[GitHub] [hbase] ramkrish86 commented on a change in pull request #868: HBASE-23296 Add CompositeBucketCache to support tiered BC

[GitBox <gi...@apache.org>]

ramkrish86 commented on a change in pull request #868: HBASE-23296 Add CompositeBucketCache to support tiered BC
URL: https://github.com/apache/hbase/pull/868#discussion_r349533873
 
 

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 File path: hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockCacheFactory.java
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 @@ -110,29 +113,35 @@ public static BlockCache createBlockCache(Configuration conf) {
           + "we will remove the deprecated config.", DEPRECATED_BLOCKCACHE_BLOCKSIZE_KEY,
         BLOCKCACHE_BLOCKSIZE_KEY);
     }
-    FirstLevelBlockCache l1Cache = createFirstLevelCache(conf);
+    BlockCache l1Cache = createFirstLevelCache(conf);
     if (l1Cache == null) {
       return null;
     }
-    boolean useExternal = conf.getBoolean(EXTERNAL_BLOCKCACHE_KEY, EXTERNAL_BLOCKCACHE_DEFAULT);
-    if (useExternal) {
-      BlockCache l2CacheInstance = createExternalBlockcache(conf);
-      return l2CacheInstance == null ?
-          l1Cache :
-          new InclusiveCombinedBlockCache(l1Cache, l2CacheInstance);
+    if (conf.getBoolean(EXTERNAL_BLOCKCACHE_KEY, EXTERNAL_BLOCKCACHE_DEFAULT)) {
+      BlockCache l2Cache = createExternalBlockcache(conf);
+      return l2Cache == null ? l1Cache : new InclusiveCombinedBlockCache(
+          (FirstLevelBlockCache)l1Cache, l2Cache);
     } else {
       // otherwise use the bucket cache.
-      BucketCache bucketCache = createBucketCache(conf);
-      if (!conf.getBoolean("hbase.bucketcache.combinedcache.enabled", true)) {
-        // Non combined mode is off from 2.0
-        LOG.warn(
-            "From HBase 2.0 onwards only combined mode of LRU cache and bucket cache is available");
+      BucketCache l2Cache = createBucketCache(conf, CacheLevel.L2);
+      if (conf.getBoolean(BUCKET_CACHE_COMPOSITE_KEY, false)) {
+        return l2Cache == null ? l1Cache : new CompositeBucketCache((BucketCache)l1Cache, l2Cache);
+      } else {
+        if (!conf.getBoolean("hbase.bucketcache.combinedcache.enabled", true)) {
+          // Non combined mode is off from 2.0
+          LOG.warn("From HBase 2.0 onwards only combined mode of LRU cache and bucket"
+              + " cache is available");
+        }
+        return l2Cache == null ? l1Cache : new CombinedBlockCache(
+            (FirstLevelBlockCache)l1Cache, l2Cache);
       }
-      return bucketCache == null ? l1Cache : new CombinedBlockCache(l1Cache, bucketCache);
     }
   }
 
-  private static FirstLevelBlockCache createFirstLevelCache(final Configuration c) {
+  private static BlockCache createFirstLevelCache(final Configuration c) {
+    if (c.getBoolean(BUCKET_CACHE_COMPOSITE_KEY, false)) {
+      return createBucketCache(c, CacheLevel.L1);
 
 Review comment:
   So L1 can be offheap - I mean the engine type and L2 is a seperate bucket cache and so it can be on file also? If both has to be offheap - we should recommend the memory usage part also. Say how much % will be good for L1 and how much for L2.

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