ReftableCompactor.java
- /*
- * Copyright (C) 2017, Google Inc. and others
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0 which is available at
- * https://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
- package org.eclipse.jgit.internal.storage.reftable;
- import java.io.IOException;
- import java.io.OutputStream;
- import java.util.ArrayDeque;
- import java.util.ArrayList;
- import java.util.List;
- import org.eclipse.jgit.internal.storage.reftable.ReftableWriter.Stats;
- import org.eclipse.jgit.lib.PersonIdent;
- import org.eclipse.jgit.lib.ReflogEntry;
- /**
- * Merges reftables and compacts them into a single output.
- * <p>
- * For a partial compaction callers should {@link #setIncludeDeletes(boolean)}
- * to {@code true} to ensure the new reftable continues to use a delete marker
- * to shadow any lower reftable that may have the reference present.
- * <p>
- * By default all log entries within the range defined by
- * {@link #setReflogExpireMinUpdateIndex(long)} and {@link #setReflogExpireMaxUpdateIndex(long)} are
- * copied, even if no references in the output file match the log records.
- * Callers may truncate the log to a more recent time horizon with
- * {@link #setReflogExpireOldestReflogTimeMillis(long)}, or disable the log altogether with
- * {@code setOldestReflogTimeMillis(Long.MAX_VALUE)}.
- */
- public class ReftableCompactor {
- private final ReftableWriter writer;
- private final ArrayDeque<ReftableReader> tables = new ArrayDeque<>();
- private boolean includeDeletes;
- private long reflogExpireMinUpdateIndex = 0;
- private long reflogExpireMaxUpdateIndex = Long.MAX_VALUE;
- private long reflogExpireOldestReflogTimeMillis;
- private Stats stats;
- /**
- * Creates a new compactor.
- *
- * @param out
- * stream to write the compacted tables to. Caller is responsible
- * for closing {@code out}.
- */
- public ReftableCompactor(OutputStream out) {
- writer = new ReftableWriter(out);
- }
- /**
- * Set configuration for the reftable.
- *
- * @param cfg
- * configuration for the reftable.
- * @return {@code this}
- */
- public ReftableCompactor setConfig(ReftableConfig cfg) {
- writer.setConfig(cfg);
- return this;
- }
- /**
- * Whether to include deletions in the output, which may be necessary for
- * partial compaction.
- *
- * @param deletes
- * {@code true} to include deletions in the output, which may be
- * necessary for partial compaction.
- * @return {@code this}
- */
- public ReftableCompactor setIncludeDeletes(boolean deletes) {
- includeDeletes = deletes;
- return this;
- }
- /**
- * Set the minimum update index for log entries that appear in the compacted
- * reftable.
- *
- * @param min
- * the minimum update index for log entries that appear in the
- * compacted reftable. This should be 1 higher than the prior
- * reftable's {@code maxUpdateIndex} if this table will be used
- * in a stack.
- * @return {@code this}
- */
- public ReftableCompactor setReflogExpireMinUpdateIndex(long min) {
- reflogExpireMinUpdateIndex = min;
- return this;
- }
- /**
- * Set the maximum update index for log entries that appear in the compacted
- * reftable.
- *
- * @param max
- * the maximum update index for log entries that appear in the
- * compacted reftable. This should be at least 1 higher than the
- * prior reftable's {@code maxUpdateIndex} if this table will be
- * used in a stack.
- * @return {@code this}
- */
- public ReftableCompactor setReflogExpireMaxUpdateIndex(long max) {
- reflogExpireMaxUpdateIndex = max;
- return this;
- }
- /**
- * Set oldest reflog time to preserve.
- *
- * @param timeMillis
- * oldest log time to preserve. Entries whose timestamps are
- * {@code >= timeMillis} will be copied into the output file. Log
- * entries that predate {@code timeMillis} will be discarded.
- * Specified in Java standard milliseconds since the epoch.
- * @return {@code this}
- */
- public ReftableCompactor setReflogExpireOldestReflogTimeMillis(long timeMillis) {
- reflogExpireOldestReflogTimeMillis = timeMillis;
- return this;
- }
- /**
- * Add all of the tables, in the specified order.
- *
- * @param readers
- * tables to compact. Tables should be ordered oldest first/most
- * recent last so that the more recent tables can shadow the
- * older results. Caller is responsible for closing the readers.
- * @throws java.io.IOException
- * update indexes of a reader cannot be accessed.
- */
- public void addAll(List<ReftableReader> readers) throws IOException {
- for (ReftableReader r : readers) {
- tables.add(r);
- }
- }
- /**
- * Write a compaction to {@code out}.
- *
- * @throws java.io.IOException
- * if tables cannot be read, or cannot be written.
- */
- public void compact() throws IOException {
- MergedReftable mr = new MergedReftable(new ArrayList<>(tables));
- mr.setIncludeDeletes(includeDeletes);
- writer.setMaxUpdateIndex(mr.maxUpdateIndex());
- writer.setMinUpdateIndex(mr.minUpdateIndex());
- writer.begin();
- mergeRefs(mr);
- mergeLogs(mr);
- writer.finish();
- stats = writer.getStats();
- }
- /**
- * Get statistics of the last written reftable.
- *
- * @return statistics of the last written reftable.
- */
- public Stats getStats() {
- return stats;
- }
- private void mergeRefs(MergedReftable mr) throws IOException {
- try (RefCursor rc = mr.allRefs()) {
- while (rc.next()) {
- writer.writeRef(rc.getRef(), rc.getRef().getUpdateIndex());
- }
- }
- }
- private void mergeLogs(MergedReftable mr) throws IOException {
- if (reflogExpireOldestReflogTimeMillis == Long.MAX_VALUE) {
- return;
- }
- try (LogCursor lc = mr.allLogs()) {
- while (lc.next()) {
- long updateIndex = lc.getUpdateIndex();
- if (updateIndex > reflogExpireMaxUpdateIndex || updateIndex < reflogExpireMinUpdateIndex) {
- continue;
- }
- String refName = lc.getRefName();
- ReflogEntry log = lc.getReflogEntry();
- if (log == null) {
- if (includeDeletes) {
- writer.deleteLog(refName, updateIndex);
- }
- continue;
- }
- PersonIdent who = log.getWho();
- if (who.getWhen().getTime() >= reflogExpireOldestReflogTimeMillis) {
- writer.writeLog(
- refName,
- updateIndex,
- who,
- log.getOldId(),
- log.getNewId(),
- log.getComment());
- }
- }
- }
- }
- }