org.eclipse.jgit.storage.file.ObjectDirectory Maven / Gradle / Ivy
/*
* Copyright (C) 2009, 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.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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package org.eclipse.jgit.storage.file;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
import org.eclipse.jgit.errors.PackMismatchException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.AbbreviatedObjectId;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectDatabase;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.RepositoryCache;
import org.eclipse.jgit.lib.RepositoryCache.FileKey;
import org.eclipse.jgit.storage.pack.CachedPack;
import org.eclipse.jgit.storage.pack.ObjectToPack;
import org.eclipse.jgit.storage.pack.PackWriter;
import org.eclipse.jgit.util.FS;
import org.eclipse.jgit.util.FileUtils;
import org.eclipse.jgit.util.IO;
import org.eclipse.jgit.util.RawParseUtils;
/**
* Traditional file system based {@link ObjectDatabase}.
*
* This is the classical object database representation for a Git repository,
* where objects are stored loose by hashing them into directories by their
* {@link ObjectId}, or are stored in compressed containers known as
* {@link PackFile}s.
*
* Optionally an object database can reference one or more alternates; other
* ObjectDatabase instances that are searched in addition to the current
* database.
*
* Databases are divided into two halves: a half that is considered to be fast
* to search (the {@code PackFile}s), and a half that is considered to be slow
* to search (loose objects). When alternates are present the fast half is fully
* searched (recursively through all alternates) before the slow half is
* considered.
*/
public class ObjectDirectory extends FileObjectDatabase {
private static final PackList NO_PACKS = new PackList(
FileSnapshot.DIRTY, new PackFile[0]);
/** Maximum number of candidates offered as resolutions of abbreviation. */
private static final int RESOLVE_ABBREV_LIMIT = 256;
private final Config config;
private final File objects;
private final File infoDirectory;
private final File packDirectory;
private final File alternatesFile;
private final File cachedPacksFile;
private final AtomicReference packList;
private final AtomicReference cachedPacks;
private final FS fs;
private final AtomicReference alternates;
private final UnpackedObjectCache unpackedObjectCache;
/**
* Initialize a reference to an on-disk object directory.
*
* @param cfg
* configuration this directory consults for write settings.
* @param dir
* the location of the objects directory.
* @param alternatePaths
* a list of alternate object directories
* @param fs
* the file system abstraction which will be necessary to perform
* certain file system operations.
* @throws IOException
* an alternate object cannot be opened.
*/
public ObjectDirectory(final Config cfg, final File dir,
File[] alternatePaths, FS fs) throws IOException {
config = cfg;
objects = dir;
infoDirectory = new File(objects, "info");
packDirectory = new File(objects, "pack");
alternatesFile = new File(infoDirectory, "alternates");
cachedPacksFile = new File(infoDirectory, "cached-packs");
packList = new AtomicReference(NO_PACKS);
cachedPacks = new AtomicReference();
unpackedObjectCache = new UnpackedObjectCache();
this.fs = fs;
alternates = new AtomicReference();
if (alternatePaths != null) {
AlternateHandle[] alt;
alt = new AlternateHandle[alternatePaths.length];
for (int i = 0; i < alternatePaths.length; i++)
alt[i] = openAlternate(alternatePaths[i]);
alternates.set(alt);
}
}
/**
* @return the location of the objects directory.
*/
public final File getDirectory() {
return objects;
}
@Override
public boolean exists() {
return objects.exists();
}
@Override
public void create() throws IOException {
FileUtils.mkdirs(objects);
FileUtils.mkdir(infoDirectory);
FileUtils.mkdir(packDirectory);
}
@Override
public ObjectDirectoryInserter newInserter() {
return new ObjectDirectoryInserter(this, config);
}
@Override
public void close() {
unpackedObjectCache.clear();
final PackList packs = packList.get();
packList.set(NO_PACKS);
for (final PackFile p : packs.packs)
p.close();
// Fully close all loaded alternates and clear the alternate list.
AlternateHandle[] alt = alternates.get();
if (alt != null) {
alternates.set(null);
for(final AlternateHandle od : alt)
od.close();
}
}
/**
* Compute the location of a loose object file.
*
* @param objectId
* identity of the loose object to map to the directory.
* @return location of the object, if it were to exist as a loose object.
*/
@Override
public File fileFor(final AnyObjectId objectId) {
return super.fileFor(objectId);
}
/**
* @return unmodifiable collection of all known pack files local to this
* directory. Most recent packs are presented first. Packs most
* likely to contain more recent objects appear before packs
* containing objects referenced by commits further back in the
* history of the repository.
*/
public Collection getPacks() {
PackList list = packList.get();
if (list == NO_PACKS)
list = scanPacks(list);
PackFile[] packs = list.packs;
return Collections.unmodifiableCollection(Arrays.asList(packs));
}
@Override
Collection getCachedPacks() throws IOException {
CachedPackList list = cachedPacks.get();
if (list == null || list.snapshot.isModified(cachedPacksFile))
list = scanCachedPacks(list);
Collection result = list.getCachedPacks();
boolean resultIsCopy = false;
for (AlternateHandle h : myAlternates()) {
Collection altPacks = h.getCachedPacks();
if (altPacks.isEmpty())
continue;
if (result.isEmpty()) {
result = altPacks;
continue;
}
if (!resultIsCopy) {
result = new ArrayList(result);
resultIsCopy = true;
}
result.addAll(altPacks);
}
return result;
}
private CachedPackList scanCachedPacks(CachedPackList old)
throws IOException {
FileSnapshot s = FileSnapshot.save(cachedPacksFile);
byte[] buf;
try {
buf = IO.readFully(cachedPacksFile);
} catch (FileNotFoundException e) {
buf = new byte[0];
}
if (old != null && old.snapshot.equals(s)
&& Arrays.equals(old.raw, buf)) {
old.snapshot.setClean(s);
return old;
}
ArrayList list = new ArrayList(4);
Set tips = new HashSet();
int ptr = 0;
while (ptr < buf.length) {
if (buf[ptr] == '#' || buf[ptr] == '\n') {
ptr = RawParseUtils.nextLF(buf, ptr);
continue;
}
if (buf[ptr] == '+') {
tips.add(ObjectId.fromString(buf, ptr + 2));
ptr = RawParseUtils.nextLF(buf, ptr + 2);
continue;
}
List names = new ArrayList(4);
while (ptr < buf.length && buf[ptr] == 'P') {
int end = RawParseUtils.nextLF(buf, ptr);
if (buf[end - 1] == '\n')
end--;
names.add(RawParseUtils.decode(buf, ptr + 2, end));
ptr = RawParseUtils.nextLF(buf, end);
}
if (!tips.isEmpty() && !names.isEmpty()) {
list.add(new LocalCachedPack(this, tips, names));
tips = new HashSet();
}
}
list.trimToSize();
return new CachedPackList(s, Collections.unmodifiableList(list), buf);
}
/**
* Add a single existing pack to the list of available pack files.
*
* @param pack
* path of the pack file to open.
* @param idx
* path of the corresponding index file.
* @return the pack that was opened and added to the database.
* @throws IOException
* index file could not be opened, read, or is not recognized as
* a Git pack file index.
*/
public PackFile openPack(final File pack, final File idx)
throws IOException {
final String p = pack.getName();
final String i = idx.getName();
if (p.length() != 50 || !p.startsWith("pack-") || !p.endsWith(".pack"))
throw new IOException(MessageFormat.format(JGitText.get().notAValidPack, pack));
if (i.length() != 49 || !i.startsWith("pack-") || !i.endsWith(".idx"))
throw new IOException(MessageFormat.format(JGitText.get().notAValidPack, idx));
if (!p.substring(0, 45).equals(i.substring(0, 45)))
throw new IOException(MessageFormat.format(JGitText.get().packDoesNotMatchIndex, pack));
PackFile res = new PackFile(idx, pack);
insertPack(res);
return res;
}
@Override
public String toString() {
return "ObjectDirectory[" + getDirectory() + "]";
}
boolean hasObject1(final AnyObjectId objectId) {
if (unpackedObjectCache.isUnpacked(objectId))
return true;
for (final PackFile p : packList.get().packs) {
try {
if (p.hasObject(objectId)) {
return true;
}
} catch (IOException e) {
// The hasObject call should have only touched the index,
// so any failure here indicates the index is unreadable
// by this process, and the pack is likewise not readable.
//
removePack(p);
continue;
}
}
return false;
}
void resolve(Set matches, AbbreviatedObjectId id)
throws IOException {
// Go through the packs once. If we didn't find any resolutions
// scan for new packs and check once more.
//
int oldSize = matches.size();
PackList pList = packList.get();
for (;;) {
for (PackFile p : pList.packs) {
try {
p.resolve(matches, id, RESOLVE_ABBREV_LIMIT);
} catch (IOException e) {
// Assume the pack is corrupted.
//
removePack(p);
}
if (matches.size() > RESOLVE_ABBREV_LIMIT)
return;
}
if (matches.size() == oldSize) {
PackList nList = scanPacks(pList);
if (nList == pList || nList.packs.length == 0)
break;
pList = nList;
continue;
}
break;
}
String fanOut = id.name().substring(0, 2);
String[] entries = new File(getDirectory(), fanOut).list();
if (entries != null) {
for (String e : entries) {
if (e.length() != Constants.OBJECT_ID_STRING_LENGTH - 2)
continue;
try {
ObjectId entId = ObjectId.fromString(fanOut + e);
if (id.prefixCompare(entId) == 0)
matches.add(entId);
} catch (IllegalArgumentException notId) {
continue;
}
if (matches.size() > RESOLVE_ABBREV_LIMIT)
return;
}
}
for (AlternateHandle alt : myAlternates()) {
alt.db.resolve(matches, id);
if (matches.size() > RESOLVE_ABBREV_LIMIT)
return;
}
}
ObjectLoader openObject1(final WindowCursor curs,
final AnyObjectId objectId) throws IOException {
if (unpackedObjectCache.isUnpacked(objectId)) {
ObjectLoader ldr = openObject2(curs, objectId.name(), objectId);
if (ldr != null)
return ldr;
else
unpackedObjectCache.remove(objectId);
}
PackList pList = packList.get();
SEARCH: for (;;) {
for (final PackFile p : pList.packs) {
try {
final ObjectLoader ldr = p.get(curs, objectId);
if (ldr != null)
return ldr;
} catch (PackMismatchException e) {
// Pack was modified; refresh the entire pack list.
//
pList = scanPacks(pList);
continue SEARCH;
} catch (IOException e) {
// Assume the pack is corrupted.
//
removePack(p);
}
}
return null;
}
}
long getObjectSize1(final WindowCursor curs, final AnyObjectId objectId)
throws IOException {
PackList pList = packList.get();
SEARCH: for (;;) {
for (final PackFile p : pList.packs) {
try {
long sz = p.getObjectSize(curs, objectId);
if (0 <= sz)
return sz;
} catch (PackMismatchException e) {
// Pack was modified; refresh the entire pack list.
//
pList = scanPacks(pList);
continue SEARCH;
} catch (IOException e) {
// Assume the pack is corrupted.
//
removePack(p);
}
}
return -1;
}
}
@Override
long getObjectSize2(WindowCursor curs, String objectName,
AnyObjectId objectId) throws IOException {
try {
File path = fileFor(objectName);
FileInputStream in = new FileInputStream(path);
try {
return UnpackedObject.getSize(in, objectId, curs);
} finally {
in.close();
}
} catch (FileNotFoundException noFile) {
return -1;
}
}
@Override
void selectObjectRepresentation(PackWriter packer, ObjectToPack otp,
WindowCursor curs) throws IOException {
PackList pList = packList.get();
SEARCH: for (;;) {
for (final PackFile p : pList.packs) {
try {
LocalObjectRepresentation rep = p.representation(curs, otp);
if (rep != null)
packer.select(otp, rep);
} catch (PackMismatchException e) {
// Pack was modified; refresh the entire pack list.
//
pList = scanPacks(pList);
continue SEARCH;
} catch (IOException e) {
// Assume the pack is corrupted.
//
removePack(p);
}
}
break SEARCH;
}
for (AlternateHandle h : myAlternates())
h.db.selectObjectRepresentation(packer, otp, curs);
}
boolean hasObject2(final String objectName) {
return fileFor(objectName).exists();
}
ObjectLoader openObject2(final WindowCursor curs,
final String objectName, final AnyObjectId objectId)
throws IOException {
try {
File path = fileFor(objectName);
FileInputStream in = new FileInputStream(path);
try {
unpackedObjectCache.add(objectId);
return UnpackedObject.open(in, path, objectId, curs);
} finally {
in.close();
}
} catch (FileNotFoundException noFile) {
unpackedObjectCache.remove(objectId);
return null;
}
}
@Override
InsertLooseObjectResult insertUnpackedObject(File tmp, ObjectId id,
boolean createDuplicate) throws IOException {
// If the object is already in the repository, remove temporary file.
//
if (unpackedObjectCache.isUnpacked(id)) {
FileUtils.delete(tmp);
return InsertLooseObjectResult.EXISTS_LOOSE;
}
if (!createDuplicate && has(id)) {
FileUtils.delete(tmp);
return InsertLooseObjectResult.EXISTS_PACKED;
}
final File dst = fileFor(id);
if (dst.exists()) {
// We want to be extra careful and avoid replacing an object
// that already exists. We can't be sure renameTo() would
// fail on all platforms if dst exists, so we check first.
//
FileUtils.delete(tmp);
return InsertLooseObjectResult.EXISTS_LOOSE;
}
if (tmp.renameTo(dst)) {
dst.setReadOnly();
unpackedObjectCache.add(id);
return InsertLooseObjectResult.INSERTED;
}
// Maybe the directory doesn't exist yet as the object
// directories are always lazily created. Note that we
// try the rename first as the directory likely does exist.
//
FileUtils.mkdir(dst.getParentFile());
if (tmp.renameTo(dst)) {
dst.setReadOnly();
unpackedObjectCache.add(id);
return InsertLooseObjectResult.INSERTED;
}
if (!createDuplicate && has(id)) {
FileUtils.delete(tmp);
return InsertLooseObjectResult.EXISTS_PACKED;
}
// The object failed to be renamed into its proper
// location and it doesn't exist in the repository
// either. We really don't know what went wrong, so
// fail.
//
FileUtils.delete(tmp);
return InsertLooseObjectResult.FAILURE;
}
boolean tryAgain1() {
final PackList old = packList.get();
if (old.snapshot.isModified(packDirectory))
return old != scanPacks(old);
return false;
}
Config getConfig() {
return config;
}
@Override
FS getFS() {
return fs;
}
private void insertPack(final PackFile pf) {
PackList o, n;
do {
o = packList.get();
// If the pack in question is already present in the list
// (picked up by a concurrent thread that did a scan?) we
// do not want to insert it a second time.
//
final PackFile[] oldList = o.packs;
final String name = pf.getPackFile().getName();
for (PackFile p : oldList) {
if (PackFile.SORT.compare(pf, p) < 0)
break;
if (name.equals(p.getPackFile().getName()))
return;
}
final PackFile[] newList = new PackFile[1 + oldList.length];
newList[0] = pf;
System.arraycopy(oldList, 0, newList, 1, oldList.length);
n = new PackList(o.snapshot, newList);
} while (!packList.compareAndSet(o, n));
}
private void removePack(final PackFile deadPack) {
PackList o, n;
do {
o = packList.get();
final PackFile[] oldList = o.packs;
final int j = indexOf(oldList, deadPack);
if (j < 0)
break;
final PackFile[] newList = new PackFile[oldList.length - 1];
System.arraycopy(oldList, 0, newList, 0, j);
System.arraycopy(oldList, j + 1, newList, j, newList.length - j);
n = new PackList(o.snapshot, newList);
} while (!packList.compareAndSet(o, n));
deadPack.close();
}
private static int indexOf(final PackFile[] list, final PackFile pack) {
for (int i = 0; i < list.length; i++) {
if (list[i] == pack)
return i;
}
return -1;
}
private PackList scanPacks(final PackList original) {
synchronized (packList) {
PackList o, n;
do {
o = packList.get();
if (o != original) {
// Another thread did the scan for us, while we
// were blocked on the monitor above.
//
return o;
}
n = scanPacksImpl(o);
if (n == o)
return n;
} while (!packList.compareAndSet(o, n));
return n;
}
}
private PackList scanPacksImpl(final PackList old) {
final Map forReuse = reuseMap(old);
final FileSnapshot snapshot = FileSnapshot.save(packDirectory);
final Set names = listPackDirectory();
final List list = new ArrayList(names.size() >> 2);
boolean foundNew = false;
for (final String indexName : names) {
// Must match "pack-[0-9a-f]{40}.idx" to be an index.
//
if (indexName.length() != 49 || !indexName.endsWith(".idx"))
continue;
final String base = indexName.substring(0, indexName.length() - 4);
final String packName = base + ".pack";
if (!names.contains(packName)) {
// Sometimes C Git's HTTP fetch transport leaves a
// .idx file behind and does not download the .pack.
// We have to skip over such useless indexes.
//
continue;
}
final PackFile oldPack = forReuse.remove(packName);
if (oldPack != null) {
list.add(oldPack);
continue;
}
final File packFile = new File(packDirectory, packName);
final File idxFile = new File(packDirectory, indexName);
list.add(new PackFile(idxFile, packFile));
foundNew = true;
}
// If we did not discover any new files, the modification time was not
// changed, and we did not remove any files, then the set of files is
// the same as the set we were given. Instead of building a new object
// return the same collection.
//
if (!foundNew && forReuse.isEmpty() && snapshot.equals(old.snapshot)) {
old.snapshot.setClean(snapshot);
return old;
}
for (final PackFile p : forReuse.values()) {
p.close();
}
if (list.isEmpty())
return new PackList(snapshot, NO_PACKS.packs);
final PackFile[] r = list.toArray(new PackFile[list.size()]);
Arrays.sort(r, PackFile.SORT);
return new PackList(snapshot, r);
}
private static Map reuseMap(final PackList old) {
final Map forReuse = new HashMap();
for (final PackFile p : old.packs) {
if (p.invalid()) {
// The pack instance is corrupted, and cannot be safely used
// again. Do not include it in our reuse map.
//
p.close();
continue;
}
final PackFile prior = forReuse.put(p.getPackFile().getName(), p);
if (prior != null) {
// This should never occur. It should be impossible for us
// to have two pack files with the same name, as all of them
// came out of the same directory. If it does, we promised to
// close any PackFiles we did not reuse, so close the second,
// readers are likely to be actively using the first.
//
forReuse.put(prior.getPackFile().getName(), prior);
p.close();
}
}
return forReuse;
}
private Set listPackDirectory() {
final String[] nameList = packDirectory.list();
if (nameList == null)
return Collections.emptySet();
final Set nameSet = new HashSet(nameList.length << 1);
for (final String name : nameList) {
if (name.startsWith("pack-"))
nameSet.add(name);
}
return nameSet;
}
AlternateHandle[] myAlternates() {
AlternateHandle[] alt = alternates.get();
if (alt == null) {
synchronized (alternates) {
alt = alternates.get();
if (alt == null) {
try {
alt = loadAlternates();
} catch (IOException e) {
alt = new AlternateHandle[0];
}
alternates.set(alt);
}
}
}
return alt;
}
private AlternateHandle[] loadAlternates() throws IOException {
final List l = new ArrayList(4);
final BufferedReader br = open(alternatesFile);
try {
String line;
while ((line = br.readLine()) != null) {
l.add(openAlternate(line));
}
} finally {
br.close();
}
return l.toArray(new AlternateHandle[l.size()]);
}
private static BufferedReader open(final File f)
throws FileNotFoundException {
return new BufferedReader(new FileReader(f));
}
private AlternateHandle openAlternate(final String location)
throws IOException {
final File objdir = fs.resolve(objects, location);
return openAlternate(objdir);
}
private AlternateHandle openAlternate(File objdir) throws IOException {
final File parent = objdir.getParentFile();
if (FileKey.isGitRepository(parent, fs)) {
FileKey key = FileKey.exact(parent, fs);
FileRepository db = (FileRepository) RepositoryCache.open(key);
return new AlternateRepository(db);
}
ObjectDirectory db = new ObjectDirectory(config, objdir, null, fs);
return new AlternateHandle(db);
}
private static final class PackList {
/** State just before reading the pack directory. */
final FileSnapshot snapshot;
/** All known packs, sorted by {@link PackFile#SORT}. */
final PackFile[] packs;
PackList(final FileSnapshot monitor, final PackFile[] packs) {
this.snapshot = monitor;
this.packs = packs;
}
}
private static final class CachedPackList {
final FileSnapshot snapshot;
final Collection packs;
final byte[] raw;
CachedPackList(FileSnapshot sn, List list, byte[] buf) {
snapshot = sn;
packs = list;
raw = buf;
}
@SuppressWarnings("unchecked")
Collection getCachedPacks() {
Collection p = packs;
return p;
}
}
@Override
public ObjectDatabase newCachedDatabase() {
return newCachedFileObjectDatabase();
}
FileObjectDatabase newCachedFileObjectDatabase() {
return new CachedObjectDirectory(this);
}
}