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- /*
- * Copyright (C) 2010, 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.lib;
-
- import java.io.IOException;
- import java.util.ArrayList;
- import java.util.Collection;
- import java.util.Iterator;
- import java.util.List;
- import java.util.Set;
-
- import org.eclipse.jgit.annotations.Nullable;
- import org.eclipse.jgit.errors.IncorrectObjectTypeException;
- import org.eclipse.jgit.errors.MissingObjectException;
-
- /**
- * Reads an {@link org.eclipse.jgit.lib.ObjectDatabase} for a single thread.
- * <p>
- * Readers that can support efficient reuse of pack encoded objects should also
- * implement the companion interface
- * {@link org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs}.
- */
- public abstract class ObjectReader implements AutoCloseable {
- /** Type hint indicating the caller doesn't know the type. */
- public static final int OBJ_ANY = -1;
-
- /**
- * The threshold at which a file will be streamed rather than loaded
- * entirely into memory.
- * @since 4.6
- */
- protected int streamFileThreshold;
-
- /**
- * Construct a new reader from the same data.
- * <p>
- * Applications can use this method to build a new reader from the same data
- * source, but for an different thread.
- *
- * @return a brand new reader, using the same data source.
- */
- public abstract ObjectReader newReader();
-
- /**
- * Obtain a unique abbreviation (prefix) of an object SHA-1.
- *
- * This method uses a reasonable default for the minimum length. Callers who
- * don't care about the minimum length should prefer this method.
- *
- * The returned abbreviation would expand back to the argument ObjectId when
- * passed to {@link #resolve(AbbreviatedObjectId)}, assuming no new objects
- * are added to this repository between calls.
- *
- * @param objectId
- * object identity that needs to be abbreviated.
- * @return SHA-1 abbreviation.
- * @throws java.io.IOException
- * the object store cannot be read.
- */
- public AbbreviatedObjectId abbreviate(AnyObjectId objectId)
- throws IOException {
- return abbreviate(objectId, 7);
- }
-
- /**
- * Obtain a unique abbreviation (prefix) of an object SHA-1.
- *
- * The returned abbreviation would expand back to the argument ObjectId when
- * passed to {@link #resolve(AbbreviatedObjectId)}, assuming no new objects
- * are added to this repository between calls.
- *
- * The default implementation of this method abbreviates the id to the
- * minimum length, then resolves it to see if there are multiple results.
- * When multiple results are found, the length is extended by 1 and resolve
- * is tried again.
- *
- * @param objectId
- * object identity that needs to be abbreviated.
- * @param len
- * minimum length of the abbreviated string. Must be in the range
- * [2, {@value Constants#OBJECT_ID_STRING_LENGTH}].
- * @return SHA-1 abbreviation. If no matching objects exist in the
- * repository, the abbreviation will match the minimum length.
- * @throws java.io.IOException
- * the object store cannot be read.
- */
- public AbbreviatedObjectId abbreviate(AnyObjectId objectId, int len)
- throws IOException {
- if (len == Constants.OBJECT_ID_STRING_LENGTH)
- return AbbreviatedObjectId.fromObjectId(objectId);
-
- AbbreviatedObjectId abbrev = objectId.abbreviate(len);
- Collection<ObjectId> matches = resolve(abbrev);
- while (1 < matches.size() && len < Constants.OBJECT_ID_STRING_LENGTH) {
- abbrev = objectId.abbreviate(++len);
- List<ObjectId> n = new ArrayList<>(8);
- for (ObjectId candidate : matches) {
- if (abbrev.prefixCompare(candidate) == 0)
- n.add(candidate);
- }
- if (1 < n.size())
- matches = n;
- else
- matches = resolve(abbrev);
- }
- return abbrev;
- }
-
- /**
- * Resolve an abbreviated ObjectId to its full form.
- *
- * This method searches for an ObjectId that begins with the abbreviation,
- * and returns at least some matching candidates.
- *
- * If the returned collection is empty, no objects start with this
- * abbreviation. The abbreviation doesn't belong to this repository, or the
- * repository lacks the necessary objects to complete it.
- *
- * If the collection contains exactly one member, the abbreviation is
- * (currently) unique within this database. There is a reasonably high
- * probability that the returned id is what was previously abbreviated.
- *
- * If the collection contains 2 or more members, the abbreviation is not
- * unique. In this case the implementation is only required to return at
- * least 2 candidates to signal the abbreviation has conflicts. User
- * friendly implementations should return as many candidates as reasonably
- * possible, as the caller may be able to disambiguate further based on
- * context. However since databases can be very large (e.g. 10 million
- * objects) returning 625,000 candidates for the abbreviation "0" is simply
- * unreasonable, so implementors should draw the line at around 256 matches.
- *
- * @param id
- * abbreviated id to resolve to a complete identity. The
- * abbreviation must have a length of at least 2.
- * @return candidates that begin with the abbreviated identity.
- * @throws java.io.IOException
- * the object store cannot be read.
- */
- public abstract Collection<ObjectId> resolve(AbbreviatedObjectId id)
- throws IOException;
-
- /**
- * Does the requested object exist in this database?
- *
- * @param objectId
- * identity of the object to test for existence of.
- * @return true if the specified object is stored in this database.
- * @throws java.io.IOException
- * the object store cannot be accessed.
- */
- public boolean has(AnyObjectId objectId) throws IOException {
- return has(objectId, OBJ_ANY);
- }
-
- /**
- * Does the requested object exist in this database?
- *
- * @param objectId
- * identity of the object to test for existence of.
- * @param typeHint
- * hint about the type of object being requested, e.g.
- * {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB};
- * {@link #OBJ_ANY} if the object type is not known, or does not
- * matter to the caller.
- * @return true if the specified object is stored in this database.
- * @throws IncorrectObjectTypeException
- * typeHint was not OBJ_ANY, and the object's actual type does
- * not match typeHint.
- * @throws java.io.IOException
- * the object store cannot be accessed.
- */
- public boolean has(AnyObjectId objectId, int typeHint) throws IOException {
- try {
- open(objectId, typeHint);
- return true;
- } catch (MissingObjectException notFound) {
- return false;
- }
- }
-
- /**
- * Open an object from this database.
- *
- * @param objectId
- * identity of the object to open.
- * @return a {@link org.eclipse.jgit.lib.ObjectLoader} for accessing the
- * object.
- * @throws org.eclipse.jgit.errors.MissingObjectException
- * the object does not exist.
- * @throws java.io.IOException
- * the object store cannot be accessed.
- */
- public ObjectLoader open(AnyObjectId objectId)
- throws MissingObjectException, IOException {
- return open(objectId, OBJ_ANY);
- }
-
- /**
- * Open an object from this database.
- *
- * @param objectId
- * identity of the object to open.
- * @param typeHint
- * hint about the type of object being requested, e.g.
- * {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB};
- * {@link #OBJ_ANY} if the object type is not known, or does not
- * matter to the caller.
- * @return a {@link org.eclipse.jgit.lib.ObjectLoader} for accessing the
- * object.
- * @throws org.eclipse.jgit.errors.MissingObjectException
- * the object does not exist.
- * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
- * typeHint was not OBJ_ANY, and the object's actual type does
- * not match typeHint.
- * @throws java.io.IOException
- * the object store cannot be accessed.
- */
- public abstract ObjectLoader open(AnyObjectId objectId, int typeHint)
- throws MissingObjectException, IncorrectObjectTypeException,
- IOException;
-
- /**
- * Returns IDs for those commits which should be considered as shallow.
- *
- * @return IDs of shallow commits
- * @throws java.io.IOException
- */
- public abstract Set<ObjectId> getShallowCommits() throws IOException;
-
- /**
- * Asynchronous object opening.
- *
- * @param objectIds
- * objects to open from the object store. The supplied collection
- * must not be modified until the queue has finished.
- * @param reportMissing
- * if true missing objects are reported by calling failure with a
- * MissingObjectException. This may be more expensive for the
- * implementation to guarantee. If false the implementation may
- * choose to report MissingObjectException, or silently skip over
- * the object with no warning.
- * @return queue to read the objects from.
- */
- public <T extends ObjectId> AsyncObjectLoaderQueue<T> open(
- Iterable<T> objectIds, final boolean reportMissing) {
- final Iterator<T> idItr = objectIds.iterator();
- return new AsyncObjectLoaderQueue<T>() {
- private T cur;
-
- @Override
- public boolean next() throws MissingObjectException, IOException {
- if (idItr.hasNext()) {
- cur = idItr.next();
- return true;
- }
- return false;
- }
-
- @Override
- public T getCurrent() {
- return cur;
- }
-
- @Override
- public ObjectId getObjectId() {
- return cur;
- }
-
- @Override
- public ObjectLoader open() throws IOException {
- return ObjectReader.this.open(cur, OBJ_ANY);
- }
-
- @Override
- public boolean cancel(boolean mayInterruptIfRunning) {
- return true;
- }
-
- @Override
- public void release() {
- // Since we are sequential by default, we don't
- // have any state to clean up if we terminate early.
- }
- };
- }
-
- /**
- * Get only the size of an object.
- * <p>
- * The default implementation of this method opens an ObjectLoader.
- * Databases are encouraged to override this if a faster access method is
- * available to them.
- *
- * @param objectId
- * identity of the object to open.
- * @param typeHint
- * hint about the type of object being requested, e.g.
- * {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB};
- * {@link #OBJ_ANY} if the object type is not known, or does not
- * matter to the caller.
- * @return size of object in bytes.
- * @throws org.eclipse.jgit.errors.MissingObjectException
- * the object does not exist.
- * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
- * typeHint was not OBJ_ANY, and the object's actual type does
- * not match typeHint.
- * @throws java.io.IOException
- * the object store cannot be accessed.
- */
- public long getObjectSize(AnyObjectId objectId, int typeHint)
- throws MissingObjectException, IncorrectObjectTypeException,
- IOException {
- return open(objectId, typeHint).getSize();
- }
-
- /**
- * Asynchronous object size lookup.
- *
- * @param objectIds
- * objects to get the size of from the object store. The supplied
- * collection must not be modified until the queue has finished.
- * @param reportMissing
- * if true missing objects are reported by calling failure with a
- * MissingObjectException. This may be more expensive for the
- * implementation to guarantee. If false the implementation may
- * choose to report MissingObjectException, or silently skip over
- * the object with no warning.
- * @return queue to read object sizes from.
- */
- public <T extends ObjectId> AsyncObjectSizeQueue<T> getObjectSize(
- Iterable<T> objectIds, final boolean reportMissing) {
- final Iterator<T> idItr = objectIds.iterator();
- return new AsyncObjectSizeQueue<T>() {
- private T cur;
-
- private long sz;
-
- @Override
- public boolean next() throws MissingObjectException, IOException {
- if (idItr.hasNext()) {
- cur = idItr.next();
- sz = getObjectSize(cur, OBJ_ANY);
- return true;
- }
- return false;
- }
-
- @Override
- public T getCurrent() {
- return cur;
- }
-
- @Override
- public ObjectId getObjectId() {
- return cur;
- }
-
- @Override
- public long getSize() {
- return sz;
- }
-
- @Override
- public boolean cancel(boolean mayInterruptIfRunning) {
- return true;
- }
-
- @Override
- public void release() {
- // Since we are sequential by default, we don't
- // have any state to clean up if we terminate early.
- }
- };
- }
-
- /**
- * Advise the reader to avoid unreachable objects.
- * <p>
- * While enabled the reader will skip over anything previously proven to be
- * unreachable. This may be dangerous in the face of concurrent writes.
- *
- * @param avoid
- * true to avoid unreachable objects.
- * @since 3.0
- */
- public void setAvoidUnreachableObjects(boolean avoid) {
- // Do nothing by default.
- }
-
- /**
- * An index that can be used to speed up ObjectWalks.
- *
- * @return the index or null if one does not exist.
- * @throws java.io.IOException
- * when the index fails to load
- * @since 3.0
- */
- public BitmapIndex getBitmapIndex() throws IOException {
- return null;
- }
-
- /**
- * Get the {@link org.eclipse.jgit.lib.ObjectInserter} from which this
- * reader was created using {@code inserter.newReader()}
- *
- * @return the {@link org.eclipse.jgit.lib.ObjectInserter} from which this
- * reader was created using {@code inserter.newReader()}, or null if
- * this reader was not created from an inserter.
- * @since 4.4
- */
- @Nullable
- public ObjectInserter getCreatedFromInserter() {
- return null;
- }
-
- /**
- * {@inheritDoc}
- * <p>
- * Release any resources used by this reader.
- * <p>
- * A reader that has been released can be used again, but may need to be
- * released after the subsequent usage.
- *
- * @since 4.0
- */
- @Override
- public abstract void close();
-
- /**
- * Sets the threshold at which a file will be streamed rather than loaded
- * entirely into memory
- *
- * @param threshold
- * the new threshold
- * @since 4.6
- */
- public void setStreamFileThreshold(int threshold) {
- streamFileThreshold = threshold;
- }
-
- /**
- * Returns the threshold at which a file will be streamed rather than loaded
- * entirely into memory
- *
- * @return the threshold in bytes
- * @since 4.6
- */
- public int getStreamFileThreshold() {
- return streamFileThreshold;
- }
-
- /**
- * Wraps a delegate ObjectReader.
- *
- * @since 4.4
- */
- public abstract static class Filter extends ObjectReader {
- /**
- * @return delegate ObjectReader to handle all processing.
- * @since 4.4
- */
- protected abstract ObjectReader delegate();
-
- @Override
- public ObjectReader newReader() {
- return delegate().newReader();
- }
-
- @Override
- public AbbreviatedObjectId abbreviate(AnyObjectId objectId)
- throws IOException {
- return delegate().abbreviate(objectId);
- }
-
- @Override
- public AbbreviatedObjectId abbreviate(AnyObjectId objectId, int len)
- throws IOException {
- return delegate().abbreviate(objectId, len);
- }
-
- @Override
- public Collection<ObjectId> resolve(AbbreviatedObjectId id)
- throws IOException {
- return delegate().resolve(id);
- }
-
- @Override
- public boolean has(AnyObjectId objectId) throws IOException {
- return delegate().has(objectId);
- }
-
- @Override
- public boolean has(AnyObjectId objectId, int typeHint) throws IOException {
- return delegate().has(objectId, typeHint);
- }
-
- @Override
- public ObjectLoader open(AnyObjectId objectId)
- throws MissingObjectException, IOException {
- return delegate().open(objectId);
- }
-
- @Override
- public ObjectLoader open(AnyObjectId objectId, int typeHint)
- throws MissingObjectException, IncorrectObjectTypeException,
- IOException {
- return delegate().open(objectId, typeHint);
- }
-
- @Override
- public Set<ObjectId> getShallowCommits() throws IOException {
- return delegate().getShallowCommits();
- }
-
- @Override
- public <T extends ObjectId> AsyncObjectLoaderQueue<T> open(
- Iterable<T> objectIds, boolean reportMissing) {
- return delegate().open(objectIds, reportMissing);
- }
-
- @Override
- public long getObjectSize(AnyObjectId objectId, int typeHint)
- throws MissingObjectException, IncorrectObjectTypeException,
- IOException {
- return delegate().getObjectSize(objectId, typeHint);
- }
-
- @Override
- public <T extends ObjectId> AsyncObjectSizeQueue<T> getObjectSize(
- Iterable<T> objectIds, boolean reportMissing) {
- return delegate().getObjectSize(objectIds, reportMissing);
- }
-
- @Override
- public void setAvoidUnreachableObjects(boolean avoid) {
- delegate().setAvoidUnreachableObjects(avoid);
- }
-
- @Override
- public BitmapIndex getBitmapIndex() throws IOException {
- return delegate().getBitmapIndex();
- }
-
- @Override
- @Nullable
- public ObjectInserter getCreatedFromInserter() {
- return delegate().getCreatedFromInserter();
- }
-
- @Override
- public void close() {
- delegate().close();
- }
- }
- }
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