Download fixes

- in corner cases, download request could have contained an incorrect
  request length. I haven't actually checked if this can be triggered
  though
- wait for downloading until anti intersection delay expires. Doesn't
  necessarily mean that it will always avoid peer's anti intersection
  delay, but it's close enough
- tracks last time an object was received. If it was too long time ago,
  reset the download request queue. This avoid situations like when a
  request gets ignored during the anti intersection delay, but it will
  keep thinking there are still pending requests as long as not all
  missing objects have been requested. This caused staggered download
  (request 1000 items, wait 1 minute, request 1000 more, wait another
  minute, ...)
- with these fixes, you should end up downloading as fast as your
  network and CPU allow
- best tested with trustedpeer

src/network/downloadthread.py

@@ -49,12 +49,15 @@ class DownloadThread(threading.Thread, StoppableThread):
                 requestChunk = 1
             for i in connections:
                 now = time.time()
+                # avoid unnecessary delay
+                if i.skipUntil >= now:
+                    continue
                 try:
                     request = i.objectsNewToMe.randomKeys(requestChunk)
                 except KeyError:
                     continue
                 payload = bytearray()
-                payload.extend(addresses.encodeVarint(len(request)))
+                chunkCount = 0
                 for chunk in request:
                     if chunk in Inventory() and not Dandelion().hasHash(chunk):
                         try:
@@ -63,12 +66,14 @@ class DownloadThread(threading.Thread, StoppableThread):
                             pass
                         continue
                     payload.extend(chunk)
+                    chunkCount += 1
                     missingObjects[chunk] = now
-                if not payload:
+                if not chunkCount:
                     continue
+                payload[0:0] = addresses.encodeVarint(chunkCount)
                 i.append_write_buf(protocol.CreatePacket('getdata', payload))
-                logger.debug("%s:%i Requesting %i objects", i.destination.host, i.destination.port, len(request))
-                requested += len(request)
+                logger.debug("%s:%i Requesting %i objects", i.destination.host, i.destination.port, chunkCount)
+                requested += chunkCount
             if time.time() >= self.lastCleaned + DownloadThread.cleanInterval:
                 self.cleanPending()
             if not requested:

src/network/objectracker.py

@@ -104,6 +104,7 @@ class ObjectTracker(object):
                         del i.objectsNewToThem[hashid]
                 except KeyError:
                     pass
+        self.objectsNewToMe.setLastObject()
 
     def hasAddr(self, addr):
         if haveBloom:

src/randomtrackingdict.py

@@ -12,6 +12,7 @@ class RandomTrackingDict(object):
         self.len = 0
         self.pendingLen = 0
         self.lastPoll = 0
+        self.lastObject = 0
         self.lock = RLock()
 
     def __len__(self):
@@ -71,14 +72,18 @@ class RandomTrackingDict(object):
     def setPendingTimeout(self, pendingTimeout):
         self.pendingTimeout = pendingTimeout
 
+    def setLastObject(self):
+        self.lastObject = time()
+
     def randomKeys(self, count=1):
         if self.len == 0 or ((self.pendingLen >= self.maxPending or
             self.pendingLen == self.len) and self.lastPoll +
             self.pendingTimeout > time()):
             raise KeyError
-        # reset if we've requested all
         with self.lock:
-            if self.pendingLen == self.len:
+            # reset if we've requested all
+            # or if last object received too long time ago
+            if self.pendingLen == self.len or self.lastObject + self.pendingTimeout > time():
                 self.pendingLen = 0
             available = self.len - self.pendingLen
             if count > available: