytes > 0:
                 self.downloadChunk = min(self.downloadChunk, self.expectBytes - len(self.read_buf))
                 if self.downloadChunk < 0:
                     self.downloadChunk = 0