Hecate/Hash2Pub
2
0
Fork 0
forked from schmittlauch/Hash2Pub
Code Issues Pull requests Releases Wiki Activity

improve documentation, contributes to #8

Browse source
This commit is contained in:
Trolli Schmittlauch 2020-02-27 22:45:24 +01:00
parent 3f9452ab7e
commit 4a89ffe25a
1 changed files with 12 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
src/Hash2Pub/FediChord.hs
View file

@ -17,15 +17,20 @@ import Network.Socket
import Data.Time.Clock.System import Data.Time.Clock.System
-- define protocol constants -- define protocol constants
-- | static definition of ID length in bits
idBits :: Integer idBits :: Integer
idBits = 256 idBits = 256
-- |NodeIDs are Integers wrapped in a newtype, to be able to redefine
-- their instance behaviour
newtype NodeID = NodeID { getNodeID :: Integer } deriving (Eq, Show, Enum) newtype NodeID = NodeID { getNodeID :: Integer } deriving (Eq, Show, Enum)
-- |NodeIDs are bounded by the value range of an unsigned Integer of length 'idBits'
instance Bounded NodeID where instance Bounded NodeID where
minBound = NodeID 0 minBound = NodeID 0
maxBound = NodeID (2^idBits - 1) maxBound = NodeID (2^idBits - 1)
-- |calculations with NodeIDs are modular arithmetic operations
instance Num NodeID where instance Num NodeID where
a + b = NodeID $ (getNodeID a + getNodeID b) `mod` (getNodeID maxBound + 1) a + b = NodeID $ (getNodeID a + getNodeID b) `mod` (getNodeID maxBound + 1)
a * b = NodeID $ (getNodeID a * getNodeID b) `mod` (getNodeID maxBound + 1) a * b = NodeID $ (getNodeID a * getNodeID b) `mod` (getNodeID maxBound + 1)
@ -35,7 +40,7 @@ instance Num NodeID where
signum = NodeID . signum . getNodeID signum = NodeID . signum . getNodeID
abs = NodeID . abs . getNodeID -- ToDo: make sure that at creation time only IDs within the range are used abs = NodeID . abs . getNodeID -- ToDo: make sure that at creation time only IDs within the range are used
-- NodeIDs on a ring are assigned an Ordering for finding a preceding node -- |NodeIDs on a ring are assigned an Ordering for finding a preceding node.
-- main idea: a node is preceding (LT) if the way forwards to the other node is smaller than the way backwards -- main idea: a node is preceding (LT) if the way forwards to the other node is smaller than the way backwards
-- problem: equality of ways /= (a == b), so even equal-way paths don't return EQ. The equality-of-ways case is assigned to LT, -- problem: equality of ways /= (a == b), so even equal-way paths don't return EQ. The equality-of-ways case is assigned to LT,
-- as preceding EpiChord nodes are nodes <=. -- as preceding EpiChord nodes are nodes <=.
@ -61,7 +66,7 @@ data NodeState = NodeState {
-- might have to be queried first -- might have to be queried first
, nodeCache :: Map.Map NodeID CacheEntry , nodeCache :: Map.Map NodeID CacheEntry
-- ^ EpiChord node cache with expiry times for nodes -- ^ EpiChord node cache with expiry times for nodes
-- as the map is ordered, lookups for the closes preceding node can be done using `lookupLE` -- as the map is ordered, lookups for the closes preceding node can be done using @lookupLT@
, successors :: [NodeID] , successors :: [NodeID]
, predecessors :: [NodeID] , predecessors :: [NodeID]
----- protocol parameters ----- ----- protocol parameters -----
@ -77,7 +82,10 @@ data NodeState = NodeState {
-- needs to be parameterisable for simulation purposes -- needs to be parameterisable for simulation purposes
} }
type CacheEntry = ( NodeState, SystemTime) -- |an entry of the 'nodeCache'
type CacheEntry = (NodeState -- ^a node's data
, SystemTime -- ^timestamp for cache entry expiration
)
-- Todo: DHT backend can learn potential initial bootstrapping points through the instances mentioned in the received AP-relay messages -- Todo: DHT backend can learn potential initial bootstrapping points through the instances mentioned in the received AP-relay messages
-- needs to know its own domain anyways for ID generation -- needs to know its own domain anyways for ID generation