109 lines
3.3 KiB
Java
109 lines
3.3 KiB
Java
package it.cavallium.dbengine.database.disk;
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import it.cavallium.dbengine.database.LLSnapshot;
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import java.io.IOException;
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import java.util.Objects;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.Executor;
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import java.util.concurrent.Phaser;
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import java.util.concurrent.atomic.AtomicLong;
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import org.apache.lucene.index.IndexCommit;
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import org.apache.lucene.index.IndexWriter;
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import org.apache.lucene.index.SnapshotDeletionPolicy;
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import org.jetbrains.annotations.Nullable;
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import reactor.core.publisher.Mono;
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import reactor.core.scheduler.Schedulers;
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public class SnapshotsManager {
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private final IndexWriter indexWriter;
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private final SnapshotDeletionPolicy snapshotter;
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private final Phaser activeTasks = new Phaser(1);
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/**
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* Last snapshot sequence number. 0 is not used
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*/
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private final AtomicLong lastSnapshotSeqNo = new AtomicLong(0);
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/**
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* LLSnapshot seq no to index commit point
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*/
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private final ConcurrentHashMap<Long, LuceneIndexSnapshot> snapshots = new ConcurrentHashMap<>();
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public SnapshotsManager(IndexWriter indexWriter,
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SnapshotDeletionPolicy snapshotter) {
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this.indexWriter = indexWriter;
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this.snapshotter = snapshotter;
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}
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public LuceneIndexSnapshot resolveSnapshot(@Nullable LLSnapshot snapshot) {
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if (snapshot == null) {
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return null;
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}
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return Objects.requireNonNull(snapshots.get(snapshot.getSequenceNumber()),
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() -> "Can't resolve snapshot " + snapshot.getSequenceNumber()
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);
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}
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public Mono<LLSnapshot> takeSnapshot() {
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return takeLuceneSnapshot().map(snapshot -> {
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var snapshotSeqNo = lastSnapshotSeqNo.incrementAndGet();
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this.snapshots.put(snapshotSeqNo, new LuceneIndexSnapshot(snapshot));
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return new LLSnapshot(snapshotSeqNo);
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});
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}
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/**
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* Use internally. This method commits before taking the snapshot if there are no commits in a new database,
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* avoiding the exception.
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*/
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private Mono<IndexCommit> takeLuceneSnapshot() {
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return Mono
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.fromCallable(snapshotter::snapshot)
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.subscribeOn(Schedulers.boundedElastic())
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.onErrorResume(ex -> Mono
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.defer(() -> {
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if (ex instanceof IllegalStateException && "No index commit to snapshot".equals(ex.getMessage())) {
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return Mono.fromCallable(() -> {
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activeTasks.register();
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try {
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indexWriter.commit();
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return snapshotter.snapshot();
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} finally {
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activeTasks.arriveAndDeregister();
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}
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});
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} else {
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return Mono.error(ex);
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}
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})
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);
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}
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public Mono<Void> releaseSnapshot(LLSnapshot snapshot) {
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return Mono.<Void>fromCallable(() -> {
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activeTasks.register();
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try {
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var indexSnapshot = this.snapshots.remove(snapshot.getSequenceNumber());
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if (indexSnapshot == null) {
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throw new IOException("LLSnapshot " + snapshot.getSequenceNumber() + " not found!");
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}
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indexSnapshot.close();
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var luceneIndexSnapshot = indexSnapshot.getSnapshot();
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snapshotter.release(luceneIndexSnapshot);
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// Delete unused files after releasing the snapshot
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indexWriter.deleteUnusedFiles();
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return null;
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} finally {
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activeTasks.arriveAndDeregister();
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}
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}).subscribeOn(Schedulers.boundedElastic());
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}
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public void close() {
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if (!activeTasks.isTerminated()) {
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activeTasks.arriveAndAwaitAdvance();
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}
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}
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}
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