1  /*
     2   * Licensed to the Apache Software Foundation (ASF) under one or more
     3   *  contributor license agreements.  The ASF licenses this file to You
     4   * under the Apache License, Version 2.0 (the "License"); you may not
     5   * use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.  For additional information regarding
    15   * copyright in this work, please see the NOTICE file in the top level
    16   * directory of this distribution.
    17   */
    18  
    19  package org.apache.roller.weblogger.business.runnable;
    20  
    21  import org.apache.commons.logging.Log;
    22  import org.apache.commons.logging.LogFactory;
    23  import org.apache.roller.weblogger.WebloggerException;
    24  import org.apache.roller.weblogger.business.WebloggerFactory;
    25  
    26  
    27  /**
    28   * An abstract class representing a scheduled task in Roller that will always
    29   * attempt to acquire a lease before doing its work.
    30   */
         /* 
    P/P   *  Method: void org.apache.roller.weblogger.business.runnable.RollerTaskWithLeasing()
          */
    31  public abstract class RollerTaskWithLeasing extends RollerTask {
    32      
             /* 
    P/P       *  Method: org.apache.roller.weblogger.business.runnable.RollerTaskWithLeasing__static_init
              * 
              *  Postconditions:
              *    init'ed(log)
              */
    33      private static Log log = LogFactory.getLog(RollerTaskWithLeasing.class);
    34      
    35      
    36      /**
    37       * Run the task.
    38       */
    39      public abstract void runTask() throws WebloggerException;
    40      
    41      
    42      /**
    43       * The run() method as called by our thread manager.
    44       *
    45       * This method is purposely defined as "final" so that any tasks that are
    46       * defined may not override it and remove any of its functionality.  It is
    47       * setup to provide some basic functionality to the running of all tasks,
    48       * such as lease acquisition and releasing.
    49       *
    50       * Roller tasks should put their logic in the runTask() method.
    51       */
    52      public final void run() {
    53          
                 /* 
    P/P           *  Method: void run()
                  * 
                  *  Preconditions:
                  *    log != null
                  *    org/apache/roller/weblogger/business/WebloggerFactory.webloggerProvider != null
                  *    org/apache/roller/weblogger/business/WebloggerFactory.webloggerProvider.webloggerInstance != null
                  *    (soft) org/apache/roller/weblogger/business/WebloggerImpl.log != null
                  * 
                  *  Presumptions:
                  *    getWeblogger(...).autoPingManager != null
                  *    getWeblogger(...).bookmarkManager != null
                  *    getWeblogger(...).fileManager != null
                  *    getWeblogger(...).pingQueueManager != null
                  *    getWeblogger(...).pingTargetManager != null
                  *    ...
                  */
    54          ThreadManager mgr = WebloggerFactory.getWeblogger().getThreadManager();
    55          
    56          boolean lockAcquired = false;
    57          try {
    58              log.debug(getName()+": Attempting to acquire lease");
    59              
    60              lockAcquired = mgr.registerLease(this);
    61              
    62              // now if we have a lock then run the task
    63              if(lockAcquired) {
    64                  log.debug(getName()+": Lease acquired, running task");
    65                  this.runTask();
    66              } else {
    67                  log.debug(getName()+": Lease NOT acquired, cannot continue");
    68                  return;
    69              }
    70              
    71          } catch (Exception ex) {
    72              log.error(getName()+": Unexpected exception", ex);
    73          } finally {
    74              
    75              if(lockAcquired) {
    76                  
    77                  log.debug(getName()+": Attempting to release lease");
    78                  
    79                  boolean lockReleased = mgr.unregisterLease(this);
    80                  
    81                  if(lockReleased) {
    82                      log.debug(getName()+": Lease released, task finished");
    83                  } else {
    84                      log.debug(getName()+": Lease NOT released, some kind of problem");
    85                  }
    86              }
    87              
    88              // always release Roller session
    89              WebloggerFactory.getWeblogger().release();
    90          }
    91          
    92      }
    93      
    94  }