Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1653 insertions, 0 deletions

diff --git a/src/rocksdb/java/benchmark/src/main/java/org/rocksdb/benchmark/DbBenchmark.java b/src/rocksdb/java/benchmark/src/main/java/org/rocksdb/benchmark/DbBenchmark.java
new file mode 100644
index 000000000..ff36c74a4
--- /dev/null
+++ b/src/rocksdb/java/benchmark/src/main/java/org/rocksdb/benchmark/DbBenchmark.java
@@ -0,0 +1,1653 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+/**
+ * Copyright (C) 2011 the original author or authors.
+ * See the notice.md file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * Licensed 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.rocksdb.benchmark;
+
+import java.io.IOException;
+import java.lang.Runnable;
+import java.lang.Math;
+import java.io.File;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.nio.ByteBuffer;
+import java.nio.file.Files;
+import java.util.Collection;
+import java.util.Date;
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import org.rocksdb.*;
+import org.rocksdb.RocksMemEnv;
+import org.rocksdb.util.SizeUnit;
+
+class Stats {
+  int id_;
+  long start_;
+  long finish_;
+  double seconds_;
+  long done_;
+  long found_;
+  long lastOpTime_;
+  long nextReport_;
+  long bytes_;
+  StringBuilder message_;
+  boolean excludeFromMerge_;
+
+  // TODO(yhchiang): use the following arguments:
+  //   (Long)Flag.stats_interval
+  //   (Integer)Flag.stats_per_interval
+
+  Stats(int id) {
+    id_ = id;
+    nextReport_ = 100;
+    done_ = 0;
+    bytes_ = 0;
+    seconds_ = 0;
+    start_ = System.nanoTime();
+    lastOpTime_ = start_;
+    finish_ = start_;
+    found_ = 0;
+    message_ = new StringBuilder("");
+    excludeFromMerge_ = false;
+  }
+
+  void merge(final Stats other) {
+    if (other.excludeFromMerge_) {
+      return;
+    }
+
+    done_ += other.done_;
+    found_ += other.found_;
+    bytes_ += other.bytes_;
+    seconds_ += other.seconds_;
+    if (other.start_ < start_) start_ = other.start_;
+    if (other.finish_ > finish_) finish_ = other.finish_;
+
+    // Just keep the messages from one thread
+    if (message_.length() == 0) {
+      message_ = other.message_;
+    }
+  }
+
+  void stop() {
+    finish_ = System.nanoTime();
+    seconds_ = (double) (finish_ - start_) * 1e-9;
+  }
+
+  void addMessage(String msg) {
+    if (message_.length() > 0) {
+      message_.append(" ");
+    }
+    message_.append(msg);
+  }
+
+  void setId(int id) { id_ = id; }
+  void setExcludeFromMerge() { excludeFromMerge_ = true; }
+
+  void finishedSingleOp(int bytes) {
+    done_++;
+    lastOpTime_ = System.nanoTime();
+    bytes_ += bytes;
+    if (done_ >= nextReport_) {
+      if (nextReport_ < 1000) {
+        nextReport_ += 100;
+      } else if (nextReport_ < 5000) {
+        nextReport_ += 500;
+      } else if (nextReport_ < 10000) {
+        nextReport_ += 1000;
+      } else if (nextReport_ < 50000) {
+        nextReport_ += 5000;
+      } else if (nextReport_ < 100000) {
+        nextReport_ += 10000;
+      } else if (nextReport_ < 500000) {
+        nextReport_ += 50000;
+      } else {
+        nextReport_ += 100000;
+      }
+      System.err.printf("... Task %s finished %d ops%30s\r", id_, done_, "");
+    }
+  }
+
+  void report(String name) {
+    // Pretend at least one op was done in case we are running a benchmark
+    // that does not call FinishedSingleOp().
+    if (done_ < 1) done_ = 1;
+
+    StringBuilder extra = new StringBuilder("");
+    if (bytes_ > 0) {
+      // Rate is computed on actual elapsed time, not the sum of per-thread
+      // elapsed times.
+      double elapsed = (finish_ - start_) * 1e-9;
+      extra.append(String.format("%6.1f MB/s", (bytes_ / 1048576.0) / elapsed));
+    }
+    extra.append(message_.toString());
+    double elapsed = (finish_ - start_);
+    double throughput = (double) done_ / (elapsed * 1e-9);
+
+    System.out.format("%-12s : %11.3f micros/op %d ops/sec;%s%s\n",
+            name, (elapsed * 1e-6) / done_,
+            (long) throughput, (extra.length() == 0 ? "" : " "), extra.toString());
+  }
+}
+
+public class DbBenchmark {
+  enum Order {
+    SEQUENTIAL,
+    RANDOM
+  }
+
+  enum DBState {
+    FRESH,
+    EXISTING
+  }
+
+  static {
+    RocksDB.loadLibrary();
+  }
+
+  abstract class BenchmarkTask implements Callable<Stats> {
+    // TODO(yhchiang): use (Integer)Flag.perf_level.
+    public BenchmarkTask(
+        int tid, long randSeed, long numEntries, long keyRange) {
+      tid_ = tid;
+      rand_ = new Random(randSeed + tid * 1000);
+      numEntries_ = numEntries;
+      keyRange_ = keyRange;
+      stats_ = new Stats(tid);
+    }
+
+    @Override public Stats call() throws RocksDBException {
+      stats_.start_ = System.nanoTime();
+      runTask();
+      stats_.finish_ = System.nanoTime();
+      return stats_;
+    }
+
+    abstract protected void runTask() throws RocksDBException;
+
+    protected int tid_;
+    protected Random rand_;
+    protected long numEntries_;
+    protected long keyRange_;
+    protected Stats stats_;
+
+    protected void getFixedKey(byte[] key, long sn) {
+      generateKeyFromLong(key, sn);
+    }
+
+    protected void getRandomKey(byte[] key, long range) {
+      generateKeyFromLong(key, Math.abs(rand_.nextLong() % range));
+    }
+  }
+
+  abstract class WriteTask extends BenchmarkTask {
+    public WriteTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch) {
+      super(tid, randSeed, numEntries, keyRange);
+      writeOpt_ = writeOpt;
+      entriesPerBatch_ = entriesPerBatch;
+      maxWritesPerSecond_ = -1;
+    }
+
+    public WriteTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch, long maxWritesPerSecond) {
+      super(tid, randSeed, numEntries, keyRange);
+      writeOpt_ = writeOpt;
+      entriesPerBatch_ = entriesPerBatch;
+      maxWritesPerSecond_ = maxWritesPerSecond;
+    }
+
+    @Override public void runTask() throws RocksDBException {
+      if (numEntries_ != DbBenchmark.this.num_) {
+        stats_.message_.append(String.format(" (%d ops)", numEntries_));
+      }
+      byte[] key = new byte[keySize_];
+      byte[] value = new byte[valueSize_];
+
+      try {
+        if (entriesPerBatch_ == 1) {
+          for (long i = 0; i < numEntries_; ++i) {
+            getKey(key, i, keyRange_);
+            DbBenchmark.this.gen_.generate(value);
+            db_.put(writeOpt_, key, value);
+            stats_.finishedSingleOp(keySize_ + valueSize_);
+            writeRateControl(i);
+            if (isFinished()) {
+              return;
+            }
+          }
+        } else {
+          for (long i = 0; i < numEntries_; i += entriesPerBatch_) {
+            WriteBatch batch = new WriteBatch();
+            for (long j = 0; j < entriesPerBatch_; j++) {
+              getKey(key, i + j, keyRange_);
+              DbBenchmark.this.gen_.generate(value);
+              batch.put(key, value);
+              stats_.finishedSingleOp(keySize_ + valueSize_);
+            }
+            db_.write(writeOpt_, batch);
+            batch.dispose();
+            writeRateControl(i);
+            if (isFinished()) {
+              return;
+            }
+          }
+        }
+      } catch (InterruptedException e) {
+        // thread has been terminated.
+      }
+    }
+
+    protected void writeRateControl(long writeCount)
+        throws InterruptedException {
+      if (maxWritesPerSecond_ <= 0) return;
+      long minInterval =
+          writeCount * TimeUnit.SECONDS.toNanos(1) / maxWritesPerSecond_;
+      long interval = System.nanoTime() - stats_.start_;
+      if (minInterval - interval > TimeUnit.MILLISECONDS.toNanos(1)) {
+        TimeUnit.NANOSECONDS.sleep(minInterval - interval);
+      }
+    }
+
+    abstract protected void getKey(byte[] key, long id, long range);
+    protected WriteOptions writeOpt_;
+    protected long entriesPerBatch_;
+    protected long maxWritesPerSecond_;
+  }
+
+  class WriteSequentialTask extends WriteTask {
+    public WriteSequentialTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch);
+    }
+    public WriteSequentialTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch,
+        long maxWritesPerSecond) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch,
+            maxWritesPerSecond);
+    }
+    @Override protected void getKey(byte[] key, long id, long range) {
+      getFixedKey(key, id);
+    }
+  }
+
+  class WriteRandomTask extends WriteTask {
+    public WriteRandomTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch);
+    }
+    public WriteRandomTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch,
+        long maxWritesPerSecond) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch,
+            maxWritesPerSecond);
+    }
+    @Override protected void getKey(byte[] key, long id, long range) {
+      getRandomKey(key, range);
+    }
+  }
+
+  class WriteUniqueRandomTask extends WriteTask {
+    static final int MAX_BUFFER_SIZE = 10000000;
+    public WriteUniqueRandomTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch);
+      initRandomKeySequence();
+    }
+    public WriteUniqueRandomTask(
+        int tid, long randSeed, long numEntries, long keyRange,
+        WriteOptions writeOpt, long entriesPerBatch,
+        long maxWritesPerSecond) {
+      super(tid, randSeed, numEntries, keyRange,
+            writeOpt, entriesPerBatch,
+            maxWritesPerSecond);
+      initRandomKeySequence();
+    }
+    @Override protected void getKey(byte[] key, long id, long range) {
+      generateKeyFromLong(key, nextUniqueRandom());
+    }
+
+    protected void initRandomKeySequence() {
+      bufferSize_ = MAX_BUFFER_SIZE;
+      if (bufferSize_ > keyRange_) {
+        bufferSize_ = (int) keyRange_;
+      }
+      currentKeyCount_ = bufferSize_;
+      keyBuffer_ = new long[MAX_BUFFER_SIZE];
+      for (int k = 0; k < bufferSize_; ++k) {
+        keyBuffer_[k] = k;
+      }
+    }
+
+    /**
+     * Semi-randomly return the next unique key.  It is guaranteed to be
+     * fully random if keyRange_ <= MAX_BUFFER_SIZE.
+     */
+    long nextUniqueRandom() {
+      if (bufferSize_ == 0) {
+        System.err.println("bufferSize_ == 0.");
+        return 0;
+      }
+      int r = rand_.nextInt(bufferSize_);
+      // randomly pick one from the keyBuffer
+      long randKey = keyBuffer_[r];
+      if (currentKeyCount_ < keyRange_) {
+        // if we have not yet inserted all keys, insert next new key to [r].
+        keyBuffer_[r] = currentKeyCount_++;
+      } else {
+        // move the last element to [r] and decrease the size by 1.
+        keyBuffer_[r] = keyBuffer_[--bufferSize_];
+      }
+      return randKey;
+    }
+
+    int bufferSize_;
+    long currentKeyCount_;
+    long[] keyBuffer_;
+  }
+
+  class ReadRandomTask extends BenchmarkTask {
+    public ReadRandomTask(
+        int tid, long randSeed, long numEntries, long keyRange) {
+      super(tid, randSeed, numEntries, keyRange);
+    }
+    @Override public void runTask() throws RocksDBException {
+      byte[] key = new byte[keySize_];
+      byte[] value = new byte[valueSize_];
+      for (long i = 0; i < numEntries_; i++) {
+        getRandomKey(key, keyRange_);
+        int len = db_.get(key, value);
+        if (len != RocksDB.NOT_FOUND) {
+          stats_.found_++;
+          stats_.finishedSingleOp(keySize_ + valueSize_);
+        } else {
+          stats_.finishedSingleOp(keySize_);
+        }
+        if (isFinished()) {
+          return;
+        }
+      }
+    }
+  }
+
+  class ReadSequentialTask extends BenchmarkTask {
+    public ReadSequentialTask(
+        int tid, long randSeed, long numEntries, long keyRange) {
+      super(tid, randSeed, numEntries, keyRange);
+    }
+    @Override public void runTask() throws RocksDBException {
+      RocksIterator iter = db_.newIterator();
+      long i;
+      for (iter.seekToFirst(), i = 0;
+           iter.isValid() && i < numEntries_;
+           iter.next(), ++i) {
+        stats_.found_++;
+        stats_.finishedSingleOp(iter.key().length + iter.value().length);
+        if (isFinished()) {
+          iter.dispose();
+          return;
+        }
+      }
+      iter.dispose();
+    }
+  }
+
+  public DbBenchmark(Map<Flag, Object> flags) throws Exception {
+    benchmarks_ = (List<String>) flags.get(Flag.benchmarks);
+    num_ = (Integer) flags.get(Flag.num);
+    threadNum_ = (Integer) flags.get(Flag.threads);
+    reads_ = (Integer) (flags.get(Flag.reads) == null ?
+        flags.get(Flag.num) : flags.get(Flag.reads));
+    keySize_ = (Integer) flags.get(Flag.key_size);
+    valueSize_ = (Integer) flags.get(Flag.value_size);
+    compressionRatio_ = (Double) flags.get(Flag.compression_ratio);
+    useExisting_ = (Boolean) flags.get(Flag.use_existing_db);
+    randSeed_ = (Long) flags.get(Flag.seed);
+    databaseDir_ = (String) flags.get(Flag.db);
+    writesPerSeconds_ = (Integer) flags.get(Flag.writes_per_second);
+    memtable_ = (String) flags.get(Flag.memtablerep);
+    maxWriteBufferNumber_ = (Integer) flags.get(Flag.max_write_buffer_number);
+    prefixSize_ = (Integer) flags.get(Flag.prefix_size);
+    keysPerPrefix_ = (Integer) flags.get(Flag.keys_per_prefix);
+    hashBucketCount_ = (Long) flags.get(Flag.hash_bucket_count);
+    usePlainTable_ = (Boolean) flags.get(Flag.use_plain_table);
+    useMemenv_ = (Boolean) flags.get(Flag.use_mem_env);
+    flags_ = flags;
+    finishLock_ = new Object();
+    // options.setPrefixSize((Integer)flags_.get(Flag.prefix_size));
+    // options.setKeysPerPrefix((Long)flags_.get(Flag.keys_per_prefix));
+    compressionType_ = (String) flags.get(Flag.compression_type);
+    compression_ = CompressionType.NO_COMPRESSION;
+    try {
+      if (compressionType_!=null) {
+          final CompressionType compressionType =
+              CompressionType.getCompressionType(compressionType_);
+          if (compressionType != null &&
+              compressionType != CompressionType.NO_COMPRESSION) {
+            System.loadLibrary(compressionType.getLibraryName());
+          }
+
+      }
+    } catch (UnsatisfiedLinkError e) {
+      System.err.format("Unable to load %s library:%s%n" +
+                        "No compression is used.%n",
+          compressionType_, e.toString());
+      compressionType_ = "none";
+    }
+    gen_ = new RandomGenerator(randSeed_, compressionRatio_);
+  }
+
+  private void prepareReadOptions(ReadOptions options) {
+    options.setVerifyChecksums((Boolean)flags_.get(Flag.verify_checksum));
+    options.setTailing((Boolean)flags_.get(Flag.use_tailing_iterator));
+  }
+
+  private void prepareWriteOptions(WriteOptions options) {
+    options.setSync((Boolean)flags_.get(Flag.sync));
+    options.setDisableWAL((Boolean)flags_.get(Flag.disable_wal));
+  }
+
+  private void prepareOptions(Options options) throws RocksDBException {
+    if (!useExisting_) {
+      options.setCreateIfMissing(true);
+    } else {
+      options.setCreateIfMissing(false);
+    }
+    if (useMemenv_) {
+      options.setEnv(new RocksMemEnv(Env.getDefault()));
+    }
+    switch (memtable_) {
+      case "skip_list":
+        options.setMemTableConfig(new SkipListMemTableConfig());
+        break;
+      case "vector":
+        options.setMemTableConfig(new VectorMemTableConfig());
+        break;
+      case "hash_linkedlist":
+        options.setMemTableConfig(
+            new HashLinkedListMemTableConfig()
+                .setBucketCount(hashBucketCount_));
+        options.useFixedLengthPrefixExtractor(prefixSize_);
+        break;
+      case "hash_skiplist":
+      case "prefix_hash":
+        options.setMemTableConfig(
+            new HashSkipListMemTableConfig()
+                .setBucketCount(hashBucketCount_));
+        options.useFixedLengthPrefixExtractor(prefixSize_);
+        break;
+      default:
+        System.err.format(
+            "unable to detect the specified memtable, " +
+                "use the default memtable factory %s%n",
+            options.memTableFactoryName());
+        break;
+    }
+    if (usePlainTable_) {
+      options.setTableFormatConfig(
+          new PlainTableConfig().setKeySize(keySize_));
+    } else {
+      BlockBasedTableConfig table_options = new BlockBasedTableConfig();
+      table_options.setBlockSize((Long)flags_.get(Flag.block_size))
+                   .setBlockCacheSize((Long)flags_.get(Flag.cache_size))
+                   .setCacheNumShardBits(
+                      (Integer)flags_.get(Flag.cache_numshardbits));
+      options.setTableFormatConfig(table_options);
+    }
+    options.setWriteBufferSize(
+        (Long)flags_.get(Flag.write_buffer_size));
+    options.setMaxWriteBufferNumber(
+        (Integer)flags_.get(Flag.max_write_buffer_number));
+    options.setMaxBackgroundCompactions(
+        (Integer)flags_.get(Flag.max_background_compactions));
+    options.getEnv().setBackgroundThreads(
+        (Integer)flags_.get(Flag.max_background_compactions));
+    options.setMaxBackgroundFlushes(
+        (Integer)flags_.get(Flag.max_background_flushes));
+    options.setMaxBackgroundJobs((Integer) flags_.get(Flag.max_background_jobs));
+    options.setMaxOpenFiles(
+        (Integer)flags_.get(Flag.open_files));
+    options.setUseFsync(
+        (Boolean)flags_.get(Flag.use_fsync));
+    options.setWalDir(
+        (String)flags_.get(Flag.wal_dir));
+    options.setDeleteObsoleteFilesPeriodMicros(
+        (Integer)flags_.get(Flag.delete_obsolete_files_period_micros));
+    options.setTableCacheNumshardbits(
+        (Integer)flags_.get(Flag.table_cache_numshardbits));
+    options.setAllowMmapReads(
+        (Boolean)flags_.get(Flag.mmap_read));
+    options.setAllowMmapWrites(
+        (Boolean)flags_.get(Flag.mmap_write));
+    options.setAdviseRandomOnOpen(
+        (Boolean)flags_.get(Flag.advise_random_on_open));
+    options.setUseAdaptiveMutex(
+        (Boolean)flags_.get(Flag.use_adaptive_mutex));
+    options.setBytesPerSync(
+        (Long)flags_.get(Flag.bytes_per_sync));
+    options.setBloomLocality(
+        (Integer)flags_.get(Flag.bloom_locality));
+    options.setMinWriteBufferNumberToMerge(
+        (Integer)flags_.get(Flag.min_write_buffer_number_to_merge));
+    options.setMemtablePrefixBloomSizeRatio((Double) flags_.get(Flag.memtable_bloom_size_ratio));
+    options.setNumLevels(
+        (Integer)flags_.get(Flag.num_levels));
+    options.setTargetFileSizeBase(
+        (Integer)flags_.get(Flag.target_file_size_base));
+    options.setTargetFileSizeMultiplier((Integer)flags_.get(Flag.target_file_size_multiplier));
+    options.setMaxBytesForLevelBase(
+        (Integer)flags_.get(Flag.max_bytes_for_level_base));
+    options.setMaxBytesForLevelMultiplier((Double) flags_.get(Flag.max_bytes_for_level_multiplier));
+    options.setLevelZeroStopWritesTrigger(
+        (Integer)flags_.get(Flag.level0_stop_writes_trigger));
+    options.setLevelZeroSlowdownWritesTrigger(
+        (Integer)flags_.get(Flag.level0_slowdown_writes_trigger));
+    options.setLevelZeroFileNumCompactionTrigger(
+        (Integer)flags_.get(Flag.level0_file_num_compaction_trigger));
+    options.setMaxCompactionBytes(
+        (Long) flags_.get(Flag.max_compaction_bytes));
+    options.setDisableAutoCompactions(
+        (Boolean)flags_.get(Flag.disable_auto_compactions));
+    options.setMaxSuccessiveMerges(
+        (Integer)flags_.get(Flag.max_successive_merges));
+    options.setWalTtlSeconds((Long)flags_.get(Flag.wal_ttl_seconds));
+    options.setWalSizeLimitMB((Long)flags_.get(Flag.wal_size_limit_MB));
+    if(flags_.get(Flag.java_comparator) != null) {
+      options.setComparator(
+          (AbstractComparator)flags_.get(Flag.java_comparator));
+    }
+
+    /* TODO(yhchiang): enable the following parameters
+    options.setCompressionType((String)flags_.get(Flag.compression_type));
+    options.setCompressionLevel((Integer)flags_.get(Flag.compression_level));
+    options.setMinLevelToCompress((Integer)flags_.get(Flag.min_level_to_compress));
+    options.setHdfs((String)flags_.get(Flag.hdfs)); // env
+    options.setStatistics((Boolean)flags_.get(Flag.statistics));
+    options.setUniversalSizeRatio(
+        (Integer)flags_.get(Flag.universal_size_ratio));
+    options.setUniversalMinMergeWidth(
+        (Integer)flags_.get(Flag.universal_min_merge_width));
+    options.setUniversalMaxMergeWidth(
+        (Integer)flags_.get(Flag.universal_max_merge_width));
+    options.setUniversalMaxSizeAmplificationPercent(
+        (Integer)flags_.get(Flag.universal_max_size_amplification_percent));
+    options.setUniversalCompressionSizePercent(
+        (Integer)flags_.get(Flag.universal_compression_size_percent));
+    // TODO(yhchiang): add RocksDB.openForReadOnly() to enable Flag.readonly
+    // TODO(yhchiang): enable Flag.merge_operator by switch
+    options.setAccessHintOnCompactionStart(
+        (String)flags_.get(Flag.compaction_fadvice));
+    // available values of fadvice are "NONE", "NORMAL", "SEQUENTIAL", "WILLNEED" for fadvice
+    */
+  }
+
+  private void run() throws RocksDBException {
+    if (!useExisting_) {
+      destroyDb();
+    }
+    Options options = new Options();
+    prepareOptions(options);
+    open(options);
+
+    printHeader(options);
+
+    for (String benchmark : benchmarks_) {
+      List<Callable<Stats>> tasks = new ArrayList<Callable<Stats>>();
+      List<Callable<Stats>> bgTasks = new ArrayList<Callable<Stats>>();
+      WriteOptions writeOpt = new WriteOptions();
+      prepareWriteOptions(writeOpt);
+      ReadOptions readOpt = new ReadOptions();
+      prepareReadOptions(readOpt);
+      int currentTaskId = 0;
+      boolean known = true;
+
+      switch (benchmark) {
+        case "fillseq":
+          tasks.add(new WriteSequentialTask(
+              currentTaskId++, randSeed_, num_, num_, writeOpt, 1));
+          break;
+        case "fillbatch":
+          tasks.add(
+              new WriteSequentialTask(currentTaskId++, randSeed_, num_, num_, writeOpt, 1000));
+          break;
+        case "fillrandom":
+          tasks.add(new WriteRandomTask(
+              currentTaskId++, randSeed_, num_, num_, writeOpt, 1));
+          break;
+        case "filluniquerandom":
+          tasks.add(new WriteUniqueRandomTask(
+              currentTaskId++, randSeed_, num_, num_, writeOpt, 1));
+          break;
+        case "fillsync":
+          writeOpt.setSync(true);
+          tasks.add(new WriteRandomTask(
+              currentTaskId++, randSeed_, num_ / 1000, num_ / 1000,
+              writeOpt, 1));
+          break;
+        case "readseq":
+          for (int t = 0; t < threadNum_; ++t) {
+            tasks.add(new ReadSequentialTask(
+                currentTaskId++, randSeed_, reads_ / threadNum_, num_));
+          }
+          break;
+        case "readrandom":
+          for (int t = 0; t < threadNum_; ++t) {
+            tasks.add(new ReadRandomTask(
+                currentTaskId++, randSeed_, reads_ / threadNum_, num_));
+          }
+          break;
+        case "readwhilewriting":
+          WriteTask writeTask = new WriteRandomTask(
+              -1, randSeed_, Long.MAX_VALUE, num_, writeOpt, 1, writesPerSeconds_);
+          writeTask.stats_.setExcludeFromMerge();
+          bgTasks.add(writeTask);
+          for (int t = 0; t < threadNum_; ++t) {
+            tasks.add(new ReadRandomTask(
+                currentTaskId++, randSeed_, reads_ / threadNum_, num_));
+          }
+          break;
+        case "readhot":
+          for (int t = 0; t < threadNum_; ++t) {
+            tasks.add(new ReadRandomTask(
+                currentTaskId++, randSeed_, reads_ / threadNum_, num_ / 100));
+          }
+          break;
+        case "delete":
+          destroyDb();
+          open(options);
+          break;
+        default:
+          known = false;
+          System.err.println("Unknown benchmark: " + benchmark);
+          break;
+      }
+      if (known) {
+        ExecutorService executor = Executors.newCachedThreadPool();
+        ExecutorService bgExecutor = Executors.newCachedThreadPool();
+        try {
+          // measure only the main executor time
+          List<Future<Stats>> bgResults = new ArrayList<Future<Stats>>();
+          for (Callable bgTask : bgTasks) {
+            bgResults.add(bgExecutor.submit(bgTask));
+          }
+          start();
+          List<Future<Stats>> results = executor.invokeAll(tasks);
+          executor.shutdown();
+          boolean finished = executor.awaitTermination(10, TimeUnit.SECONDS);
+          if (!finished) {
+            System.out.format(
+                "Benchmark %s was not finished before timeout.",
+                benchmark);
+            executor.shutdownNow();
+          }
+          setFinished(true);
+          bgExecutor.shutdown();
+          finished = bgExecutor.awaitTermination(10, TimeUnit.SECONDS);
+          if (!finished) {
+            System.out.format(
+                "Benchmark %s was not finished before timeout.",
+                benchmark);
+            bgExecutor.shutdownNow();
+          }
+
+          stop(benchmark, results, currentTaskId);
+        } catch (InterruptedException e) {
+          System.err.println(e);
+        }
+      }
+      writeOpt.dispose();
+      readOpt.dispose();
+    }
+    options.dispose();
+    db_.close();
+  }
+
+  private void printHeader(Options options) {
+    int kKeySize = 16;
+    System.out.printf("Keys:     %d bytes each\n", kKeySize);
+    System.out.printf("Values:   %d bytes each (%d bytes after compression)\n",
+        valueSize_,
+        (int) (valueSize_ * compressionRatio_ + 0.5));
+    System.out.printf("Entries:  %d\n", num_);
+    System.out.printf("RawSize:  %.1f MB (estimated)\n",
+        ((double)(kKeySize + valueSize_) * num_) / SizeUnit.MB);
+    System.out.printf("FileSize:   %.1f MB (estimated)\n",
+        (((kKeySize + valueSize_ * compressionRatio_) * num_) / SizeUnit.MB));
+    System.out.format("Memtable Factory: %s%n", options.memTableFactoryName());
+    System.out.format("Prefix:   %d bytes%n", prefixSize_);
+    System.out.format("Compression: %s%n", compressionType_);
+    printWarnings();
+    System.out.printf("------------------------------------------------\n");
+  }
+
+  void printWarnings() {
+    boolean assertsEnabled = false;
+    assert assertsEnabled = true; // Intentional side effect!!!
+    if (assertsEnabled) {
+      System.out.printf(
+          "WARNING: Assertions are enabled; benchmarks unnecessarily slow\n");
+    }
+  }
+
+  private void open(Options options) throws RocksDBException {
+    System.out.println("Using database directory: " + databaseDir_);
+    db_ = RocksDB.open(options, databaseDir_);
+  }
+
+  private void start() {
+    setFinished(false);
+    startTime_ = System.nanoTime();
+  }
+
+  private void stop(
+      String benchmark, List<Future<Stats>> results, int concurrentThreads) {
+    long endTime = System.nanoTime();
+    double elapsedSeconds =
+        1.0d * (endTime - startTime_) / TimeUnit.SECONDS.toNanos(1);
+
+    Stats stats = new Stats(-1);
+    int taskFinishedCount = 0;
+    for (Future<Stats> result : results) {
+      if (result.isDone()) {
+        try {
+          Stats taskStats = result.get(3, TimeUnit.SECONDS);
+          if (!result.isCancelled()) {
+            taskFinishedCount++;
+          }
+          stats.merge(taskStats);
+        } catch (Exception e) {
+          // then it's not successful, the output will indicate this
+        }
+      }
+    }
+    String extra = "";
+    if (benchmark.indexOf("read") >= 0) {
+      extra = String.format(" %d / %d found; ", stats.found_, stats.done_);
+    } else {
+      extra = String.format(" %d ops done; ", stats.done_);
+    }
+
+    System.out.printf(
+        "%-16s : %11.5f micros/op; %6.1f MB/s;%s %d / %d task(s) finished.\n",
+        benchmark, elapsedSeconds / stats.done_ * 1e6,
+        (stats.bytes_ / 1048576.0) / elapsedSeconds, extra,
+        taskFinishedCount, concurrentThreads);
+  }
+
+  public void generateKeyFromLong(byte[] slice, long n) {
+    assert(n >= 0);
+    int startPos = 0;
+
+    if (keysPerPrefix_ > 0) {
+      long numPrefix = (num_ + keysPerPrefix_ - 1) / keysPerPrefix_;
+      long prefix = n % numPrefix;
+      int bytesToFill = Math.min(prefixSize_, 8);
+      for (int i = 0; i < bytesToFill; ++i) {
+        slice[i] = (byte) (prefix % 256);
+        prefix /= 256;
+      }
+      for (int i = 8; i < bytesToFill; ++i) {
+        slice[i] = '0';
+      }
+      startPos = bytesToFill;
+    }
+
+    for (int i = slice.length - 1; i >= startPos; --i) {
+      slice[i] = (byte) ('0' + (n % 10));
+      n /= 10;
+    }
+  }
+
+  private void destroyDb() {
+    if (db_ != null) {
+      db_.close();
+    }
+    // TODO(yhchiang): develop our own FileUtil
+    // FileUtil.deleteDir(databaseDir_);
+  }
+
+  private void printStats() {
+  }
+
+  static void printHelp() {
+    System.out.println("usage:");
+    for (Flag flag : Flag.values()) {
+      System.out.format("  --%s%n\t%s%n",
+          flag.name(),
+          flag.desc());
+      if (flag.getDefaultValue() != null) {
+        System.out.format("\tDEFAULT: %s%n",
+            flag.getDefaultValue().toString());
+      }
+    }
+  }
+
+  public static void main(String[] args) throws Exception {
+    Map<Flag, Object> flags = new EnumMap<Flag, Object>(Flag.class);
+    for (Flag flag : Flag.values()) {
+      if (flag.getDefaultValue() != null) {
+        flags.put(flag, flag.getDefaultValue());
+      }
+    }
+    for (String arg : args) {
+      boolean valid = false;
+      if (arg.equals("--help") || arg.equals("-h")) {
+        printHelp();
+        System.exit(0);
+      }
+      if (arg.startsWith("--")) {
+        try {
+          String[] parts = arg.substring(2).split("=");
+          if (parts.length >= 1) {
+            Flag key = Flag.valueOf(parts[0]);
+            if (key != null) {
+              Object value = null;
+              if (parts.length >= 2) {
+                value = key.parseValue(parts[1]);
+              }
+              flags.put(key, value);
+              valid = true;
+            }
+          }
+        }
+        catch (Exception e) {
+        }
+      }
+      if (!valid) {
+        System.err.println("Invalid argument " + arg);
+        System.exit(1);
+      }
+    }
+    new DbBenchmark(flags).run();
+  }
+
+  private enum Flag {
+    benchmarks(Arrays.asList("fillseq", "readrandom", "fillrandom"),
+        "Comma-separated list of operations to run in the specified order\n"
+            + "\tActual benchmarks:\n"
+            + "\t\tfillseq          -- write N values in sequential key order in async mode.\n"
+            + "\t\tfillrandom       -- write N values in random key order in async mode.\n"
+            + "\t\tfillbatch        -- write N/1000 batch where each batch has 1000 values\n"
+            + "\t\t                   in sequential key order in sync mode.\n"
+            + "\t\tfillsync         -- write N/100 values in random key order in sync mode.\n"
+            + "\t\tfill100K         -- write N/1000 100K values in random order in async mode.\n"
+            + "\t\treadseq          -- read N times sequentially.\n"
+            + "\t\treadrandom       -- read N times in random order.\n"
+            + "\t\treadhot          -- read N times in random order from 1% section of DB.\n"
+            + "\t\treadwhilewriting -- measure the read performance of multiple readers\n"
+            + "\t\t                   with a bg single writer.  The write rate of the bg\n"
+            + "\t\t                   is capped by --writes_per_second.\n"
+            + "\tMeta Operations:\n"
+            + "\t\tdelete            -- delete DB") {
+      @Override public Object parseValue(String value) {
+        return new ArrayList<String>(Arrays.asList(value.split(",")));
+      }
+    },
+    compression_ratio(0.5d,
+        "Arrange to generate values that shrink to this fraction of\n" +
+        "\ttheir original size after compression.") {
+      @Override public Object parseValue(String value) {
+        return Double.parseDouble(value);
+      }
+    },
+    use_existing_db(false,
+        "If true, do not destroy the existing database.  If you set this\n" +
+        "\tflag and also specify a benchmark that wants a fresh database,\n" +
+        "\tthat benchmark will fail.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    num(1000000,
+        "Number of key/values to place in database.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    threads(1,
+        "Number of concurrent threads to run.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    reads(null,
+        "Number of read operations to do.  If negative, do --nums reads.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    key_size(16,
+        "The size of each key in bytes.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    value_size(100,
+        "The size of each value in bytes.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    write_buffer_size(4L * SizeUnit.MB,
+        "Number of bytes to buffer in memtable before compacting\n" +
+        "\t(initialized to default value by 'main'.)") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    max_write_buffer_number(2,
+             "The number of in-memory memtables. Each memtable is of size\n" +
+             "\twrite_buffer_size.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    prefix_size(0, "Controls the prefix size for HashSkipList, HashLinkedList,\n" +
+                   "\tand plain table.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    keys_per_prefix(0, "Controls the average number of keys generated\n" +
+             "\tper prefix, 0 means no special handling of the prefix,\n" +
+             "\ti.e. use the prefix comes with the generated random number.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    memtablerep("skip_list",
+        "The memtable format.  Available options are\n" +
+        "\tskip_list,\n" +
+        "\tvector,\n" +
+        "\thash_linkedlist,\n" +
+        "\thash_skiplist (prefix_hash.)") {
+      @Override public Object parseValue(String value) {
+        return value;
+      }
+    },
+    hash_bucket_count(SizeUnit.MB,
+        "The number of hash buckets used in the hash-bucket-based\n" +
+        "\tmemtables.  Memtables that currently support this argument are\n" +
+        "\thash_linkedlist and hash_skiplist.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    writes_per_second(10000,
+        "The write-rate of the background writer used in the\n" +
+        "\t`readwhilewriting` benchmark.  Non-positive number indicates\n" +
+        "\tusing an unbounded write-rate in `readwhilewriting` benchmark.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    use_plain_table(false,
+        "Use plain-table sst format.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    cache_size(-1L,
+        "Number of bytes to use as a cache of uncompressed data.\n" +
+        "\tNegative means use default settings.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    seed(0L,
+        "Seed base for random number generators.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    num_levels(7,
+        "The total number of levels.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    numdistinct(1000L,
+        "Number of distinct keys to use. Used in RandomWithVerify to\n" +
+        "\tread/write on fewer keys so that gets are more likely to find the\n" +
+        "\tkey and puts are more likely to update the same key.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    merge_keys(-1L,
+        "Number of distinct keys to use for MergeRandom and\n" +
+        "\tReadRandomMergeRandom.\n" +
+        "\tIf negative, there will be FLAGS_num keys.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    bloom_locality(0,"Control bloom filter probes locality.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    duration(0,"Time in seconds for the random-ops tests to run.\n" +
+        "\tWhen 0 then num & reads determine the test duration.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    num_multi_db(0,
+        "Number of DBs used in the benchmark. 0 means single DB.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    histogram(false,"Print histogram of operation timings.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    min_write_buffer_number_to_merge(
+        defaultOptions_.minWriteBufferNumberToMerge(),
+        "The minimum number of write buffers that will be merged together\n" +
+        "\tbefore writing to storage. This is cheap because it is an\n" +
+        "\tin-memory merge. If this feature is not enabled, then all these\n" +
+        "\twrite buffers are flushed to L0 as separate files and this\n" +
+        "\tincreases read amplification because a get request has to check\n" +
+        "\tin all of these files. Also, an in-memory merge may result in\n" +
+        "\twriting less data to storage if there are duplicate records\n" +
+        "\tin each of these individual write buffers.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_background_compactions(
+        defaultOptions_.maxBackgroundCompactions(),
+        "The maximum number of concurrent background compactions\n" +
+        "\tthat can occur in parallel.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_background_flushes(
+        defaultOptions_.maxBackgroundFlushes(),
+        "The maximum number of concurrent background flushes\n" +
+        "\tthat can occur in parallel.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_background_jobs(defaultOptions_.maxBackgroundJobs(),
+        "The maximum number of concurrent background jobs\n"
+            + "\tthat can occur in parallel.") {
+      @Override
+      public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    /* TODO(yhchiang): enable the following
+    compaction_style((int32_t) defaultOptions_.compactionStyle(),
+        "style of compaction: level-based vs universal.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },*/
+    universal_size_ratio(0,
+        "Percentage flexibility while comparing file size\n" +
+        "\t(for universal compaction only).") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    universal_min_merge_width(0,"The minimum number of files in a\n" +
+        "\tsingle compaction run (for universal compaction only).") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    universal_max_merge_width(0,"The max number of files to compact\n" +
+        "\tin universal style compaction.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    universal_max_size_amplification_percent(0,
+        "The max size amplification for universal style compaction.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    universal_compression_size_percent(-1,
+        "The percentage of the database to compress for universal\n" +
+        "\tcompaction. -1 means compress everything.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    block_size(defaultBlockBasedTableOptions_.blockSize(),
+        "Number of bytes in a block.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    compressed_cache_size(-1L,
+        "Number of bytes to use as a cache of compressed data.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    open_files(defaultOptions_.maxOpenFiles(),
+        "Maximum number of files to keep open at the same time\n" +
+        "\t(use default if == 0)") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    bloom_bits(-1,"Bloom filter bits per key. Negative means\n" +
+        "\tuse default settings.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    memtable_bloom_size_ratio(0.0d, "Ratio of memtable used by the bloom filter.\n"
+            + "\t0 means no bloom filter.") {
+      @Override public Object parseValue(String value) {
+        return Double.parseDouble(value);
+      }
+    },
+    cache_numshardbits(-1,"Number of shards for the block cache\n" +
+        "\tis 2 ** cache_numshardbits. Negative means use default settings.\n" +
+        "\tThis is applied only if FLAGS_cache_size is non-negative.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    verify_checksum(false,"Verify checksum for every block read\n" +
+        "\tfrom storage.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    statistics(false,"Database statistics.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    writes(-1L, "Number of write operations to do. If negative, do\n" +
+        "\t--num reads.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    sync(false,"Sync all writes to disk.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    use_fsync(false,"If true, issue fsync instead of fdatasync.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    disable_wal(false,"If true, do not write WAL for write.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    wal_dir("", "If not empty, use the given dir for WAL.") {
+      @Override public Object parseValue(String value) {
+        return value;
+      }
+    },
+    target_file_size_base(2 * 1048576,"Target file size at level-1") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    target_file_size_multiplier(1,
+        "A multiplier to compute target level-N file size (N >= 2)") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_bytes_for_level_base(10 * 1048576,
+      "Max bytes for level-1") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_bytes_for_level_multiplier(10.0d,
+        "A multiplier to compute max bytes for level-N (N >= 2)") {
+      @Override public Object parseValue(String value) {
+        return Double.parseDouble(value);
+      }
+    },
+    level0_stop_writes_trigger(12,"Number of files in level-0\n" +
+        "\tthat will trigger put stop.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    level0_slowdown_writes_trigger(8,"Number of files in level-0\n" +
+        "\tthat will slow down writes.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    level0_file_num_compaction_trigger(4,"Number of files in level-0\n" +
+        "\twhen compactions start.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    readwritepercent(90,"Ratio of reads to reads/writes (expressed\n" +
+        "\tas percentage) for the ReadRandomWriteRandom workload. The\n" +
+        "\tdefault value 90 means 90% operations out of all reads and writes\n" +
+        "\toperations are reads. In other words, 9 gets for every 1 put.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    mergereadpercent(70,"Ratio of merges to merges&reads (expressed\n" +
+        "\tas percentage) for the ReadRandomMergeRandom workload. The\n" +
+        "\tdefault value 70 means 70% out of all read and merge operations\n" +
+        "\tare merges. In other words, 7 merges for every 3 gets.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    deletepercent(2,"Percentage of deletes out of reads/writes/\n" +
+        "\tdeletes (used in RandomWithVerify only). RandomWithVerify\n" +
+        "\tcalculates writepercent as (100 - FLAGS_readwritepercent -\n" +
+        "\tdeletepercent), so deletepercent must be smaller than (100 -\n" +
+        "\tFLAGS_readwritepercent)") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    delete_obsolete_files_period_micros(0,"Option to delete\n" +
+        "\tobsolete files periodically. 0 means that obsolete files are\n" +
+        "\tdeleted after every compaction run.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    compression_type("snappy",
+        "Algorithm used to compress the database.") {
+      @Override public Object parseValue(String value) {
+        return value;
+      }
+    },
+    compression_level(-1,
+        "Compression level. For zlib this should be -1 for the\n" +
+        "\tdefault level, or between 0 and 9.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    min_level_to_compress(-1,"If non-negative, compression starts\n" +
+        "\tfrom this level. Levels with number < min_level_to_compress are\n" +
+        "\tnot compressed. Otherwise, apply compression_type to\n" +
+        "\tall levels.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    table_cache_numshardbits(4,"") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    stats_interval(0L, "Stats are reported every N operations when\n" +
+        "\tthis is greater than zero. When 0 the interval grows over time.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    stats_per_interval(0,"Reports additional stats per interval when\n" +
+        "\tthis is greater than 0.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    perf_level(0,"Level of perf collection.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    soft_rate_limit(0.0d,"") {
+      @Override public Object parseValue(String value) {
+        return Double.parseDouble(value);
+      }
+    },
+    hard_rate_limit(0.0d,"When not equal to 0 this make threads\n" +
+        "\tsleep at each stats reporting interval until the compaction\n" +
+        "\tscore for all levels is less than or equal to this value.") {
+      @Override public Object parseValue(String value) {
+        return Double.parseDouble(value);
+      }
+    },
+    rate_limit_delay_max_milliseconds(1000,
+        "When hard_rate_limit is set then this is the max time a put will\n" +
+        "\tbe stalled.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    max_compaction_bytes(0L, "Limit number of bytes in one compaction to be lower than this\n" +
+            "\threshold. But it's not guaranteed.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    readonly(false,"Run read only benchmarks.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    disable_auto_compactions(false,"Do not auto trigger compactions.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    wal_ttl_seconds(0L,"Set the TTL for the WAL Files in seconds.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    wal_size_limit_MB(0L,"Set the size limit for the WAL Files\n" +
+        "\tin MB.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    /* TODO(yhchiang): enable the following
+    direct_reads(rocksdb::EnvOptions().use_direct_reads,
+        "Allow direct I/O reads.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+      },
+    direct_writes(rocksdb::EnvOptions().use_direct_reads,
+      "Allow direct I/O reads.") {
+      @Override public Object parseValue(String value) {
+      return parseBoolean(value);
+      }
+      },
+    */
+    mmap_read(false,
+        "Allow reads to occur via mmap-ing files.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    mmap_write(false,
+        "Allow writes to occur via mmap-ing files.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    advise_random_on_open(defaultOptions_.adviseRandomOnOpen(),
+        "Advise random access on table file open.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    compaction_fadvice("NORMAL",
+      "Access pattern advice when a file is compacted.") {
+      @Override public Object parseValue(String value) {
+        return value;
+      }
+    },
+    use_tailing_iterator(false,
+        "Use tailing iterator to access a series of keys instead of get.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    use_adaptive_mutex(defaultOptions_.useAdaptiveMutex(),
+        "Use adaptive mutex.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    bytes_per_sync(defaultOptions_.bytesPerSync(),
+        "Allows OS to incrementally sync files to disk while they are\n" +
+        "\tbeing written, in the background. Issue one request for every\n" +
+        "\tbytes_per_sync written. 0 turns it off.") {
+      @Override public Object parseValue(String value) {
+        return Long.parseLong(value);
+      }
+    },
+    filter_deletes(false," On true, deletes use bloom-filter and drop\n" +
+        "\tthe delete if key not present.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    max_successive_merges(0,"Maximum number of successive merge\n" +
+        "\toperations on a key in the memtable.") {
+      @Override public Object parseValue(String value) {
+        return Integer.parseInt(value);
+      }
+    },
+    db(getTempDir("rocksdb-jni"),
+       "Use the db with the following name.") {
+      @Override public Object parseValue(String value) {
+        return value;
+      }
+    },
+    use_mem_env(false, "Use RocksMemEnv instead of default filesystem based\n" +
+        "environment.") {
+      @Override public Object parseValue(String value) {
+        return parseBoolean(value);
+      }
+    },
+    java_comparator(null, "Class name of a Java Comparator to use instead\n" +
+        "\tof the default C++ ByteWiseComparatorImpl. Must be available on\n" +
+        "\tthe classpath") {
+      @Override
+      protected Object parseValue(final String value) {
+        try {
+          final ComparatorOptions copt = new ComparatorOptions();
+          final Class<AbstractComparator> clsComparator =
+              (Class<AbstractComparator>)Class.forName(value);
+          final Constructor cstr =
+              clsComparator.getConstructor(ComparatorOptions.class);
+          return cstr.newInstance(copt);
+        } catch(final ClassNotFoundException cnfe) {
+          throw new IllegalArgumentException("Java Comparator '" + value + "'" +
+              " not found on the classpath", cnfe);
+        } catch(final NoSuchMethodException nsme) {
+          throw new IllegalArgumentException("Java Comparator '" + value + "'" +
+              " does not have a public ComparatorOptions constructor", nsme);
+        } catch(final IllegalAccessException | InstantiationException
+            | InvocationTargetException ie) {
+          throw new IllegalArgumentException("Unable to construct Java" +
+              " Comparator '" + value + "'", ie);
+        }
+      }
+    };
+
+    private Flag(Object defaultValue, String desc) {
+      defaultValue_ = defaultValue;
+      desc_ = desc;
+    }
+
+    public Object getDefaultValue() {
+      return defaultValue_;
+    }
+
+    public String desc() {
+      return desc_;
+    }
+
+    public boolean parseBoolean(String value) {
+      if (value.equals("1")) {
+        return true;
+      } else if (value.equals("0")) {
+        return false;
+      }
+      return Boolean.parseBoolean(value);
+    }
+
+    protected abstract Object parseValue(String value);
+
+    private final Object defaultValue_;
+    private final String desc_;
+  }
+
+  private final static String DEFAULT_TEMP_DIR = "/tmp";
+
+  private static String getTempDir(final String dirName) {
+    try {
+      return Files.createTempDirectory(dirName).toAbsolutePath().toString();
+    } catch(final IOException ioe) {
+      System.err.println("Unable to create temp directory, defaulting to: " +
+          DEFAULT_TEMP_DIR);
+      return DEFAULT_TEMP_DIR + File.pathSeparator + dirName;
+    }
+  }
+
+  private static class RandomGenerator {
+    private final byte[] data_;
+    private int dataLength_;
+    private int position_;
+    private double compressionRatio_;
+    Random rand_;
+
+    private RandomGenerator(long seed, double compressionRatio) {
+      // We use a limited amount of data over and over again and ensure
+      // that it is larger than the compression window (32KB), and also
+      byte[] value = new byte[100];
+      // large enough to serve all typical value sizes we want to write.
+      rand_ = new Random(seed);
+      dataLength_ = value.length * 10000;
+      data_ = new byte[dataLength_];
+      compressionRatio_ = compressionRatio;
+      int pos = 0;
+      while (pos < dataLength_) {
+        compressibleBytes(value);
+        System.arraycopy(value, 0, data_, pos,
+                         Math.min(value.length, dataLength_ - pos));
+        pos += value.length;
+      }
+    }
+
+    private void compressibleBytes(byte[] value) {
+      int baseLength = value.length;
+      if (compressionRatio_ < 1.0d) {
+        baseLength = (int) (compressionRatio_ * value.length + 0.5);
+      }
+      if (baseLength <= 0) {
+        baseLength = 1;
+      }
+      int pos;
+      for (pos = 0; pos < baseLength; ++pos) {
+        value[pos] = (byte) (' ' + rand_.nextInt(95));  // ' ' .. '~'
+      }
+      while (pos < value.length) {
+        System.arraycopy(value, 0, value, pos,
+                         Math.min(baseLength, value.length - pos));
+        pos += baseLength;
+      }
+    }
+
+    private void generate(byte[] value) {
+      if (position_ + value.length > data_.length) {
+        position_ = 0;
+        assert(value.length <= data_.length);
+      }
+      position_ += value.length;
+      System.arraycopy(data_, position_ - value.length,
+                       value, 0, value.length);
+    }
+  }
+
+  boolean isFinished() {
+    synchronized(finishLock_) {
+      return isFinished_;
+    }
+  }
+
+  void setFinished(boolean flag) {
+    synchronized(finishLock_) {
+      isFinished_ = flag;
+    }
+  }
+
+  RocksDB db_;
+  final List<String> benchmarks_;
+  final int num_;
+  final int reads_;
+  final int keySize_;
+  final int valueSize_;
+  final int threadNum_;
+  final int writesPerSeconds_;
+  final long randSeed_;
+  final boolean useExisting_;
+  final String databaseDir_;
+  double compressionRatio_;
+  RandomGenerator gen_;
+  long startTime_;
+
+  // env
+  boolean useMemenv_;
+
+  // memtable related
+  final int maxWriteBufferNumber_;
+  final int prefixSize_;
+  final int keysPerPrefix_;
+  final String memtable_;
+  final long hashBucketCount_;
+
+  // sst format related
+  boolean usePlainTable_;
+
+  Object finishLock_;
+  boolean isFinished_;
+  Map<Flag, Object> flags_;
+  // as the scope of a static member equals to the scope of the problem,
+  // we let its c++ pointer to be disposed in its finalizer.
+  static Options defaultOptions_ = new Options();
+  static BlockBasedTableConfig defaultBlockBasedTableOptions_ =
+    new BlockBasedTableConfig();
+  String compressionType_;
+  CompressionType compression_;
+}