X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=atomix-storage%2Fsrc%2Fmain%2Fjava%2Fio%2Fatomix%2Fstorage%2Fjournal%2FFileChannelJournalSegmentWriter.java;h=f4c7ec52c3c53f7d739eff7fa30da1945010f8d1;hb=3924193f0176e3f114a2dc82e45a49a684fe2375;hp=b43aa3d443fbe08eaccc0c851bd33418c832a855;hpb=b2106c7c4fbc91f6cdfd8bf4371b723db6fdae2f;p=controller.git

diff --git a/atomix-storage/src/main/java/io/atomix/storage/journal/FileChannelJournalSegmentWriter.java b/atomix-storage/src/main/java/io/atomix/storage/journal/FileChannelJournalSegmentWriter.java
index b43aa3d443..f4c7ec52c3 100644
--- a/atomix-storage/src/main/java/io/atomix/storage/journal/FileChannelJournalSegmentWriter.java
+++ b/atomix-storage/src/main/java/io/atomix/storage/journal/FileChannelJournalSegmentWriter.java
@@ -1,5 +1,6 @@
 /*
- * Copyright 2017-present Open Networking Foundation
+ * Copyright 2017-2022 Open Networking Foundation and others.  All rights reserved.
+ * Copyright (c) 2024 PANTHEON.tech, s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,9 +23,9 @@ import java.io.IOException;
 import java.nio.BufferOverflowException;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
+import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
 import java.util.zip.CRC32;
-import java.util.zip.Checksum;
 
 /**
  * Segment writer.
@@ -41,15 +42,12 @@ import java.util.zip.Checksum;
  *
  * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
  */
-class FileChannelJournalSegmentWriter<E> implements JournalWriter<E> {
-  private final FileChannel channel;
-  private final JournalSegment<E> segment;
-  private final int maxEntrySize;
-  private final JournalIndex index;
-  private final JournalSerdes namespace;
+final class FileChannelJournalSegmentWriter<E> extends JournalSegmentWriter<E> {
+  private static final ByteBuffer ZERO_ENTRY_HEADER = ByteBuffer.wrap(new byte[ENTRY_HEADER_BYTES]);
+
   private final ByteBuffer memory;
-  private final long firstIndex;
   private Indexed<E> lastEntry;
+  private long currentPosition;
 
   FileChannelJournalSegmentWriter(
       FileChannel channel,
@@ -57,39 +55,52 @@ class FileChannelJournalSegmentWriter<E> implements JournalWriter<E> {
       int maxEntrySize,
       JournalIndex index,
       JournalSerdes namespace) {
-    this.channel = channel;
-    this.segment = segment;
-    this.maxEntrySize = maxEntrySize;
-    this.index = index;
-    this.memory = ByteBuffer.allocate((maxEntrySize + Integer.BYTES + Integer.BYTES) * 2);
-    memory.limit(0);
-    this.namespace = namespace;
-    this.firstIndex = segment.index();
+    super(channel, segment, maxEntrySize, index, namespace);
+    memory = allocMemory(maxEntrySize);
     reset(0);
   }
 
+  FileChannelJournalSegmentWriter(JournalSegmentWriter<E> previous, int position) {
+    super(previous);
+    memory = allocMemory(maxEntrySize);
+    lastEntry = previous.getLastEntry();
+    currentPosition = position;
+  }
+
+  private static ByteBuffer allocMemory(int maxEntrySize) {
+    final var buf = ByteBuffer.allocate((maxEntrySize + ENTRY_HEADER_BYTES) * 2);
+    buf.limit(0);
+    return buf;
+  }
+
+  @Override
+  MappedByteBuffer buffer() {
+    return null;
+  }
+
+  @Override
+  MappedJournalSegmentWriter<E> toMapped() {
+    return new MappedJournalSegmentWriter<>(this, (int) currentPosition);
+  }
+
+  @Override
+  FileChannelJournalSegmentWriter<E> toFileChannel() {
+    return this;
+  }
+
   @Override
-  public void reset(long index) {
+  void reset(long index) {
     long nextIndex = firstIndex;
 
     // Clear the buffer indexes.
+    currentPosition = JournalSegmentDescriptor.BYTES;
+
     try {
-      channel.position(JournalSegmentDescriptor.BYTES);
-      memory.clear().flip();
-
-      // Record the current buffer position.
-      long position = channel.position();
-
-      // Read more bytes from the segment if necessary.
-      if (memory.remaining() < maxEntrySize) {
-        memory.clear();
-        channel.read(memory);
-        channel.position(position);
-        memory.flip();
-      }
+      // Clear memory buffer and read fist chunk
+      channel.read(memory.clear(), JournalSegmentDescriptor.BYTES);
+      memory.flip();
 
       // Read the entry length.
-      memory.mark();
       int length = memory.getInt();
 
       // If the length is non-zero, read the entry.
@@ -98,144 +109,99 @@ class FileChannelJournalSegmentWriter<E> implements JournalWriter<E> {
         // Read the checksum of the entry.
         final long checksum = memory.getInt() & 0xFFFFFFFFL;
 
+        // Slice off the entry's bytes
+        final ByteBuffer entryBytes = memory.slice();
+        entryBytes.limit(length);
+
         // Compute the checksum for the entry bytes.
-        final Checksum crc32 = new CRC32();
-        crc32.update(memory.array(), memory.position(), length);
-
-        // If the stored checksum equals the computed checksum, return the entry.
-        if (checksum == crc32.getValue()) {
-          int limit = memory.limit();
-          memory.limit(memory.position() + length);
-          final E entry = namespace.deserialize(memory);
-          memory.limit(limit);
-          lastEntry = new Indexed<>(nextIndex, entry, length);
-          this.index.index(nextIndex, (int) position);
-          nextIndex++;
-        } else {
+        final CRC32 crc32 = new CRC32();
+        crc32.update(entryBytes);
+
+        // If the stored checksum does not equal the computed checksum, do not proceed further
+        if (checksum != crc32.getValue()) {
           break;
         }
 
+        entryBytes.rewind();
+        final E entry = namespace.deserialize(entryBytes);
+        lastEntry = new Indexed<>(nextIndex, entry, length);
+        this.index.index(nextIndex, (int) currentPosition);
+        nextIndex++;
+
         // Update the current position for indexing.
-        position = channel.position() + memory.position();
+        currentPosition = currentPosition + ENTRY_HEADER_BYTES + length;
+        memory.position(memory.position() + length);
 
         // Read more bytes from the segment if necessary.
         if (memory.remaining() < maxEntrySize) {
-          channel.position(position);
-          memory.clear();
-          channel.read(memory);
-          channel.position(position);
+          channel.read(memory.compact());
           memory.flip();
         }
 
-        memory.mark();
         length = memory.getInt();
       }
-
-      // Reset the buffer to the previous mark.
-      channel.position(channel.position() + memory.reset().position());
     } catch (BufferUnderflowException e) {
-      try {
-        channel.position(channel.position() + memory.reset().position());
-      } catch (IOException e2) {
-        throw new StorageException(e2);
-      }
+      // No-op, position is only updated on success
     } catch (IOException e) {
       throw new StorageException(e);
     }
   }
 
   @Override
-  public long getLastIndex() {
-    return lastEntry != null ? lastEntry.index() : segment.index() - 1;
-  }
-
-  @Override
-  public Indexed<E> getLastEntry() {
+  Indexed<E> getLastEntry() {
     return lastEntry;
   }
 
-  @Override
-  public long getNextIndex() {
-    if (lastEntry != null) {
-      return lastEntry.index() + 1;
-    } else {
-      return firstIndex;
-    }
-  }
-
-  @Override
-  public void append(Indexed<E> entry) {
-    final long nextIndex = getNextIndex();
-
-    // If the entry's index is greater than the next index in the segment, skip some entries.
-    if (entry.index() > nextIndex) {
-      throw new IndexOutOfBoundsException("Entry index is not sequential");
-    }
-
-    // If the entry's index is less than the next index, truncate the segment.
-    if (entry.index() < nextIndex) {
-      truncate(entry.index() - 1);
-    }
-    append(entry.entry());
-  }
-
   @Override
   @SuppressWarnings("unchecked")
-  public <T extends E> Indexed<T> append(T entry) {
+  <T extends E> Indexed<T> append(T entry) {
     // Store the entry index.
     final long index = getNextIndex();
 
+    // Serialize the entry.
     try {
-      // Serialize the entry.
-      memory.clear();
-      memory.position(Integer.BYTES + Integer.BYTES);
-      try {
-        namespace.serialize(entry, memory);
-      } catch (KryoException e) {
-        throw new StorageException.TooLarge("Entry size exceeds maximum allowed bytes (" + maxEntrySize + ")");
-      }
-      memory.flip();
+      namespace.serialize(entry, memory.clear().position(ENTRY_HEADER_BYTES));
+    } catch (KryoException e) {
+      throw new StorageException.TooLarge("Entry size exceeds maximum allowed bytes (" + maxEntrySize + ")");
+    }
+    memory.flip();
 
-      final int length = memory.limit() - (Integer.BYTES + Integer.BYTES);
+    final int length = memory.limit() - ENTRY_HEADER_BYTES;
 
-      // Ensure there's enough space left in the buffer to store the entry.
-      long position = channel.position();
-      if (segment.descriptor().maxSegmentSize() - position < length + Integer.BYTES + Integer.BYTES) {
-        throw new BufferOverflowException();
-      }
+    // Ensure there's enough space left in the buffer to store the entry.
+    if (maxSegmentSize - currentPosition < length + ENTRY_HEADER_BYTES) {
+      throw new BufferOverflowException();
+    }
 
-      // If the entry length exceeds the maximum entry size then throw an exception.
-      if (length > maxEntrySize) {
-        throw new StorageException.TooLarge("Entry size " + length + " exceeds maximum allowed bytes (" + maxEntrySize + ")");
-      }
+    // If the entry length exceeds the maximum entry size then throw an exception.
+    if (length > maxEntrySize) {
+      throw new StorageException.TooLarge("Entry size " + length + " exceeds maximum allowed bytes (" + maxEntrySize + ")");
+    }
+
+    // Compute the checksum for the entry.
+    final CRC32 crc32 = new CRC32();
+    crc32.update(memory.array(), ENTRY_HEADER_BYTES, memory.limit() - ENTRY_HEADER_BYTES);
+    final long checksum = crc32.getValue();
 
-      // Compute the checksum for the entry.
-      final Checksum crc32 = new CRC32();
-      crc32.update(memory.array(), Integer.BYTES + Integer.BYTES, memory.limit() - (Integer.BYTES + Integer.BYTES));
-      final long checksum = crc32.getValue();
-
-      // Create a single byte[] in memory for the entire entry and write it as a batch to the underlying buffer.
-      memory.putInt(0, length);
-      memory.putInt(Integer.BYTES, (int) checksum);
-      channel.write(memory);
-
-      // Update the last entry with the correct index/term/length.
-      Indexed<E> indexedEntry = new Indexed<>(index, entry, length);
-      this.lastEntry = indexedEntry;
-      this.index.index(index, (int) position);
-      return (Indexed<T>) indexedEntry;
+    // Create a single byte[] in memory for the entire entry and write it as a batch to the underlying buffer.
+    memory.putInt(0, length).putInt(Integer.BYTES, (int) checksum);
+    try {
+      channel.write(memory, currentPosition);
     } catch (IOException e) {
       throw new StorageException(e);
     }
-  }
 
-  @Override
-  public void commit(long index) {
+    // Update the last entry with the correct index/term/length.
+    Indexed<E> indexedEntry = new Indexed<>(index, entry, length);
+    this.lastEntry = indexedEntry;
+    this.index.index(index, (int) currentPosition);
 
+    currentPosition = currentPosition + ENTRY_HEADER_BYTES + length;
+    return (Indexed<T>) indexedEntry;
   }
 
   @Override
-  public void truncate(long index) {
+  void truncate(long index) {
     // If the index is greater than or equal to the last index, skip the truncate.
     if (index >= getLastIndex()) {
       return;
@@ -248,30 +214,23 @@ class FileChannelJournalSegmentWriter<E> implements JournalWriter<E> {
     this.index.truncate(index);
 
     try {
-      if (index < segment.index()) {
+      if (index < firstIndex) {
         // Reset the writer to the first entry.
-        channel.position(JournalSegmentDescriptor.BYTES);
+        currentPosition = JournalSegmentDescriptor.BYTES;
       } else {
         // Reset the writer to the given index.
         reset(index);
       }
 
-      // Zero entries at the current position.
-      // FIXME: This is quite inefficient, we essentially want to zero-out part of the file, but it is not quite clear
-      //        how much: this overwrites at least two entries. I believe we should be able to get by with wiping the
-      //        header of the current entry.
-      memory.clear();
-      for (int i = 0; i < memory.limit(); i++) {
-        memory.put(i, (byte) 0);
-      }
-      channel.write(memory, channel.position());
+      // Zero the entry header at current channel position.
+      channel.write(ZERO_ENTRY_HEADER.asReadOnlyBuffer(), currentPosition);
     } catch (IOException e) {
       throw new StorageException(e);
     }
   }
 
   @Override
-  public void flush() {
+  void flush() {
     try {
       if (channel.isOpen()) {
         channel.force(true);
@@ -282,7 +241,7 @@ class FileChannelJournalSegmentWriter<E> implements JournalWriter<E> {
   }
 
   @Override
-  public void close() {
+  void close() {
     flush();
   }
 }