+clu #13584 Accept joining to be WeaklyUp during network split

* experimental feature, disabled by default
* Adding documentation to mention weakly up members.
  plus adding new diagram.

akka-cluster/src/multi-jvm/scala/akka/cluster/MemberWeaklyUpSpec.scala

@@ -0,0 +1,119 @@
+/**
+ * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.cluster
+
+import scala.language.postfixOps
+import scala.concurrent.duration._
+import akka.remote.testkit.MultiNodeConfig
+import akka.remote.testkit.MultiNodeSpec
+import akka.remote.transport.ThrottlerTransportAdapter.Direction
+import akka.testkit._
+import com.typesafe.config.ConfigFactory
+import akka.cluster.MemberStatus.WeaklyUp
+
+object MemberWeaklyUpSpec extends MultiNodeConfig {
+  val first = role("first")
+  val second = role("second")
+  val third = role("third")
+  val fourth = role("fourth")
+  val fifth = role("fifth")
+
+  commonConfig(debugConfig(on = false).
+    withFallback(ConfigFactory.parseString("""
+        akka.remote.retry-gate-closed-for = 3 s
+        akka.cluster.allow-weakly-up-members = on
+        """)).
+    withFallback(MultiNodeClusterSpec.clusterConfig))
+
+  testTransport(on = true)
+}
+
+class MemberWeaklyUpMultiJvmNode1 extends MemberWeaklyUpSpec
+class MemberWeaklyUpMultiJvmNode2 extends MemberWeaklyUpSpec
+class MemberWeaklyUpMultiJvmNode3 extends MemberWeaklyUpSpec
+class MemberWeaklyUpMultiJvmNode4 extends MemberWeaklyUpSpec
+class MemberWeaklyUpMultiJvmNode5 extends MemberWeaklyUpSpec
+
+abstract class MemberWeaklyUpSpec
+  extends MultiNodeSpec(MemberWeaklyUpSpec)
+  with MultiNodeClusterSpec {
+
+  import MemberWeaklyUpSpec._
+
+  muteMarkingAsUnreachable()
+
+  val side1 = Vector(first, second)
+  val side2 = Vector(third, fourth, fifth)
+
+  "A cluster of 3 members" must {
+
+    "reach initial convergence" taggedAs LongRunningTest in {
+      awaitClusterUp(first, third, fourth)
+
+      enterBarrier("after-1")
+    }
+
+    "detect network partition and mark nodes on other side as unreachable" taggedAs LongRunningTest in within(20 seconds) {
+      runOn(first) {
+        // split the cluster in two parts (first, second) / (third, fourth, fifth)
+        for (role1 ← side1; role2 ← side2) {
+          testConductor.blackhole(role1, role2, Direction.Both).await
+        }
+      }
+      enterBarrier("after-split")
+
+      runOn(first) {
+        awaitAssert(clusterView.unreachableMembers.map(_.address) should be(Set(address(third), address(fourth))))
+      }
+
+      runOn(third, fourth) {
+        awaitAssert(clusterView.unreachableMembers.map(_.address) should be(Set(address(first))))
+      }
+
+      enterBarrier("after-2")
+    }
+
+    "accept joining on each side and set status to WeaklyUp" taggedAs LongRunningTest in within(20 seconds) {
+      runOn(second) {
+        Cluster(system).join(first)
+      }
+      runOn(fifth) {
+        Cluster(system).join(fourth)
+      }
+      enterBarrier("joined")
+
+      runOn(side1: _*) {
+        awaitAssert {
+          clusterView.members.size should be(4)
+          clusterView.members.exists { m ⇒ m.address == address(second) && m.status == WeaklyUp } should be(true)
+        }
+      }
+
+      runOn(side2: _*) {
+        awaitAssert {
+          clusterView.members.size should be(4)
+          clusterView.members.exists { m ⇒ m.address == address(fifth) && m.status == WeaklyUp } should be(true)
+        }
+      }
+
+      enterBarrier("after-3")
+    }
+
+    "change status to Up after healed network partition" taggedAs LongRunningTest in within(20 seconds) {
+      runOn(first) {
+        for (role1 ← side1; role2 ← side2) {
+          testConductor.passThrough(role1, role2, Direction.Both).await
+        }
+      }
+      enterBarrier("after-passThrough")
+
+      awaitAllReachable()
+      awaitMembersUp(5)
+
+      enterBarrier("after-4")
+    }
+
+  }
+
+}

akka-cluster/src/multi-jvm/scala/akka/cluster/MinMembersBeforeUpSpec.scala

@@ -26,6 +26,17 @@ object MinMembersBeforeUpMultiJvmSpec extends MultiNodeConfig {
     withFallback(MultiNodeClusterSpec.clusterConfigWithFailureDetectorPuppet))
 }
 
+object MinMembersBeforeUpWithWeaklyUpMultiJvmSpec extends MultiNodeConfig {
+  val first = role("first")
+  val second = role("second")
+  val third = role("third")
+
+  commonConfig(debugConfig(on = false).withFallback(ConfigFactory.parseString("""
+      akka.cluster.min-nr-of-members = 3
+      akka.cluster.allow-weakly-up-members = on""")).
+    withFallback(MultiNodeClusterSpec.clusterConfigWithFailureDetectorPuppet))
+}
+
 object MinMembersOfRoleBeforeUpMultiJvmSpec extends MultiNodeConfig {
   val first = role("first")
   val second = role("second")
@@ -46,6 +57,10 @@ class MinMembersBeforeUpMultiJvmNode1 extends MinMembersBeforeUpSpec
 class MinMembersBeforeUpMultiJvmNode2 extends MinMembersBeforeUpSpec
 class MinMembersBeforeUpMultiJvmNode3 extends MinMembersBeforeUpSpec
 
+class MinMembersBeforeUpWithWeaklyUpMultiJvmNode1 extends MinMembersBeforeUpSpec
+class MinMembersBeforeUpWithWeaklyUpMultiJvmNode2 extends MinMembersBeforeUpSpec
+class MinMembersBeforeUpWithWeaklyUpMultiJvmNode3 extends MinMembersBeforeUpSpec
+
 class MinMembersOfRoleBeforeUpMultiJvmNode1 extends MinMembersOfRoleBeforeUpSpec
 class MinMembersOfRoleBeforeUpMultiJvmNode2 extends MinMembersOfRoleBeforeUpSpec
 class MinMembersOfRoleBeforeUpMultiJvmNode3 extends MinMembersOfRoleBeforeUpSpec
@@ -63,6 +78,19 @@ abstract class MinMembersBeforeUpSpec extends MinMembersBeforeUpBase(MinMembersB
   }
 }
 
+abstract class MinMembersBeforeUpWithWeaklyUpSpec extends MinMembersBeforeUpBase(MinMembersBeforeUpMultiJvmSpec) {
+
+  override def first: RoleName = MinMembersBeforeUpWithWeaklyUpMultiJvmSpec.first
+  override def second: RoleName = MinMembersBeforeUpWithWeaklyUpMultiJvmSpec.second
+  override def third: RoleName = MinMembersBeforeUpWithWeaklyUpMultiJvmSpec.third
+
+  "Cluster leader" must {
+    "wait with moving members to UP until minimum number of members have joined with weakly up enabled" taggedAs LongRunningTest in {
+      testWaitMovingMembersToUp()
+    }
+  }
+}
+
 abstract class MinMembersOfRoleBeforeUpSpec extends MinMembersBeforeUpBase(MinMembersOfRoleBeforeUpMultiJvmSpec) {
 
   override def first: RoleName = MinMembersOfRoleBeforeUpMultiJvmSpec.first