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/*
* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH under
* one or more contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright ownership.
* Licensed under the Zeebe Community License 1.1. You may not use this file
* except in compliance with the Zeebe Community License 1.1.
*/
package io.camunda.zeebe.journal.file;
import io.camunda.zeebe.journal.CorruptedJournalException;
import io.camunda.zeebe.journal.JournalException;
import io.camunda.zeebe.util.FileUtil;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import org.agrona.IoUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/** Create a segment file. Load a segment from the segment file. */
final class SegmentLoader {
private static final Logger LOGGER = LoggerFactory.getLogger(SegmentLoader.class);
private static final ByteOrder ENDIANNESS = ByteOrder.LITTLE_ENDIAN;
private final SegmentAllocator allocator;
private final long minFreeDiskSpace;
private final JournalMetrics metrics;
SegmentLoader(final int minFreeDiskSpace, final JournalMetrics metrics) {
this(minFreeDiskSpace, metrics, SegmentAllocator.fill());
}
SegmentLoader(
final long minFreeDiskSpace, final JournalMetrics metrics, final SegmentAllocator allocator) {
this.minFreeDiskSpace = minFreeDiskSpace;
this.metrics = metrics;
this.allocator = allocator;
}
Segment createSegment(
final Path segmentFile,
final SegmentDescriptor descriptor,
final long lastWrittenAsqn,
final JournalIndex journalIndex) {
final MappedByteBuffer mappedSegment;
try {
mappedSegment = mapNewSegment(segmentFile, descriptor);
} catch (final IOException e) {
throw new JournalException(
String.format("Failed to create new segment file %s", segmentFile), e);
}
try {
descriptor.copyTo(mappedSegment);
mappedSegment.force();
} catch (final InternalError e) {
throw new JournalException(
String.format(
"Failed to ensure durability of segment %s with descriptor %s, rolling back",
segmentFile, descriptor),
e);
}
// while flushing the file's contents ensures its data is present on disk on recovery, it's also
// necessary to flush the directory to ensure that the file itself is visible as an entry of
// that directory after recovery
try {
FileUtil.flushDirectory(segmentFile.getParent());
} catch (final IOException e) {
throw new JournalException(
String.format("Failed to flush journal directory after creating segment %s", segmentFile),
e);
}
return loadSegment(segmentFile, mappedSegment, descriptor, lastWrittenAsqn, journalIndex);
}
UninitializedSegment createUninitializedSegment(
final Path segmentFile, final SegmentDescriptor descriptor, final JournalIndex journalIndex) {
final MappedByteBuffer mappedSegment;
try {
mappedSegment = mapNewSegment(segmentFile, descriptor);
} catch (final IOException e) {
throw new JournalException(
String.format("Failed to create new segment file %s", segmentFile), e);
}
// while flushing the file's contents ensures its data is present on disk on recovery, it's also
// necessary to flush the directory to ensure that the file itself is visible as an entry of
// that directory after recovery
try {
FileUtil.flushDirectory(segmentFile.getParent());
} catch (final IOException e) {
throw new JournalException(
String.format("Failed to flush journal directory after creating segment %s", segmentFile),
e);
}
return new UninitializedSegment(
new SegmentFile(segmentFile.toFile()),
descriptor.id(),
descriptor.maxSegmentSize(),
mappedSegment,
journalIndex);
}
Segment loadExistingSegment(
final Path segmentFile, final long lastWrittenAsqn, final JournalIndex journalIndex) {
try (final var channel =
FileChannel.open(segmentFile, StandardOpenOption.READ, StandardOpenOption.WRITE)) {
MappedByteBuffer mappedSegment;
final var initialMappedLength = Files.size(segmentFile);
mappedSegment = mapSegment(channel, initialMappedLength);
final var descriptor = readDescriptor(mappedSegment, segmentFile.getFileName().toString());
if (descriptor.maxSegmentSize() > initialMappedLength) {
// remap with actual size
IoUtil.unmap(mappedSegment);
mappedSegment = mapSegment(channel, descriptor.maxSegmentSize());
}
return loadSegment(segmentFile, mappedSegment, descriptor, lastWrittenAsqn, journalIndex);
} catch (final IOException e) {
throw new JournalException(
String.format("Failed to load existing segment %s", segmentFile), e);
}
}
/* ---- Internal methods ------ */
private Segment loadSegment(
final Path file,
final MappedByteBuffer buffer,
final SegmentDescriptor descriptor,
final long lastWrittenAsqn,
final JournalIndex journalIndex) {
final SegmentFile segmentFile = new SegmentFile(file.toFile());
return new Segment(segmentFile, descriptor, buffer, lastWrittenAsqn, journalIndex, metrics);
}
private MappedByteBuffer mapSegment(final FileChannel channel, final long segmentSize)
throws IOException {
final var mappedSegment = channel.map(MapMode.READ_WRITE, 0, segmentSize);
mappedSegment.order(ENDIANNESS);
return mappedSegment;
}
private SegmentDescriptor readDescriptor(final ByteBuffer buffer, final String fileName) {
try {
return new SegmentDescriptorReader().readFrom(buffer);
} catch (final IndexOutOfBoundsException e) {
throw new JournalException(
String.format(
"Expected to read descriptor of segment '%s', but nothing was read.", fileName),
e);
} catch (final UnknownVersionException e) {
throw new CorruptedJournalException(
String.format("Couldn't read or recognize version of segment '%s'.", fileName), e);
}
}
private MappedByteBuffer mapNewSegment(final Path segmentPath, final SegmentDescriptor descriptor)
throws IOException {
final var maxSegmentSize = descriptor.maxSegmentSize();
checkDiskSpace(segmentPath, maxSegmentSize);
try (final var channel =
FileChannel.open(
segmentPath,
StandardOpenOption.READ,
StandardOpenOption.WRITE,
StandardOpenOption.CREATE_NEW)) {
allocateSegment(maxSegmentSize, channel);
return mapSegment(channel, maxSegmentSize);
} catch (final FileAlreadyExistsException e) {
LOGGER.warn(
"Failed to create segment {}: an unused file already existed, and will be replaced",
segmentPath,
e);
Files.delete(segmentPath);
return mapNewSegment(segmentPath, descriptor);
}
}
private void checkDiskSpace(final Path segmentPath, final int maxSegmentSize) {
final var available = segmentPath.getParent().toFile().getUsableSpace();
final var required = Math.max(maxSegmentSize, minFreeDiskSpace);
if (available < required) {
throw new JournalException.OutOfDiskSpace(
"Not enough space to allocate a new journal segment. Required: %s, Available: %s"
.formatted(required, available));
}
}
private void allocateSegment(final int maxSegmentSize, final FileChannel channel)
throws IOException {
try (final var ignored = metrics.observeSegmentAllocation()) {
allocator.allocate(channel, maxSegmentSize);
}
}
}
