001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.master.procedure;
019
020import java.io.IOException;
021import org.apache.hadoop.hbase.ServerName;
022import org.apache.hadoop.hbase.procedure2.FailedRemoteDispatchException;
023import org.apache.hadoop.hbase.procedure2.Procedure;
024import org.apache.hadoop.hbase.procedure2.ProcedureEvent;
025import org.apache.hadoop.hbase.procedure2.ProcedureSuspendedException;
026import org.apache.hadoop.hbase.procedure2.ProcedureYieldException;
027import org.apache.hadoop.hbase.procedure2.RemoteProcedureDispatcher;
028import org.apache.hadoop.hbase.procedure2.RemoteProcedureException;
029import org.apache.yetus.audience.InterfaceAudience;
030import org.slf4j.Logger;
031import org.slf4j.LoggerFactory;
032
033@InterfaceAudience.Private
034/**
035 * The base class for Procedures that run {@link java.util.concurrent.Callable}s on a (remote)
036 * RegionServer; e.g. asking a RegionServer to split a WAL file as a sub-procedure of the
037 * ServerCrashProcedure recovery process.
038 * <p>
039 * To implement a new Procedure type, extend this class and override remoteCallBuild() and
040 * complete(). The dispatch and callback will be handled for you here, internally.
041 * <p>
042 * The Procedure works as follows. It uses {@link RSProcedureDispatcher}, the same system used
043 * dispatching Region OPEN and CLOSE RPCs, to pass a Callable to a RegionServer. Examples include
044 * {@link org.apache.hadoop.hbase.regionserver.SplitWALCallable} and
045 * {@link org.apache.hadoop.hbase.replication.regionserver.RefreshPeerCallable}. Rather than
046 * assign/unassign, the Master calls #executeProcedures against the remote RegionServer wrapping a
047 * Callable in a {@link ExecuteProceduresRequest}. Upon successful dispatch, the Procedure then
048 * suspends itself on the Master-side and relinqushes its executor worker. On receipt, the
049 * RegionServer submits the Callable to its executor service. When the Callable completes, it adds
050 * itself to a queue on the RegionServer side for processing by a background thread, the
051 * {@link RemoteProcedureResultReporter}. It picks up the completed Callable from the queue and RPCs
052 * the master at #reportProcedureDone with the procedure id and whether success or failure. The
053 * master calls complete() setting success or failure state and then reschedules the suspended
054 * Procedure so it can finish.
055 * <p>
056 * Here are some details on operation:
057 * <p>
058 * If adding the operation to the dispatcher fails, addOperationToNode will throw
059 * FailedRemoteDispatchException, and this Procedure will return 'null'. The Procedure Executor will
060 * then mark this procedure as 'complete' (though we failed to dispatch our task). In this case, the
061 * upper layer of this procedure must have a way to check if this Procedure really succeeded or not
062 * and have appropriate handling.
063 * <p>
064 * If sending the operation to remote RS failed, dispatcher will call remoteCallFailed() to handle
065 * this which calls remoteOperationDone with the exception. If the targetServer crashed but this
066 * procedure has no response, than dispatcher will call remoteOperationFailed() which also calls
067 * remoteOperationDone with the exception. If the operation is successful, then
068 * remoteOperationCompleted will be called and actually calls the remoteOperationDone without
069 * exception. In remoteOperationDone, we'll check if the procedure is already get wake up by others.
070 * Then developer could implement complete() based on their own purpose. But basic logic is that if
071 * operation succeed, set succ to true and do the clean work. If operation failed and require to
072 * resend it to the same server, leave the succ as false. If operation failed and require to resend
073 * it to another server, set succ to true and upper layer should be able to find out this operation
074 * not work and send a operation to another server.
075 */
076public abstract class ServerRemoteProcedure extends Procedure<MasterProcedureEnv>
077  implements RemoteProcedureDispatcher.RemoteProcedure<MasterProcedureEnv, ServerName> {
078  protected static final Logger LOG = LoggerFactory.getLogger(ServerRemoteProcedure.class);
079  protected ProcedureEvent<?> event;
080  protected ServerName targetServer;
081  protected boolean dispatched;
082  protected boolean succ;
083
084  protected abstract void complete(MasterProcedureEnv env, Throwable error);
085
086  @Override
087  protected synchronized Procedure<MasterProcedureEnv>[] execute(MasterProcedureEnv env)
088    throws ProcedureYieldException, ProcedureSuspendedException, InterruptedException {
089    if (dispatched) {
090      if (succ) {
091        return null;
092      }
093      dispatched = false;
094    }
095    try {
096      env.getRemoteDispatcher().addOperationToNode(targetServer, this);
097    } catch (FailedRemoteDispatchException frde) {
098      LOG.warn("Can not send remote operation {} to {}, this operation will "
099        + "be retried to send to another server", this.getProcId(), targetServer);
100      return null;
101    }
102    dispatched = true;
103    event = new ProcedureEvent<>(this);
104    event.suspendIfNotReady(this);
105    throw new ProcedureSuspendedException();
106  }
107
108  @Override
109  protected synchronized void completionCleanup(MasterProcedureEnv env) {
110    env.getRemoteDispatcher().removeCompletedOperation(targetServer, this);
111  }
112
113  @Override
114  public synchronized void remoteCallFailed(MasterProcedureEnv env, ServerName serverName,
115    IOException exception) {
116    remoteOperationDone(env, exception);
117  }
118
119  @Override
120  public synchronized void remoteOperationCompleted(MasterProcedureEnv env) {
121    remoteOperationDone(env, null);
122  }
123
124  @Override
125  public synchronized void remoteOperationFailed(MasterProcedureEnv env,
126    RemoteProcedureException error) {
127    remoteOperationDone(env, error);
128  }
129
130  synchronized void remoteOperationDone(MasterProcedureEnv env, Throwable error) {
131    if (this.isFinished()) {
132      LOG.info("This procedure {} is already finished, skip the rest processes", this.getProcId());
133      return;
134    }
135    if (event == null) {
136      LOG.warn("procedure event for {} is null, maybe the procedure is created when recovery",
137        getProcId());
138      return;
139    }
140    complete(env, error);
141    event.wake(env.getProcedureScheduler());
142    event = null;
143  }
144}