/**
    * 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.hbase.procedure;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.RejectedExecutionException;
  import java.util.concurrent.SynchronousQueue;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.DaemonThreadFactory;
  import org.apache.hadoop.hbase.errorhandling.ForeignException;
  
  import com.google.common.collect.MapMaker;
  
  /**
   * Process to kick off and manage a running {@link Subprocedure} on a member. This is the
   * specialized part of a {@link Procedure} that actually does procedure type-specific work
   * and reports back to the coordinator as it completes each phase.
   */
  @InterfaceAudience.Private
  public class ProcedureMember implements Closeable {
    private static final Log LOG = LogFactory.getLog(ProcedureMember.class);
  
    final static long KEEP_ALIVE_MILLIS_DEFAULT = 5000;
  
    private final SubprocedureFactory builder;
    private final ProcedureMemberRpcs rpcs;
  
    private final ConcurrentMap<String,Subprocedure> subprocs =
        new MapMaker().concurrencyLevel(4).weakValues().makeMap();
    private final ExecutorService pool;
  
    /**
     * Instantiate a new ProcedureMember.  This is a slave that executes subprocedures.
     *
     * @param rpcs controller used to send notifications to the procedure coordinator
     * @param pool thread pool to submit subprocedures
     * @param factory class that creates instances of a subprocedure.
     */
    public ProcedureMember(ProcedureMemberRpcs rpcs, ThreadPoolExecutor pool,
        SubprocedureFactory factory) {
      this.pool = pool;
      this.rpcs = rpcs;
      this.builder = factory;
    }
  
    /**
     * Default thread pool for the procedure
     *
     * @param memberName
     * @param procThreads the maximum number of threads to allow in the pool
     */
    public static ThreadPoolExecutor defaultPool(String memberName, int procThreads) {
      return defaultPool(memberName, procThreads, KEEP_ALIVE_MILLIS_DEFAULT);
    }
  
    /**
     * Default thread pool for the procedure
     *
     * @param memberName
     * @param procThreads the maximum number of threads to allow in the pool
     * @param keepAliveMillis the maximum time (ms) that excess idle threads will wait for new tasks
     */
    public static ThreadPoolExecutor defaultPool(String memberName, int procThreads,
        long keepAliveMillis) {
      return new ThreadPoolExecutor(1, procThreads, keepAliveMillis, TimeUnit.MILLISECONDS,
          new SynchronousQueue<Runnable>(),
          new DaemonThreadFactory("member: '" + memberName + "' subprocedure-pool"));
    }
  
    /**
     * Package exposed.  Not for public use.
     *
     * @return reference to the Procedure member's rpcs object
     */
    ProcedureMemberRpcs getRpcs() {
      return rpcs;
   }
 
 
   /**
    * This is separated from execution so that we can detect and handle the case where the
    * subprocedure is invalid and inactionable due to bad info (like DISABLED snapshot type being
    * sent here)
    * @param opName
    * @param data
    * @return subprocedure
    */
   public Subprocedure createSubprocedure(String opName, byte[] data) {
     return builder.buildSubprocedure(opName, data);
   }
 
   /**
    * Submit an subprocedure for execution.  This starts the local acquire phase.
    * @param subproc the subprocedure to execute.
    * @return <tt>true</tt> if the subprocedure was started correctly, <tt>false</tt> if it
    *         could not be started. In the latter case, the subprocedure holds a reference to
    *         the exception that caused the failure.
    */
   public boolean submitSubprocedure(Subprocedure subproc) {
      // if the submitted subprocedure was null, bail.
     if (subproc == null) {
       LOG.warn("Submitted null subprocedure, nothing to run here.");
       return false;
     }
 
     String procName = subproc.getName();
     if (procName == null || procName.length() == 0) {
       LOG.error("Subproc name cannot be null or the empty string");
       return false;
     }
 
     // make sure we aren't already running an subprocedure of that name
     Subprocedure rsub = subprocs.get(procName);
     if (rsub != null) {
       if (!rsub.isComplete()) {
         LOG.error("Subproc '" + procName + "' is already running. Bailing out");
         return false;
       }
       LOG.warn("A completed old subproc "  +  procName + " is still present, removing");
       if (!subprocs.remove(procName, rsub)) {
         LOG.error("Another thread has replaced existing subproc '" + procName + "'. Bailing out");
         return false;
       }
     }
 
     LOG.debug("Submitting new Subprocedure:" + procName);
 
     // kick off the subprocedure
     try {
       if (subprocs.putIfAbsent(procName, subproc) == null) {
         this.pool.submit(subproc);
         return true;
       } else {
         LOG.error("Another thread has submitted subproc '" + procName + "'. Bailing out");
         return false;
       }
     } catch (RejectedExecutionException e) {
       subprocs.remove(procName, subproc);
 
       // the thread pool is full and we can't run the subprocedure
       String msg = "Subprocedure pool is full!";
       subproc.cancel(msg, e.getCause());
     }
 
     LOG.error("Failed to start subprocedure '" + procName + "'");
     return false;
   }
 
    /**
     * Notification that procedure coordinator has reached the global barrier
     * @param procName name of the subprocedure that should start running the in-barrier phase
     */
    public void receivedReachedGlobalBarrier(String procName) {
      Subprocedure subproc = subprocs.get(procName);
      if (subproc == null) {
        LOG.warn("Unexpected reached glabal barrier message for Sub-Procedure '" + procName + "'");
        return;
      }
      subproc.receiveReachedGlobalBarrier();
    }
 
   /**
    * Best effort attempt to close the threadpool via Thread.interrupt.
    */
   @Override
   public void close() throws IOException {
     // have to use shutdown now to break any latch waiting
     pool.shutdownNow();
   }
 
   /**
    * Shutdown the threadpool, and wait for upto timeoutMs millis before bailing
    * @param timeoutMs timeout limit in millis
    * @return true if successfully, false if bailed due to timeout.
    * @throws InterruptedException
    */
   boolean closeAndWait(long timeoutMs) throws InterruptedException {
     pool.shutdown();
     return pool.awaitTermination(timeoutMs, TimeUnit.MILLISECONDS);
   }
 
   /**
    * The connection to the rest of the procedure group (member and coordinator) has been
    * broken/lost/failed. This should fail any interested subprocedure, but not attempt to notify
    * other members since we cannot reach them anymore.
    * @param message description of the error
    * @param cause the actual cause of the failure
    * @param procName the name of the procedure we'd cancel due to the error.
    */
   public void controllerConnectionFailure(final String message, final Throwable cause,
       final String procName) {
     LOG.error(message, cause);
     if (procName == null) {
       return;
     }
     Subprocedure toNotify = subprocs.get(procName);
     if (toNotify != null) {
       toNotify.cancel(message, cause);
     }
   }
 
   /**
    * Send abort to the specified procedure
    * @param procName name of the procedure to about
    * @param ee exception information about the abort
    */
   public void receiveAbortProcedure(String procName, ForeignException ee) {
     LOG.debug("Request received to abort procedure " + procName, ee);
     // if we know about the procedure, notify it
     Subprocedure sub = subprocs.get(procName);
     if (sub == null) {
       LOG.info("Received abort on procedure with no local subprocedure " + procName +
           ", ignoring it.", ee);
       return; // Procedure has already completed
     }
     String msg = "Propagating foreign exception to subprocedure " + sub.getName();
     LOG.error(msg, ee);
     sub.cancel(msg, ee);
   }
 }