BatchedWrite xref

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    1   /***
    2    *
    3    * Copyright 2004 Hiram Chirino
    4    *
    5    * Licensed under the Apache License, Version 2.0 (the "License");
    6    * you may not use this file except in compliance with the License.
    7    * You may obtain a copy of the License at
    8    *
    9    * http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   **/
    18  package org.activeio.journal.active;
    19
    20  import org.activeio.Packet;
    21
    22  import EDU.oswego.cs.dl.util.concurrent.Latch;
    23
    24  /***
    25   * This contains all the data needed to write and force a list of records to a
    26   * LogFile. The more records that can be cramed into a single BatchedWrite, the
    27   * higher throughput that can be achived by a write and force operation.
    28   *
    29   * @version $Revision: 1.1 $
    30   */
    31  final public class BatchedWrite {
    32
    33      private final Packet packet;
    34      public Throwable error;
    35      private Location mark;
    36      private boolean appendDisabled = false;
    37      private boolean appendInProgress = false;
    38      private Latch writeDoneLatch;
    39
    40      /***
    41       * @param packet
    42       */
    43      public BatchedWrite(Packet packet) {
    44          this.packet = packet;
    45      }
    46
    47      /***
    48       * @throws InterruptedException
    49       *
    50       */
    51      synchronized private void disableAppend() throws InterruptedException {
    52          appendDisabled = true;
    53          while (appendInProgress) {
    54              wait();
    55          }
    56      }
    57
    58      /***
    59       * @param packet2
    60       * @param mark2
    61       * @return
    62       */
    63      public boolean append(Record record, Location recordMark, boolean force) {
    64
    65          synchronized (this) {
    66              if (appendDisabled)
    67                  return false;
    68              appendInProgress = true;
    69          }
    70
    71
    72          if( force && writeDoneLatch==null)
    73              writeDoneLatch = new Latch();
    74
    75          record.read(packet);
    76
    77          // if we fit the record in this batch
    78          if ( !record.hasRemaining() ) {
    79              if (recordMark != null)
    80                  mark = recordMark;
    81          }
    82
    83          synchronized (this) {
    84              appendInProgress = false;
    85              this.notify();
    86
    87              if (appendDisabled)
    88                  return false;
    89              else
    90                  return packet.remaining() > 0;
    91          }
    92      }
    93
    94      public void waitForForce() throws Throwable {
    95          if( writeDoneLatch!=null ) {
    96              writeDoneLatch.acquire();
    97              synchronized (this) {
    98                  if (error != null)
    99                      throw error;
    100             }
    101         }
    102     }
    103
    104     public void forced() {
    105         if( writeDoneLatch!=null ) {
    106             writeDoneLatch.release();
    107         }
    108     }
    109
    110     public void writeFailed(Throwable error) {
    111         if( writeDoneLatch!=null ) {
    112             synchronized (this) {
    113                 this.error = error;
    114             }
    115             writeDoneLatch.release();
    116         }
    117     }
    118
    119     public Packet getPacket() {
    120         return packet;
    121     }
    122
    123     /***
    124      * @return
    125      */
    126     public Location getMark() {
    127         return mark;
    128     }
    129
    130     /***
    131      * @throws InterruptedException
    132      *
    133      */
    134     public void flip() throws InterruptedException {
    135         disableAppend();
    136         packet.flip();
    137     }
    138
    139     public boolean getForce() {
    140         return writeDoneLatch!=null;
    141     }
    142
    143 }