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Merge pull request #1230 from akka/wip-3076-gossip-merge-changes-ban

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Don't increment vector-clock on merge and merge locally. See #3076
This commit is contained in:
Viktor Klang (√) 2013-03-12 08:49:30 -07:00
commit 05593f5dd8
7 changed files with 68 additions and 167 deletions
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131
akka-cluster/src/main/scala/akka/cluster/ClusterDaemon.scala
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@ -289,7 +289,6 @@ private[cluster] final class ClusterCoreDaemon(publisher: ActorRef) extends Acto
def initialized: Actor.Receive = {
case msg: GossipEnvelope ⇒ receiveGossip(msg)
case msg: GossipMergeConflict ⇒ receiveGossipMerge(msg)
case GossipTick ⇒ gossip()
case ReapUnreachableTick ⇒ reapUnreachableMembers()
case LeaderActionsTick ⇒ leaderActions()
@ -505,35 +504,6 @@ private[cluster] final class ClusterCoreDaemon(publisher: ActorRef) extends Acto
publish(latestGossip)
}
/**
* When conflicting versions of received and local [[akka.cluster.Gossip]] is detected
* it's forwarded to the leader for conflict resolution. Trying to simultaneously
* resolving conflicts at several nodes creates new conflicts. Therefore the leader resolves
* conflicts to limit divergence. To avoid overload there is also a configurable rate
* limit of how many conflicts that are handled by second. If the limit is
* exceeded the conflicting gossip messages are dropped and will reappear later.
*/
def receiveGossipMerge(merge: GossipMergeConflict): Unit = {
stats = stats.incrementMergeConflictCount
val rate = mergeRate(stats.mergeConflictCount)
if (rate <= MaxGossipMergeRate) {
receiveGossip(merge.a.copy(conversation = false))
receiveGossip(merge.b.copy(conversation = false))
// use one-way gossip from leader to reduce load of leader
def sendBack(to: Address): Unit = {
if (to != selfAddress && !latestGossip.overview.unreachable.exists(_.address == to))
oneWayGossipTo(to)
}
sendBack(merge.a.from)
sendBack(merge.b.from)
} else {
log.debug("Dropping gossip merge conflict due to rate [{}] / s ", rate)
}
}
/**
* Receive new gossip.
*/
@ -547,70 +517,47 @@ private[cluster] final class ClusterCoreDaemon(publisher: ActorRef) extends Acto
} else if (localGossip.overview.isNonDownUnreachable(from)) {
log.debug("Ignoring received gossip from unreachable [{}] ", from)
} else {
// leader handles merge conflicts, or when they have different views of how is leader
val handleMerge = localGossip.leader == Some(selfAddress) || localGossip.leader != remoteGossip.leader
val comparison = remoteGossip.version tryCompareTo localGossip.version
val conflict = comparison.isEmpty
if (conflict && !handleMerge) {
// delegate merge resolution to leader to reduce number of simultaneous resolves,
// which will result in new conflicts
val (winningGossip, talkback, newStats) = comparison match {
case None ⇒
// conflicting versions, merge
(remoteGossip merge localGossip, true, stats.incrementMergeCount)
case Some(0) ⇒
// same version
(remoteGossip mergeSeen localGossip, !remoteGossip.seenByAddress(selfAddress), stats.incrementSameCount)
case Some(x) if x < 0 ⇒
// local is newer
(localGossip, true, stats.incrementNewerCount)
case _ ⇒
// remote is newer
(remoteGossip, !remoteGossip.seenByAddress(selfAddress), stats.incrementOlderCount)
}
stats = stats.incrementMergeDetectedCount
log.debug("Merge conflict [{}] detected [{}] <> [{}]", stats.mergeDetectedCount, selfAddress, from)
stats = newStats
latestGossip = winningGossip seen selfAddress
stats = stats.incrementMergeConflictCount
val rate = mergeRate(stats.mergeConflictCount)
// for all new joining nodes we remove them from the failure detector
latestGossip.members foreach {
node ⇒ if (node.status == Joining && !localGossip.members(node)) failureDetector.remove(node.address)
}
if (rate <= MaxGossipMergeRate)
localGossip.leader foreach { clusterCore(_) ! GossipMergeConflict(GossipEnvelope(selfAddress, localGossip), envelope) }
else
log.debug("Skipping gossip merge conflict due to rate [{}] / s ", rate)
log.debug("Cluster Node [{}] - Receiving gossip from [{}]", selfAddress, from)
} else {
if (conflict) {
log.debug(
"""Couldn't establish a causal relationship between "remote" gossip and "local" gossip - Remote[{}] - Local[{}] - merged them into [{}]""",
remoteGossip, localGossip, winningGossip)
}
val (winningGossip, talkback, newStats) = comparison match {
case None ⇒
// conflicting versions, merge, and new version
((remoteGossip merge localGossip) :+ vclockNode, true, stats)
case Some(0) ⇒
// same version
// TODO optimize talkback based on how the merged seen differs
(remoteGossip mergeSeen localGossip, !remoteGossip.hasSeen(selfAddress), stats.incrementSameCount)
case Some(x) if x < 0 ⇒
// local is newer
(localGossip, true, stats.incrementNewerCount)
case _ ⇒
// remote is newer
(remoteGossip, !remoteGossip.hasSeen(selfAddress), stats.incrementOlderCount)
}
stats = stats.incrementReceivedGossipCount
publish(latestGossip)
stats = newStats
latestGossip = winningGossip seen selfAddress
// for all new joining nodes we remove them from the failure detector
(latestGossip.members -- localGossip.members).foreach {
node ⇒ if (node.status == Joining) failureDetector.remove(node.address)
}
log.debug("Cluster Node [{}] - Receiving gossip from [{}]", selfAddress, from)
if (conflict) {
stats = stats.incrementMergeCount
log.debug(
"""Couldn't establish a causal relationship between "remote" gossip and "local" gossip - Remote[{}] - Local[{}] - merged them into [{}]""",
remoteGossip, localGossip, winningGossip)
}
stats = stats.incrementReceivedGossipCount
publish(latestGossip)
if (envelope.conversation && talkback) {
// send back gossip to sender when sender had different view, i.e. merge, or sender had
// older or sender had newer
gossipTo(from)
}
if (envelope.conversation && talkback) {
// send back gossip to sender when sender had different view, i.e. merge, or sender had
// older or sender had newer
gossipTo(from)
}
}
}
@ -621,8 +568,6 @@ private[cluster] final class ClusterCoreDaemon(publisher: ActorRef) extends Acto
* Initiates a new round of gossip.
*/
def gossip(): Unit = {
stats = stats.copy(mergeConflictCount = 0)
log.debug("Cluster Node [{}] - Initiating new round of gossip", selfAddress)
if (!isSingletonCluster && isAvailable) {
@ -1053,9 +998,7 @@ private[cluster] class OnMemberUpListener(callback: Runnable) extends Actor with
*/
private[cluster] case class ClusterStats(
receivedGossipCount: Long = 0L,
mergeConflictCount: Long = 0L,
mergeCount: Long = 0L,
mergeDetectedCount: Long = 0L,
sameCount: Long = 0L,
newerCount: Long = 0L,
olderCount: Long = 0L) {
@ -1063,15 +1006,9 @@ private[cluster] case class ClusterStats(
def incrementReceivedGossipCount(): ClusterStats =
copy(receivedGossipCount = receivedGossipCount + 1)
def incrementMergeConflictCount(): ClusterStats =
copy(mergeConflictCount = mergeConflictCount + 1)
def incrementMergeCount(): ClusterStats =
copy(mergeCount = mergeCount + 1)
def incrementMergeDetectedCount(): ClusterStats =
copy(mergeDetectedCount = mergeDetectedCount + 1)
def incrementSameCount(): ClusterStats =
copy(sameCount = sameCount + 1)
@ -1084,9 +1021,7 @@ private[cluster] case class ClusterStats(
def :+(that: ClusterStats): ClusterStats = {
ClusterStats(
this.receivedGossipCount + that.receivedGossipCount,
this.mergeConflictCount + that.mergeConflictCount,
this.mergeCount + that.mergeCount,
this.mergeDetectedCount + that.mergeDetectedCount,
this.sameCount + that.sameCount,
this.newerCount + that.newerCount,
this.olderCount + that.olderCount)
@ -1095,9 +1030,7 @@ private[cluster] case class ClusterStats(
def :-(that: ClusterStats): ClusterStats = {
ClusterStats(
this.receivedGossipCount - that.receivedGossipCount,
this.mergeConflictCount - that.mergeConflictCount,
this.mergeCount - that.mergeCount,
this.mergeDetectedCount - that.mergeDetectedCount,
this.sameCount - that.sameCount,
this.newerCount - that.newerCount,
this.olderCount - that.olderCount)