reftable: compact merged tables
A compaction of reftables is just copying the results of a
MergedReftable into a ReftableWriter. Wrap this up into a utility.
Change-Id: I6f5677d923e9628993a2d8b4b007a9b8662c9045
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java
index b6306d0..f9ebaf6 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java
@@ -261,6 +261,33 @@
}
}
+ @Test
+ public void compaction() throws IOException {
+ List<Ref> delta1 = Arrays.asList(
+ ref("refs/heads/next", 4),
+ ref("refs/heads/master", 1));
+ List<Ref> delta2 = Arrays.asList(delete("refs/heads/next"));
+ List<Ref> delta3 = Arrays.asList(ref("refs/heads/master", 8));
+
+ ReftableCompactor compactor = new ReftableCompactor();
+ compactor.addAll(Arrays.asList(
+ read(write(delta1)),
+ read(write(delta2)),
+ read(write(delta3))));
+ ByteArrayOutputStream out = new ByteArrayOutputStream();
+ compactor.compact(out);
+ byte[] table = out.toByteArray();
+
+ ReftableReader reader = read(table);
+ try (RefCursor rc = reader.allRefs()) {
+ assertTrue(rc.next());
+ Ref r = rc.getRef();
+ assertEquals("refs/heads/master", r.getName());
+ assertEquals(id(8), r.getObjectId());
+ assertFalse(rc.next());
+ }
+ }
+
private static MergedReftable merge(byte[]... table) {
List<Reftable> stack = new ArrayList<>(table.length);
for (byte[] b : table) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java
new file mode 100644
index 0000000..a91cdc8
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2017, Google Inc.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ * names of its contributors may be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+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.lib.PersonIdent;
+import org.eclipse.jgit.internal.storage.reftable.ReftableWriter.Stats;
+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 #setMinUpdateIndex(long)} and {@link #setMaxUpdateIndex(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 #setOldestReflogTimeMillis(long)}, or disable the log altogether with
+ * {@code setOldestReflogTimeMillis(Long.MAX_VALUE)}.
+ */
+public class ReftableCompactor {
+ private final ReftableWriter writer = new ReftableWriter();
+ private final ArrayDeque<Reftable> tables = new ArrayDeque<>();
+
+ private boolean includeDeletes;
+ private long minUpdateIndex;
+ private long maxUpdateIndex;
+ private long oldestReflogTimeMillis;
+ private Stats stats;
+
+ /**
+ * @param cfg
+ * configuration for the reftable.
+ * @return {@code this}
+ */
+ public ReftableCompactor setConfig(ReftableConfig cfg) {
+ writer.setConfig(cfg);
+ return this;
+ }
+
+ /**
+ * @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;
+ }
+
+ /**
+ * @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 setMinUpdateIndex(long min) {
+ minUpdateIndex = min;
+ return this;
+ }
+
+ /**
+ * @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 setMaxUpdateIndex(long max) {
+ maxUpdateIndex = max;
+ return this;
+ }
+
+ /**
+ * @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 setOldestReflogTimeMillis(long timeMillis) {
+ oldestReflogTimeMillis = 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.
+ */
+ public void addAll(List<? extends Reftable> readers) {
+ tables.addAll(readers);
+ }
+
+ /**
+ * Write a compaction to {@code out}.
+ *
+ * @param out
+ * stream to write the compacted tables to. Caller is responsible
+ * for closing {@code out}.
+ * @throws IOException
+ * if tables cannot be read, or cannot be written.
+ */
+ public void compact(OutputStream out) throws IOException {
+ MergedReftable mr = new MergedReftable(new ArrayList<>(tables));
+ mr.setIncludeDeletes(includeDeletes);
+
+ writer.setMinUpdateIndex(minUpdateIndex);
+ writer.setMaxUpdateIndex(maxUpdateIndex);
+ writer.begin(out);
+ mergeRefs(mr);
+ mergeLogs(mr);
+ writer.finish();
+ stats = writer.getStats();
+ }
+
+ /** @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());
+ }
+ }
+ }
+
+ private void mergeLogs(MergedReftable mr) throws IOException {
+ if (oldestReflogTimeMillis == Long.MAX_VALUE) {
+ return;
+ }
+
+ try (LogCursor lc = mr.allLogs()) {
+ while (lc.next()) {
+ long updateIndex = lc.getUpdateIndex();
+ if (updateIndex < minUpdateIndex
+ || updateIndex > maxUpdateIndex) {
+ // Cannot merge log records outside the header's range.
+ 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() >= oldestReflogTimeMillis) {
+ writer.writeLog(
+ refName,
+ updateIndex,
+ who,
+ log.getOldId(),
+ log.getNewId(),
+ log.getComment());
+ }
+ }
+ }
+ }
+}
