implement k-choices join functions
large commit, contains a number of things: - k-choices #2 cost calculation - k-choices parameters - adjusting ASN.1 network messages to contain all values required for cost calculation #71 - adjusting stats to contain required values - k-choices node and vserver join functions - placeholder/ dummy invocation of k-choices join
This commit is contained in:
parent
62da66aade
commit
3b6d129bfc
|
|
@ -111,6 +111,7 @@ LoadRequestPayload ::= SEQUENCE {
|
|||
LoadResponsePayload ::= SEQUENCE {
|
||||
loadSum REAL,
|
||||
remainingLoadTarget REAL,
|
||||
totalCapacity REAL,
|
||||
lowerBound NodeID
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -49,6 +49,9 @@ readConfig = do
|
|||
, confRequestTimeout = 5 * 10^6 `div` speedup
|
||||
, confRequestRetries = 3
|
||||
, confEnableKChoices = loadBalancingEnabled /= "off"
|
||||
, confKChoicesOverload = 0.9
|
||||
, confKChoicesUnderload = 0.1
|
||||
, confKChoicesMaxVS = 8
|
||||
}
|
||||
sConf = ServiceConf
|
||||
{ confSubscriptionExpiryTime = 24*3600 / fromIntegral speedup
|
||||
|
|
|
|||
|
|
@ -193,6 +193,7 @@ encodePayload payload'@LoadResponsePayload{} =
|
|||
[ Start Sequence
|
||||
, Real $ loadSum payload'
|
||||
, Real $ loadRemainingTarget payload'
|
||||
, Real $ loadTotalCapacity payload'
|
||||
, IntVal . getNodeID $ loadSegmentLowerBound payload'
|
||||
, End Sequence
|
||||
]
|
||||
|
|
@ -472,10 +473,12 @@ parseLoadResponsePayload :: ParseASN1 ActionPayload
|
|||
parseLoadResponsePayload = onNextContainer Sequence $ do
|
||||
loadSum' <- parseReal
|
||||
loadRemainingTarget' <- parseReal
|
||||
loadTotalCapacity' <- parseReal
|
||||
loadSegmentLowerBound' <- fromInteger <$> parseInteger
|
||||
pure LoadResponsePayload
|
||||
{ loadSum = loadSum'
|
||||
, loadRemainingTarget = loadRemainingTarget'
|
||||
, loadTotalCapacity = loadTotalCapacity'
|
||||
, loadSegmentLowerBound = loadSegmentLowerBound'
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -93,6 +93,7 @@ import Hash2Pub.FediChordTypes (CacheEntry (..),
|
|||
getKeyID, localCompare,
|
||||
rMapFromList, rMapLookupPred,
|
||||
rMapLookupSucc,
|
||||
remainingLoadTarget,
|
||||
setPredecessors, setSuccessors)
|
||||
import Hash2Pub.ProtocolTypes
|
||||
import Hash2Pub.RingMap
|
||||
|
|
@ -292,7 +293,7 @@ handleIncomingRequest nsSTM sendQ msgSet sourceAddr = do
|
|||
-- only when joined
|
||||
Leave -> if isJoined ns then dropSpoofedIDs sourceIP nsSTM msgSet respondLeave else pure Nothing
|
||||
Stabilise -> if isJoined ns then dropSpoofedIDs sourceIP nsSTM msgSet respondStabilise else pure Nothing
|
||||
QueryLoad -> if isJoined ns then Just <$> respondLoadQuery nsSTM msgSet else pure Nothing
|
||||
QueryLoad -> if isJoined ns then Just <$> respondQueryLoad nsSTM msgSet else pure Nothing
|
||||
)
|
||||
-- for single part request, response starts with part number 1. For multipart requests, response starts with part number n+1.
|
||||
|
||||
|
|
@ -433,8 +434,8 @@ respondPing nsSTM msgSet = do
|
|||
}
|
||||
pure $ serialiseMessage sendMessageSize pingResponse
|
||||
|
||||
respondLoadQuery :: Service s (RealNodeSTM s) => LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
|
||||
respondLoadQuery nsSTM msgSet = do
|
||||
respondQueryLoad :: Service s (RealNodeSTM s) => LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
|
||||
respondQueryLoad nsSTM msgSet = do
|
||||
nsSnap <- readTVarIO nsSTM
|
||||
-- this message cannot be split reasonably, so just
|
||||
-- consider the first payload
|
||||
|
|
@ -444,14 +445,18 @@ respondLoadQuery nsSTM msgSet = do
|
|||
responsePl <- maybe (pure Nothing) (\pl ->
|
||||
case pl of
|
||||
LoadRequestPayload{} -> do
|
||||
serv <- nodeService <$> readTVarIO (parentRealNode nsSnap)
|
||||
parentNode <- readTVarIO (parentRealNode nsSnap)
|
||||
let
|
||||
serv = nodeService parentNode
|
||||
conf = nodeConfig parentNode
|
||||
lStats <- getServiceLoadStats serv
|
||||
let
|
||||
directSucc = getNid . head . predecessors $ nsSnap
|
||||
handledTagSum = sum . takeRMapSuccessorsFromTo directSucc (loadSegmentUpperBound pl) $ loadPerTag lStats
|
||||
pure $ Just LoadResponsePayload
|
||||
{ loadSum = handledTagSum
|
||||
, loadRemainingTarget = remainingLoadTarget lStats
|
||||
, loadRemainingTarget = remainingLoadTarget conf lStats
|
||||
, loadTotalCapacity = totalCapacity lStats
|
||||
, loadSegmentLowerBound = directSucc
|
||||
}
|
||||
_ -> pure Nothing
|
||||
|
|
@ -808,7 +813,9 @@ requestQueryLoad ns upperIdBound target = do
|
|||
{ segmentLowerKeyBound = loadSegmentLowerBound loadResPl
|
||||
, segmentUpperKeyBound = upperIdBound
|
||||
, segmentLoad = loadSum loadResPl
|
||||
, segmentOwnerLoadTarget = loadRemainingTarget loadResPl
|
||||
, segmentOwnerRemainingLoadTarget = loadRemainingTarget loadResPl
|
||||
, segmentOwnerCapacity = loadTotalCapacity loadResPl
|
||||
, segmentCurrentOwner = target
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -63,6 +63,7 @@ import Control.Exception
|
|||
import Control.Monad (forM_, forever)
|
||||
import Control.Monad.Except
|
||||
import Crypto.Hash
|
||||
import Data.Bifunctor (first)
|
||||
import qualified Data.ByteArray as BA
|
||||
import qualified Data.ByteString as BS
|
||||
import qualified Data.ByteString.UTF8 as BSU
|
||||
|
|
@ -71,9 +72,11 @@ import Data.Foldable (foldr')
|
|||
import Data.Functor.Identity
|
||||
import Data.HashMap.Strict (HashMap)
|
||||
import qualified Data.HashMap.Strict as HMap
|
||||
import Data.HashSet (HashSet)
|
||||
import qualified Data.HashSet as HSet
|
||||
import Data.IP (IPv6, fromHostAddress6,
|
||||
toHostAddress6)
|
||||
import Data.List ((\\))
|
||||
import Data.List (sortBy, sortOn, (\\))
|
||||
import qualified Data.Map.Strict as Map
|
||||
import Data.Maybe (catMaybes, fromJust, fromMaybe,
|
||||
isJust, isNothing, mapMaybe)
|
||||
|
|
@ -123,7 +126,9 @@ fediChordInit initConf serviceRunner = do
|
|||
fediThreadsAsync <- if confEnableKChoices initConf
|
||||
then
|
||||
-- TODO: k-choices way of joining
|
||||
async (fediMainThreads serverSock realNodeSTM)
|
||||
-- placeholder
|
||||
runExceptT (kChoicesNodeJoin realNodeSTM ("foo", fromIntegral 3))
|
||||
>> async (fediMainThreads serverSock realNodeSTM)
|
||||
else do
|
||||
-- without k-choices, just initialise a single vserver
|
||||
firstVS <- nodeStateInit realNodeSTM 0
|
||||
|
|
@ -148,6 +153,23 @@ fediChordInit initConf serviceRunner = do
|
|||
joinedState
|
||||
pure (fediThreadsAsync, realNodeSTM)
|
||||
|
||||
|
||||
-- | Create a new vserver and join it through a provided remote node.
|
||||
-- TODO: Many fediChord* functions already cover parts of this, refactor these to use
|
||||
-- this function.
|
||||
fediChordJoinNewVs :: (MonadError String m, MonadIO m, Service s (RealNodeSTM s))
|
||||
=> RealNodeSTM s -- ^ parent real node
|
||||
-> Integer -- ^ vserver ID
|
||||
-> RemoteNodeState -- ^ target node to join on
|
||||
-> m (NodeID, LocalNodeStateSTM s) -- ^ on success: (vserver ID, TVar of vserver)
|
||||
fediChordJoinNewVs nodeSTM vsId target = do
|
||||
newVs <- liftIO $ nodeStateInit nodeSTM vsId
|
||||
newVsSTM <- liftIO $ newTVarIO newVs
|
||||
liftIO . putStrLn $ "Trying to join on " <> show (getNid target)
|
||||
liftIO $ putStrLn "send a Join"
|
||||
_ <- liftIO . requestJoin target $ newVsSTM
|
||||
pure (getNid newVs, newVsSTM)
|
||||
|
||||
-- | initialises the 'NodeState' for this local node.
|
||||
-- Separated from 'fediChordInit' to be usable in tests.
|
||||
nodeStateInit :: Service s (RealNodeSTM s) => RealNodeSTM s -> Integer -> IO (LocalNodeState s)
|
||||
|
|
@ -178,6 +200,114 @@ nodeStateInit realNodeSTM vsID' = do
|
|||
}
|
||||
pure initialState
|
||||
|
||||
|
||||
kChoicesNodeJoin :: (MonadError String m, MonadIO m, Service s (RealNodeSTM s))
|
||||
=> RealNodeSTM s
|
||||
-> (String, PortNumber) -- ^ domain and port of a bootstrapping node
|
||||
-> m ()
|
||||
kChoicesNodeJoin nodeSTM bootstrapNode = do
|
||||
node <- liftIO $ readTVarIO nodeSTM
|
||||
-- use vserver 0 as origin of bootstrapping messages
|
||||
vs0 <- liftIO $ nodeStateInit nodeSTM 0
|
||||
vs0STM <- liftIO $ newTVarIO vs0
|
||||
|
||||
ownLoadStats <- liftIO . getServiceLoadStats . nodeService $ node
|
||||
let
|
||||
conf = nodeConfig node
|
||||
-- T_a of k-choices
|
||||
-- compute load target
|
||||
joinLoadTarget = totalCapacity ownLoadStats * (confKChoicesUnderload conf + confKChoicesOverload conf) / 2
|
||||
initialJoins = confKChoicesMaxVS conf `div` 2
|
||||
-- edge case: however small the target is, at least join 1 vs
|
||||
-- kCoicesVsJoin until target is met
|
||||
joinedVss <- vsJoins vs0STM (totalCapacity ownLoadStats) (vservers node) joinLoadTarget (fromIntegral initialJoins) nodeSTM
|
||||
liftIO . atomically . modifyTVar' nodeSTM $ \node' -> node'
|
||||
{ vservers = HMap.union (vservers node') joinedVss }
|
||||
pure ()
|
||||
|
||||
where
|
||||
vsJoins :: (MonadError String m, MonadIO m, Service s (RealNodeSTM s))
|
||||
=> LocalNodeStateSTM s -> Double -> VSMap s -> Double -> Int -> RealNodeSTM s -> m (VSMap s)
|
||||
vsJoins _ _ vsmap _ 0 _ = pure vsmap
|
||||
vsJoins queryVsSTM capacity vsmap remainingTargetLoad remainingJoins nodeSTM'
|
||||
| remainingTargetLoad <= 0 = pure vsmap
|
||||
| otherwise = (do
|
||||
|
||||
(acquiredLoad, (newNid, newVs)) <- kChoicesVsJoin queryVsSTM bootstrapNode capacity vsmap nodeSTM' remainingTargetLoad
|
||||
-- on successful vserver join add the new VS to node and recurse
|
||||
vsJoins queryVsSTM capacity (HMap.insert newNid newVs vsmap) (remainingTargetLoad - acquiredLoad) (pred remainingJoins) nodeSTM'
|
||||
)
|
||||
-- TODO: decide on whether and how to catch errors
|
||||
-- error cause 1: not a single queried node has responded -> indicates permanent failure
|
||||
-- error cause 2: only a certain join failed, just ignore that join target for now, but problem: it will be the chosen
|
||||
-- target even at the next attempt again
|
||||
-- `catchError` (const .
|
||||
|
||||
kChoicesVsJoin :: (MonadError String m, MonadIO m, Service s (RealNodeSTM s))
|
||||
=> LocalNodeStateSTM s -- ^ vserver to be used for querying
|
||||
-> (String, PortNumber) -- ^ domain and port of a bootstrapping node
|
||||
-> Double -- ^ own capacity
|
||||
-> VSMap s -- ^ currently active VServers
|
||||
-> RealNodeSTM s -- ^ parent node is needed for initialising a new vserver
|
||||
-> Double -- ^ remaining load target
|
||||
-> m (Double, (NodeID, LocalNodeStateSTM s)) -- ^ on success return tuple of acquired load and newly acquired vserver
|
||||
kChoicesVsJoin queryVsSTM bootstrapNode capacity activeVss nodeSTM remainingTarget = do
|
||||
conf <- nodeConfig <$> liftIO (readTVarIO nodeSTM)
|
||||
-- generate all possible vs IDs
|
||||
let
|
||||
activeVsSet = HMap.keysSet activeVss
|
||||
-- tuples of node IDs and vserver IDs, because vserver IDs are needed for
|
||||
-- LocalNodeState creation
|
||||
nonJoinedIDs = filter (not . flip HSet.member activeVsSet . fst) [ (genNodeID (confIP conf) (confDomain conf) (fromInteger v), v) | v <- [0..confKChoicesMaxVS conf]]
|
||||
queryVs <- liftIO $ readTVarIO queryVsSTM
|
||||
|
||||
-- query load of all possible segments
|
||||
-- simplification: treat each load lookup failure as a general unavailability of that segment
|
||||
-- TODO: retries for transient failures
|
||||
segmentLoads <- fmap catMaybes . forM nonJoinedIDs $ (\(vsNid, vsId) -> (do
|
||||
lookupResp <- liftIO $ bootstrapQueryId queryVsSTM bootstrapNode vsNid
|
||||
currentlyResponsible <- liftEither lookupResp
|
||||
segment <- requestQueryLoad queryVs vsNid currentlyResponsible
|
||||
pure $ Just (segment, vsId, currentlyResponsible)
|
||||
-- store segment stats and vserver ID together, so it's clear
|
||||
-- which vs needs to be joined to acquire this segment
|
||||
) `catchError` const (pure Nothing)
|
||||
)
|
||||
|
||||
|
||||
-- cost calculation and sort by cost
|
||||
-- edge case: no possible ID has responded
|
||||
(mincost, vsId, toJoinOn) <- maybe (throwError "received no load information") pure
|
||||
. headMay
|
||||
. sortOn (\(cost, _, _) -> cost)
|
||||
. fmap (\(segment, vsId, toJoinOn) -> (kChoicesJoinCost remainingTarget capacity segment, vsId, toJoinOn))
|
||||
$ segmentLoads
|
||||
-- join at min cost
|
||||
joinedNode <- fediChordJoinNewVs nodeSTM vsId toJoinOn
|
||||
pure (mincost, joinedNode)
|
||||
|
||||
-- Possible optimisation:
|
||||
-- Instead of sampling all join candidates again at each invocation, querying
|
||||
-- all segment loads before the first join and trying to re-use these
|
||||
-- load information can save round trips.
|
||||
-- possible edge case: detect when joining a subsegment of one already owned
|
||||
-- joining into own segments => When first joining into segment S1 and then
|
||||
-- later joining into the subsegment S2, the
|
||||
-- resulting load l(S1+S2) = l(S1) != l(S1) + l(S2)
|
||||
-- => need to re-query the load of both S1 and S2
|
||||
-- possible edge case 2: taking multiple segments from the same owner
|
||||
-- changes the remainingLoadTarget at each vsJoin. This target change
|
||||
-- needs to be accounted for starting from the 2nd vsJoin.
|
||||
|
||||
kChoicesJoinCost :: Double -- ^ own remaining load target
|
||||
-> Double -- ^ own capacity
|
||||
-> SegmentLoadStats
|
||||
-> Double
|
||||
kChoicesJoinCost remainingOwnLoad ownCap segment =
|
||||
abs (segmentOwnerRemainingLoadTarget segment + segmentLoad segment) / segmentOwnerCapacity segment
|
||||
+ abs (remainingOwnLoad - segmentLoad segment) / ownCap
|
||||
- abs (segmentOwnerRemainingLoadTarget segment) / segmentOwnerCapacity segment
|
||||
|
||||
-- | Join a new node into the DHT, using a provided bootstrap node as initial cache seed
|
||||
-- for resolving the new node's position.
|
||||
fediChordBootstrapJoin :: Service s (RealNodeSTM s)
|
||||
|
|
@ -277,8 +407,7 @@ bootstrapQueryId nsSTM (bootstrapHost, bootstrapPort) targetID = do
|
|||
Just (FORWARD resultset) -> foldr' (addCacheEntryPure now) cacheAcc resultset
|
||||
)
|
||||
initCache resp
|
||||
currentlyResponsible <- runExceptT $ queryIdLookupLoop bootstrapCache ns 50 $ getNid ns
|
||||
pure currentlyResponsible
|
||||
runExceptT $ queryIdLookupLoop bootstrapCache ns 50 $ getNid ns
|
||||
|
||||
|
||||
-- | join a node to the DHT using the global node cache
|
||||
|
|
@ -296,6 +425,7 @@ fediChordVserverJoin nsSTM = do
|
|||
joinResult <- liftIO $ requestJoin currentlyResponsible nsSTM
|
||||
liftEither joinResult
|
||||
|
||||
|
||||
fediChordVserverLeave :: (MonadError String m, MonadIO m, Service s (RealNodeSTM s)) => LocalNodeState s -> m ()
|
||||
fediChordVserverLeave ns = do
|
||||
-- TODO: deal with failure of all successors, e.g. by invoking a stabilise
|
||||
|
|
|
|||
|
|
@ -18,8 +18,10 @@ module Hash2Pub.FediChordTypes
|
|||
, RemoteNodeState (..)
|
||||
, RealNode (..)
|
||||
, RealNodeSTM
|
||||
, VSMap
|
||||
, LoadStats (..)
|
||||
, emptyLoadStats
|
||||
, remainingLoadTarget
|
||||
, SegmentLoadStats (..)
|
||||
, setSuccessors
|
||||
, setPredecessors
|
||||
|
|
@ -153,7 +155,7 @@ a `localCompare` b
|
|||
-- Also contains shared data and config values.
|
||||
-- TODO: more data structures for k-choices bookkeeping
|
||||
data RealNode s = RealNode
|
||||
{ vservers :: HashMap NodeID (LocalNodeStateSTM s)
|
||||
{ vservers :: VSMap s
|
||||
-- ^ map of all active VServer node IDs to their node state
|
||||
, nodeConfig :: FediChordConf
|
||||
-- ^ holds the initial configuration read at program start
|
||||
|
|
@ -168,6 +170,8 @@ data RealNode s = RealNode
|
|||
, nodeService :: s (RealNodeSTM s)
|
||||
}
|
||||
|
||||
|
||||
type VSMap s = HashMap NodeID (LocalNodeStateSTM s)
|
||||
type RealNodeSTM s = TVar (RealNode s)
|
||||
|
||||
-- | represents a node and all its important state
|
||||
|
|
@ -438,6 +442,12 @@ data FediChordConf = FediChordConf
|
|||
-- ^ how often re-sending a timed-out request can be retried
|
||||
, confEnableKChoices :: Bool
|
||||
-- ^ whether to enable k-choices load balancing
|
||||
, confKChoicesOverload :: Double
|
||||
-- ^ fraction of capacity above which a node considers itself overloaded
|
||||
, confKChoicesUnderload :: Double
|
||||
-- ^ fraction of capacity below which a node considers itself underloaded
|
||||
, confKChoicesMaxVS :: Integer
|
||||
-- ^ upper limit of vserver index κ
|
||||
}
|
||||
deriving (Show, Eq)
|
||||
|
||||
|
|
@ -448,11 +458,18 @@ data LoadStats = LoadStats
|
|||
-- ^ map of loads for each handled tag
|
||||
, totalCapacity :: Double
|
||||
-- ^ total designated capacity of the service
|
||||
, remainingLoadTarget :: Double
|
||||
-- ^ current mismatch between actual load and target load/capacity
|
||||
, compensatedLoadSum :: Double
|
||||
-- ^ effective load reevant for load balancing after compensating for
|
||||
}
|
||||
deriving (Show, Eq)
|
||||
|
||||
-- | calculates the mismatch from the target load by taking into account the
|
||||
-- underload and overload limits
|
||||
remainingLoadTarget :: FediChordConf -> LoadStats -> Double
|
||||
remainingLoadTarget conf lstats = targetLoad - compensatedLoadSum lstats
|
||||
where
|
||||
targetLoad = totalCapacity lstats * (confKChoicesUnderload conf + confKChoicesOverload conf) / 2
|
||||
|
||||
data SegmentLoadStats = SegmentLoadStats
|
||||
{ segmentLowerKeyBound :: NodeID
|
||||
-- ^ segment start key
|
||||
|
|
@ -460,8 +477,12 @@ data SegmentLoadStats = SegmentLoadStats
|
|||
-- ^ segment end key
|
||||
, segmentLoad :: Double
|
||||
-- ^ sum of load of all keys in the segment
|
||||
, segmentOwnerLoadTarget :: Double
|
||||
-- ^ remaining load target of the current segment handler
|
||||
, segmentOwnerRemainingLoadTarget :: Double
|
||||
-- ^ remaining load target of the current segment handler:
|
||||
, segmentOwnerCapacity :: Double
|
||||
-- ^ total capacity of the current segment handler node, used for normalisation
|
||||
, segmentCurrentOwner :: RemoteNodeState
|
||||
-- ^ the current owner of the segment that needs to be joined on
|
||||
}
|
||||
|
||||
-- TODO: figure out a better way of initialising
|
||||
|
|
@ -469,7 +490,7 @@ emptyLoadStats :: LoadStats
|
|||
emptyLoadStats = LoadStats
|
||||
{ loadPerTag = emptyRMap
|
||||
, totalCapacity = 0
|
||||
, remainingLoadTarget = 0
|
||||
, compensatedLoadSum = 0
|
||||
}
|
||||
|
||||
-- ====== Service Types ============
|
||||
|
|
|
|||
|
|
@ -890,12 +890,13 @@ evaluateLoadStats currentStats currentSubscribers = do
|
|||
)
|
||||
(0, emptyRMap)
|
||||
$ rMapToListWithKeys currentSubscribers
|
||||
-- TODO: use underload and overload limits instead of capacity
|
||||
let remainingLoadTarget' = totalCapacity' - loadSum - postFetchRate currentStats
|
||||
pure LoadStats
|
||||
{ loadPerTag = loadPerTag'
|
||||
, totalCapacity = totalCapacity'
|
||||
, remainingLoadTarget = remainingLoadTarget'
|
||||
-- load caused by post fetches cannot be influenced by re-balancing nodes,
|
||||
-- but still reduces the totally available capacity
|
||||
, compensatedLoadSum = loadSum + postFetchRate currentStats
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -82,6 +82,7 @@ data ActionPayload = QueryIDRequestPayload
|
|||
| LoadResponsePayload
|
||||
{ loadSum :: Double
|
||||
, loadRemainingTarget :: Double
|
||||
, loadTotalCapacity :: Double
|
||||
, loadSegmentLowerBound :: NodeID
|
||||
}
|
||||
deriving (Show, Eq)
|
||||
|
|
|
|||
Loading…
Reference in a new issue