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https://issues.apache.org/jira/browse/HDDS-1499?focusedWorklogId=242144&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-242144
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ASF GitHub Bot logged work on HDDS-1499:
----------------------------------------
Author: ASF GitHub Bot
Created on: 14/May/19 23:45
Start Date: 14/May/19 23:45
Worklog Time Spent: 10m
Work Description: arp7 commented on pull request #798: HDDS-1499.
OzoneManager Cache.
URL: https://github.com/apache/hadoop/pull/798#discussion_r284026725
##########
File path:
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/cache/TableCache.java
##########
@@ -0,0 +1,73 @@
+/*
+ * 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.hadoop.utils.db.cache;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Evolving;
+
+/**
+ * Cache used for RocksDB tables.
+ * @param <CACHEKEY>
+ * @param <CACHEVALUE>
+ */
+
+@Private
+@Evolving
+public interface TableCache<CACHEKEY extends CacheKey,
+ CACHEVALUE extends CacheValue> {
+
+ /**
+ * Return the value for the key if it is present, otherwise return null.
+ * @param cacheKey
+ * @return CACHEVALUE
+ */
+ CACHEVALUE get(CACHEKEY cacheKey);
+
+ /**
+ * Add an entry to the cache, if the key already exists it overrides.
+ * @param cacheKey
+ * @param value
+ */
+ void put(CACHEKEY cacheKey, CACHEVALUE value);
+
+ /**
+ * Removes all the entries from the cache which are having epoch value less
+ * than or equal to specified epoch value.
+ * @param epoch
+ */
+ void cleanup(long epoch);
+
+ /**
+ * Return the size of the cache.
+ * @return size
+ */
+ int size();
+
+ /**
+ * Defines type of cache need to be used by OM RocksDB tables.
+ */
+ enum CACHETYPE {
Review comment:
One feedback from Anu was to not differentiate between full and partial
cache while initializing so caller does not have to make a choice.
Instead we try to limit cache size by configuration and load as many entries
as possible. If we cannot load all entries then we could set a flag that it is
a partial cache. The implementation will certainly be a bit more complex.
~~I don't have a strong opinion either way. I am +1 with current approach
also.~~
On second thought I am leaning towards removing this distinction.
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Issue Time Tracking
-------------------
Worklog Id: (was: 242144)
Time Spent: 4h 50m (was: 4h 40m)
> OzoneManager Cache
> ------------------
>
> Key: HDDS-1499
> URL: https://issues.apache.org/jira/browse/HDDS-1499
> Project: Hadoop Distributed Data Store
> Issue Type: Sub-task
> Components: Ozone Manager
> Reporter: Bharat Viswanadham
> Assignee: Bharat Viswanadham
> Priority: Major
> Labels: pull-request-available
> Time Spent: 4h 50m
> Remaining Estimate: 0h
>
> In this Jira, we shall implement a cache for Table.
> As with OM HA, we are planning to implement double buffer implementation to
> flush transaction in a batch, instead of using rocksdb put() for every
> operation. When this comes in to place we need cache in OzoneManager HA to
> handle/server the requests for validation/returning responses.
>
> This Jira will implement Cache as an integral part of the table. In this way
> users using this table does not need to handle like check cache/db. For this,
> we can update get API in the table to handle the cache.
>
> This Jira will implement:
> # Cache as a part of each Table.
> # Uses this cache in get().
> # Exposes api for cleanup, add entries to cache.
> Usage to add the entries in to cache will be done in further jira's.
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