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596 lines
19 KiB
596 lines
19 KiB
/* |
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* Copyright (C) 2010, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php |
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.lib; |
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import java.io.IOException; |
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import java.util.ArrayList; |
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import java.util.Collection; |
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import java.util.Iterator; |
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import java.util.List; |
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import java.util.Set; |
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import org.eclipse.jgit.annotations.Nullable; |
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import org.eclipse.jgit.errors.IncorrectObjectTypeException; |
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import org.eclipse.jgit.errors.MissingObjectException; |
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/** |
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* Reads an {@link org.eclipse.jgit.lib.ObjectDatabase} for a single thread. |
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* <p> |
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* Readers that can support efficient reuse of pack encoded objects should also |
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* implement the companion interface |
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* {@link org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs}. |
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*/ |
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public abstract class ObjectReader implements AutoCloseable { |
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/** Type hint indicating the caller doesn't know the type. */ |
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public static final int OBJ_ANY = -1; |
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/** |
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* The threshold at which a file will be streamed rather than loaded |
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* entirely into memory. |
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* @since 4.6 |
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*/ |
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protected int streamFileThreshold; |
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/** |
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* Construct a new reader from the same data. |
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* <p> |
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* Applications can use this method to build a new reader from the same data |
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* source, but for an different thread. |
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* |
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* @return a brand new reader, using the same data source. |
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*/ |
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public abstract ObjectReader newReader(); |
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/** |
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* Obtain a unique abbreviation (prefix) of an object SHA-1. |
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* |
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* This method uses a reasonable default for the minimum length. Callers who |
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* don't care about the minimum length should prefer this method. |
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* |
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* The returned abbreviation would expand back to the argument ObjectId when |
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* passed to {@link #resolve(AbbreviatedObjectId)}, assuming no new objects |
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* are added to this repository between calls. |
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* |
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* @param objectId |
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* object identity that needs to be abbreviated. |
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* @return SHA-1 abbreviation. |
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* @throws java.io.IOException |
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* the object store cannot be read. |
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*/ |
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public AbbreviatedObjectId abbreviate(AnyObjectId objectId) |
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throws IOException { |
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return abbreviate(objectId, 7); |
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} |
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/** |
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* Obtain a unique abbreviation (prefix) of an object SHA-1. |
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* |
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* The returned abbreviation would expand back to the argument ObjectId when |
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* passed to {@link #resolve(AbbreviatedObjectId)}, assuming no new objects |
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* are added to this repository between calls. |
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* |
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* The default implementation of this method abbreviates the id to the |
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* minimum length, then resolves it to see if there are multiple results. |
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* When multiple results are found, the length is extended by 1 and resolve |
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* is tried again. |
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* |
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* @param objectId |
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* object identity that needs to be abbreviated. |
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* @param len |
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* minimum length of the abbreviated string. Must be in the range |
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* [2, {@value Constants#OBJECT_ID_STRING_LENGTH}]. |
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* @return SHA-1 abbreviation. If no matching objects exist in the |
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* repository, the abbreviation will match the minimum length. |
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* @throws java.io.IOException |
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* the object store cannot be read. |
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*/ |
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public AbbreviatedObjectId abbreviate(AnyObjectId objectId, int len) |
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throws IOException { |
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if (len == Constants.OBJECT_ID_STRING_LENGTH) |
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return AbbreviatedObjectId.fromObjectId(objectId); |
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AbbreviatedObjectId abbrev = objectId.abbreviate(len); |
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Collection<ObjectId> matches = resolve(abbrev); |
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while (1 < matches.size() && len < Constants.OBJECT_ID_STRING_LENGTH) { |
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abbrev = objectId.abbreviate(++len); |
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List<ObjectId> n = new ArrayList<>(8); |
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for (ObjectId candidate : matches) { |
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if (abbrev.prefixCompare(candidate) == 0) |
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n.add(candidate); |
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} |
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if (1 < n.size()) |
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matches = n; |
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else |
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matches = resolve(abbrev); |
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} |
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return abbrev; |
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} |
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/** |
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* Resolve an abbreviated ObjectId to its full form. |
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* |
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* This method searches for an ObjectId that begins with the abbreviation, |
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* and returns at least some matching candidates. |
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* |
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* If the returned collection is empty, no objects start with this |
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* abbreviation. The abbreviation doesn't belong to this repository, or the |
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* repository lacks the necessary objects to complete it. |
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* |
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* If the collection contains exactly one member, the abbreviation is |
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* (currently) unique within this database. There is a reasonably high |
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* probability that the returned id is what was previously abbreviated. |
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* |
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* If the collection contains 2 or more members, the abbreviation is not |
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* unique. In this case the implementation is only required to return at |
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* least 2 candidates to signal the abbreviation has conflicts. User |
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* friendly implementations should return as many candidates as reasonably |
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* possible, as the caller may be able to disambiguate further based on |
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* context. However since databases can be very large (e.g. 10 million |
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* objects) returning 625,000 candidates for the abbreviation "0" is simply |
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* unreasonable, so implementors should draw the line at around 256 matches. |
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* |
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* @param id |
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* abbreviated id to resolve to a complete identity. The |
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* abbreviation must have a length of at least 2. |
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* @return candidates that begin with the abbreviated identity. |
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* @throws java.io.IOException |
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* the object store cannot be read. |
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*/ |
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public abstract Collection<ObjectId> resolve(AbbreviatedObjectId id) |
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throws IOException; |
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/** |
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* Does the requested object exist in this database? |
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* |
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* @param objectId |
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* identity of the object to test for existence of. |
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* @return true if the specified object is stored in this database. |
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* @throws java.io.IOException |
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* the object store cannot be accessed. |
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*/ |
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public boolean has(AnyObjectId objectId) throws IOException { |
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return has(objectId, OBJ_ANY); |
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} |
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/** |
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* Does the requested object exist in this database? |
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* |
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* @param objectId |
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* identity of the object to test for existence of. |
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* @param typeHint |
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* hint about the type of object being requested, e.g. |
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* {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB}; |
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* {@link #OBJ_ANY} if the object type is not known, or does not |
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* matter to the caller. |
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* @return true if the specified object is stored in this database. |
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* @throws IncorrectObjectTypeException |
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* typeHint was not OBJ_ANY, and the object's actual type does |
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* not match typeHint. |
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* @throws java.io.IOException |
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* the object store cannot be accessed. |
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*/ |
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public boolean has(AnyObjectId objectId, int typeHint) throws IOException { |
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try { |
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open(objectId, typeHint); |
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return true; |
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} catch (MissingObjectException notFound) { |
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return false; |
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} |
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} |
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/** |
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* Open an object from this database. |
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* |
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* @param objectId |
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* identity of the object to open. |
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* @return a {@link org.eclipse.jgit.lib.ObjectLoader} for accessing the |
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* object. |
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* @throws org.eclipse.jgit.errors.MissingObjectException |
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* the object does not exist. |
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* @throws java.io.IOException |
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* the object store cannot be accessed. |
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*/ |
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public ObjectLoader open(AnyObjectId objectId) |
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throws MissingObjectException, IOException { |
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return open(objectId, OBJ_ANY); |
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} |
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/** |
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* Open an object from this database. |
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* |
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* @param objectId |
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* identity of the object to open. |
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* @param typeHint |
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* hint about the type of object being requested, e.g. |
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* {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB}; |
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* {@link #OBJ_ANY} if the object type is not known, or does not |
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* matter to the caller. |
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* @return a {@link org.eclipse.jgit.lib.ObjectLoader} for accessing the |
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* object. |
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* @throws org.eclipse.jgit.errors.MissingObjectException |
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* the object does not exist. |
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* @throws org.eclipse.jgit.errors.IncorrectObjectTypeException |
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* typeHint was not OBJ_ANY, and the object's actual type does |
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* not match typeHint. |
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* @throws java.io.IOException |
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* the object store cannot be accessed. |
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*/ |
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public abstract ObjectLoader open(AnyObjectId objectId, int typeHint) |
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throws MissingObjectException, IncorrectObjectTypeException, |
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IOException; |
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/** |
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* Returns IDs for those commits which should be considered as shallow. |
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* |
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* @return IDs of shallow commits |
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* @throws java.io.IOException |
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*/ |
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public abstract Set<ObjectId> getShallowCommits() throws IOException; |
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/** |
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* Asynchronous object opening. |
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* |
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* @param objectIds |
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* objects to open from the object store. The supplied collection |
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* must not be modified until the queue has finished. |
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* @param reportMissing |
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* if true missing objects are reported by calling failure with a |
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* MissingObjectException. This may be more expensive for the |
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* implementation to guarantee. If false the implementation may |
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* choose to report MissingObjectException, or silently skip over |
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* the object with no warning. |
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* @return queue to read the objects from. |
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*/ |
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public <T extends ObjectId> AsyncObjectLoaderQueue<T> open( |
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Iterable<T> objectIds, final boolean reportMissing) { |
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final Iterator<T> idItr = objectIds.iterator(); |
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return new AsyncObjectLoaderQueue<T>() { |
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private T cur; |
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@Override |
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public boolean next() throws MissingObjectException, IOException { |
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if (idItr.hasNext()) { |
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cur = idItr.next(); |
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return true; |
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} |
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return false; |
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} |
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@Override |
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public T getCurrent() { |
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return cur; |
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} |
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@Override |
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public ObjectId getObjectId() { |
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return cur; |
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} |
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@Override |
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public ObjectLoader open() throws IOException { |
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return ObjectReader.this.open(cur, OBJ_ANY); |
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} |
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@Override |
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public boolean cancel(boolean mayInterruptIfRunning) { |
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return true; |
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} |
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@Override |
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public void release() { |
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// Since we are sequential by default, we don't |
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// have any state to clean up if we terminate early. |
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} |
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}; |
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} |
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/** |
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* Get only the size of an object. |
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* <p> |
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* The default implementation of this method opens an ObjectLoader. |
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* Databases are encouraged to override this if a faster access method is |
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* available to them. |
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* |
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* @param objectId |
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* identity of the object to open. |
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* @param typeHint |
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* hint about the type of object being requested, e.g. |
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* {@link org.eclipse.jgit.lib.Constants#OBJ_BLOB}; |
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* {@link #OBJ_ANY} if the object type is not known, or does not |
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* matter to the caller. |
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* @return size of object in bytes. |
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* @throws org.eclipse.jgit.errors.MissingObjectException |
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* the object does not exist. |
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* @throws org.eclipse.jgit.errors.IncorrectObjectTypeException |
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* typeHint was not OBJ_ANY, and the object's actual type does |
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* not match typeHint. |
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* @throws java.io.IOException |
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* the object store cannot be accessed. |
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*/ |
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public long getObjectSize(AnyObjectId objectId, int typeHint) |
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throws MissingObjectException, IncorrectObjectTypeException, |
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IOException { |
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return open(objectId, typeHint).getSize(); |
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} |
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/** |
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* Asynchronous object size lookup. |
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* |
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* @param objectIds |
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* objects to get the size of from the object store. The supplied |
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* collection must not be modified until the queue has finished. |
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* @param reportMissing |
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* if true missing objects are reported by calling failure with a |
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* MissingObjectException. This may be more expensive for the |
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* implementation to guarantee. If false the implementation may |
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* choose to report MissingObjectException, or silently skip over |
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* the object with no warning. |
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* @return queue to read object sizes from. |
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*/ |
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public <T extends ObjectId> AsyncObjectSizeQueue<T> getObjectSize( |
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Iterable<T> objectIds, final boolean reportMissing) { |
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final Iterator<T> idItr = objectIds.iterator(); |
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return new AsyncObjectSizeQueue<T>() { |
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private T cur; |
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private long sz; |
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@Override |
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public boolean next() throws MissingObjectException, IOException { |
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if (idItr.hasNext()) { |
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cur = idItr.next(); |
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sz = getObjectSize(cur, OBJ_ANY); |
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return true; |
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} |
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return false; |
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} |
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@Override |
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public T getCurrent() { |
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return cur; |
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} |
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@Override |
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public ObjectId getObjectId() { |
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return cur; |
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} |
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@Override |
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public long getSize() { |
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return sz; |
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} |
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@Override |
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public boolean cancel(boolean mayInterruptIfRunning) { |
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return true; |
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} |
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@Override |
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public void release() { |
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// Since we are sequential by default, we don't |
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// have any state to clean up if we terminate early. |
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} |
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}; |
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} |
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/** |
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* Advise the reader to avoid unreachable objects. |
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* <p> |
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* While enabled the reader will skip over anything previously proven to be |
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* unreachable. This may be dangerous in the face of concurrent writes. |
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* |
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* @param avoid |
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* true to avoid unreachable objects. |
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* @since 3.0 |
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*/ |
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public void setAvoidUnreachableObjects(boolean avoid) { |
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// Do nothing by default. |
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} |
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/** |
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* An index that can be used to speed up ObjectWalks. |
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* |
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* @return the index or null if one does not exist. |
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* @throws java.io.IOException |
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* when the index fails to load |
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* @since 3.0 |
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*/ |
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public BitmapIndex getBitmapIndex() throws IOException { |
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return null; |
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} |
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/** |
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* Get the {@link org.eclipse.jgit.lib.ObjectInserter} from which this |
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* reader was created using {@code inserter.newReader()} |
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* |
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* @return the {@link org.eclipse.jgit.lib.ObjectInserter} from which this |
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* reader was created using {@code inserter.newReader()}, or null if |
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* this reader was not created from an inserter. |
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* @since 4.4 |
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*/ |
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@Nullable |
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public ObjectInserter getCreatedFromInserter() { |
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return null; |
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} |
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/** |
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* {@inheritDoc} |
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* <p> |
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* Release any resources used by this reader. |
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* <p> |
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* A reader that has been released can be used again, but may need to be |
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* released after the subsequent usage. |
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* |
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* @since 4.0 |
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*/ |
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@Override |
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public abstract void close(); |
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/** |
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* Sets the threshold at which a file will be streamed rather than loaded |
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* entirely into memory |
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* |
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* @param threshold |
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* the new threshold |
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* @since 4.6 |
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*/ |
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public void setStreamFileThreshold(int threshold) { |
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streamFileThreshold = threshold; |
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} |
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/** |
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* Returns the threshold at which a file will be streamed rather than loaded |
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* entirely into memory |
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* |
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* @return the threshold in bytes |
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* @since 4.6 |
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*/ |
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public int getStreamFileThreshold() { |
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return streamFileThreshold; |
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} |
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/** |
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* Wraps a delegate ObjectReader. |
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* |
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* @since 4.4 |
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*/ |
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public static abstract class Filter extends ObjectReader { |
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/** |
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* @return delegate ObjectReader to handle all processing. |
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* @since 4.4 |
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*/ |
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protected abstract ObjectReader delegate(); |
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@Override |
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public ObjectReader newReader() { |
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return delegate().newReader(); |
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} |
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@Override |
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public AbbreviatedObjectId abbreviate(AnyObjectId objectId) |
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throws IOException { |
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return delegate().abbreviate(objectId); |
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} |
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@Override |
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public AbbreviatedObjectId abbreviate(AnyObjectId objectId, int len) |
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throws IOException { |
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return delegate().abbreviate(objectId, len); |
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} |
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@Override |
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public Collection<ObjectId> resolve(AbbreviatedObjectId id) |
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throws IOException { |
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return delegate().resolve(id); |
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} |
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@Override |
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public boolean has(AnyObjectId objectId) throws IOException { |
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return delegate().has(objectId); |
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} |
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@Override |
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public boolean has(AnyObjectId objectId, int typeHint) throws IOException { |
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return delegate().has(objectId, typeHint); |
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} |
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@Override |
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public ObjectLoader open(AnyObjectId objectId) |
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throws MissingObjectException, IOException { |
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return delegate().open(objectId); |
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} |
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@Override |
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public ObjectLoader open(AnyObjectId objectId, int typeHint) |
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throws MissingObjectException, IncorrectObjectTypeException, |
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IOException { |
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return delegate().open(objectId, typeHint); |
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} |
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@Override |
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public Set<ObjectId> getShallowCommits() throws IOException { |
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return delegate().getShallowCommits(); |
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} |
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@Override |
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public <T extends ObjectId> AsyncObjectLoaderQueue<T> open( |
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Iterable<T> objectIds, boolean reportMissing) { |
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return delegate().open(objectIds, reportMissing); |
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} |
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@Override |
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public long getObjectSize(AnyObjectId objectId, int typeHint) |
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throws MissingObjectException, IncorrectObjectTypeException, |
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IOException { |
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return delegate().getObjectSize(objectId, typeHint); |
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} |
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@Override |
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public <T extends ObjectId> AsyncObjectSizeQueue<T> getObjectSize( |
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Iterable<T> objectIds, boolean reportMissing) { |
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return delegate().getObjectSize(objectIds, reportMissing); |
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} |
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@Override |
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public void setAvoidUnreachableObjects(boolean avoid) { |
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delegate().setAvoidUnreachableObjects(avoid); |
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} |
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@Override |
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public BitmapIndex getBitmapIndex() throws IOException { |
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return delegate().getBitmapIndex(); |
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} |
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@Override |
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@Nullable |
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public ObjectInserter getCreatedFromInserter() { |
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return delegate().getCreatedFromInserter(); |
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} |
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@Override |
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public void close() { |
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delegate().close(); |
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} |
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} |
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}
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