[GitHub] [kafka] vcrfxia commented on a diff in pull request #13188: KAFKA-14491: [5/N] Basic operations for RocksDB versioned store

["vcrfxia (via GitHub)" <gi...@apache.org>]

vcrfxia commented on code in PR #13188:
URL: https://github.com/apache/kafka/pull/13188#discussion_r1171931840


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streams/src/main/java/org/apache/kafka/streams/state/VersionedKeyValueStore.java:
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@@ -0,0 +1,99 @@
+/*
+ * 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.streams.state;
+
+import org.apache.kafka.streams.errors.InvalidStateStoreException;
+import org.apache.kafka.streams.processor.StateStore;
+
+/**
+ * A key-value store that stores multiple record versions per key, and supports timestamp-based
+ * retrieval operations to return the latest record (per key) as of a specified timestamp.
+ * Only one record is stored per key and timestamp, i.e., a second call to
+ * {@link #put(Object, Object, long)} with the same key and timestamp will replace the first.
+ * <p>
+ * Each store instance has an associated, fixed-duration "history retention" which specifies
+ * how long old record versions should be kept for. In particular, a versioned store guarantees
+ * to return accurate results for calls to {@link #get(Object, long)} where the provided timestamp
+ * bound is within history retention of the current observed stream time. (Queries with timestamp
+ * bound older than the specified history retention are considered invalid.)
+ *
+ * @param <K> The key type
+ * @param <V> The value type
+ */
+public interface VersionedKeyValueStore<K, V> extends StateStore {
+
+    /**
+     * Add a new record version associated with this key.
+     *
+     * @param key       The key
+     * @param value     The value, it can be {@code null};
+     *                  if the serialized bytes are also {@code null} it is interpreted as a delete
+     * @param timestamp The timestamp for this record version
+     * @throws NullPointerException If {@code null} is used for key.
+     */
+    void put(K key, V value, long timestamp);
+
+    /**
+     * Delete the value associated with this key from the store, at the specified timestamp
+     * (if there is such a value), and return the deleted value.
+     * <p>
+     * This operation is semantically equivalent to {@link #get(Object, long)} #get(key, timestamp))}
+     * followed by {@link #put(Object, Object, long) #put(key, null, timestamp)}.
+     *
+     * @param key       The key
+     * @param timestamp The timestamp for this delete
+     * @return The value and timestamp of the latest record associated with this key
+     *         as of the deletion timestamp (inclusive), or {@code null} if any of
+     *         (1) the store contains no records for this key, (2) the latest record
+     *         for this key as of the deletion timestamp is a tombstone, or
+     *         (3) the deletion timestamp is older than this store's history retention
+     *         (i.e., this store no longer contains data for the provided timestamp).
+     * @throws NullPointerException If {@code null} is used for key.
+     */
+    VersionedRecord<V> delete(K key, long timestamp);
+
+    /**
+     * Get the latest (by timestamp) record associated with this key.
+     *
+     * @param key The key to fetch
+     * @return The value and timestamp of the latest record associated with this key, or
+     *         {@code null} if either (1) the store contains no records for this key or (2) the
+     *         latest record for this key is a tombstone.
+     * @throws NullPointerException       If null is used for key.
+     * @throws InvalidStateStoreException if the store is not initialized

Review Comment:
   Updated in https://github.com/apache/kafka/pull/13615.



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