ratis-server/src/main/java/org/apache/ratis/server/metrics/SegmentedRaftLogMetrics.java

/*
 * 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.ratis.server.metrics;

import com.codahale.metrics.Gauge;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Timer;
import org.apache.ratis.protocol.RaftGroupMemberId;
import org.apache.ratis.server.raftlog.segmented.SegmentedRaftLogCache;
import org.apache.ratis.util.DataQueue;

import java.util.Queue;

public class SegmentedRaftLogMetrics extends RaftLogMetricsBase {
  //////////////////////////////
  // Raft Log Write Path Metrics
  /////////////////////////////
  /** Time taken to flush log. */
  public static final String RAFT_LOG_FLUSH_TIME = "flushTime";
  /** Number of times of log flushed. */
  public static final String RAFT_LOG_FLUSH_COUNT = "flushCount";
  /** Time taken to log sync. */
  public static final String RAFT_LOG_SYNC_TIME = "syncTime";
  /** Raft log data queue size which at any time gives the number of log related operations in the queue. */
  public static final String RAFT_LOG_DATA_QUEUE_SIZE = "dataQueueSize";
  /** Raft log worker queue size which at any time gives number of committed entries that are to be synced. */
  public static final String RAFT_LOG_WORKER_QUEUE_SIZE = "workerQueueSize";
  /** Number of raft log entries synced in each flush call. */
  public static final String RAFT_LOG_SYNC_BATCH_SIZE = "syncBatchSize";
  /** Count of RaftLogCache Misses */
  public static final String RAFT_LOG_CACHE_MISS_COUNT = "cacheMissCount";
  /** Count of RaftLogCache Hits */
  public static final String RAFT_LOG_CACHE_HIT_COUNT = "cacheHitCount";
  /** Number of SegmentedRaftLogCache::closedSegments */
  public static final String RAFT_LOG_CACHE_CLOSED_SEGMENTS_NUM = "closedSegmentsNum";
  /** Size of SegmentedRaftLogCache::closedSegments in bytes */
  public static final String RAFT_LOG_CACHE_CLOSED_SEGMENTS_SIZE_IN_BYTES = "closedSegmentsSizeInBytes";
  /** Size of SegmentedRaftLogCache::openSegment in bytes */
  public static final String RAFT_LOG_CACHE_OPEN_SEGMENT_SIZE_IN_BYTES = "openSegmentSizeInBytes";
  /** Total time taken to append a raft log entry */
  public static final String RAFT_LOG_APPEND_ENTRY_LATENCY = "appendEntryLatency";
  /** Time spent by a Raft log operation in the queue. */
  public static final String RAFT_LOG_TASK_QUEUE_TIME = "enqueuedTime";
  /**
   * Time taken for a Raft log operation to get into the queue after being requested.
   * This is the time that it has to wait for the queue to be non-full.
   */
  public static final String RAFT_LOG_TASK_ENQUEUE_DELAY = "queueingDelay";
  /** Time taken for a Raft log operation to complete execution. */
  public static final String RAFT_LOG_TASK_EXECUTION_TIME = "%sExecutionTime";
  /** Number of entries appended to the raft log */
  public static final String RAFT_LOG_APPEND_ENTRY_COUNT = "appendEntryCount";
  public static final String RAFT_LOG_PURGE_METRIC = "purgeLog";

  //////////////////////////////
  // Raft Log Read Path Metrics
  /////////////////////////////
  /** Time required to read a raft log entry from actual raft log file and create a raft log entry */
  public static final String RAFT_LOG_READ_ENTRY_LATENCY = "readEntryLatency";
  /** Time required to load and process raft log segments during restart */
  public static final String RAFT_LOG_LOAD_SEGMENT_LATENCY = "segmentLoadLatency";

  public SegmentedRaftLogMetrics(RaftGroupMemberId serverId) {
    super(serverId);
  }

  public void addDataQueueSizeGauge(DataQueue queue) {
    registry.gauge(RAFT_LOG_DATA_QUEUE_SIZE, () -> () -> {
      //q.size() is O(1) operation
      return queue.size();
    });
  }

  public void addClosedSegmentsNum(SegmentedRaftLogCache cache) {
    registry.gauge(RAFT_LOG_CACHE_CLOSED_SEGMENTS_NUM, () -> () -> {
      return cache.getCachedSegmentNum();
    });
  }

  public void addClosedSegmentsSizeInBytes(SegmentedRaftLogCache cache) {
    registry.gauge(RAFT_LOG_CACHE_CLOSED_SEGMENTS_SIZE_IN_BYTES, () -> () -> {
      return cache.getClosedSegmentsSizeInBytes();
    });
  }

  public void addOpenSegmentSizeInBytes(SegmentedRaftLogCache cache) {
    registry.gauge(RAFT_LOG_CACHE_OPEN_SEGMENT_SIZE_IN_BYTES, () -> () -> {
      return cache.getOpenSegmentSizeInBytes();
    });
  }

  public void addLogWorkerQueueSizeGauge(Queue queue) {
    registry.gauge(RAFT_LOG_WORKER_QUEUE_SIZE, () -> () -> queue.size());
  }

  public void addFlushBatchSizeGauge(MetricRegistry.MetricSupplier<Gauge> supplier) {
    registry.gauge(RAFT_LOG_SYNC_BATCH_SIZE, supplier);
  }

  private Timer getTimer(String timerName) {
    return registry.timer(timerName);
  }

  public Timer getFlushTimer() {
    return getTimer(RAFT_LOG_FLUSH_TIME);
  }

  public Timer getRaftLogSyncTimer() {
    return getTimer(RAFT_LOG_SYNC_TIME);
  }

  public void onRaftLogCacheHit() {
    registry.counter(RAFT_LOG_CACHE_HIT_COUNT).inc();
  }

  public void onRaftLogCacheMiss() {
    registry.counter(RAFT_LOG_CACHE_MISS_COUNT).inc();
  }

  public void onRaftLogFlush() {
    registry.counter(RAFT_LOG_FLUSH_COUNT).inc();
  }

  public void onRaftLogAppendEntry() {
    registry.counter(RAFT_LOG_APPEND_ENTRY_COUNT).inc();
  }

  public Timer getRaftLogAppendEntryTimer() {
    return getTimer(RAFT_LOG_APPEND_ENTRY_LATENCY);
  }

  public Timer getRaftLogQueueTimer() {
    return getTimer(RAFT_LOG_TASK_QUEUE_TIME);
  }

  public Timer getRaftLogEnqueueDelayTimer() {
    return getTimer(RAFT_LOG_TASK_ENQUEUE_DELAY);
  }

  public Timer getRaftLogTaskExecutionTimer(String taskName) {
    return getTimer(String.format(RAFT_LOG_TASK_EXECUTION_TIME, taskName));
  }

  public Timer getRaftLogReadEntryTimer() {
    return getTimer(RAFT_LOG_READ_ENTRY_LATENCY);
  }

  public Timer getRaftLogLoadSegmentTimer() {
    return getTimer(RAFT_LOG_LOAD_SEGMENT_LATENCY);
  }

  public Timer getRaftLogPurgeTimer() {
    return getTimer(RAFT_LOG_PURGE_METRIC);
  }
}