MasterNodeChangePredicate should use the node instance to detect master change #25877
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…er change This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart.
bleskes
added
:Distributed Coordination/Discovery-Plugins
ywelsch
suggested changes
Jul 25, 2017
| public static Predicate<ClusterState> build(ClusterState currentState) { | ||
| final long currentVersion = currentState.version(); | ||
| final String currentMaster = currentState.nodes().getMasterNodeId(); | ||
| final String currentMasterId = currentState.nodes().getMasterNode().getEphemeralId(); |
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NullPointerException if getMasterNode() returns null?
| final String newMasterId = newState.nodes().getMasterNode().getEphemeralId(); | ||
| final boolean accept; | ||
| if (newMaster == null) { | ||
| if (newMasterId == null) { |
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newMasterId (= getEphemeralId()) cannot be null, getMasterNode() can be, however.
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bad refactoring. yikes. will fix and check for the testing coverage.
| if (newMasterId == null) { | ||
| accept = false; | ||
| } else if (newMaster.equals(currentMaster) == false){ | ||
| } else if (newMasterId.equals(currentMasterId) == false){ |
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maybe it's nicer to just capture the DiscoveryNode object here and use equals on that (internally it will use the ephemeral id for comparison anyhow).
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That's I had it before. I refactored it as I prefer to have explicit references to places that depends on the ephemeral id. I know we use the disco nodes themselves in many places but I don't want to add another one.
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|
Thx @ywelsch . I addressed your feedback. Can you take another look please? |
ywelsch
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Jul 26, 2017
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LGTM (after addressing 3 nits)
| if (newMaster == null) { | ||
| accept = false; | ||
| } else if (newMaster.equals(currentMaster) == false){ | ||
| } else if (newMaster.getEphemeralId().equals(currentMasterId) == false){ |
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space missing between closing and opening bracket: false){
|
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| public void testDelegateToFailingMaster() throws ExecutionException, InterruptedException { | ||
| boolean failsWithConnectTransportException = randomBoolean(); | ||
| boolean failsWithConnectTransportException = true || randomBoolean(); |
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You probably want to remove true || before pushing ;-)
| // reset the same state to increment a version simulating a join of an existing node | ||
| setState(clusterService, clusterService.state()); | ||
| if (randomBoolean()) { | ||
| // simulate master node removal removal |
bleskes
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Jul 26, 2017
…er change (#25877) This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart. Fixes #25471
bleskes
added a commit
that referenced
this pull request
Jul 26, 2017
…er change (#25877) This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart. Fixes #25471
bleskes
added a commit
that referenced
this pull request
Jul 26, 2017
…er change (#25877) This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart. Fixes #25471
bleskes
added a commit
that referenced
this pull request
Jul 26, 2017
…er change (#25877) This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart. Fixes #25471
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This predicate is used to deal with the intricacies of detecting when a master is reelected/nodes rejoins an existing master. The current implementation is based on nodeIds, which is fine if the master really change. If the nodeId is equal the code falls back to detecting an increment in the cluster state version which happens when a node is re-elected or when the node rejoins. Sadly this doesn't cover the case where the same node is elected after a full restart of all master nodes. In that case we recover the cluster state from disk but the version is reset back to 0. To fix this, the check should be done based on ephemeral IDs which are reset on restart.
Fixes #25471