atomix-storage/src/main/java/io/atomix/storage/journal/SegmentedJournalWriter.java

   1 /*
   2  * Copyright 2017-present Open Networking Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not 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.
  15  */
  16 package io.atomix.storage.journal;
  17
  18 import java.nio.BufferOverflowException;
  19
  20 /**
  21  * Raft log writer.
  22  */
  23 public final class SegmentedJournalWriter<E> implements JournalWriter<E> {
  24   private final SegmentedJournal<E> journal;
  25   private JournalSegment<E> currentSegment;
  26   private MappableJournalSegmentWriter<E> currentWriter;
  27
  28   SegmentedJournalWriter(SegmentedJournal<E> journal) {
  29     this.journal = journal;
  30     this.currentSegment = journal.getLastSegment();
  31     this.currentWriter = currentSegment.acquireWriter();
  32   }
  33
  34   @Override
  35   public long getLastIndex() {
  36     return currentWriter.getLastIndex();
  37   }
  38
  39   @Override
  40   public Indexed<E> getLastEntry() {
  41     return currentWriter.getLastEntry();
  42   }
  43
  44   @Override
  45   public long getNextIndex() {
  46     return currentWriter.getNextIndex();
  47   }
  48
  49   @Override
  50   public void reset(long index) {
  51     if (index > currentSegment.index()) {
  52       currentSegment.releaseWriter();
  53       currentSegment = journal.resetSegments(index);
  54       currentWriter = currentSegment.acquireWriter();
  55     } else {
  56       truncate(index - 1);
  57     }
  58     journal.resetHead(index);
  59   }
  60
  61   @Override
  62   public void commit(long index) {
  63     if (index > journal.getCommitIndex()) {
  64       journal.setCommitIndex(index);
  65       if (journal.isFlushOnCommit()) {
  66         flush();
  67       }
  68     }
  69   }
  70
  71   @Override
  72   public <T extends E> Indexed<T> append(T entry) {
  73     try {
  74       return currentWriter.append(entry);
  75     } catch (BufferOverflowException e) {
  76       if (currentSegment.index() == currentWriter.getNextIndex()) {
  77         throw e;
  78       }
  79     }
  80
  81     moveToNextSegment();
  82     return currentWriter.append(entry);
  83   }
  84
  85   @Override
  86   public void append(Indexed<E> entry) {
  87     try {
  88       currentWriter.append(entry);
  89       return;
  90     } catch (BufferOverflowException e) {
  91       if (currentSegment.index() == currentWriter.getNextIndex()) {
  92         throw e;
  93       }
  94     }
  95
  96     moveToNextSegment();
  97     currentWriter.append(entry);
  98   }
  99
 100   private void moveToNextSegment() {
 101     currentWriter.flush();
 102     currentSegment.releaseWriter();
 103     currentSegment = journal.getNextSegment();
 104     currentWriter = currentSegment.acquireWriter();
 105   }
 106
 107   @Override
 108   public void truncate(long index) {
 109     if (index < journal.getCommitIndex()) {
 110       throw new IndexOutOfBoundsException("Cannot truncate committed index: " + index);
 111     }
 112
 113     // Delete all segments with first indexes greater than the given index.
 114     while (index < currentSegment.index() && currentSegment != journal.getFirstSegment()) {
 115       currentSegment.releaseWriter();
 116       journal.removeSegment(currentSegment);
 117       currentSegment = journal.getLastSegment();
 118       currentWriter = currentSegment.acquireWriter();
 119     }
 120
 121     // Truncate the current index.
 122     currentWriter.truncate(index);
 123
 124     // Reset segment readers.
 125     journal.resetTail(index + 1);
 126   }
 127
 128   @Override
 129   public void flush() {
 130     currentWriter.flush();
 131   }
 132
 133   @Override
 134   public void close() {
 135     currentWriter.close();
 136   }
 137 }