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https://issues.apache.org/jira/browse/CURATOR-584?focusedWorklogId=544082&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-544082
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ASF GitHub Bot logged work on CURATOR-584:
------------------------------------------
Author: ASF GitHub Bot
Created on: 29/Jan/21 07:41
Start Date: 29/Jan/21 07:41
Worklog Time Spent: 10m
Work Description: eolivelli commented on a change in pull request #376:
URL: https://github.com/apache/curator/pull/376#discussion_r566630026
##########
File path:
curator-framework/src/main/java/org/apache/curator/framework/imps/SetDataBuilderImpl.java
##########
@@ -210,6 +230,47 @@ public Stat forPath(String path) throws Exception
return this;
}
+ private void backgroundCheckIdempotent(final CuratorFrameworkImpl client,
final OperationAndData<PathAndBytes> mainOperationAndData, final String path,
final Backgrounding backgrounding)
+ {
+ final AsyncCallback.DataCallback dataCallback = new
AsyncCallback.DataCallback()
+ {
+ @Override
+ public void processResult(int rc, String path, Object ctx, byte[]
data, Stat stat)
+ {
+ if ( rc == KeeperException.Code.OK.intValue() )
+ {
+ if ( failNextIdempotentCheckForTesting )
+ {
+ failNextIdempotentCheckForTesting = false;
+ rc =
KeeperException.Code.CONNECTIONLOSS.intValue();
+ }
+ else if ( !idempotentSetMatches(stat.getVersion(),
mainOperationAndData.getData().getData(), data) )
+ {
+ rc = KeeperException.Code.BADVERSION.intValue();
+ }
+ }
+ CuratorEvent event = new CuratorEventImpl(client,
CuratorEventType.SET_DATA, rc, path, null, ctx, stat, null, null, null, null,
null);
+ client.processBackgroundOperation(mainOperationAndData,
event);
+ }
+ };
+ BackgroundOperation<PathAndBytes> operation = new
BackgroundOperation<PathAndBytes>()
+ {
+ @Override
+ public void
performBackgroundOperation(OperationAndData<PathAndBytes> op) throws Exception
+ {
+ try
+ {
+ client.getZooKeeper().getData(path, false, dataCallback,
backgrounding.getContext());
+ }
+ catch ( KeeperException e )
+ {
+ // ignore
Review comment:
log ?
##########
File path:
curator-framework/src/main/java/org/apache/curator/framework/imps/CreateBuilderImpl.java
##########
@@ -807,6 +826,53 @@ public void
performBackgroundOperation(OperationAndData<PathAndBytes> op) throws
client.queueOperation(new OperationAndData<>(operation, null, null,
null, null, null));
}
+ private void backgroundCheckIdempotent(final CuratorFrameworkImpl client,
final OperationAndData<PathAndBytes> mainOperationAndData, final String path,
final Backgrounding backgrounding)
+ {
+ final AsyncCallback.DataCallback dataCallback = new
AsyncCallback.DataCallback()
+ {
+ @Override
+ public void processResult(int rc, String path, Object ctx, byte[]
data, Stat stat)
+ {
+ if ( rc == KeeperException.Code.NONODE.intValue() )
+ {
+ client.queueOperation(mainOperationAndData); // try to
create it again
+ }
+ else
+ {
+ if ( rc == KeeperException.Code.OK.intValue() )
+ {
+ if ( failNextIdempotentCheckForTesting )
+ {
+ failNextIdempotentCheckForTesting = false;
+ rc =
KeeperException.Code.CONNECTIONLOSS.intValue();
+ }
+ else if ( !IdempotentUtils.matches(0,
mainOperationAndData.getData().getData(), stat.getVersion(), data) )
+ {
+ rc = KeeperException.Code.NODEEXISTS.intValue();
+ }
+ }
+ sendBackgroundResponse(rc, path, ctx, path, stat,
mainOperationAndData);
+ }
+ }
+ };
+ BackgroundOperation<PathAndBytes> operation = new
BackgroundOperation<PathAndBytes>()
+ {
+ @Override
+ public void
performBackgroundOperation(OperationAndData<PathAndBytes> op) throws Exception
+ {
+ try
+ {
+ client.getZooKeeper().getData(path, false, dataCallback,
backgrounding.getContext());
+ }
+ catch ( KeeperException e )
+ {
+ // ignore
Review comment:
log ?
##########
File path: pom.xml
##########
@@ -68,7 +68,7 @@
<!-- versions -->
<zookeeper-version>3.6.0</zookeeper-version>
- <maven-bundle-plugin-version>4.1.0</maven-bundle-plugin-version>
+ <maven-bundle-plugin-version>5.1.1</maven-bundle-plugin-version>
Review comment:
It should be fine to make the upgrade
##########
File path:
curator-framework/src/main/java/org/apache/curator/framework/imps/IdempotentUtils.java
##########
@@ -0,0 +1,53 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.curator.framework.imps;
+
+/*
+ * Utilties Class for idempotent operatons.
+ */
+class IdempotentUtils
+{
+
+ /**
+ * Returns whether the version and data currently in the node match what
would be expected in the idempotent retry case.
+ */
+ static boolean matches(int expectedVersion, byte[] expectedData, int
actualVersion, byte[] actualData)
+ {
+ return expectedVersion == actualVersion && matches(expectedData,
actualData);
+ }
+
+ /**
+ * Returns whether the data currently in the node matches what would be
expected in the idempotent retry case (ignoring version).
+ */
+ static boolean matches(byte[] expectedData, byte[] actualData)
+ {
+ if ( expectedData.length != actualData.length )
Review comment:
can we use java.util.Arrays.equals ?
##########
File path:
curator-framework/src/main/java/org/apache/curator/framework/imps/SetDataBuilderImpl.java
##########
@@ -51,6 +62,8 @@ public SetDataBuilderImpl(CuratorFrameworkImpl client,
Backgrounding backgroundi
this.backgrounding = backgrounding;
this.version = version;
this.compress = compress;
+ // TODO jslocum - this is only public for x-async api. Should I add
idempotent there too?
Review comment:
can we link a JIRA ?
##########
File path:
curator-framework/src/main/java/org/apache/curator/framework/imps/CreateBuilderImpl.java
##########
@@ -87,6 +93,7 @@ public CreateBuilderImpl(CuratorFrameworkImpl client,
CreateMode createMode, Bac
this.createParentsAsContainers = createParentsAsContainers;
this.compress = compress;
this.setDataIfExists = setDataIfExists;
+ this.idempotent = false; // TODO should I add this to async framework
as well? Looks like that's the reason this is a public constructor
Review comment:
can we please remove TODO and create an issue ?
or we can leave here the TODO but put the link to the JIRA
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Issue Time Tracking
-------------------
Worklog Id: (was: 544082)
Time Spent: 2h 50m (was: 2h 40m)
> Curator Client Fault Tolerance Extensions
> -----------------------------------------
>
> Key: CURATOR-584
> URL: https://issues.apache.org/jira/browse/CURATOR-584
> Project: Apache Curator
> Issue Type: Improvement
> Reporter: Josh Slocum
> Assignee: Jordan Zimmerman
> Priority: Minor
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
> Tl;dr My team at Indeed has developed ZooKeeper functionality to handle
> stateful retrying of connectionloss for write operations, and we wanted to
> reach out to discuss if this is something the Curator team may be interested
> in incorporating.
> We initially reached out to the Zookeeper team
> (https://issues.apache.org/jira/browse/ZOOKEEPER-3927) but were redirected to
> Curator as the better place to contribute them. The changes could be
> relatively easily added as additional parameters and/or extensions of the
> existing retry behavior in Curator's write operations.
>
> Hi Curator Devs,
> My team uses zookeeper extensively as part of a distributed key-value store
> we've built at Indeed (think HBase replacement). Due to our deployment setup
> co-locating our database daemons with our large hadoop cluster, and the
> network-intensive nature of a lot of our compute jobs, we were experiencing a
> large amount of transient ConnectionLoss issues. This was especially
> problematic on important write operations, such as the creation deletion of
> distributed locks/leases or updating distributed state in the cluster.
> We saw that some existing zookeeper client wrappers handled retrying in the
> presence of ConnectionLoss, but all of the ones we looked at (including
> Curator) didn't allow for retrying writes wiith all of the proper state.
> Consider the case of retrying a create. If the initial create had succeeded
> on the server, but the client got connectionloss, the client would get a
> NodeExists exception on the retried request, even though the znode was
> created. This resulted in many issues. For the distributed lock/lease
> example, to other nodes, it looked like the calling node had been successful
> acquiring the "lock", and to the calling node, it appeared that it was not
> able to acquire the "lock", which results in a deadlock.
> Curator has parameters that can modify the behavior upon retry, but those
> were not sufficient. For example, create() has orSetData(), and delete() has
> guaranteed().
> To solve this, we implemented a set of "connection-loss tolerant primitives"
> for the main types of write operations. They handle a connection loss by
> retrying the operation in a loop, but upon error cases in the retry, inspect
> the current state to see if it matches the case where a previous round that
> got connectionloss actually succeeded.
> * createRetriable(String path, byte[] data)
> * setDataRetriable(String path, byte[] newData, int currentVersion)
> * deleteRetriable(String path, int currentVersion)
> * compareAndDeleteRetriable(String path, byte[] currentData, int
> currentVersion)
> For example, in createRetriable, it will retry the create again on connection
> loss. If the retried call gets a NodeExists exception, it will check to see
> if (getData(path) == data and dataVersion == 0). If it does, it assumes the
> first create succeeded and returns success, otherwise it propagates the
> NodeExists exception.
> These primitives have allowed us to program our ZooKeeper layer as if
> ConnectionLoss isn't a transient state we have to worry about, since they
> have essentially the same guarantees as the non-retriable functions in the
> zookeeper api do (with a slight difference in semantics).
> Because these behaviors could be relatively easily added to Curator as
> additional parameters to the existing mechanisms, and (to my knowledge)
> aren't implemented anywhere else, we think it could be a useful contribution
> to the Curator project. If this isn't something that Curator is interested in
> incorporating, Indeed may also consider open sourcing it as a standalone
> library.
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