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- /*
- * Copyright (C) 2008-2010, Google Inc.
- * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
- * 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 java.io.IOException;
- import java.text.MessageFormat;
-
- import org.eclipse.jgit.errors.MissingObjectException;
- import org.eclipse.jgit.internal.JGitText;
- import org.eclipse.jgit.revwalk.RevCommit;
- import org.eclipse.jgit.revwalk.RevObject;
- import org.eclipse.jgit.revwalk.RevWalk;
-
- /**
- * Creates, updates or deletes any reference.
- */
- public abstract class RefUpdate {
- /** Status of an update request. */
- public static enum Result {
- /** The ref update/delete has not been attempted by the caller. */
- NOT_ATTEMPTED,
-
- /**
- * The ref could not be locked for update/delete.
- * <p>
- * This is generally a transient failure and is usually caused by
- * another process trying to access the ref at the same time as this
- * process was trying to update it. It is possible a future operation
- * will be successful.
- */
- LOCK_FAILURE,
-
- /**
- * Same value already stored.
- * <p>
- * Both the old value and the new value are identical. No change was
- * necessary for an update. For delete the branch is removed.
- */
- NO_CHANGE,
-
- /**
- * The ref was created locally for an update, but ignored for delete.
- * <p>
- * The ref did not exist when the update started, but it was created
- * successfully with the new value.
- */
- NEW,
-
- /**
- * The ref had to be forcefully updated/deleted.
- * <p>
- * The ref already existed but its old value was not fully merged into
- * the new value. The configuration permitted a forced update to take
- * place, so ref now contains the new value. History associated with the
- * objects not merged may no longer be reachable.
- */
- FORCED,
-
- /**
- * The ref was updated/deleted in a fast-forward way.
- * <p>
- * The tracking ref already existed and its old value was fully merged
- * into the new value. No history was made unreachable.
- */
- FAST_FORWARD,
-
- /**
- * Not a fast-forward and not stored.
- * <p>
- * The tracking ref already existed but its old value was not fully
- * merged into the new value. The configuration did not allow a forced
- * update/delete to take place, so ref still contains the old value. No
- * previous history was lost.
- */
- REJECTED,
-
- /**
- * Rejected because trying to delete the current branch.
- * <p>
- * Has no meaning for update.
- */
- REJECTED_CURRENT_BRANCH,
-
- /**
- * The ref was probably not updated/deleted because of I/O error.
- * <p>
- * Unexpected I/O error occurred when writing new ref. Such error may
- * result in uncertain state, but most probably ref was not updated.
- * <p>
- * This kind of error doesn't include {@link #LOCK_FAILURE}, which is a
- * different case.
- */
- IO_FAILURE,
-
- /**
- * The ref was renamed from another name
- * <p>
- */
- RENAMED
- }
-
- /** New value the caller wants this ref to have. */
- private ObjectId newValue;
-
- /** Does this specification ask for forced updated (rewind/reset)? */
- private boolean force;
-
- /** Identity to record action as within the reflog. */
- private PersonIdent refLogIdent;
-
- /** Message the caller wants included in the reflog. */
- private String refLogMessage;
-
- /** Should the Result value be appended to {@link #refLogMessage}. */
- private boolean refLogIncludeResult;
-
- /** Old value of the ref, obtained after we lock it. */
- private ObjectId oldValue;
-
- /** If non-null, the value {@link #oldValue} must have to continue. */
- private ObjectId expValue;
-
- /** Result of the update operation. */
- private Result result = Result.NOT_ATTEMPTED;
-
- private final Ref ref;
-
- /**
- * Is this RefUpdate detaching a symbolic ref?
- *
- * We need this info since this.ref will normally be peeled of in case of
- * detaching a symbolic ref (HEAD for example).
- *
- * Without this flag we cannot decide whether the ref has to be updated or
- * not in case when it was a symbolic ref and the newValue == oldValue.
- */
- private boolean detachingSymbolicRef;
-
- private boolean checkConflicting = true;
-
- /**
- * Construct a new update operation for the reference.
- * <p>
- * {@code ref.getObjectId()} will be used to seed {@link #getOldObjectId()},
- * which callers can use as part of their own update logic.
- *
- * @param ref
- * the reference that will be updated by this operation.
- */
- protected RefUpdate(final Ref ref) {
- this.ref = ref;
- oldValue = ref.getObjectId();
- refLogMessage = ""; //$NON-NLS-1$
- }
-
- /** @return the reference database this update modifies. */
- protected abstract RefDatabase getRefDatabase();
-
- /** @return the repository storing the database's objects. */
- protected abstract Repository getRepository();
-
- /**
- * Try to acquire the lock on the reference.
- * <p>
- * If the locking was successful the implementor must set the current
- * identity value by calling {@link #setOldObjectId(ObjectId)}.
- *
- * @param deref
- * true if the lock should be taken against the leaf level
- * reference; false if it should be taken exactly against the
- * current reference.
- * @return true if the lock was acquired and the reference is likely
- * protected from concurrent modification; false if it failed.
- * @throws IOException
- * the lock couldn't be taken due to an unexpected storage
- * failure, and not because of a concurrent update.
- */
- protected abstract boolean tryLock(boolean deref) throws IOException;
-
- /** Releases the lock taken by {@link #tryLock} if it succeeded. */
- protected abstract void unlock();
-
- /**
- * @param desiredResult
- * @return {@code result}
- * @throws IOException
- */
- protected abstract Result doUpdate(Result desiredResult) throws IOException;
-
- /**
- * @param desiredResult
- * @return {@code result}
- * @throws IOException
- */
- protected abstract Result doDelete(Result desiredResult) throws IOException;
-
- /**
- * @param target
- * @return {@link Result#NEW} on success.
- * @throws IOException
- */
- protected abstract Result doLink(String target) throws IOException;
-
- /**
- * Get the name of the ref this update will operate on.
- *
- * @return name of underlying ref.
- */
- public String getName() {
- return getRef().getName();
- }
-
- /** @return the reference this update will create or modify. */
- public Ref getRef() {
- return ref;
- }
-
- /**
- * Get the new value the ref will be (or was) updated to.
- *
- * @return new value. Null if the caller has not configured it.
- */
- public ObjectId getNewObjectId() {
- return newValue;
- }
-
- /**
- * Tells this RefUpdate that it is actually detaching a symbolic ref.
- */
- public void setDetachingSymbolicRef() {
- detachingSymbolicRef = true;
- }
-
- /**
- * Set the new value the ref will update to.
- *
- * @param id
- * the new value.
- */
- public void setNewObjectId(final AnyObjectId id) {
- newValue = id.copy();
- }
-
- /**
- * @return the expected value of the ref after the lock is taken, but before
- * update occurs. Null to avoid the compare and swap test. Use
- * {@link ObjectId#zeroId()} to indicate expectation of a
- * non-existant ref.
- */
- public ObjectId getExpectedOldObjectId() {
- return expValue;
- }
-
- /**
- * @param id
- * the expected value of the ref after the lock is taken, but
- * before update occurs. Null to avoid the compare and swap test.
- * Use {@link ObjectId#zeroId()} to indicate expectation of a
- * non-existant ref.
- */
- public void setExpectedOldObjectId(final AnyObjectId id) {
- expValue = id != null ? id.toObjectId() : null;
- }
-
- /**
- * Check if this update wants to forcefully change the ref.
- *
- * @return true if this update should ignore merge tests.
- */
- public boolean isForceUpdate() {
- return force;
- }
-
- /**
- * Set if this update wants to forcefully change the ref.
- *
- * @param b
- * true if this update should ignore merge tests.
- */
- public void setForceUpdate(final boolean b) {
- force = b;
- }
-
- /** @return identity of the user making the change in the reflog. */
- public PersonIdent getRefLogIdent() {
- return refLogIdent;
- }
-
- /**
- * Set the identity of the user appearing in the reflog.
- * <p>
- * The timestamp portion of the identity is ignored. A new identity with the
- * current timestamp will be created automatically when the update occurs
- * and the log record is written.
- *
- * @param pi
- * identity of the user. If null the identity will be
- * automatically determined based on the repository
- * configuration.
- */
- public void setRefLogIdent(final PersonIdent pi) {
- refLogIdent = pi;
- }
-
- /**
- * Get the message to include in the reflog.
- *
- * @return message the caller wants to include in the reflog; null if the
- * update should not be logged.
- */
- public String getRefLogMessage() {
- return refLogMessage;
- }
-
- /** @return {@code true} if the ref log message should show the result. */
- protected boolean isRefLogIncludingResult() {
- return refLogIncludeResult;
- }
-
- /**
- * Set the message to include in the reflog.
- *
- * @param msg
- * the message to describe this change. It may be null if
- * appendStatus is null in order not to append to the reflog
- * @param appendStatus
- * true if the status of the ref change (fast-forward or
- * forced-update) should be appended to the user supplied
- * message.
- */
- public void setRefLogMessage(final String msg, final boolean appendStatus) {
- if (msg == null && !appendStatus)
- disableRefLog();
- else if (msg == null && appendStatus) {
- refLogMessage = ""; //$NON-NLS-1$
- refLogIncludeResult = true;
- } else {
- refLogMessage = msg;
- refLogIncludeResult = appendStatus;
- }
- }
-
- /** Don't record this update in the ref's associated reflog. */
- public void disableRefLog() {
- refLogMessage = null;
- refLogIncludeResult = false;
- }
-
- /**
- * The old value of the ref, prior to the update being attempted.
- * <p>
- * This value may differ before and after the update method. Initially it is
- * populated with the value of the ref before the lock is taken, but the old
- * value may change if someone else modified the ref between the time we
- * last read it and when the ref was locked for update.
- *
- * @return the value of the ref prior to the update being attempted; null if
- * the updated has not been attempted yet.
- */
- public ObjectId getOldObjectId() {
- return oldValue;
- }
-
- /**
- * Set the old value of the ref.
- *
- * @param old
- * the old value.
- */
- protected void setOldObjectId(ObjectId old) {
- oldValue = old;
- }
-
- /**
- * Get the status of this update.
- * <p>
- * The same value that was previously returned from an update method.
- *
- * @return the status of the update.
- */
- public Result getResult() {
- return result;
- }
-
- private void requireCanDoUpdate() {
- if (newValue == null)
- throw new IllegalStateException(JGitText.get().aNewObjectIdIsRequired);
- }
-
- /**
- * Force the ref to take the new value.
- * <p>
- * This is just a convenient helper for setting the force flag, and as such
- * the merge test is performed.
- *
- * @return the result status of the update.
- * @throws IOException
- * an unexpected IO error occurred while writing changes.
- */
- public Result forceUpdate() throws IOException {
- force = true;
- return update();
- }
-
- /**
- * Gracefully update the ref to the new value.
- * <p>
- * Merge test will be performed according to {@link #isForceUpdate()}.
- * <p>
- * This is the same as:
- *
- * <pre>
- * return update(new RevWalk(getRepository()));
- * </pre>
- *
- * @return the result status of the update.
- * @throws IOException
- * an unexpected IO error occurred while writing changes.
- */
- public Result update() throws IOException {
- RevWalk rw = new RevWalk(getRepository());
- try {
- return update(rw);
- } finally {
- rw.release();
- }
- }
-
- /**
- * Gracefully update the ref to the new value.
- * <p>
- * Merge test will be performed according to {@link #isForceUpdate()}.
- *
- * @param walk
- * a RevWalk instance this update command can borrow to perform
- * the merge test. The walk will be reset to perform the test.
- * @return the result status of the update.
- * @throws IOException
- * an unexpected IO error occurred while writing changes.
- */
- public Result update(final RevWalk walk) throws IOException {
- requireCanDoUpdate();
- try {
- return result = updateImpl(walk, new Store() {
- @Override
- Result execute(Result status) throws IOException {
- if (status == Result.NO_CHANGE)
- return status;
- return doUpdate(status);
- }
- });
- } catch (IOException x) {
- result = Result.IO_FAILURE;
- throw x;
- }
- }
-
- /**
- * Delete the ref.
- * <p>
- * This is the same as:
- *
- * <pre>
- * return delete(new RevWalk(getRepository()));
- * </pre>
- *
- * @return the result status of the delete.
- * @throws IOException
- */
- public Result delete() throws IOException {
- RevWalk rw = new RevWalk(getRepository());
- try {
- return delete(rw);
- } finally {
- rw.release();
- }
- }
-
- /**
- * Delete the ref.
- *
- * @param walk
- * a RevWalk instance this delete command can borrow to perform
- * the merge test. The walk will be reset to perform the test.
- * @return the result status of the delete.
- * @throws IOException
- */
- public Result delete(final RevWalk walk) throws IOException {
- final String myName = getRef().getLeaf().getName();
- if (myName.startsWith(Constants.R_HEADS)) {
- Ref head = getRefDatabase().getRef(Constants.HEAD);
- while (head.isSymbolic()) {
- head = head.getTarget();
- if (myName.equals(head.getName()))
- return result = Result.REJECTED_CURRENT_BRANCH;
- }
- }
-
- try {
- return result = updateImpl(walk, new Store() {
- @Override
- Result execute(Result status) throws IOException {
- return doDelete(status);
- }
- });
- } catch (IOException x) {
- result = Result.IO_FAILURE;
- throw x;
- }
- }
-
- /**
- * Replace this reference with a symbolic reference to another reference.
- * <p>
- * This exact reference (not its traversed leaf) is replaced with a symbolic
- * reference to the requested name.
- *
- * @param target
- * name of the new target for this reference. The new target name
- * must be absolute, so it must begin with {@code refs/}.
- * @return {@link Result#NEW} or {@link Result#FORCED} on success.
- * @throws IOException
- */
- public Result link(String target) throws IOException {
- if (!target.startsWith(Constants.R_REFS))
- throw new IllegalArgumentException(MessageFormat.format(JGitText.get().illegalArgumentNotA, Constants.R_REFS));
- if (checkConflicting && getRefDatabase().isNameConflicting(getName()))
- return Result.LOCK_FAILURE;
- try {
- if (!tryLock(false))
- return Result.LOCK_FAILURE;
-
- final Ref old = getRefDatabase().getRef(getName());
- if (old != null && old.isSymbolic()) {
- final Ref dst = old.getTarget();
- if (target.equals(dst.getName()))
- return result = Result.NO_CHANGE;
- }
-
- if (old != null && old.getObjectId() != null)
- setOldObjectId(old.getObjectId());
-
- final Ref dst = getRefDatabase().getRef(target);
- if (dst != null && dst.getObjectId() != null)
- setNewObjectId(dst.getObjectId());
-
- return result = doLink(target);
- } catch (IOException x) {
- result = Result.IO_FAILURE;
- throw x;
- } finally {
- unlock();
- }
- }
-
- private Result updateImpl(final RevWalk walk, final Store store)
- throws IOException {
- RevObject newObj;
- RevObject oldObj;
-
- // don't make expensive conflict check if this is an existing Ref
- if (oldValue == null && checkConflicting && getRefDatabase().isNameConflicting(getName()))
- return Result.LOCK_FAILURE;
- try {
- if (!tryLock(true))
- return Result.LOCK_FAILURE;
- if (expValue != null) {
- final ObjectId o;
- o = oldValue != null ? oldValue : ObjectId.zeroId();
- if (!AnyObjectId.equals(expValue, o))
- return Result.LOCK_FAILURE;
- }
- if (oldValue == null)
- return store.execute(Result.NEW);
-
- newObj = safeParse(walk, newValue);
- oldObj = safeParse(walk, oldValue);
- if (newObj == oldObj && !detachingSymbolicRef)
- return store.execute(Result.NO_CHANGE);
-
- if (newObj instanceof RevCommit && oldObj instanceof RevCommit) {
- if (walk.isMergedInto((RevCommit) oldObj, (RevCommit) newObj))
- return store.execute(Result.FAST_FORWARD);
- }
-
- if (isForceUpdate())
- return store.execute(Result.FORCED);
- return Result.REJECTED;
- } finally {
- unlock();
- }
- }
-
- /**
- * Enable/disable the check for conflicting ref names. By default conflicts
- * are checked explicitly.
- *
- * @param check
- */
- public void setCheckConflicting(boolean check) {
- checkConflicting = check;
- }
-
- private static RevObject safeParse(final RevWalk rw, final AnyObjectId id)
- throws IOException {
- try {
- return id != null ? rw.parseAny(id) : null;
- } catch (MissingObjectException e) {
- // We can expect some objects to be missing, like if we are
- // trying to force a deletion of a branch and the object it
- // points to has been pruned from the database due to freak
- // corruption accidents (it happens with 'git new-work-dir').
- //
- return null;
- }
- }
-
- /**
- * Handle the abstraction of storing a ref update. This is because both
- * updating and deleting of a ref have merge testing in common.
- */
- private abstract class Store {
- abstract Result execute(Result status) throws IOException;
- }
- }
|