ObjectToPack.java
/*
* Copyright (C) 2008-2010, Google Inc.
* Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com> 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.internal.storage.pack;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.transport.PackedObjectInfo;
/**
* Per-object state used by
* {@link org.eclipse.jgit.internal.storage.pack.PackWriter}.
* <p>
* {@code PackWriter} uses this class to track the things it needs to include in
* the newly generated pack file, and how to efficiently obtain the raw data for
* each object as they are written to the output stream.
*/
public class ObjectToPack extends PackedObjectInfo {
private static final int REUSE_AS_IS = 1 << 0;
private static final int DELTA_ATTEMPTED = 1 << 1;
private static final int DO_NOT_DELTA = 1 << 2;
private static final int EDGE = 1 << 3;
private static final int ATTEMPT_DELTA_MASK = REUSE_AS_IS | DELTA_ATTEMPTED;
private static final int TYPE_SHIFT = 5;
private static final int EXT_SHIFT = 8;
private static final int EXT_MASK = 0xf;
private static final int DELTA_SHIFT = 12;
private static final int NON_EXT_MASK = ~(EXT_MASK << EXT_SHIFT);
private static final int NON_DELTA_MASK = 0xfff;
/** Other object being packed that this will delta against. */
private ObjectId deltaBase;
/**
* Bit field, from bit 0 to bit 31:
* <ul>
* <li>1 bit: canReuseAsIs</li>
* <li>1 bit: deltaAttempted</li>
* <li>1 bit: doNotDelta</li>
* <li>1 bit: edgeObject</li>
* <li>1 bit: unused</li>
* <li>3 bits: type</li>
* <li>4 bits: subclass flags (if any)</li>
* <li>--</li>
* <li>20 bits: deltaDepth</li>
* </ul>
*/
private int flags;
/** Hash of the object's tree path. */
private int pathHash;
/** If present, deflated delta instruction stream for this object. */
private DeltaCache.Ref cachedDelta;
/**
* Construct for the specified object id.
*
* @param src
* object id of object for packing
* @param type
* real type code of the object, not its in-pack type.
*/
public ObjectToPack(AnyObjectId src, int type) {
super(src);
flags = type << TYPE_SHIFT;
}
/**
* Get delta base object id if object is going to be packed in delta
* representation
*
* @return delta base object id if object is going to be packed in delta
* representation; null otherwise - if going to be packed as a whole
* object.
*/
public final ObjectId getDeltaBaseId() {
return deltaBase;
}
/**
* Get delta base object to pack if object is going to be packed in delta
* representation and delta is specified as object to pack
*
* @return delta base object to pack if object is going to be packed in
* delta representation and delta is specified as object to pack;
* null otherwise - if going to be packed as a whole object or delta
* base is specified only as id.
*/
public final ObjectToPack getDeltaBase() {
if (deltaBase instanceof ObjectToPack)
return (ObjectToPack) deltaBase;
return null;
}
/**
* Set delta base for the object. Delta base set by this method is used
* by {@link PackWriter} to write object - determines its representation
* in a created pack.
*
* @param deltaBase
* delta base object or null if object should be packed as a
* whole object.
*
*/
final void setDeltaBase(ObjectId deltaBase) {
this.deltaBase = deltaBase;
}
final void setCachedDelta(DeltaCache.Ref data) {
cachedDelta = data;
}
final DeltaCache.Ref popCachedDelta() {
DeltaCache.Ref r = cachedDelta;
if (r != null)
cachedDelta = null;
return r;
}
final void clearDeltaBase() {
this.deltaBase = null;
if (cachedDelta != null) {
cachedDelta.clear();
cachedDelta.enqueue();
cachedDelta = null;
}
}
/**
* Whether object is going to be written as delta
*
* @return true if object is going to be written as delta; false otherwise.
*/
public final boolean isDeltaRepresentation() {
return deltaBase != null;
}
/**
* Check if object is already written in a pack. This information is
* used to achieve delta-base precedence in a pack file.
*
* @return true if object is already written; false otherwise.
*/
public final boolean isWritten() {
return 1 < getOffset(); // markWantWrite sets 1.
}
/** {@inheritDoc} */
@Override
public final int getType() {
return (flags >> TYPE_SHIFT) & 0x7;
}
final int getDeltaDepth() {
return flags >>> DELTA_SHIFT;
}
final void setDeltaDepth(int d) {
flags = (d << DELTA_SHIFT) | (flags & NON_DELTA_MASK);
}
final int getChainLength() {
return getDeltaDepth();
}
final void setChainLength(int len) {
setDeltaDepth(len);
}
final void clearChainLength() {
flags &= NON_DELTA_MASK;
}
final boolean wantWrite() {
return getOffset() == 1;
}
final void markWantWrite() {
setOffset(1);
}
/**
* Whether an existing representation was selected to be reused as-is into
* the pack stream.
*
* @return true if an existing representation was selected to be reused
* as-is into the pack stream.
*/
public final boolean isReuseAsIs() {
return (flags & REUSE_AS_IS) != 0;
}
final void setReuseAsIs() {
flags |= REUSE_AS_IS;
}
/**
* Forget the reuse information previously stored.
* <p>
* Implementations may subclass this method, but they must also invoke the
* super version with {@code super.clearReuseAsIs()} to ensure the flag is
* properly cleared for the writer.
*/
protected void clearReuseAsIs() {
flags &= ~REUSE_AS_IS;
}
final boolean isDoNotDelta() {
return (flags & DO_NOT_DELTA) != 0;
}
final void setDoNotDelta() {
flags |= DO_NOT_DELTA;
}
final boolean isEdge() {
return (flags & EDGE) != 0;
}
final void setEdge() {
flags |= EDGE;
}
final boolean doNotAttemptDelta() {
// Do not attempt if delta attempted and object reuse.
return (flags & ATTEMPT_DELTA_MASK) == ATTEMPT_DELTA_MASK;
}
final void setDeltaAttempted(boolean deltaAttempted) {
if (deltaAttempted)
flags |= DELTA_ATTEMPTED;
else
flags &= ~DELTA_ATTEMPTED;
}
/**
* Get the extended flags on this object, in the range [0x0, 0xf].
*
* @return the extended flags on this object, in the range [0x0, 0xf].
*/
protected final int getExtendedFlags() {
return (flags >>> EXT_SHIFT) & EXT_MASK;
}
/**
* Determine if a particular extended flag bit has been set.
*
* This implementation may be faster than calling
* {@link #getExtendedFlags()} and testing the result.
*
* @param flag
* the flag mask to test, must be between 0x0 and 0xf.
* @return true if any of the bits matching the mask are non-zero.
*/
protected final boolean isExtendedFlag(int flag) {
return (flags & (flag << EXT_SHIFT)) != 0;
}
/**
* Set an extended flag bit.
*
* This implementation is more efficient than getting the extended flags,
* adding the bit, and setting them all back.
*
* @param flag
* the bits to set, must be between 0x0 and 0xf.
*/
protected final void setExtendedFlag(int flag) {
flags |= (flag & EXT_MASK) << EXT_SHIFT;
}
/**
* Clear an extended flag bit.
*
* This implementation is more efficient than getting the extended flags,
* removing the bit, and setting them all back.
*
* @param flag
* the bits to clear, must be between 0x0 and 0xf.
*/
protected final void clearExtendedFlag(int flag) {
flags &= ~((flag & EXT_MASK) << EXT_SHIFT);
}
/**
* Set the extended flags used by the subclass.
*
* Subclass implementations may store up to 4 bits of information inside of
* the internal flags field already used by the base ObjectToPack instance.
*
* @param extFlags
* additional flag bits to store in the flags field. Due to space
* constraints only values [0x0, 0xf] are permitted.
*/
protected final void setExtendedFlags(int extFlags) {
flags = ((extFlags & EXT_MASK) << EXT_SHIFT) | (flags & NON_EXT_MASK);
}
final int getFormat() {
if (isReuseAsIs()) {
if (isDeltaRepresentation())
return StoredObjectRepresentation.PACK_DELTA;
return StoredObjectRepresentation.PACK_WHOLE;
}
return StoredObjectRepresentation.FORMAT_OTHER;
}
// Overload weight into CRC since we don't need them at the same time.
final int getWeight() {
return getCRC();
}
final void setWeight(int weight) {
setCRC(weight);
}
final int getPathHash() {
return pathHash;
}
final void setPathHash(int hc) {
pathHash = hc;
}
final int getCachedSize() {
return pathHash;
}
final void setCachedSize(int sz) {
pathHash = sz;
}
/**
* Remember a specific representation for reuse at a later time.
* <p>
* Implementers should remember the representation chosen, so it can be
* reused at a later time.
* {@link org.eclipse.jgit.internal.storage.pack.PackWriter} may invoke this
* method multiple times for the same object, each time saving the current
* best representation found.
*
* @param ref
* the object representation.
*/
public void select(StoredObjectRepresentation ref) {
// Empty by default.
}
/** {@inheritDoc} */
@SuppressWarnings("nls")
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append("ObjectToPack[");
buf.append(Constants.typeString(getType()));
buf.append(" ");
buf.append(name());
if (wantWrite())
buf.append(" wantWrite");
if (isReuseAsIs())
buf.append(" reuseAsIs");
if (isDoNotDelta())
buf.append(" doNotDelta");
if (isEdge())
buf.append(" edge");
if (getDeltaDepth() > 0)
buf.append(" depth=").append(getDeltaDepth());
if (isDeltaRepresentation()) {
if (getDeltaBase() != null)
buf.append(" base=inpack:").append(getDeltaBase().name());
else
buf.append(" base=edge:").append(getDeltaBaseId().name());
}
if (isWritten())
buf.append(" offset=").append(getOffset());
buf.append("]");
return buf.toString();
}
}