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Add minimum cap for ReadMajority/WriteMajority #21618

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This commit is contained in:
inakov 2017-01-18 14:13:40 +02:00
parent 91d6a3f125
commit e043a9fffe
4 changed files with 56 additions and 7 deletions
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28
akka-distributed-data/src/main/scala/akka/cluster/ddata/Replicator.scala
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@ -193,6 +193,8 @@ object Replicator {
Props(new Replicator(settings)).withDeploy(Deploy.local).withDispatcher(settings.dispatcher)
}
val DefaultMajorityMinCap: Int = 0
sealed trait ReadConsistency {
def timeout: FiniteDuration
}
@ -202,7 +204,9 @@ object Replicator {
final case class ReadFrom(n: Int, timeout: FiniteDuration) extends ReadConsistency {
require(n >= 2, "ReadFrom n must be >= 2, use ReadLocal for n=1")
}
final case class ReadMajority(timeout: FiniteDuration) extends ReadConsistency
final case class ReadMajority(timeout: FiniteDuration, minCap: Int = DefaultMajorityMinCap) extends ReadConsistency {
def this(timeout: FiniteDuration) = this(timeout, DefaultMajorityMinCap)
}
final case class ReadAll(timeout: FiniteDuration) extends ReadConsistency
sealed trait WriteConsistency {
@ -214,7 +218,9 @@ object Replicator {
final case class WriteTo(n: Int, timeout: FiniteDuration) extends WriteConsistency {
require(n >= 2, "WriteTo n must be >= 2, use WriteLocal for n=1")
}
final case class WriteMajority(timeout: FiniteDuration) extends WriteConsistency
final case class WriteMajority(timeout: FiniteDuration, minCap: Int = DefaultMajorityMinCap) extends WriteConsistency {
def this(timeout: FiniteDuration) = this(timeout, DefaultMajorityMinCap)
}
final case class WriteAll(timeout: FiniteDuration) extends WriteConsistency
/**
@ -1489,6 +1495,16 @@ final class Replicator(settings: ReplicatorSettings) extends Actor with ActorLog
private[akka] object ReadWriteAggregator {
case object SendToSecondary
val MaxSecondaryNodes = 10
def calculateMajorityWithMinCap(minCap: Int, numberOfNodes: Int): Int = {
if (numberOfNodes <= minCap) {
numberOfNodes
} else {
val majority = numberOfNodes / 2 + 1
if (majority <= minCap) minCap
else majority
}
}
}
/**
@ -1571,9 +1587,9 @@ private[akka] class WriteAggregator(
override val doneWhenRemainingSize = consistency match {
case WriteTo(n, _) ⇒ nodes.size - (n - 1)
case _: WriteAll ⇒ 0
case _: WriteMajority ⇒
case WriteMajority(_, minCap) ⇒
val N = nodes.size + 1
val w = N / 2 + 1 // write to at least (N/2+1) nodes
val w = calculateMajorityWithMinCap(minCap, N)
N - w
case WriteLocal ⇒
throw new IllegalArgumentException("WriteLocal not supported by WriteAggregator")
@ -1678,9 +1694,9 @@ private[akka] class ReadAggregator(
override val doneWhenRemainingSize = consistency match {
case ReadFrom(n, _) ⇒ nodes.size - (n - 1)
case _: ReadAll ⇒ 0
case _: ReadMajority ⇒
case ReadMajority(_, minCap) ⇒
val N = nodes.size + 1
val r = N / 2 + 1 // read from at least (N/2+1) nodes
val r = calculateMajorityWithMinCap(minCap, N)
N - r
case ReadLocal ⇒
throw new IllegalArgumentException("ReadLocal not supported by ReadAggregator")