Github user bowenli86 commented on a diff in the pull request:
https://github.com/apache/flink/pull/3359#discussion_r141942758
--- Diff:
flink-contrib/flink-timerserivce-rocksdb/src/main/java/org/apache/flink/contrib/streaming/api/operators/RocksDBInternalTimerService.java
---
@@ -0,0 +1,797 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.contrib.streaming.api.operators;
+
+
+import org.apache.flink.api.common.typeutils.base.IntSerializer;
+import org.apache.flink.api.common.typeutils.base.LongSerializer;
+import org.apache.flink.api.java.tuple.Tuple4;
+import org.apache.flink.core.fs.FileSystem;
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.core.memory.DataInputViewStreamWrapper;
+import org.apache.flink.core.memory.DataOutputViewStreamWrapper;
+import org.apache.flink.runtime.state.KeyGroupRange;
+import org.apache.flink.runtime.state.KeyGroupRangeAssignment;
+import org.apache.flink.streaming.api.operators.InternalTimer;
+import org.apache.flink.streaming.api.operators.InternalTimerService;
+import org.apache.flink.streaming.api.operators.KeyContext;
+import org.apache.flink.streaming.runtime.tasks.ProcessingTimeService;
+import org.apache.flink.util.Preconditions;
+import org.rocksdb.ColumnFamilyDescriptor;
+import org.rocksdb.ColumnFamilyHandle;
+import org.rocksdb.ColumnFamilyOptions;
+import org.rocksdb.CompactionStyle;
+import org.rocksdb.DBOptions;
+import org.rocksdb.RocksDB;
+import org.rocksdb.RocksDBException;
+import org.rocksdb.RocksIterator;
+import org.rocksdb.StringAppendOperator;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * {@link InternalTimerService} that stores timers in RocksDB.
+ */
+public class RocksDBInternalTimerService<K, N> extends
InternalTimerService<K, N> {
+
+ private static Logger LOG =
LoggerFactory.getLogger(RocksDBInternalTimerService.class);
+
+ /** The data base where stores all timers */
+ private final RocksDB db;
+
+ /** The path where the rocksdb locates */
+ private final Path dbPath;
+
+ /**
+ * The in-memory heaps backed by rocksdb to retrieve the next timer to
trigger. Each
+ * partition's leader is stored in the heap. When the timers in a
partition is changed, we
+ * will change the partition's leader and update the heap accordingly.
+ */
+ private final int numPartitions;
+ private final PersistentTimerHeap eventTimeHeap;
+ private final PersistentTimerHeap processingTimeHeap;
+
+ private static int MAX_PARTITIONS = (1 << 16);
+
+ public RocksDBInternalTimerService(
+ int totalKeyGroups,
+ KeyGroupRange keyGroupRange,
+ KeyContext keyContext,
+ ProcessingTimeService processingTimeService,
+ Path dbPath) {
+
+ super(totalKeyGroups, keyGroupRange, keyContext,
processingTimeService);
+
+ this.dbPath = dbPath;
+
+ try {
+ FileSystem fileSystem = this.dbPath.getFileSystem();
+ if (fileSystem.exists(this.dbPath)) {
+ fileSystem.delete(this.dbPath, true);
+ }
+
+ fileSystem.mkdirs(dbPath);
+ } catch (IOException e) {
+ throw new RuntimeException("Error while creating
directory for rocksdb timer service.", e);
+ }
+
+ ColumnFamilyOptions columnFamilyOptions = new
ColumnFamilyOptions()
+ .setMergeOperator(new StringAppendOperator())
+ .setCompactionStyle(CompactionStyle.UNIVERSAL);
+ ColumnFamilyDescriptor defaultColumnDescriptor = new
ColumnFamilyDescriptor("default".getBytes(), columnFamilyOptions);
+
+ DBOptions dbOptions = new DBOptions()
--- End diff --
Users who use RocksDB backend may already have a DBOptions defined, either
with their own params or from PredefinedOptions or PreDefinedOptions.DEFAULT.
In that case, we should use that DBOptions here.
In cases that users don't use RocksDB state backend, move this options to
PredefinedOptions.class as an enum, and reference it as
PredefinedOptions.INTERNAL_TIME_SERVICE
---
