bharatviswa504 commented on a change in pull request #1588: HDDS-1986. Fix
listkeys API.
URL: https://github.com/apache/hadoop/pull/1588#discussion_r332591385
##########
File path:
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OmMetadataManagerImpl.java
##########
@@ -680,26 +688,85 @@ public boolean isBucketEmpty(String volume, String
bucket)
seekPrefix = getBucketKey(volumeName, bucketName + OM_KEY_PREFIX);
}
int currentCount = 0;
- try (TableIterator<String, ? extends KeyValue<String, OmKeyInfo>> keyIter =
- getKeyTable()
- .iterator()) {
- KeyValue<String, OmKeyInfo> kv = keyIter.seek(seekKey);
- while (currentCount < maxKeys && keyIter.hasNext()) {
- kv = keyIter.next();
- // Skip the Start key if needed.
- if (kv != null && skipStartKey && kv.getKey().equals(seekKey)) {
- continue;
+
+
+ TreeMap<String, OmKeyInfo> cacheKeyMap = new TreeMap<>();
+ Set<String> deletedKeySet = new TreeSet<>();
+ Iterator<Map.Entry<CacheKey<String>, CacheValue<OmKeyInfo>>> iterator =
+ keyTable.cacheIterator();
+
+ //TODO: We can avoid this iteration if table cache has stored entries in
+ // treemap. Currently HashMap is used in Cache. HashMap get operation is an
+ // constant time operation, where as for treeMap get is log(n).
+ // So if we move to treemap, the get operation will be affected. As get
+ // is frequent operation on table. So, for now in list we iterate cache map
+ // and construct treeMap which match with keyPrefix and are greater than or
+ // equal to startKey. Later we can revisit this, if list operation
+ // is becoming slow.
+ while (iterator.hasNext()) {
Review comment:
The key cache is not full cache, so if double buffer flush is going on well
in background, this should have around couple of 100 entries. When I started
freon with 10 threads, i see the value of maximum iteration is 200. So, almost
in the cache we have 200 entries. (But on tried with busy workload clusters,
slow disks)
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