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https://issues.apache.org/jira/browse/HDDS-1499?focusedWorklogId=242682&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-242682
]
ASF GitHub Bot logged work on HDDS-1499:
----------------------------------------
Author: ASF GitHub Bot
Created on: 15/May/19 17:17
Start Date: 15/May/19 17:17
Worklog Time Spent: 10m
Work Description: bharatviswa504 commented on pull request #798:
HDDS-1499. OzoneManager Cache.
URL: https://github.com/apache/hadoop/pull/798#discussion_r284363194
##########
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:
Actually, this cache is used for correctness reasons for further operations
validation and read operation correctness. (As when double buffer comes in to
the place we don't commit to DB immediately)
And also we are cleaning up the cache after flush, so I am not sure what is
the use of loading entries. This cache is mainly for correctness reasons.
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Issue Time Tracking
-------------------
Worklog Id: (was: 242682)
Time Spent: 5h 50m (was: 5h 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: 5h 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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