github
/
jgit
mirror of https://gitee.com/github-mirror-repo/jgit.git
1
0
Fork 0
Code Issues Releases Wiki Activity
Browse Source

reftable: merge-join reftables 

MergedReftable combines multiple reference tables together in a stack,
allowing higher/later tables to shadow earlier/lower tables.  This
forms the basis of a transaction system, where each transaction writes
a new reftable containing only the modified references, and readers
perform a merge on the fly to get the latest value.

Change-Id: Ic2cb750141e8c61a8b2726b2eb95195acb6ddc83
stable-4.9
Shawn Pearce 8 years ago
parent
7da2fe6be8
commit
77d8eead6d
2 changed files with 699 additions and 0 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Unified View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 324
      org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java
  2. 375
      org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/MergedReftable.java

324
org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java
Unescape View File

@ -0,0 +1,324 @@
/*
* 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 static org.eclipse.jgit.lib.Constants.HEAD;
import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH;
import static org.eclipse.jgit.lib.Constants.R_HEADS;
import static org.eclipse.jgit.lib.Ref.Storage.NEW;
import static org.eclipse.jgit.lib.Ref.Storage.PACKED;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.eclipse.jgit.internal.storage.io.BlockSource;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectIdRef;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.RefComparator;
import org.junit.Test;
public class MergedReftableTest {
@Test
public void noTables() throws IOException {
MergedReftable mr = merge(new byte[0][]);
try (RefCursor rc = mr.allRefs()) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(HEAD)) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(R_HEADS)) {
assertFalse(rc.next());
}
}
@Test
public void oneEmptyTable() throws IOException {
MergedReftable mr = merge(write());
try (RefCursor rc = mr.allRefs()) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(HEAD)) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(R_HEADS)) {
assertFalse(rc.next());
}
}
@Test
public void twoEmptyTables() throws IOException {
MergedReftable mr = merge(write(), write());
try (RefCursor rc = mr.allRefs()) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(HEAD)) {
assertFalse(rc.next());
}
try (RefCursor rc = mr.seekRef(R_HEADS)) {
assertFalse(rc.next());
}
}
@SuppressWarnings("boxing")
@Test
public void oneTableScan() throws IOException {
List<Ref> refs = new ArrayList<>();
for (int i = 1; i <= 567; i++) {
refs.add(ref(String.format("refs/heads/%03d", i), i));
}
MergedReftable mr = merge(write(refs));
try (RefCursor rc = mr.allRefs()) {
for (Ref exp : refs) {
assertTrue("has " + exp.getName(), rc.next());
Ref act = rc.getRef();
assertEquals(exp.getName(), act.getName());
assertEquals(exp.getObjectId(), act.getObjectId());
}
assertFalse(rc.next());
}
}
@Test
public void deleteIsHidden() throws IOException {
List<Ref> delta1 = Arrays.asList(
ref("refs/heads/apple", 1),
ref("refs/heads/master", 2));
List<Ref> delta2 = Arrays.asList(delete("refs/heads/apple"));
MergedReftable mr = merge(write(delta1), write(delta2));
try (RefCursor rc = mr.allRefs()) {
assertTrue(rc.next());
assertEquals("refs/heads/master", rc.getRef().getName());
assertEquals(id(2), rc.getRef().getObjectId());
assertFalse(rc.next());
}
}
@Test
public void twoTableSeek() throws IOException {
List<Ref> delta1 = Arrays.asList(
ref("refs/heads/apple", 1),
ref("refs/heads/master", 2));
List<Ref> delta2 = Arrays.asList(ref("refs/heads/banana", 3));
MergedReftable mr = merge(write(delta1), write(delta2));
try (RefCursor rc = mr.seekRef("refs/heads/master")) {
assertTrue(rc.next());
assertEquals("refs/heads/master", rc.getRef().getName());
assertEquals(id(2), rc.getRef().getObjectId());
assertFalse(rc.next());
}
}
@Test
public void twoTableById() throws IOException {
List<Ref> delta1 = Arrays.asList(
ref("refs/heads/apple", 1),
ref("refs/heads/master", 2));
List<Ref> delta2 = Arrays.asList(ref("refs/heads/banana", 3));
MergedReftable mr = merge(write(delta1), write(delta2));
try (RefCursor rc = mr.byObjectId(id(2))) {
assertTrue(rc.next());
assertEquals("refs/heads/master", rc.getRef().getName());
assertEquals(id(2), rc.getRef().getObjectId());
assertFalse(rc.next());
}
}
@SuppressWarnings("boxing")
@Test
public void fourTableScan() throws IOException {
List<Ref> base = new ArrayList<>();
for (int i = 1; i <= 567; i++) {
base.add(ref(String.format("refs/heads/%03d", i), i));
}
List<Ref> delta1 = Arrays.asList(
ref("refs/heads/next", 4),
ref(String.format("refs/heads/%03d", 55), 4096));
List<Ref> delta2 = Arrays.asList(
delete("refs/heads/next"),
ref(String.format("refs/heads/%03d", 55), 8192));
List<Ref> delta3 = Arrays.asList(
ref("refs/heads/master", 4242),
ref(String.format("refs/heads/%03d", 42), 5120),
ref(String.format("refs/heads/%03d", 98), 6120));
List<Ref> expected = merge(base, delta1, delta2, delta3);
MergedReftable mr = merge(
write(base),
write(delta1),
write(delta2),
write(delta3));
try (RefCursor rc = mr.allRefs()) {
for (Ref exp : expected) {
assertTrue("has " + exp.getName(), rc.next());
Ref act = rc.getRef();
assertEquals(exp.getName(), act.getName());
assertEquals(exp.getObjectId(), act.getObjectId());
}
assertFalse(rc.next());
}
}
@Test
public void scanIncludeDeletes() throws IOException {
List<Ref> delta1 = Arrays.asList(ref("refs/heads/next", 4));
List<Ref> delta2 = Arrays.asList(delete("refs/heads/next"));
List<Ref> delta3 = Arrays.asList(ref("refs/heads/master", 8));
MergedReftable mr = merge(write(delta1), write(delta2), write(delta3));
mr.setIncludeDeletes(true);
try (RefCursor rc = mr.allRefs()) {
assertTrue(rc.next());
Ref r = rc.getRef();
assertEquals("refs/heads/master", r.getName());
assertEquals(id(8), r.getObjectId());
assertTrue(rc.next());
r = rc.getRef();
assertEquals("refs/heads/next", r.getName());
assertEquals(NEW, r.getStorage());
assertNull(r.getObjectId());
assertFalse(rc.next());
}
}
@SuppressWarnings("boxing")
@Test
public void oneTableSeek() throws IOException {
List<Ref> refs = new ArrayList<>();
for (int i = 1; i <= 567; i++) {
refs.add(ref(String.format("refs/heads/%03d", i), i));
}
MergedReftable mr = merge(write(refs));
for (Ref exp : refs) {
try (RefCursor rc = mr.seekRef(exp.getName())) {
assertTrue("has " + exp.getName(), rc.next());
Ref act = rc.getRef();
assertEquals(exp.getName(), act.getName());
assertEquals(exp.getObjectId(), act.getObjectId());
assertFalse(rc.next());
}
}
}
private static MergedReftable merge(byte[]... table) {
List<Reftable> stack = new ArrayList<>(table.length);
for (byte[] b : table) {
stack.add(read(b));
}
return new MergedReftable(stack);
}
private static ReftableReader read(byte[] table) {
return new ReftableReader(BlockSource.from(table));
}
private static Ref ref(String name, int id) {
return new ObjectIdRef.PeeledNonTag(PACKED, name, id(id));
}
private static Ref delete(String name) {
return new ObjectIdRef.Unpeeled(NEW, name, null);
}
private static ObjectId id(int i) {
byte[] buf = new byte[OBJECT_ID_LENGTH];
buf[0] = (byte) (i & 0xff);
buf[1] = (byte) ((i >>> 8) & 0xff);
buf[2] = (byte) ((i >>> 16) & 0xff);
buf[3] = (byte) (i >>> 24);
return ObjectId.fromRaw(buf);
}
private byte[] write(Ref... refs) throws IOException {
return write(Arrays.asList(refs));
}
private byte[] write(Collection<Ref> refs) throws IOException {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
ReftableWriter writer = new ReftableWriter().begin(buffer);
for (Ref r : RefComparator.sort(refs)) {
writer.writeRef(r);
}
writer.finish();
return buffer.toByteArray();
}
@SafeVarargs
private static List<Ref> merge(List<Ref>... tables) {
Map<String, Ref> expect = new HashMap<>();
for (List<Ref> t : tables) {
for (Ref r : t) {
if (r.getStorage() == NEW && r.getObjectId() == null) {
expect.remove(r.getName());
} else {
expect.put(r.getName(), r);
}
}
}
List<Ref> expected = new ArrayList<>(expect.values());
Collections.sort(expected, RefComparator.INSTANCE);
return expected;
}
}

375
org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/MergedReftable.java
Unescape View File

@ -0,0 +1,375 @@
/*
* 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.util.List;
import java.util.PriorityQueue;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.ReflogEntry;
/**
* Merges multiple reference tables together.
* <p>
* A {@link MergedReftable} merge-joins multiple {@link ReftableReader} on the
* fly. Tables higher/later in the stack shadow lower/earlier tables, hiding
* references that been updated/replaced.
* <p>
* By default deleted references are skipped and not returned to the caller.
* {@link #setIncludeDeletes(boolean)} can be used to modify this behavior if
* the caller needs to preserve deletions during partial compaction.
* <p>
* A {@code MergedReftable} is not thread-safe.
*/
public class MergedReftable extends Reftable {
private final Reftable[] tables;
/**
* Initialize a merged table reader.
* <p>
* The tables in {@code tableStack} will be closed when this
* {@code MergedReftable} is closed.
*
* @param tableStack
* stack of tables to read from. The base of the stack is at
* index 0, the most recent should be at the top of the stack at
* {@code tableStack.size() - 1}. The top of the stack (higher
* index) shadows the base of the stack (lower index).
*/
public MergedReftable(List<Reftable> tableStack) {
tables = tableStack.toArray(new Reftable[0]);
// Tables must expose deletes to this instance to correctly
// shadow references from lower tables.
for (Reftable t : tables) {
t.setIncludeDeletes(true);
}
}
@Override
public RefCursor allRefs() throws IOException {
MergedRefCursor m = new MergedRefCursor();
for (int i = 0; i < tables.length; i++) {
m.add(new RefQueueEntry(tables[i].allRefs(), i));
}
return m;
}
@Override
public RefCursor seekRef(String name) throws IOException {
if (name.endsWith("/")) { //$NON-NLS-1$
return seekRefPrefix(name);
}
return seekSingleRef(name);
}
private RefCursor seekRefPrefix(String name) throws IOException {
MergedRefCursor m = new MergedRefCursor();
for (int i = 0; i < tables.length; i++) {
m.add(new RefQueueEntry(tables[i].seekRef(name), i));
}
return m;
}
private RefCursor seekSingleRef(String name) throws IOException {
// Walk the tables from highest priority (end of list) to lowest.
// As soon as the reference is found (queue not empty), all lower
// priority tables are irrelevant as current table shadows them.
MergedRefCursor m = new MergedRefCursor();
for (int i = tables.length - 1; i >= 0 && m.queue.isEmpty(); i--) {
m.add(new RefQueueEntry(tables[i].seekRef(name), i));
}
return m;
}
@Override
public RefCursor byObjectId(AnyObjectId name) throws IOException {
MergedRefCursor m = new MergedRefCursor();
for (int i = 0; i < tables.length; i++) {
m.add(new RefQueueEntry(tables[i].byObjectId(name), i));
}
return m;
}
@Override
public LogCursor allLogs() throws IOException {
MergedLogCursor m = new MergedLogCursor();
for (int i = 0; i < tables.length; i++) {
m.add(new LogQueueEntry(tables[i].allLogs(), i));
}
return m;
}
@Override
public LogCursor seekLog(String refName, long updateIdx)
throws IOException {
MergedLogCursor m = new MergedLogCursor();
for (int i = 0; i < tables.length; i++) {
m.add(new LogQueueEntry(tables[i].seekLog(refName, updateIdx), i));
}
return m;
}
@Override
public void close() throws IOException {
for (Reftable t : tables) {
t.close();
}
}
int queueSize() {
return Math.max(1, tables.length);
}
private class MergedRefCursor extends RefCursor {
private final PriorityQueue<RefQueueEntry> queue;
private RefQueueEntry head;
private Ref ref;
MergedRefCursor() {
queue = new PriorityQueue<>(queueSize(), RefQueueEntry::compare);
}
void add(RefQueueEntry t) throws IOException {
// Common case is many iterations over the same RefQueueEntry
// for the bottom of the stack (scanning all refs). Its almost
// always less than the top of the queue. Avoid the queue's
// O(log N) insertion and removal costs for this common case.
if (!t.rc.next()) {
t.rc.close();
} else if (head == null) {
RefQueueEntry p = queue.peek();
if (p == null || RefQueueEntry.compare(t, p) < 0) {
head = t;
} else {
head = queue.poll();
queue.add(t);
}
} else if (RefQueueEntry.compare(t, head) > 0) {
queue.add(t);
} else {
queue.add(head);
head = t;
}
}
@Override
public boolean next() throws IOException {
for (;;) {
RefQueueEntry t = poll();
if (t == null) {
return false;
}
ref = t.rc.getRef();
boolean include = includeDeletes || !t.rc.wasDeleted();
skipShadowedRefs(ref.getName());
add(t);
if (include) {
return true;
}
}
}
private RefQueueEntry poll() {
RefQueueEntry e = head;
if (e != null) {
head = null;
return e;
}
return queue.poll();
}
private void skipShadowedRefs(String name) throws IOException {
for (;;) {
RefQueueEntry t = head != null ? head : queue.peek();
if (t != null && name.equals(t.name())) {
add(poll());
} else {
break;
}
}
}
@Override
public Ref getRef() {
return ref;
}
@Override
public void close() {
while (!queue.isEmpty()) {
queue.remove().rc.close();
}
}
}
private static class RefQueueEntry {
static int compare(RefQueueEntry a, RefQueueEntry b) {
int cmp = a.name().compareTo(b.name());
if (cmp == 0) {
// higher index shadows lower index, so higher index first.
cmp = b.stackIdx - a.stackIdx;
}
return cmp;
}
final RefCursor rc;
final int stackIdx;
RefQueueEntry(RefCursor rc, int stackIdx) {
this.rc = rc;
this.stackIdx = stackIdx;
}
String name() {
return rc.getRef().getName();
}
}
private class MergedLogCursor extends LogCursor {
private final PriorityQueue<LogQueueEntry> queue;
private String refName;
private long updateIndex;
private ReflogEntry entry;
MergedLogCursor() {
queue = new PriorityQueue<>(queueSize(), LogQueueEntry::compare);
}
void add(LogQueueEntry t) throws IOException {
if (t.lc.next()) {
queue.add(t);
} else {
t.lc.close();
}
}
@Override
public boolean next() throws IOException {
for (;;) {
LogQueueEntry t = queue.poll();
if (t == null) {
return false;
}
refName = t.lc.getRefName();
updateIndex = t.lc.getUpdateIndex();
entry = t.lc.getReflogEntry();
boolean include = includeDeletes || entry != null;
skipShadowed(refName, updateIndex);
add(t);
if (include) {
return true;
}
}
}
private void skipShadowed(String name, long index) throws IOException {
for (;;) {
LogQueueEntry t = queue.peek();
if (t != null && name.equals(t.name()) && index == t.index()) {
add(queue.remove());
} else {
break;
}
}
}
@Override
public String getRefName() {
return refName;
}
@Override
public long getUpdateIndex() {
return updateIndex;
}
@Override
public ReflogEntry getReflogEntry() {
return entry;
}
@Override
public void close() {
while (!queue.isEmpty()) {
queue.remove().lc.close();
}
}
}
private static class LogQueueEntry {
static int compare(LogQueueEntry a, LogQueueEntry b) {
int cmp = a.name().compareTo(b.name());
if (cmp == 0) {
// higher update index sorts first.
cmp = Long.signum(b.index() - a.index());
}
if (cmp == 0) {
// higher index comes first.
cmp = b.stackIdx - a.stackIdx;
}
return cmp;
}
final LogCursor lc;
final int stackIdx;
LogQueueEntry(LogCursor lc, int stackIdx) {
this.lc = lc;
this.stackIdx = stackIdx;
}
String name() {
return lc.getRefName();
}
long index() {
return lc.getUpdateIndex();
}
}
}
Write Preview
Loading…
Cancel
Save