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 commit(final long index) {
  51         if (index > journal.getCommitIndex()) {
  52             journal.setCommitIndex(index);
  53             if (journal.isFlushOnCommit()) {
  54                 flush();
  55             }
  56         }
  57     }
  58
  59     @Override
  60     public long append(final ByteBuf buf) {
  61         var index = currentWriter.append(buf);
  62         if (index != null) {
  63             return index;
  64         }
  65         //  Slow path: we do not have enough capacity
  66         currentWriter.flush();
  67         currentSegment.releaseWriter();
  68         currentSegment = journal.createNextSegment();
  69         currentWriter = currentSegment.acquireWriter();
  70         return verifyNotNull(currentWriter.append(buf));
  71     }
  72
  73     @Override
  74     public void reset(final long index) {
  75         final long commitIndex = journal.getCommitIndex();
  76         if (index <= commitIndex) {
  77           // also catches index == 0, which is not a valid next index
  78           throw new IndexOutOfBoundsException("Cannot reset to: " + index + ", committed index: " + commitIndex);
  79         }
  80
  81         if (index > currentSegment.firstIndex()) {
  82             currentSegment.releaseWriter();
  83             currentSegment = journal.resetSegments(index);
  84             currentWriter = currentSegment.acquireWriter();
  85         } else {
  86             checkedTruncate(index - 1);
  87         }
  88         journal.resetHead(index);
  89     }
  90
  91     @Override
  92     public void truncate(final long index) {
  93         if (index < journal.getCommitIndex()) {
  94             throw new IndexOutOfBoundsException("Cannot truncate committed index: " + index);
  95         }
  96         checkedTruncate(index);
  97     }
  98
  99     private void checkedTruncate(final long index) {
 100         // Delete all segments with first indexes greater than the given index.
 101         while (index < currentSegment.firstIndex() && currentSegment != journal.firstSegment()) {
 102             currentSegment.releaseWriter();
 103             journal.removeSegment(currentSegment);
 104             currentSegment = journal.lastSegment();
 105             currentWriter = currentSegment.acquireWriter();
 106         }
 107
 108         // Truncate the current index.
 109         currentWriter.truncate(index);
 110
 111         // Reset segment readers.
 112         journal.resetTail(index + 1);
 113     }
 114
 115     @Override
 116     public void flush() {
 117         currentWriter.flush();
 118     }
 119 }