[
https://issues.apache.org/jira/browse/ARTEMIS-2118?focusedWorklogId=200909&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-200909
]
ASF GitHub Bot logged work on ARTEMIS-2118:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 19/Feb/19 21:58
Start Date: 19/Feb/19 21:58
Worklog Time Spent: 10m
Work Description: michaelandrepearce commented on pull request #2548:
ARTEMIS-2118 Enhanced Message Groups Support
URL: https://github.com/apache/activemq-artemis/pull/2548#discussion_r258247586
##########
File path:
artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/BucketMessageGroups.java
##########
@@ -0,0 +1,164 @@
+/*
+ * 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.activemq.artemis.core.server.impl;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Predicate;
+import org.apache.activemq.artemis.api.core.SimpleString;
+
+/**
+ * BucketMessageGroups, stores values against a bucket, where the bucket used
is based on the provided key objects hash.
+ *
+ * As such where keys compute to the same bucket they will act on that stored
value, not the unique specific key.
+ *
+ * The number of buckets is provided at construction.
+ */
+public class BucketMessageGroups<C> implements MessageGroups<C> {
+
+ //This _AMQ_GROUP_BUCKET_INT_KEY uses the post-fixed value after this key,
as an int, it is used for a few cases:
+ //1) For the admin screen we need to show a group key so we have to map
back from int to something, as it expects SimpleString.
+ //2) Admin users still need to interact with a specific bucket/group e.g.
they may need to reset a bucket.
+ //3) Choice of key is we want to avoid risk of clashing with users groups
keys.
+ //4) Actually makes testing a little easier as we know how the parsed int
will hash.
+ private static SimpleString _AMQ_GROUP_BUCKET_INT_KEY = new
SimpleString("_AMQ_GROUP_BUCKET_INT_KEY_");
+
+ private final int bucketCount;
+ private C[] buckets;
+ private int size = 0;
+
+ public BucketMessageGroups(int bucketCount) {
+ if (bucketCount < 1) {
+ throw new IllegalArgumentException("Bucket count must be greater than
0");
+ }
+ this.bucketCount = bucketCount;
+ }
+
+ private int getBucket(SimpleString key) {
+ Object bucketKey = key;
+ if (key.startsWith(_AMQ_GROUP_BUCKET_INT_KEY)) {
+ bucketKey = retrieveBucketIntFromKey(key);
+ }
+ return getHashBucket(bucketKey, bucketCount);
+ }
+
+ private static int getHashBucket(final Object key, final int bucketCount) {
+ return (key.hashCode() & Integer.MAX_VALUE) % bucketCount;
Review comment:
Ive responded to this same comment several times yes. That only works if
buckets is power of two and we have to honour the bucket count set.
The actual performance compared to everything is tiny. Note we actually have
mod in journal code fyi.
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Issue Time Tracking
-------------------
Worklog Id: (was: 200909)
Time Spent: 9h 40m (was: 9.5h)
> Enhanced Message Groups Support
> --------------------------------
>
> Key: ARTEMIS-2118
> URL: https://issues.apache.org/jira/browse/ARTEMIS-2118
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Components: Broker
> Reporter: Michael Andre Pearce
> Assignee: Michael Andre Pearce
> Priority: Major
> Time Spent: 9h 40m
> Remaining Estimate: 0h
>
> This ticket is for supporting some Message Group Enhancements.
>
> Currently Artemis implements message groups in a simple way, equivalent to
> SimpleMessageGroupMap in activemq5.
> [http://activemq.apache.org/message-groups.html]
> "SimpleMessageGroupMap keeps track of every group but suffers from unbounded
> memory use."
>
> For use cases migrating from activemq5 its important artemis supports similar
> MessageGroupHashBucked feature.
> "MessageGroupHashBucked keeps track of every group and has bounded memory
> use."
> As such, this JIRA is to add support for being able to enable a semantic
> equivalent to MessageGroupHashBucket from activemq5, at the queue level.
>
> Also currently it is not possible for a specific queue disable grouping, this
> can be useful where a shared address by many queues, where some consumers
> care for ordering and others do not.
> Lastly add an ability to rebalance message groups when a consumer is added,
> this is useful where you want groups more evenly balanced when consumers come
> online, even after dispatching started.
>
>
>
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