+++ /dev/null
-/*
- * Copyright 2015-present Open Networking Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package io.atomix.storage.journal;
-
-import com.google.common.annotations.VisibleForTesting;
-
-import java.nio.ByteBuffer;
-
-import static com.google.common.base.MoreObjects.toStringHelper;
-import static java.util.Objects.requireNonNull;
-
-/**
- * Stores information about a {@link JournalSegment} of the log.
- * <p>
- * The segment descriptor manages metadata related to a single segment of the log. Descriptors are stored within the
- * first {@code 64} bytes of each segment in the following order:
- * <ul>
- * <li>{@code id} (64-bit signed integer) - A unique segment identifier. This is a monotonically increasing number within
- * each log. Segments with in-sequence identifiers should contain in-sequence indexes.</li>
- * <li>{@code index} (64-bit signed integer) - The effective first index of the segment. This indicates the index at which
- * the first entry should be written to the segment. Indexes are monotonically increasing thereafter.</li>
- * <li>{@code version} (64-bit signed integer) - The version of the segment. Versions are monotonically increasing
- * starting at {@code 1}. Versions will only be incremented whenever the segment is rewritten to another memory/disk
- * space, e.g. after log compaction.</li>
- * <li>{@code maxSegmentSize} (32-bit unsigned integer) - The maximum number of bytes allowed in the segment.</li>
- * <li>{@code maxEntries} (32-bit signed integer) - The total number of expected entries in the segment. This is the final
- * number of entries allowed within the segment both before and after compaction. This entry count is used to determine
- * the count of internal indexing and deduplication facilities.</li>
- * <li>{@code updated} (64-bit signed integer) - The last update to the segment in terms of milliseconds since the epoch.
- * When the segment is first constructed, the {@code updated} time is {@code 0}. Once all entries in the segment have
- * been committed, the {@code updated} time should be set to the current time. Log compaction should not result in a
- * change to {@code updated}.</li>
- * <li>{@code locked} (8-bit boolean) - A boolean indicating whether the segment is locked. Segments will be locked once
- * all entries have been committed to the segment. The lock state of each segment is used to determine log compaction
- * and recovery behavior.</li>
- * </ul>
- * The remainder of the 64 segment header bytes are reserved for future metadata.
- *
- * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
- */
-public final class JournalSegmentDescriptor {
- public static final int BYTES = 64;
-
- // Current segment version.
- @VisibleForTesting
- static final int VERSION = 1;
-
- // The lengths of each field in the header.
- private static final int VERSION_LENGTH = Integer.BYTES; // 32-bit signed integer
- private static final int ID_LENGTH = Long.BYTES; // 64-bit signed integer
- private static final int INDEX_LENGTH = Long.BYTES; // 64-bit signed integer
- private static final int MAX_SIZE_LENGTH = Integer.BYTES; // 32-bit signed integer
- private static final int MAX_ENTRIES_LENGTH = Integer.BYTES; // 32-bit signed integer
- private static final int UPDATED_LENGTH = Long.BYTES; // 64-bit signed integer
-
- // The positions of each field in the header.
- private static final int VERSION_POSITION = 0; // 0
- private static final int ID_POSITION = VERSION_POSITION + VERSION_LENGTH; // 4
- private static final int INDEX_POSITION = ID_POSITION + ID_LENGTH; // 12
- private static final int MAX_SIZE_POSITION = INDEX_POSITION + INDEX_LENGTH; // 20
- private static final int MAX_ENTRIES_POSITION = MAX_SIZE_POSITION + MAX_SIZE_LENGTH; // 24
- private static final int UPDATED_POSITION = MAX_ENTRIES_POSITION + MAX_ENTRIES_LENGTH; // 28
-
- /**
- * Returns a descriptor builder.
- * <p>
- * The descriptor builder will write segment metadata to a {@code 48} byte in-memory buffer.
- *
- * @return The descriptor builder.
- */
- public static Builder builder() {
- return new Builder(ByteBuffer.allocate(BYTES));
- }
-
- /**
- * Returns a descriptor builder for the given descriptor buffer.
- *
- * @param buffer The descriptor buffer.
- * @return The descriptor builder.
- * @throws NullPointerException if {@code buffer} is null
- */
- public static Builder builder(ByteBuffer buffer) {
- return new Builder(buffer);
- }
-
- private final ByteBuffer buffer;
- private final int version;
- private final long id;
- private final long index;
- private final int maxSegmentSize;
- private final int maxEntries;
- private volatile long updated;
- private volatile boolean locked;
-
- /**
- * @throws NullPointerException if {@code buffer} is null
- */
- public JournalSegmentDescriptor(ByteBuffer buffer) {
- this.buffer = buffer;
- this.version = buffer.getInt();
- this.id = buffer.getLong();
- this.index = buffer.getLong();
- this.maxSegmentSize = buffer.getInt();
- this.maxEntries = buffer.getInt();
- this.updated = buffer.getLong();
- this.locked = buffer.get() == 1;
- }
-
- /**
- * Returns the segment version.
- * <p>
- * Versions are monotonically increasing starting at {@code 1}.
- *
- * @return The segment version.
- */
- public int version() {
- return version;
- }
-
- /**
- * Returns the segment identifier.
- * <p>
- * The segment ID is a monotonically increasing number within each log. Segments with in-sequence identifiers should
- * contain in-sequence indexes.
- *
- * @return The segment identifier.
- */
- public long id() {
- return id;
- }
-
- /**
- * Returns the segment index.
- * <p>
- * The index indicates the index at which the first entry should be written to the segment. Indexes are monotonically
- * increasing thereafter.
- *
- * @return The segment index.
- */
- public long index() {
- return index;
- }
-
- /**
- * Returns the maximum count of the segment.
- *
- * @return The maximum allowed count of the segment.
- */
- public int maxSegmentSize() {
- return maxSegmentSize;
- }
-
- /**
- * Returns the maximum number of entries allowed in the segment.
- *
- * @return The maximum number of entries allowed in the segment.
- */
- public int maxEntries() {
- return maxEntries;
- }
-
- /**
- * Returns last time the segment was updated.
- * <p>
- * When the segment is first constructed, the {@code updated} time is {@code 0}. Once all entries in the segment have
- * been committed, the {@code updated} time should be set to the current time. Log compaction should not result in a
- * change to {@code updated}.
- *
- * @return The last time the segment was updated in terms of milliseconds since the epoch.
- */
- public long updated() {
- return updated;
- }
-
- /**
- * Writes an update to the descriptor.
- */
- public void update(long timestamp) {
- if (!locked) {
- buffer.putLong(UPDATED_POSITION, timestamp);
- this.updated = timestamp;
- }
- }
-
- /**
- * Copies the segment to a new buffer.
- */
- JournalSegmentDescriptor copyTo(ByteBuffer buffer) {
- buffer.putInt(version);
- buffer.putLong(id);
- buffer.putLong(index);
- buffer.putInt(maxSegmentSize);
- buffer.putInt(maxEntries);
- buffer.putLong(updated);
- buffer.put(locked ? (byte) 1 : (byte) 0);
- return this;
- }
-
- @Override
- public String toString() {
- return toStringHelper(this)
- .add("version", version)
- .add("id", id)
- .add("index", index)
- .add("updated", updated)
- .toString();
- }
-
- /**
- * Segment descriptor builder.
- */
- public static class Builder {
- private final ByteBuffer buffer;
-
- private Builder(ByteBuffer buffer) {
- this.buffer = requireNonNull(buffer, "buffer cannot be null");
- buffer.putInt(VERSION_POSITION, VERSION);
- }
-
- /**
- * Sets the segment identifier.
- *
- * @param id The segment identifier.
- * @return The segment descriptor builder.
- */
- public Builder withId(long id) {
- buffer.putLong(ID_POSITION, id);
- return this;
- }
-
- /**
- * Sets the segment index.
- *
- * @param index The segment starting index.
- * @return The segment descriptor builder.
- */
- public Builder withIndex(long index) {
- buffer.putLong(INDEX_POSITION, index);
- return this;
- }
-
- /**
- * Sets maximum count of the segment.
- *
- * @param maxSegmentSize The maximum count of the segment.
- * @return The segment descriptor builder.
- */
- public Builder withMaxSegmentSize(int maxSegmentSize) {
- buffer.putInt(MAX_SIZE_POSITION, maxSegmentSize);
- return this;
- }
-
- /**
- * Sets the maximum number of entries in the segment.
- *
- * @param maxEntries The maximum number of entries in the segment.
- * @return The segment descriptor builder.
- * @deprecated since 3.0.2
- */
- @Deprecated
- public Builder withMaxEntries(int maxEntries) {
- buffer.putInt(MAX_ENTRIES_POSITION, maxEntries);
- return this;
- }
-
- /**
- * Builds the segment descriptor.
- *
- * @return The built segment descriptor.
- */
- public JournalSegmentDescriptor build() {
- buffer.rewind();
- return new JournalSegmentDescriptor(buffer);
- }
- }
-}
Code Review / controller.git / blobdiff