cmccabe commented on a change in pull request #9901: URL: https://github.com/apache/kafka/pull/9901#discussion_r568157113
########## File path: metadata/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java ########## @@ -0,0 +1,449 @@ +/* + * 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.kafka.timeline; + +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; +import java.util.NoSuchElementException; + + +/** + * SnapshottableHashTable implements a hash table that supports creating point-in-time + * snapshots. Each snapshot is immutable once it is created; the past cannot be changed. + * We handle divergences between the current state and historical state by copying a + * reference to elements that have been deleted or overwritten into the snapshot tiers Review comment: good catch. I updated the JavaDoc. ########## File path: metadata/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java ########## @@ -0,0 +1,449 @@ +/* + * 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.kafka.timeline; + +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; +import java.util.NoSuchElementException; + + +/** + * SnapshottableHashTable implements a hash table that supports creating point-in-time + * snapshots. Each snapshot is immutable once it is created; the past cannot be changed. + * We handle divergences between the current state and historical state by copying a + * reference to elements that have been deleted or overwritten into the snapshot tiers + * in which they still exist. Each tier has its own hash table. + * + * In order to retrieve an object from epoch E, we only have to check two tiers: the Review comment: updated ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
