Distributed Hash Table

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• Distributed Hah Table is a Simple Key-Value storage based on Chord design.

• The Simplified version of Chord covers three things:

  • ID space partitioning/re-partitioning.
  • Ring based routing
  • Node joins

• SHA-1 hash function is used to lexically arrange nodes in a ring and find the location for a particular key to be stored.

• Each node maintains a successor and predecessor pointer for nodes in the ring.

• Content Provider is File Based key-value storage where:

  • The first column name is “key” and is used to store all keys.
  • The second column is “value” and is used to store all values associated with corresponding keys.

PTest

• Inserts 50 arbitrary key-value pairs in the DHT and queries to check if they exist and returns success/failure messages.

LDump

• When touched, this button dumps and displays all the <key, value> pairs stored in local partition of the node.

GDump

• When touched, this button dumps and displays all the <key, value> pairs stored in the entire DHT.

References

[1] Read about Chord here

[2] Single best resource on Android, Android dev

[3] Link to Chord repository on Github, here