hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/safemode/HealthyPipelineSafeModeRule.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.hadoop.hdds.scm.safemode;

import java.util.HashSet;
import java.util.Set;

import org.apache.hadoop.hdds.HddsConfigKeys;
import org.apache.hadoop.hdds.conf.ConfigurationSource;
import org.apache.hadoop.hdds.protocol.proto.HddsProtos;
import org.apache.hadoop.hdds.scm.events.SCMEvents;
import org.apache.hadoop.hdds.scm.pipeline.Pipeline;
import org.apache.hadoop.hdds.scm.pipeline.PipelineID;
import org.apache.hadoop.hdds.scm.pipeline.PipelineManager;
import org.apache.hadoop.hdds.server.events.EventQueue;
import org.apache.hadoop.hdds.server.events.TypedEvent;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Class defining Safe mode exit criteria for Pipelines.
 *
 * This rule defines percentage of healthy pipelines need to be reported.
 * Once safe mode exit happens, this rules take care of writes can go
 * through in a cluster.
 */
public class HealthyPipelineSafeModeRule extends SafeModeExitRule<Pipeline> {

  public static final Logger LOG =
      LoggerFactory.getLogger(HealthyPipelineSafeModeRule.class);
  private int healthyPipelineThresholdCount;
  private int currentHealthyPipelineCount = 0;
  private final double healthyPipelinesPercent;
  private final Set<PipelineID> processedPipelineIDs = new HashSet<>();

  HealthyPipelineSafeModeRule(String ruleName, EventQueue eventQueue,
      PipelineManager pipelineManager,
      SCMSafeModeManager manager, ConfigurationSource configuration) {
    super(manager, ruleName, eventQueue);
    healthyPipelinesPercent =
        configuration.getDouble(HddsConfigKeys.
                HDDS_SCM_SAFEMODE_HEALTHY_PIPELINE_THRESHOLD_PCT,
            HddsConfigKeys.
                HDDS_SCM_SAFEMODE_HEALTHY_PIPELINE_THRESHOLD_PCT_DEFAULT);

    int minDatanodes = configuration.getInt(
        HddsConfigKeys.HDDS_SCM_SAFEMODE_MIN_DATANODE,
        HddsConfigKeys.HDDS_SCM_SAFEMODE_MIN_DATANODE_DEFAULT);

    // We only care about THREE replica pipeline
    int minHealthyPipelines = minDatanodes /
        HddsProtos.ReplicationFactor.THREE_VALUE;

    Preconditions.checkArgument(
        (healthyPipelinesPercent >= 0.0 && healthyPipelinesPercent <= 1.0),
        HddsConfigKeys.
            HDDS_SCM_SAFEMODE_HEALTHY_PIPELINE_THRESHOLD_PCT
            + " value should be >= 0.0 and <= 1.0");

    // We want to wait for RATIS THREE factor write pipelines
    int pipelineCount = pipelineManager.getPipelines(
        HddsProtos.ReplicationType.RATIS, HddsProtos.ReplicationFactor.THREE,
        Pipeline.PipelineState.ALLOCATED).size();

    // This value will be zero when pipeline count is 0.
    // On a fresh installed cluster, there will be zero pipelines in the SCM
    // pipeline DB.
    healthyPipelineThresholdCount = Math.max(minHealthyPipelines,
        (int) Math.ceil(healthyPipelinesPercent * pipelineCount));

    LOG.info("Total pipeline count is {}, healthy pipeline " +
        "threshold count is {}", pipelineCount, healthyPipelineThresholdCount);

    getSafeModeMetrics().setNumHealthyPipelinesThreshold(
        healthyPipelineThresholdCount);
  }

  @VisibleForTesting
  public void setHealthyPipelineThresholdCount(int actualPipelineCount) {
    healthyPipelineThresholdCount =
        (int) Math.ceil(healthyPipelinesPercent * actualPipelineCount);
  }

  @Override
  protected TypedEvent<Pipeline> getEventType() {
    return SCMEvents.OPEN_PIPELINE;
  }

  @Override
  protected boolean validate() {
    if (currentHealthyPipelineCount >= healthyPipelineThresholdCount) {
      return true;
    }
    return false;
  }

  @Override
  protected void process(Pipeline pipeline) {

    // When SCM is in safe mode for long time, already registered
    // datanode can send pipeline report again, or SCMPipelineManager will
    // create new pipelines.
    Preconditions.checkNotNull(pipeline);
    if (pipeline.getType() == HddsProtos.ReplicationType.RATIS &&
        pipeline.getFactor() == HddsProtos.ReplicationFactor.THREE &&
        pipeline.isHealthy() &&
        !processedPipelineIDs.contains(pipeline.getId())) {
      getSafeModeMetrics().incCurrentHealthyPipelinesCount();
      currentHealthyPipelineCount++;
      processedPipelineIDs.add(pipeline.getId());
    }

    if (scmInSafeMode()) {
      SCMSafeModeManager.getLogger().info(
          "SCM in safe mode. Healthy pipelines reported count is {}, " +
              "required healthy pipeline reported count is {}",
          currentHealthyPipelineCount, healthyPipelineThresholdCount);
    }
  }

  @Override
  protected void cleanup() {
    processedPipelineIDs.clear();
  }

  @VisibleForTesting
  public int getCurrentHealthyPipelineCount() {
    return currentHealthyPipelineCount;
  }

  @VisibleForTesting
  public int getHealthyPipelineThresholdCount() {
    return healthyPipelineThresholdCount;
  }
}