net.i2p.router.tunnel
Class BatchedPreprocessor

java.lang.Object
  extended by net.i2p.router.tunnel.TrivialPreprocessor
      extended by net.i2p.router.tunnel.BatchedPreprocessor
All Implemented Interfaces:
TunnelGateway.QueuePreprocessor
Direct Known Subclasses:
BatchedRouterPreprocessor

public class BatchedPreprocessor
extends TrivialPreprocessor

Batching preprocessor that will briefly delay the sending of a message if it doesn't fill up a full tunnel message, in which case it queues up an additional flush task. This is a very simple threshold algorithm - as soon as there is enough data for a full tunnel message, it is sent. If after the delay there still isn't enough data, what is available is sent and padded. As explained in the tunnel document, the preprocessor has a lot of potential flexibility in delay, padding, or even reordering. We keep things relatively simple for now. However much of the efficiency results from the clients selecting the correct MTU in the streaming lib such that the maximum-size streaming lib message fits in an integral number of tunnel messages. See ConnectionOptions in the streaming lib for details. Aside from obvious goals of minimizing delay and padding, we also want to minimize the number of tunnel messages a message occupies, to minimize the impact of a router dropping a tunnel message. So there is some benefit in starting a message in a new tunnel message, especially if it will fit perfectly if we do that (a 964 or 1956 byte message, for example). An idea for the future... If we are in the middle of a tunnel msg and starting a new i2np msg, and this one won't fit, let's look to see if we have somthing that would fit instead by reordering: if (allocated > 0 && msg.getFragment == 0) { for (j = i+1, j < pending.size(); j++) { if it will fit and it is fragment 0 { msg = pending.remove(j) pending.add(0, msg) } } }


Field Summary
(package private) static long DEFAULT_DELAY
           
 
Fields inherited from class net.i2p.router.tunnel.TrivialPreprocessor
_context, _dataCache, _log, IV_SIZE, PREPROCESSED_SIZE
 
Constructor Summary
BatchedPreprocessor(RouterContext ctx, java.lang.String name)
           
 
Method Summary
 long getDelayAmount()
          how long do we want to wait before flushing
protected  long getSendDelay()
          Wait up to this long before sending (flushing) a small tunnel message Warning - overridden in BatchedRouterPreprocessor
 boolean preprocessQueue(java.util.List<TunnelGateway.Pending> pending, TunnelGateway.Sender sender, TunnelGateway.Receiver rec)
          Return true if there were messages remaining, and we should queue up a delayed flush to clear them NOTE: Unused here, see BatchedPreprocessor override, super is not called.
protected  void send(java.util.List<TunnelGateway.Pending> pending, int startAt, int sendThrough, TunnelGateway.Sender sender, TunnelGateway.Receiver rec)
          Preprocess the messages from the pending list, grouping items startAt through sendThrough (though only part of the last one may be fully sent), delivering them through the sender/receiver.
 
Methods inherited from class net.i2p.router.tunnel.TrivialPreprocessor
getInstructionAugmentationSize, getInstructionsSize, notePreprocessing, preprocess, writeFirstFragment, writeSubsequentFragment
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_DELAY

static long DEFAULT_DELAY
Constructor Detail

BatchedPreprocessor

public BatchedPreprocessor(RouterContext ctx,
                           java.lang.String name)
Method Detail

getSendDelay

protected long getSendDelay()
Wait up to this long before sending (flushing) a small tunnel message Warning - overridden in BatchedRouterPreprocessor


getDelayAmount

public long getDelayAmount()
how long do we want to wait before flushing

Specified by:
getDelayAmount in interface TunnelGateway.QueuePreprocessor
Overrides:
getDelayAmount in class TrivialPreprocessor

preprocessQueue

public boolean preprocessQueue(java.util.List<TunnelGateway.Pending> pending,
                               TunnelGateway.Sender sender,
                               TunnelGateway.Receiver rec)
Description copied from class: TrivialPreprocessor
Return true if there were messages remaining, and we should queue up a delayed flush to clear them NOTE: Unused here, see BatchedPreprocessor override, super is not called.

Specified by:
preprocessQueue in interface TunnelGateway.QueuePreprocessor
Overrides:
preprocessQueue in class TrivialPreprocessor
Parameters:
pending - list of Pending objects for messages either unsent or partly sent. This list should be update with any values removed (the preprocessor owns the lock) Messages are not removed from the list until actually sent. The status of unsent and partially-sent messages is stored in the Pending structure.
Returns:
true if we should delay before preprocessing again

send

protected void send(java.util.List<TunnelGateway.Pending> pending,
                    int startAt,
                    int sendThrough,
                    TunnelGateway.Sender sender,
                    TunnelGateway.Receiver rec)
Preprocess the messages from the pending list, grouping items startAt through sendThrough (though only part of the last one may be fully sent), delivering them through the sender/receiver.

Parameters:
startAt - first index in pending to send (inclusive)
sendThrough - last index in pending to send (inclusive)