Author: toad
Date: 2009-03-20 18:57:47 +0000 (Fri, 20 Mar 2009)
New Revision: 26117
Modified:
trunk/freenet/src/freenet/node/PeerManager.java
Log:
Document logic (comments)
Modified: trunk/freenet/src/freenet/node/PeerManager.java
===================================================================
--- trunk/freenet/src/freenet/node/PeerManager.java 2009-03-20 18:36:24 UTC
(rev 26116)
+++ trunk/freenet/src/freenet/node/PeerManager.java 2009-03-20 18:57:47 UTC
(rev 26117)
@@ -990,6 +990,28 @@
PeerNode best = closestNotBackedOff;
+ /**
+ * Various things are "advisory" i.e. they are taken into
account but do not cause a request not to be routed at all:
+ * - Backoff: A node is backed off for a period after it
rejects a request;
+ * this is randomised and increases exponentially if no
requests are accepted;
+ * a longer period is imposed for timeouts after a request has
been accepted
+ * and transfer failures.
+ * - Recent failures: After various kinds of failures we impose
a timeout,
+ * until when we will try to avoid sending the same key to that
node. This is
+ * part of per-node failure tables.
+ * Combining these:
+ * - If there are nodes which are both not backed off and not
timed out, we
+ * route to whichever of those nodes is closest to the target
location. If we
+ * are still here, all nodes are either backed off or timed out.
+ * - If there are nodes which are timed out but not backed off,
choose the node
+ * whose timeout expires soonest. Hence if a single key is
requested
+ * continually, we round-robin between nodes. If we still don't
have a winner,
+ * we know all nodes are backed off.
+ * - If there are nodes which are backed off but not timed out,
choose the node
+ * which is closest to the target but is not backed off. If we
still don't have
+ * a winner, all nodes are backed off AND timed out.
+ * - Choose the backed off node whose timeout expires soonest.
+ */
if(best == null) {
if(leastRecentlyTimedOut != null) {
// FIXME downgrade to DEBUG
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