Add statistics

Author: Ankit Gupta

java/org/rocksdb/Statistics.java

@@ -0,0 +1,30 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb;
+
+/**
+ * Statistics to analyze the performance of a db. Pointer for statistics object
+ * is managed by Options class.
+ */
+public class Statistics {
+  
+  private long statsHandle_;
+  
+  public Statistics(long statsHandle) {
+    statsHandle_ = statsHandle;
+  }
+  
+  public long getTickerCount(StatisticsType statisticsType) {
+    assert(isInitialized());
+    return getTickerCount0(statisticsType.getValue(), statsHandle_);
+  }
+  
+  private boolean isInitialized() {
+    return (statsHandle_ != 0);
+  }
+  
+  private native long getTickerCount0(int ticker, long handle);
+}

java/org/rocksdb/StatisticsType.java

@@ -0,0 +1,123 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb;
+
+public enum StatisticsType {
+  // total block cache misses
+  // REQUIRES: BLOCK_CACHE_MISS == BLOCK_CACHE_INDEX_MISS +
+  //                               BLOCK_CACHE_FILTER_MISS +
+  //                               BLOCK_CACHE_DATA_MISS;
+  BLOCK_CACHE_MISS(0),
+  // total block cache hit
+  // REQUIRES: BLOCK_CACHE_HIT == BLOCK_CACHE_INDEX_HIT +
+  //                              BLOCK_CACHE_FILTER_HIT +
+  //                              BLOCK_CACHE_DATA_HIT;
+  BLOCK_CACHE_HIT(1),
+  // # of blocks added to block cache.
+  BLOCK_CACHE_ADD(2),
+  // # of times cache miss when accessing index block from block cache.
+  BLOCK_CACHE_INDEX_MISS(3),
+  // # of times cache hit when accessing index block from block cache.
+  BLOCK_CACHE_INDEX_HIT(4),
+  // # of times cache miss when accessing filter block from block cache.
+  BLOCK_CACHE_FILTER_MISS(5),
+  // # of times cache hit when accessing filter block from block cache.
+  BLOCK_CACHE_FILTER_HIT(6),
+  // # of times cache miss when accessing data block from block cache.
+  BLOCK_CACHE_DATA_MISS(7),
+  // # of times cache hit when accessing data block from block cache.
+  BLOCK_CACHE_DATA_HIT(8),
+  // # of times bloom filter has avoided file reads.
+  BLOOM_FILTER_USEFUL(9),
+
+  // # of memtable hits.
+  MEMTABLE_HIT(10),
+  // # of memtable misses.
+  MEMTABLE_MISS(11),
+
+  /**
+   * COMPACTION_KEY_DROP_* count the reasons for key drop during compaction
+   * There are 3 reasons currently.
+   */
+  COMPACTION_KEY_DROP_NEWER_ENTRY(12),  // key was written with a newer value.
+  COMPACTION_KEY_DROP_OBSOLETE(13),     // The key is obsolete.
+  COMPACTION_KEY_DROP_USER(14),  // user compaction function has dropped the key.
+
+  // Number of keys written to the database via the Put and Write call's
+  NUMBER_KEYS_WRITTEN(15),
+  // Number of Keys read,
+  NUMBER_KEYS_READ(16),
+  // Number keys updated, if inplace update is enabled
+  NUMBER_KEYS_UPDATED(17),
+  // Bytes written / read
+  BYTES_WRITTEN(18),
+  BYTES_READ(19),
+  NO_FILE_CLOSES(20),
+  NO_FILE_OPENS(21),
+  NO_FILE_ERRORS(22),
+  // Time system had to wait to do LO-L1 compactions
+  STALL_L0_SLOWDOWN_MICROS(23),
+  // Time system had to wait to move memtable to L1.
+  STALL_MEMTABLE_COMPACTION_MICROS(24),
+  // write throttle because of too many files in L0
+  STALL_L0_NUM_FILES_MICROS(25),
+  RATE_LIMIT_DELAY_MILLIS(26),
+  NO_ITERATORS(27),  // number of iterators currently open
+
+  // Number of MultiGet calls, keys read, and bytes read
+  NUMBER_MULTIGET_CALLS(28),
+  NUMBER_MULTIGET_KEYS_READ(29),
+  NUMBER_MULTIGET_BYTES_READ(30),
+
+  // Number of deletes records that were not required to be
+  // written to storage because key does not exist
+  NUMBER_FILTERED_DELETES(31),
+  NUMBER_MERGE_FAILURES(32),
+  SEQUENCE_NUMBER(33),
+
+  // number of times bloom was checked before creating iterator on a
+  // file, and the number of times the check was useful in avoiding
+  // iterator creation (and thus likely IOPs).
+  BLOOM_FILTER_PREFIX_CHECKED(34),
+  BLOOM_FILTER_PREFIX_USEFUL(35),
+
+  // Number of times we had to reseek inside an iteration to skip
+  // over large number of keys with same userkey.
+  NUMBER_OF_RESEEKS_IN_ITERATION(36),
+
+  // Record the number of calls to GetUpadtesSince. Useful to keep track of
+  // transaction log iterator refreshes
+  GET_UPDATES_SINCE_CALLS(37),
+  BLOCK_CACHE_COMPRESSED_MISS(38),  // miss in the compressed block cache
+  BLOCK_CACHE_COMPRESSED_HIT(39),   // hit in the compressed block cache
+  WAL_FILE_SYNCED(40),              // Number of times WAL sync is done
+  WAL_FILE_BYTES(41),               // Number of bytes written to WAL
+
+  // Writes can be processed by requesting thread or by the thread at the
+  // head of the writers queue.
+  WRITE_DONE_BY_SELF(42),
+  WRITE_DONE_BY_OTHER(43),
+  WRITE_WITH_WAL(44),       // Number of Write calls that request WAL
+  COMPACT_READ_BYTES(45),   // Bytes read during compaction
+  COMPACT_WRITE_BYTES(46),  // Bytes written during compaction
+
+  // Number of table's properties loaded directly from file, without creating
+  // table reader object.
+  NUMBER_DIRECT_LOAD_TABLE_PROPERTIES(47),
+  NUMBER_SUPERVERSION_ACQUIRES(48),
+  NUMBER_SUPERVERSION_RELEASES(49),
+  NUMBER_SUPERVERSION_CLEANUPS(50);
+  
+  private final int value_;
+    
+  private StatisticsType(int value) {
+    value_ = value;
+  }
+  
+  public int getValue() {
+    return value_;
+  }
+}

java/rocksjni/statistics.cc

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+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+//
+// This file implements the "bridge" between Java and C++ and enables
+// calling c++ rocksdb::Statistics methods from Java side.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <jni.h>
+#include <string>
+#include <memory>
+
+#include "include/org_rocksdb_Statistics.h"
+#include "rocksjni/portal.h"
+#include "rocksdb/statistics.h"
+#include "rocksdb/options.h"
+
+/*
+ * Class:     org_rocksdb_Statistics
+ * Method:    getTickerCount0
+ * Signature: (IJ)J
+ */
+jlong Java_org_rocksdb_Statistics_getTickerCount0(
+    JNIEnv* env, jobject jobj, int ticker, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Statistics*>(handle);
+  assert(st != nullptr);
+  
+  return st->getTickerCount(static_cast<rocksdb::Tickers>(ticker));
+}