Created DHT Resources (markdown)

DHT-Resources.md

@@ -0,0 +1,55 @@
+Some links I found useful while doing DHT work
+
+[http://xlattice.sourceforge.net/components/protocol/kademlia/specs.html](http://xlattice.sourceforge.net/components/protocol/kademlia/specs.html)
+
+[http://www.maymounkov.org/papers/maymounkov-kademlia-lncs.pdf](http://www.maymounkov.org/papers/maymounkov-kademlia-lncs.pdf) ([https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf](https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf) alternative as it was offline)
+
+[http://blog.notdot.net/2009/11/Implementing-a-DHT-in-Go-part-2](http://blog.notdot.net/2009/11/Implementing-a-DHT-in-Go-part-2)
+
+[http://www.scs.stanford.edu/17au-cs244b/labs/projects/kaplan-nelson_ma_rachleff.pdf](http://www.scs.stanford.edu/17au-cs244b/labs/projects/kaplan-nelson_ma_rachleff.pdf)
+
+[http://www.bittorrent.org/beps/bep_0005.html](http://www.bittorrent.org/beps/bep_0005.html)
+
+[blog.libtorrent.org/2016/09/dht-bootstrap-node](https://blog.libtorrent.org/2016/09/dht-bootstrap-node)
+
+[https://github.com/lbryio/reflector-cluster/issues/41](https://github.com/lbryio/reflector-cluster/issues/41)
+
+torrent specific: [https://wiki.theory.org/BitTorrentDraftDHTProtocol](https://wiki.theory.org/BitTorrentDraftDHTProtocol) and torrent general: [https://wiki.theory.org/BitTorrentSpecification](https://wiki.theory.org/BitTorrentSpecification)
+
+## Naive IterativeFind description
+
+_grin made this up_
+
+naive iterativeFind description (bounded parallelism, not loose parallelism):
+
+`target` = hash that you're looking for
+
+`activeNodes = []`, always sorted by distance to target
+
+`toContact = []`, always sorted by distance to target
+
+`contacted = {}`
+
+start!
+
+put all nodes in routing table into the toContact list
+
+run `ALPHA` workers
+
+each worker will asynchronously:
+
+- pop first node in toContact list, mark it as contacted, contact it
+- if node does not reply in some time, drop it and move on to next node
+- if node replies, insert it into activeNodes
+- if node replies with the value for FindValue call, return that value and immediately end the whole process
+- if node replies with contacts, insert the contacts that have not been contacted yet into toContact
+- if `len(toContact) == 0` (and there are no outstanding request) or `len(activeNodes) >= K && dist(target, activeNodes[K-1]) < dist(target, toContact[0])`, quit
+
+if FindValue found a value, return it. otherwise return first K activeNodes
+
+caveats:
+
+- if you're doing the optimization of caching FindValue results at the closest node that didn't have it, you can't simply stop the search when you get a value. you have to keep going so you can find the closest node that didn't return a value
+- this algorithm doesn't stop early when its unlikely to find closer nodes. to do this, you have to change two things
+    - only add the K closest nodes to the shortlist at the start of the search
+    - for the termination condition, track the closest node seen so far. if responses from the shortlist are not getting you any closer to the target, stop searching