HDDS-3244. Improve write efficiency by opening RocksDB only once (#709)

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/utils/ContainerCache.java

@@ -160,4 +160,19 @@ public void removeDB(String containerDBPath) {
       lock.unlock();
     }
   }
+
+  /**
+   * Add a DB handler into cache.
+   *
+   * @param containerDBPath - DB path of the container.
+   * @param db - DB handler
+   */
+  public void addDB(String containerDBPath, ReferenceCountedDB db) {
+    lock.lock();
+    try {
+      this.putIfAbsent(containerDBPath, db);
+    } finally {
+      lock.unlock();
+    }
+  }
 }

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/BlockUtils.java

@@ -95,6 +95,20 @@ public static void shutdownCache(ContainerCache cache)  {
     cache.shutdownCache();
   }
 
+  /**
+   * Add a DB handler into cache.
+   *
+   * @param db - DB handler.
+   * @param containerDBPath - DB path of the container.
+   * @param conf configuration.
+   */
+  public static void addDB(ReferenceCountedDB db, String containerDBPath,
+      Configuration conf) {
+    ContainerCache cache = ContainerCache.getInstance(conf);
+    Preconditions.checkNotNull(cache);
+    cache.addDB(containerDBPath, db);
+  }
+
   /**
    * Parses the {@link BlockData} from a bytes array.
    *

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/KeyValueContainerUtil.java

@@ -73,14 +73,6 @@ public static void createContainerMetaData(File containerMetaDataPath, File
       throw new IOException("Unable to create directory for metadata storage." +
           " Path: " + containerMetaDataPath);
     }
-    MetadataStore store = MetadataStoreBuilder.newBuilder().setConf(conf)
-        .setCreateIfMissing(true).setDbFile(dbFile).build();
-
-    // we close since the SCM pre-creates containers.
-    // we will open and put Db handle into a cache when keys are being created
-    // in a container.
-
-    store.close();
 
     if (!chunksPath.mkdirs()) {
       LOG.error("Unable to create chunks directory Container {}",
@@ -91,6 +83,13 @@ public static void createContainerMetaData(File containerMetaDataPath, File
       throw new IOException("Unable to create directory for data storage." +
           " Path: " + chunksPath);
     }
+
+    MetadataStore store = MetadataStoreBuilder.newBuilder().setConf(conf)
+        .setCreateIfMissing(true).setDbFile(dbFile).build();
+    ReferenceCountedDB db =
+        new ReferenceCountedDB(store, dbFile.getAbsolutePath());
+    //add db handler into cache
+    BlockUtils.addDB(db, dbFile.getAbsolutePath(), conf);
   }
 
   /**