bharatviswa504 commented on a change in pull request #798: HDDS-1499.
OzoneManager Cache.
URL: https://github.com/apache/hadoop/pull/798#discussion_r284392124
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File path:
hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/TypedTable.java
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@@ -69,8 +94,40 @@ 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.
+ *
+ * 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.
+ if (cache != null) {
+ CacheValue<VALUE> cacheValue = cache.get(new CacheKey<>(key));
+ if (cacheValue == null) {
+ return getFromTable(key);
+ } else {
+ // Doing this because, if the Cache Value Last operation is deleted
+ // means it will eventually removed from DB. So, we should return null.
+ if (cacheValue.getLastOperation() != CacheValue.OperationType.DELETED)
{
+ return cacheValue.getValue();
+ } else {
+ return null;
Review comment:
Done.
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