/*
* 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.
*
* 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.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.JGitText;
import org.eclipse.jgit.errors.PackMismatchException;
import org.eclipse.jgit.events.ConfigChangedEvent;
import org.eclipse.jgit.events.ConfigChangedListener;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.CoreConfig;
import org.eclipse.jgit.lib.ObjectDatabase;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
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.ObjectToPack;
import org.eclipse.jgit.storage.pack.PackWriter;
import org.eclipse.jgit.util.FS;
/**
* Traditional file system based {@link ObjectDatabase}.
* <p>
* 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.
* <p>
* Optionally an object database can reference one or more alternates; other
* ObjectDatabase instances that are searched in addition to the current
* database.
* <p>
* 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 implements
ConfigChangedListener {
private static final PackList NO_PACKS = new PackList(-1, -1, new PackFile[0]);
private final Config config;
private final File objects;
private final File infoDirectory;
private final File packDirectory;
private final File alternatesFile;
private final AtomicReference<PackList> packList;
private final FS fs;
private final AtomicReference<AlternateHandle[]> alternates;
private int streamFileThreshold;
/**
* Initialize a reference to an on-disk object directory.
*
* @param cfg
* configuration this directory consults for write settings.
* @param dir
* the location of the <code>objects</code> 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");
packList = new AtomicReference<PackList>(NO_PACKS);
this.fs = fs;
alternates = new AtomicReference<AlternateHandle[]>();
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);
}
onConfigChanged(new ConfigChangedEvent());
}
public void onConfigChanged(ConfigChangedEvent event) {
CoreConfig core = config.get(CoreConfig.KEY);
streamFileThreshold = core.getStreamFileThreshold();
}
/**
* @return the location of the <code>objects</code> directory.
*/
public final File getDirectory() {
return objects;
}
@Override
public boolean exists() {
return objects.exists();
}
@Override
public void create() throws IOException {
objects.mkdirs();
infoDirectory.mkdir();
packDirectory.mkdir();
}
@Override
public ObjectInserter newInserter() {
return new ObjectDirectoryInserter(this, config);
}
@Override
public void close() {
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.
*/
public File fileFor(final AnyObjectId objectId) {
return fileFor(objectId.name());
}
private File fileFor(final String objectName) {
final String d = objectName.substring(0, 2);
final String f = objectName.substring(2);
return new File(new File(objects, d), f);
}
/**
* @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<PackFile> getPacks() {
final PackFile[] packs = packList.get().packs;
return Collections.unmodifiableCollection(Arrays.asList(packs));
}
/**
* 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.
* @throws IOException
* index file could not be opened, read, or is not recognized as
* a Git pack file index.
*/
public void 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));
insertPack(new PackFile(idx, pack));
}
@Override
public String toString() {
return "ObjectDirectory[" + getDirectory() + "]";
}
boolean hasObject1(final AnyObjectId objectId) {
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;
}
ObjectLoader openObject1(final WindowCursor curs,
final AnyObjectId objectId) throws IOException {
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 {
return UnpackedObject.open(in, path, objectId, curs);
} finally {
in.close();
}
} catch (FileNotFoundException noFile) {
return null;
}
}
boolean tryAgain1() {
final PackList old = packList.get();
if (old.tryAgain(packDirectory.lastModified()))
return old != scanPacks(old);
return false;
}
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.lastRead, o.lastModified, 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.lastRead, o.lastModified, 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<String, PackFile> forReuse = reuseMap(old);
final long lastRead = System.currentTimeMillis();
final long lastModified = packDirectory.lastModified();
final Set<String> names = listPackDirectory();
final List<PackFile> list = new ArrayList<PackFile>(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 && lastModified == old.lastModified && forReuse.isEmpty())
return old.updateLastRead(lastRead);
for (final PackFile p : forReuse.values()) {
p.close();
}
if (list.isEmpty())
return new PackList(lastRead, lastModified, NO_PACKS.packs);
final PackFile[] r = list.toArray(new PackFile[list.size()]);
Arrays.sort(r, PackFile.SORT);
return new PackList(lastRead, lastModified, r);
}
private static Map<String, PackFile> reuseMap(final PackList old) {
final Map<String, PackFile> forReuse = new HashMap<String, PackFile>();
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<String> listPackDirectory() {
final String[] nameList = packDirectory.list();
if (nameList == null)
return Collections.emptySet();
final Set<String> nameSet = new HashSet<String>(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<AlternateHandle> l = new ArrayList<AlternateHandle>(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 {
/** Last wall-clock time the directory was read. */
volatile long lastRead;
/** Last modification time of {@link ObjectDirectory#packDirectory}. */
final long lastModified;
/** All known packs, sorted by {@link PackFile#SORT}. */
final PackFile[] packs;
private boolean cannotBeRacilyClean;
PackList(final long lastRead, final long lastModified,
final PackFile[] packs) {
this.lastRead = lastRead;
this.lastModified = lastModified;
this.packs = packs;
this.cannotBeRacilyClean = notRacyClean(lastRead);
}
private boolean notRacyClean(final long read) {
return read - lastModified > 2 * 60 * 1000L;
}
PackList updateLastRead(final long now) {
if (notRacyClean(now))
cannotBeRacilyClean = true;
lastRead = now;
return this;
}
boolean tryAgain(final long currLastModified) {
// Any difference indicates the directory was modified.
//
if (lastModified != currLastModified)
return true;
// We have already determined the last read was far enough
// after the last modification that any new modifications
// are certain to change the last modified time.
//
if (cannotBeRacilyClean)
return false;
if (notRacyClean(lastRead)) {
// Our last read should have marked cannotBeRacilyClean,
// but this thread may not have seen the change. The read
// of the volatile field lastRead should have fixed that.
//
return false;
}
// We last read this directory too close to its last observed
// modification time. We may have missed a modification. Scan
// the directory again, to ensure we still see the same state.
//
return true;
}
}
@Override
public ObjectDatabase newCachedDatabase() {
return newCachedFileObjectDatabase();
}
FileObjectDatabase newCachedFileObjectDatabase() {
return new CachedObjectDirectory(this);
}
@Override
int getStreamFileThreshold() {
return streamFileThreshold;
}
}