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https://issues.apache.org/jira/browse/HDDS-1499?focusedWorklogId=244378&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-244378
]
ASF GitHub Bot logged work on HDDS-1499:
----------------------------------------
Author: ASF GitHub Bot
Created on: 17/May/19 22:15
Start Date: 17/May/19 22:15
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_r285304435
##########
File path:
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/TypedTable.java
##########
@@ -69,8 +79,34 @@ public boolean isEmpty() throws IOException {
return rawTable.isEmpty();
}
+ /**
+ * Returns the value mapped to the given key in byte array or returns null
+ * if the key is not found.
+ *
+ * Caller's of this method should use synchronization mechanism, when
+ * accessing. First it will check from cache, if it has entry return the
+ * value, otherwise get from the RocksDB table.
+ *
+ * @param key metadata key
+ * @return VALUE
+ * @throws IOException
+ */
@Override
public VALUE get(KEY key) throws IOException {
+ // Here the metadata lock will guarantee that cache is not updated for same
+ // key during get key.
+ CacheValue< VALUE > cacheValue = cache.get(new CacheKey<>(key));
+ if (cacheValue == null) {
+ // If no cache for the table or if it does not exist in cache get from
+ // RocksDB table.
+ return getFromTable(key);
+ } else {
+ // We have a value in cache, return the value.
+ return cacheValue.getValue();
Review comment:
Yes actual value in CacheValue can be null.
**Implementation of CacheValue getValue**
public VALUE getValue() {
return value.orNull();
}
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Issue Time Tracking
-------------------
Worklog Id: (was: 244378)
Time Spent: 10h (was: 9h 50m)
> 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: 10h
> 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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