RefAdvertiser.java
/*
* Copyright (C) 2008, 2020 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.transport;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.eclipse.jgit.lib.Constants.OBJECT_ID_STRING_LENGTH;
import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SYMREF;
import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_PEELED;
import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_SYMREF_TARGET;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.RefComparator;
import org.eclipse.jgit.lib.Repository;
/**
* Support for the start of {@link org.eclipse.jgit.transport.UploadPack} and
* {@link org.eclipse.jgit.transport.ReceivePack}.
*/
public abstract class RefAdvertiser {
/** Advertiser which frames lines in a {@link PacketLineOut} format. */
public static class PacketLineOutRefAdvertiser extends RefAdvertiser {
private final CharsetEncoder utf8 = UTF_8.newEncoder();
private final PacketLineOut pckOut;
private byte[] binArr = new byte[256];
private ByteBuffer binBuf = ByteBuffer.wrap(binArr);
private char[] chArr = new char[256];
private CharBuffer chBuf = CharBuffer.wrap(chArr);
/**
* Create a new advertiser for the supplied stream.
*
* @param out
* the output stream.
*/
public PacketLineOutRefAdvertiser(PacketLineOut out) {
pckOut = out;
}
@Override
public void advertiseId(AnyObjectId id, String refName)
throws IOException {
id.copyTo(binArr, 0);
binArr[OBJECT_ID_STRING_LENGTH] = ' ';
binBuf.position(OBJECT_ID_STRING_LENGTH + 1);
append(refName);
if (first) {
first = false;
if (!capablities.isEmpty()) {
append('\0');
for (String cap : capablities) {
append(' ');
append(cap);
}
}
}
append('\n');
pckOut.writePacket(binArr, 0, binBuf.position());
}
private void append(String str) throws CharacterCodingException {
int n = str.length();
if (n > chArr.length) {
chArr = new char[n + 256];
chBuf = CharBuffer.wrap(chArr);
}
str.getChars(0, n, chArr, 0);
chBuf.position(0).limit(n);
utf8.reset();
for (;;) {
CoderResult cr = utf8.encode(chBuf, binBuf, true);
if (cr.isOverflow()) {
grow();
} else if (cr.isUnderflow()) {
break;
} else {
cr.throwException();
}
}
}
private void append(int b) {
if (!binBuf.hasRemaining()) {
grow();
}
binBuf.put((byte) b);
}
private void grow() {
int cnt = binBuf.position();
byte[] tmp = new byte[binArr.length << 1];
System.arraycopy(binArr, 0, tmp, 0, cnt);
binArr = tmp;
binBuf = ByteBuffer.wrap(binArr);
binBuf.position(cnt);
}
@Override
protected void writeOne(CharSequence line) throws IOException {
pckOut.writeString(line.toString());
}
@Override
protected void end() throws IOException {
pckOut.end();
}
}
private final StringBuilder tmpLine = new StringBuilder(100);
private final char[] tmpId = new char[Constants.OBJECT_ID_STRING_LENGTH];
final Set<String> capablities = new LinkedHashSet<>();
private final Set<ObjectId> sent = new HashSet<>();
private Repository repository;
private boolean derefTags;
boolean first = true;
private boolean useProtocolV2;
/* only used in protocol v2 */
private final Map<String, String> symrefs = new HashMap<>();
/**
* Initialize this advertiser with a repository for peeling tags.
*
* @param src
* the repository to read from.
*/
public void init(Repository src) {
repository = src;
}
/**
* @param b
* true if this advertiser should advertise using the protocol
* v2 format, false otherwise
* @since 5.0
*/
public void setUseProtocolV2(boolean b) {
useProtocolV2 = b;
}
/**
* Toggle tag peeling.
* <p>
* <p>
* This method must be invoked prior to any of the following:
* <ul>
* <li>{@link #send(Map)}</li>
* <li>{@link #send(Collection)}</li>
* </ul>
*
* @param deref
* true to show the dereferenced value of a tag as the special
* ref <code>$tag^{}</code> ; false to omit it from the output.
*/
public void setDerefTags(boolean deref) {
derefTags = deref;
}
/**
* Add one protocol capability to the initial advertisement.
* <p>
* This method must be invoked prior to any of the following:
* <ul>
* <li>{@link #send(Map)}</li>
* <li>{@link #send(Collection)}</li>
* <li>{@link #advertiseHave(AnyObjectId)}</li>
* </ul>
*
* @param name
* the name of a single protocol capability supported by the
* caller. The set of capabilities are sent to the client in the
* advertisement, allowing the client to later selectively enable
* features it recognizes.
*/
public void advertiseCapability(String name) {
capablities.add(name);
}
/**
* Add one protocol capability with a value ({@code "name=value"}).
*
* @param name
* name of the capability.
* @param value
* value. If null the capability will not be added.
* @since 4.0
*/
public void advertiseCapability(String name, String value) {
if (value != null) {
capablities.add(name + '=' + value);
}
}
/**
* Add a symbolic ref to capabilities.
* <p>
* This method must be invoked prior to any of the following:
* <ul>
* <li>{@link #send(Map)}</li>
* <li>{@link #send(Collection)}</li>
* <li>{@link #advertiseHave(AnyObjectId)}</li>
* </ul>
*
* @param from
* The symbolic ref, e.g. "HEAD"
* @param to
* The real ref it points to, e.g. "refs/heads/master"
* @since 3.6
*/
public void addSymref(String from, String to) {
if (useProtocolV2) {
symrefs.put(from, to);
} else {
advertiseCapability(OPTION_SYMREF, from + ':' + to);
}
}
/**
* Format an advertisement for the supplied refs.
*
* @param refs
* zero or more refs to format for the client. The collection is
* sorted before display if necessary, and therefore may appear
* in any order.
* @return set of ObjectIds that were advertised to the client.
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
* @deprecated use {@link #send(Collection)} instead.
*/
@Deprecated
public Set<ObjectId> send(Map<String, Ref> refs) throws IOException {
return send(refs.values());
}
/**
* Format an advertisement for the supplied refs.
*
* @param refs
* zero or more refs to format for the client. The collection is
* sorted before display if necessary, and therefore may appear
* in any order.
* @return set of ObjectIds that were advertised to the client.
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
* @since 5.0
*/
public Set<ObjectId> send(Collection<Ref> refs) throws IOException {
for (Ref ref : RefComparator.sort(refs)) {
// TODO(jrn) revive the SortedMap optimization e.g. by introducing
// SortedList
ObjectId objectId = ref.getObjectId();
if (objectId == null) {
continue;
}
if (useProtocolV2) {
String symrefPart = symrefs.containsKey(ref.getName())
? (' ' + REF_ATTR_SYMREF_TARGET
+ symrefs.get(ref.getName()))
: ""; //$NON-NLS-1$
String peelPart = ""; //$NON-NLS-1$
if (derefTags) {
if (!ref.isPeeled() && repository != null) {
ref = repository.getRefDatabase().peel(ref);
}
ObjectId peeledObjectId = ref.getPeeledObjectId();
if (peeledObjectId != null) {
peelPart = ' ' + REF_ATTR_PEELED
+ peeledObjectId.getName();
}
}
writeOne(objectId.getName() + " " + ref.getName() + symrefPart //$NON-NLS-1$
+ peelPart + "\n"); //$NON-NLS-1$
continue;
}
advertiseAny(objectId, ref.getName());
if (!derefTags)
continue;
if (!ref.isPeeled()) {
if (repository == null)
continue;
ref = repository.getRefDatabase().peel(ref);
}
if (ref.getPeeledObjectId() != null)
advertiseAny(ref.getPeeledObjectId(), ref.getName() + "^{}"); //$NON-NLS-1$
}
return sent;
}
/**
* Advertise one object is available using the magic {@code .have}.
* <p>
* The magic {@code .have} advertisement is not available for fetching by a
* client, but can be used by a client when considering a delta base
* candidate before transferring data in a push. Within the record created
* by this method the ref name is simply the invalid string {@code .have}.
*
* @param id
* identity of the object that is assumed to exist.
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
*/
public void advertiseHave(AnyObjectId id) throws IOException {
advertiseAnyOnce(id, ".have"); //$NON-NLS-1$
}
/**
* Whether no advertisements have been sent yet.
*
* @return true if no advertisements have been sent yet.
*/
public boolean isEmpty() {
return first;
}
private void advertiseAnyOnce(AnyObjectId obj, String refName)
throws IOException {
if (!sent.contains(obj))
advertiseAny(obj, refName);
}
private void advertiseAny(AnyObjectId obj, String refName)
throws IOException {
sent.add(obj.toObjectId());
advertiseId(obj, refName);
}
/**
* Advertise one object under a specific name.
* <p>
* If the advertised object is a tag, this method does not advertise the
* peeled version of it.
*
* @param id
* the object to advertise.
* @param refName
* name of the reference to advertise the object as, can be any
* string not including the NUL byte.
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
*/
public void advertiseId(AnyObjectId id, String refName)
throws IOException {
tmpLine.setLength(0);
id.copyTo(tmpId, tmpLine);
tmpLine.append(' ');
tmpLine.append(refName);
if (first) {
first = false;
if (!capablities.isEmpty()) {
tmpLine.append('\0');
for (String capName : capablities) {
tmpLine.append(' ');
tmpLine.append(capName);
}
tmpLine.append(' ');
}
}
tmpLine.append('\n');
writeOne(tmpLine);
}
/**
* Write a single advertisement line.
*
* @param line
* the advertisement line to be written. The line always ends
* with LF. Never null or the empty string.
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
*/
protected abstract void writeOne(CharSequence line) throws IOException;
/**
* Mark the end of the advertisements.
*
* @throws java.io.IOException
* the underlying output stream failed to write out an
* advertisement record.
*/
protected abstract void end() throws IOException;
}