MDCLoggingContext.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.solr.logging;

import static org.apache.solr.common.cloud.ZkStateReader.COLLECTION_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.CORE_NAME_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.NODE_NAME_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.REPLICA_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.SHARD_ID_PROP;

import java.util.function.Supplier;

import org.apache.solr.cloud.CloudDescriptor;
import org.apache.solr.cloud.ZkController;
import org.apache.solr.core.CoreContainer;
import org.apache.solr.core.CoreDescriptor;
import org.apache.solr.core.SolrCore;
import org.slf4j.MDC;

/**
 * Set's per thread context info for logging. Nested calls will use the top level parent for all context. The first
 * caller always owns the context until it calls {@link #clear()}. Always call {@link #setCore(SolrCore)} or
 * {@link #setCoreDescriptor(CoreContainer, CoreDescriptor)} and then {@link #clear()} in a finally block.
 */
public class MDCLoggingContext {
  // When a thread sets context and finds that the context is already set, we should noop and ignore the finally clear
  private static ThreadLocal<Integer> CALL_DEPTH = ThreadLocal.withInitial(new Supplier<Integer>() {
    @Override
    public Integer get() {
      return 0;
    }
  });
  
  private static void setCollection(String collection) {
    if (collection != null) {
      MDC.put(COLLECTION_PROP, "c:" + collection);
    } else {
      MDC.remove(COLLECTION_PROP);
    }
  }
  
  private static void setShard(String shard) {
    if (shard != null) {
      MDC.put(SHARD_ID_PROP, "s:" + shard);
    } else {
      MDC.remove(SHARD_ID_PROP);
    }
  }
  
  private static void setReplica(String replica) {
    if (replica != null) {
      MDC.put(REPLICA_PROP, "r:" + replica);
    } else {
      MDC.remove(REPLICA_PROP);
    }
  }
  
  private static void setCoreName(String core) {
    if (core != null) {
      MDC.put(CORE_NAME_PROP, "x:" + core);
    } else {
      MDC.remove(CORE_NAME_PROP);
    }
  }
  
  public static void setNode(CoreContainer cc) {
    if (cc != null) {
      ZkController zk = cc.getZkController();
      if (zk != null) {
        setNode(zk.getNodeName());
      }
    }
  }
  
  // we allow the host to be set like this because it is the same for any thread
  // in the thread pool - we can't do this with the per core properties!
  public static void setNode(String node) {
    int used = CALL_DEPTH.get();
    if (used == 0) {
      setNodeName(node);
    }
  }
  
  private static void setNodeName(String node) {
    if (node != null) {
      MDC.put(NODE_NAME_PROP, "n:" + node);
    } else {
      MDC.remove(NODE_NAME_PROP);
    }
  }
  
  public static void setCore(SolrCore core) {
    if (core != null) {
      setCoreDescriptor(core.getCoreContainer(), core.getCoreDescriptor());
    }
  }
  
  public static void setCoreDescriptor(CoreContainer coreContainer, CoreDescriptor cd) {
    if (cd != null) {
      int callDepth = CALL_DEPTH.get();
      CALL_DEPTH.set(callDepth + 1);
      if (callDepth > 0) {
        return;
      }
      
      setCoreName(cd.getName());
      if (coreContainer != null) {
        ZkController zkController = coreContainer.getZkController();
        if (zkController != null) {
          setNodeName(zkController.getNodeName());
        }
      }
      
      CloudDescriptor ccd = cd.getCloudDescriptor();
      if (ccd != null) {
        setCollection(ccd.getCollectionName());
        setShard(ccd.getShardId());
        setReplica(ccd.getCoreNodeName());
      }
    }
  }
  
  public static void clear() {
    int used = CALL_DEPTH.get();
    CALL_DEPTH.set(used - 1);
    if (used == 0) {
      MDC.remove(COLLECTION_PROP);
      MDC.remove(CORE_NAME_PROP);
      MDC.remove(REPLICA_PROP);
      MDC.remove(SHARD_ID_PROP);
    }
  }
  
  private static void removeAll() {
    MDC.remove(COLLECTION_PROP);
    MDC.remove(CORE_NAME_PROP);
    MDC.remove(REPLICA_PROP);
    MDC.remove(SHARD_ID_PROP);
    MDC.remove(NODE_NAME_PROP);
  }
  
  public static void reset() {
    CALL_DEPTH.set(0);
    removeAll();
  }
}