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/* * Copyright (C) 2010, 2013 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.lib; import static java.util.stream.Collectors.toList; import static java.util.stream.Collectors.toSet; import java.io.IOException; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import org.eclipse.jgit.annotations.NonNull; import org.eclipse.jgit.annotations.Nullable; /** * Abstraction of name to {@link org.eclipse.jgit.lib.ObjectId} mapping. * <p> * A reference database stores a mapping of reference names to * {@link org.eclipse.jgit.lib.ObjectId}. Every * {@link org.eclipse.jgit.lib.Repository} has a single reference database, * mapping names to the tips of the object graph contained by the * {@link org.eclipse.jgit.lib.ObjectDatabase}. */ public abstract class RefDatabase { /** * Order of prefixes to search when using non-absolute references. * <p> * {@link #findRef(String)} takes this search space into consideration * when locating a reference by name. The first entry in the path is * always {@code ""}, ensuring that absolute references are resolved * without further mangling. */ protected static final String[] SEARCH_PATH = { "", //$NON-NLS-1$ Constants.R_REFS, // Constants.R_TAGS, // Constants.R_HEADS, // Constants.R_REMOTES // }; /** * Maximum number of times a {@link SymbolicRef} can be traversed. * <p> * If the reference is nested deeper than this depth, the implementation * should either fail, or at least claim the reference does not exist. * * @since 4.2 */ public static final int MAX_SYMBOLIC_REF_DEPTH = 5; /** * Magic value for {@link #getRefsByPrefix(String)} to return all * references. */ public static final String ALL = "";//$NON-NLS-1$ /** * Initialize a new reference database at this location. * * @throws java.io.IOException * the database could not be created. */ public abstract void create() throws IOException; /** * Close any resources held by this database. */ public abstract void close(); /** * With versioning, each reference has a version number that increases on * update. See {@link Ref#getUpdateIndex()}. * * @implSpec This method returns false by default. Implementations * supporting versioning must override it to return true. * @return true if the implementation assigns update indices to references. * @since 5.3 */ public boolean hasVersioning() { return false; } /** * Determine if a proposed reference name overlaps with an existing one. * <p> * Reference names use '/' as a component separator, and may be stored in a * hierarchical storage such as a directory on the local filesystem. * <p> * If the reference "refs/heads/foo" exists then "refs/heads/foo/bar" must * not exist, as a reference cannot have a value and also be a container for * other references at the same time. * <p> * If the reference "refs/heads/foo/bar" exists than the reference * "refs/heads/foo" cannot exist, for the same reason. * * @param name * proposed name. * @return true if the name overlaps with an existing reference; false if * using this name right now would be safe. * @throws java.io.IOException * the database could not be read to check for conflicts. * @see #getConflictingNames(String) */ public abstract boolean isNameConflicting(String name) throws IOException; /** * Determine if a proposed reference cannot coexist with existing ones. If * the passed name already exists, it's not considered a conflict. * * @param name * proposed name to check for conflicts against * @return a collection of full names of existing refs which would conflict * with the passed ref name; empty collection when there are no * conflicts * @throws java.io.IOException * @since 2.3 * @see #isNameConflicting(String) */ @NonNull public Collection<String> getConflictingNames(String name) throws IOException { Map<String, Ref> allRefs = getRefs(ALL); // Cannot be nested within an existing reference. int lastSlash = name.lastIndexOf('/'); while (0 < lastSlash) { String needle = name.substring(0, lastSlash); if (allRefs.containsKey(needle)) return Collections.singletonList(needle); lastSlash = name.lastIndexOf('/', lastSlash - 1); } List<String> conflicting = new ArrayList<>(); // Cannot be the container of an existing reference. String prefix = name + '/'; for (String existing : allRefs.keySet()) if (existing.startsWith(prefix)) conflicting.add(existing); return conflicting; } /** * Create a new update command to create, modify or delete a reference. * * @param name * the name of the reference. * @param detach * if {@code true} and {@code name} is currently a * {@link org.eclipse.jgit.lib.SymbolicRef}, the update will * replace it with an {@link org.eclipse.jgit.lib.ObjectIdRef}. * Otherwise, the update will recursively traverse * {@link org.eclipse.jgit.lib.SymbolicRef}s and operate on the * leaf {@link org.eclipse.jgit.lib.ObjectIdRef}. * @return a new update for the requested name; never null. * @throws java.io.IOException * the reference space cannot be accessed. */ @NonNull public abstract RefUpdate newUpdate(String name, boolean detach) throws IOException; /** * Create a new update command to rename a reference. * * @param fromName * name of reference to rename from * @param toName * name of reference to rename to * @return an update command that knows how to rename a branch to another. * @throws java.io.IOException * the reference space cannot be accessed. */ @NonNull public abstract RefRename newRename(String fromName, String toName) throws IOException; /** * Create a new batch update to attempt on this database. * <p> * The default implementation performs a sequential update of each command. * * @return a new batch update object. */ @NonNull public BatchRefUpdate newBatchUpdate() { return new BatchRefUpdate(this); } /** * Whether the database is capable of performing batch updates as atomic * transactions. * <p> * If true, by default {@link org.eclipse.jgit.lib.BatchRefUpdate} instances * will perform updates atomically, meaning either all updates will succeed, * or all updates will fail. It is still possible to turn off this behavior * on a per-batch basis by calling {@code update.setAtomic(false)}. * <p> * If false, {@link org.eclipse.jgit.lib.BatchRefUpdate} instances will * never perform updates atomically, and calling * {@code update.setAtomic(true)} will cause the entire batch to fail with * {@code REJECTED_OTHER_REASON}. * <p> * This definition of atomicity is stronger than what is provided by * {@link org.eclipse.jgit.transport.ReceivePack}. {@code ReceivePack} will * attempt to reject all commands if it knows in advance some commands may * fail, even if the storage layer does not support atomic transactions. * Here, atomicity applies even in the case of unforeseeable errors. * * @return whether transactions are atomic by default. * @since 3.6 */ public boolean performsAtomicTransactions() { return false; } /** * Compatibility synonym for {@link #findRef(String)}. * * @param name * the name of the reference. May be a short name which must be * searched for using the standard {@link #SEARCH_PATH}. * @return the reference (if it exists); else {@code null}. * @throws IOException * the reference space cannot be accessed. * @deprecated Use {@link #findRef(String)} instead. */ @Deprecated @Nullable public final Ref getRef(String name) throws IOException { return findRef(name); } /** * Read a single reference. * <p> * Aside from taking advantage of {@link #SEARCH_PATH}, this method may be * able to more quickly resolve a single reference name than obtaining the * complete namespace by {@code getRefs(ALL).get(name)}. * <p> * To read a specific reference without using @{link #SEARCH_PATH}, see * {@link #exactRef(String)}. * * @param name * the name of the reference. May be a short name which must be * searched for using the standard {@link #SEARCH_PATH}. * @return the reference (if it exists); else {@code null}. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.3 */ @Nullable public final Ref findRef(String name) throws IOException { String[] names = new String[SEARCH_PATH.length]; for (int i = 0; i < SEARCH_PATH.length; i++) { names[i] = SEARCH_PATH[i] + name; } return firstExactRef(names); } /** * Read a single reference. * <p> * Unlike {@link #findRef}, this method expects an unshortened reference * name and does not search using the standard {@link #SEARCH_PATH}. * * @param name * the unabbreviated name of the reference. * @return the reference (if it exists); else {@code null}. * @throws java.io.IOException * the reference space cannot be accessed. * @since 4.1 */ @Nullable public abstract Ref exactRef(String name) throws IOException; /** * Read the specified references. * <p> * This method expects a list of unshortened reference names and returns * a map from reference names to refs. Any named references that do not * exist will not be included in the returned map. * * @param refs * the unabbreviated names of references to look up. * @return modifiable map describing any refs that exist among the ref * ref names supplied. The map can be an unsorted map. * @throws java.io.IOException * the reference space cannot be accessed. * @since 4.1 */ @NonNull public Map<String, Ref> exactRef(String... refs) throws IOException { Map<String, Ref> result = new HashMap<>(refs.length); for (String name : refs) { Ref ref = exactRef(name); if (ref != null) { result.put(name, ref); } } return result; } /** * Find the first named reference. * <p> * This method expects a list of unshortened reference names and returns * the first that exists. * * @param refs * the unabbreviated names of references to look up. * @return the first named reference that exists (if any); else {@code null}. * @throws java.io.IOException * the reference space cannot be accessed. * @since 4.1 */ @Nullable public Ref firstExactRef(String... refs) throws IOException { for (String name : refs) { Ref ref = exactRef(name); if (ref != null) { return ref; } } return null; } /** * Returns all refs. * <p> * This includes {@code HEAD}, branches under {@code ref/heads/}, tags * under {@code refs/tags/}, etc. It does not include pseudo-refs like * {@code FETCH_HEAD}; for those, see {@link #getAdditionalRefs}. * <p> * Symbolic references to a non-existent ref (for example, * {@code HEAD} pointing to a branch yet to be born) are not included. * <p> * Callers interested in only a portion of the ref hierarchy can call * {@link #getRefsByPrefix} instead. * * @return immutable list of all refs. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.0 */ @NonNull public List<Ref> getRefs() throws IOException { return getRefsByPrefix(ALL); } /** * Get a section of the reference namespace. * * @param prefix * prefix to search the namespace with; must end with {@code /}. * If the empty string ({@link #ALL}), obtain a complete snapshot * of all references. * @return modifiable map that is a complete snapshot of the current * reference namespace, with {@code prefix} removed from the start * of each key. The map can be an unsorted map. * @throws java.io.IOException * the reference space cannot be accessed. * @deprecated use {@link #getRefsByPrefix} instead */ @NonNull @Deprecated public abstract Map<String, Ref> getRefs(String prefix) throws IOException; /** * Returns refs whose names start with a given prefix. * <p> * The default implementation uses {@link #getRefs(String)}. Implementors of * {@link RefDatabase} should override this method directly if a better * implementation is possible. * * @param prefix string that names of refs should start with; may be * empty (to return all refs). * @return immutable list of refs whose names start with {@code prefix}. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.0 */ @NonNull public List<Ref> getRefsByPrefix(String prefix) throws IOException { Map<String, Ref> coarseRefs; int lastSlash = prefix.lastIndexOf('/'); if (lastSlash == -1) { coarseRefs = getRefs(ALL); } else { coarseRefs = getRefs(prefix.substring(0, lastSlash + 1)); } List<Ref> result; if (lastSlash + 1 == prefix.length()) { result = coarseRefs.values().stream().collect(toList()); } else { String p = prefix.substring(lastSlash + 1); result = coarseRefs.entrySet().stream().filter(e -> e.getKey().startsWith(p)).map(e -> e.getValue()) .collect(toList()); } return Collections.unmodifiableList(result); } /** * Returns refs whose names start with one of the given prefixes. * <p> * The default implementation uses {@link #getRefsByPrefix(String)}. * Implementors of {@link RefDatabase} should override this method directly * if a better implementation is possible. * * @param prefixes * strings that names of refs should start with. * @return immutable list of refs whose names start with one of * {@code prefixes}. Refs can be unsorted and may contain duplicates * if the prefixes overlap. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.2 */ @NonNull public List<Ref> getRefsByPrefix(String... prefixes) throws IOException { List<Ref> result = new ArrayList<>(); for (String prefix : prefixes) { result.addAll(getRefsByPrefix(prefix)); } return Collections.unmodifiableList(result); } /** * Returns all refs that resolve directly to the given {@link ObjectId}. * Includes peeled {@linkObjectId}s. This is the inverse lookup of * {@link #exactRef(String...)}. * * <p> * The default implementation uses a linear scan. Implementors of * {@link RefDatabase} should override this method directly if a better * implementation is possible. * * @param id * {@link ObjectId} to resolve * @return a {@link Set} of {@link Ref}s whose tips point to the provided * id. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.4 */ @NonNull public Set<Ref> getTipsWithSha1(ObjectId id) throws IOException { return getRefs().stream().filter(r -> id.equals(r.getObjectId()) || id.equals(r.getPeeledObjectId())) .collect(toSet()); } /** * If the ref database does not support fast inverse queries, it may * be advantageous to build a complete SHA1 to ref map in advance for * multiple uses. To let applications decide on this decision, * this function indicates whether the inverse map is available. * * @return whether this RefDatabase supports fast inverse ref queries. * @throws IOException on I/O problems. * @since 5.6 */ public boolean hasFastTipsWithSha1() throws IOException { return false; } /** * Check if any refs exist in the ref database. * <p> * This uses the same definition of refs as {@link #getRefs()}. In * particular, returns {@code false} in a new repository with no refs * under {@code refs/} and {@code HEAD} pointing to a branch yet to be * born, and returns {@code true} in a repository with no refs under * {@code refs/} and a detached {@code HEAD} pointing to history. * * @return true if the database has refs. * @throws java.io.IOException * the reference space cannot be accessed. * @since 5.0 */ public boolean hasRefs() throws IOException { return !getRefs().isEmpty(); } /** * Get the additional reference-like entities from the repository. * <p> * The result list includes non-ref items such as MERGE_HEAD and * FETCH_RESULT cast to be refs. The names of these refs are not returned by * <code>getRefs()</code> but are accepted by {@link #findRef(String)} * and {@link #exactRef(String)}. * * @return a list of additional refs * @throws java.io.IOException * the reference space cannot be accessed. */ @NonNull public abstract List<Ref> getAdditionalRefs() throws IOException; /** * Peel a possibly unpeeled reference by traversing the annotated tags. * <p> * If the reference cannot be peeled (as it does not refer to an annotated * tag) the peeled id stays null, but * {@link org.eclipse.jgit.lib.Ref#isPeeled()} will be true. * <p> * Implementors should check {@link org.eclipse.jgit.lib.Ref#isPeeled()} * before performing any additional work effort. * * @param ref * The reference to peel * @return {@code ref} if {@code ref.isPeeled()} is true; otherwise a new * Ref object representing the same data as Ref, but isPeeled() will * be true and getPeeledObjectId() will contain the peeled object * (or {@code null}). * @throws java.io.IOException * the reference space or object space cannot be accessed. */ @NonNull public abstract Ref peel(Ref ref) throws IOException; /** * Triggers a refresh of all internal data structures. * <p> * In case the RefDatabase implementation has internal caches this method * will trigger that all these caches are cleared. * <p> * Implementors should overwrite this method if they use any kind of caches. */ public void refresh() { // nothing } /** * Try to find the specified name in the ref map using {@link #SEARCH_PATH}. * * @param map * map of refs to search within. Names should be fully qualified, * e.g. "refs/heads/master". * @param name * short name of ref to find, e.g. "master" to find * "refs/heads/master" in map. * @return The first ref matching the name, or {@code null} if not found. * @since 3.4 */ @Nullable public static Ref findRef(Map<String, Ref> map, String name) { for (String prefix : SEARCH_PATH) { String fullname = prefix + name; Ref ref = map.get(fullname); if (ref != null) return ref; } return null; } }