This partially fixes the issue of packets not being retransmitted
before they expire in 10 seconds, introduced in 0.9.48 as reported by
jogger at http://zzz.i2p/topics/3003
Fast retransmit was also suggested by jogger as a solution and discussed in that thread.
This code is based on the requirements for TCP fast retransmit
as specified in RFC 5681 but cannot precisely follow the RFC
as UDP messages can be dropped without affecting later messages:
- nack counter is per-message, not per-connection
- some interactions with the retransmit timer when in fast retx mode
- msg expiration is currently 10s but max RTO is 60s
- interactions with individual fragment transmission implemented in 0.9.48-5
- this is a sender-side fix but it depends on far-end ack resend strategy
Maintain a local message sequence number and store
it in OMF, previously unused as codel is disabled
Removed acked messages from _outboundMessages as usual,
but stores message and seq. numbers in a LinkedHashMap,
so we may interpret additional acks as nacks.
Calculate the highest-acked seq. number for every incoming packet.
Marks messages older than highest acked as nacked
Fast-retransmits after 3 nacks
Window and SST adjustments per RFC 5681 sec. 2.4
Reduce resend ack quantity and timeout to improve odds of receiving "nacks"
Disable wakeup of OMF from IMF; should not be needed now that PS calls nudge()
PS.acked(partial) now returns true if any fragment was acked, not if complete
Log tweaks
Still todo: possible additional changes to ack resend strategy;
possible parameter adjustments including msg expiration;
confirm that OMF wakeup in IMF is not required;
further testing and cleanups;
take additional ideas from alternative proposal in MR !8;
stat tweaks;
find related tickets to close
Reviewed by and contains code from zlatinb in MR !8
This builds on several previous SSU improvements; see #2427 for a list.
ref: gitlab MRs !8!9!10!11
Always request new LS for subsessions also
Don't reuse LS object for subsessions
Cancel rerequest timer as necessary
Fixes watchdog warnings
Fixes console status for subsessions in different states
javadocs
Workaround the bug on the sending side for pre-0.9.49 routers by sending fragments in reverse order.
Bug introduced in commit 9c4558d891 Sep 20 2014.
This partially reverts that commit.
Reported by and adapted from a patch by zlatinb
if all fragments will not fit in the window.
Track per-fragment send count.
Reset send window when retransmitting.
Update send window when partial acks received.
Make OMS.getMaxSends() and getPushCount() track different things.
Change OMS.push() to be called by OMF and return the pushed fragments.
Use size of smallest fragment rather than total size to determine if we can send a message now.
This is an improved fix for ticket #2505.
Eliminate repeated calls to OMS.getLifetime()
Log tweaks and reduce log levels
Improves throughput on lossy connections.
Reduces latency for large messages.
This is prep for reducing DEFAULT_SEND_WINDOW_BYTES and W+, which
would have exacerbated these issues.
Additional changes to follow, implementing Westwood+, see #2427
- Change router ECIES SKM to use N pattern, remove Elligator2, to match proposal changes
- Allow encrypted messages to ECIES routers
- Allow ECIES routers to become floodfill
- Add XDH factory to VM comm system for tests
