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

   1 /*
   2  * Copyright 2017-2022 Open Networking Foundation and others.  All rights reserved.
   3  * Copyright (c) 2024 PANTHEON.tech, s.r.o. and others.
   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 package io.atomix.storage.journal;
  18
  19 import static com.google.common.base.Verify.verifyNotNull;
  20 import static java.util.Objects.requireNonNull;
  21
  22 import io.netty.buffer.ByteBuf;
  23
  24 /**
  25  * A {@link ByteBufWriter} implementation.
  26  */
  27 final class SegmentedByteBufWriter implements ByteBufWriter {
  28     private final SegmentedByteBufJournal journal;
  29
  30     private JournalSegment currentSegment;
  31     private JournalSegmentWriter currentWriter;
  32
  33     SegmentedByteBufWriter(final SegmentedByteBufJournal journal) {
  34         this.journal = requireNonNull(journal);
  35         currentSegment = journal.lastSegment();
  36         currentWriter = currentSegment.acquireWriter();
  37     }
  38
  39     @Override
  40     public long lastIndex() {
  41         return currentWriter.getLastIndex();
  42     }
  43
  44     @Override
  45     public long nextIndex() {
  46         return currentWriter.getNextIndex();
  47     }
  48
  49     @Override
  50     public void reset(final long index) {
  51         if (index > currentSegment.firstIndex()) {
  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(final 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 long append(final ByteBuf buf) {
  73         var index = currentWriter.append(buf);
  74         if (index != null) {
  75             return index;
  76         }
  77         //  Slow path: we do not have enough capacity
  78         currentWriter.flush();
  79         currentSegment.releaseWriter();
  80         currentSegment = journal.createNextSegment();
  81         currentWriter = currentSegment.acquireWriter();
  82         return verifyNotNull(currentWriter.append(buf));
  83     }
  84
  85     @Override
  86     public void truncate(final long index) {
  87         if (index < journal.getCommitIndex()) {
  88             throw new IndexOutOfBoundsException("Cannot truncate committed index: " + index);
  89         }
  90
  91         // Delete all segments with first indexes greater than the given index.
  92         while (index < currentSegment.firstIndex() && currentSegment != journal.firstSegment()) {
  93             currentSegment.releaseWriter();
  94             journal.removeSegment(currentSegment);
  95             currentSegment = journal.lastSegment();
  96             currentWriter = currentSegment.acquireWriter();
  97         }
  98
  99         // Truncate the current index.
 100         currentWriter.truncate(index);
 101
 102         // Reset segment readers.
 103         journal.resetTail(index + 1);
 104     }
 105
 106     @Override
 107     public void flush() {
 108         currentWriter.flush();
 109     }
 110 }