| /* |
| * Copyright (C) 2016, 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.internal.ketch; |
| |
| import static org.eclipse.jgit.internal.ketch.KetchReplica.State.AHEAD; |
| import static org.eclipse.jgit.internal.ketch.KetchReplica.State.DIVERGENT; |
| import static org.eclipse.jgit.internal.ketch.KetchReplica.State.LAGGING; |
| import static org.eclipse.jgit.internal.ketch.KetchReplica.State.UNKNOWN; |
| import static org.eclipse.jgit.lib.Constants.OBJ_COMMIT; |
| |
| import java.io.IOException; |
| import java.util.Collections; |
| import java.util.Map; |
| |
| import org.eclipse.jgit.errors.MissingObjectException; |
| import org.eclipse.jgit.lib.AnyObjectId; |
| import org.eclipse.jgit.lib.ObjectId; |
| import org.eclipse.jgit.lib.Ref; |
| import org.eclipse.jgit.lib.Repository; |
| import org.eclipse.jgit.revwalk.RevCommit; |
| import org.eclipse.jgit.revwalk.RevWalk; |
| import org.eclipse.jgit.transport.ReceiveCommand; |
| |
| /** |
| * A helper to check if a {@link KetchReplica} is ahead or behind the leader. |
| */ |
| class LagCheck implements AutoCloseable { |
| private final KetchReplica replica; |
| private final Repository repo; |
| private RevWalk rw; |
| private ObjectId remoteId; |
| |
| LagCheck(KetchReplica replica, Repository repo) { |
| this.replica = replica; |
| this.repo = repo; |
| initRevWalk(); |
| } |
| |
| private void initRevWalk() { |
| if (rw != null) { |
| rw.close(); |
| } |
| |
| rw = new RevWalk(repo); |
| rw.setRetainBody(false); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public void close() { |
| if (rw != null) { |
| rw.close(); |
| rw = null; |
| } |
| } |
| |
| ObjectId getRemoteId() { |
| return remoteId; |
| } |
| |
| KetchReplica.State check(ObjectId acceptId, ReceiveCommand acceptCmd) { |
| remoteId = acceptId; |
| if (remoteId == null) { |
| // Nothing advertised by the replica, value is unknown. |
| return UNKNOWN; |
| } |
| |
| if (AnyObjectId.isEqual(remoteId, ObjectId.zeroId())) { |
| // Replica does not have the txnAccepted reference. |
| return LAGGING; |
| } |
| |
| try { |
| RevCommit remote; |
| try { |
| remote = parseRemoteCommit(acceptCmd.getRefName()); |
| } catch (RefGoneException gone) { |
| // Replica does not have the txnAccepted reference. |
| return LAGGING; |
| } catch (MissingObjectException notFound) { |
| // Local repository does not know this commit so it cannot |
| // be including the replica's log. |
| return DIVERGENT; |
| } |
| |
| RevCommit head = rw.parseCommit(acceptCmd.getNewId()); |
| if (rw.isMergedInto(remote, head)) { |
| return LAGGING; |
| } |
| |
| // TODO(sop) Check term to see if my leader was deposed. |
| if (rw.isMergedInto(head, remote)) { |
| return AHEAD; |
| } |
| return DIVERGENT; |
| } catch (IOException err) { |
| KetchReplica.log.error(String.format( |
| "Cannot compare %s", //$NON-NLS-1$ |
| acceptCmd.getRefName()), err); |
| return UNKNOWN; |
| } |
| } |
| |
| private RevCommit parseRemoteCommit(String refName) |
| throws IOException, MissingObjectException, RefGoneException { |
| try { |
| return rw.parseCommit(remoteId); |
| } catch (MissingObjectException notLocal) { |
| // Fall through and try to acquire the object by fetching it. |
| } |
| |
| ReplicaFetchRequest fetch = new ReplicaFetchRequest( |
| Collections.singleton(refName), |
| Collections.<ObjectId> emptySet()); |
| try { |
| replica.blockingFetch(repo, fetch); |
| } catch (IOException fetchErr) { |
| KetchReplica.log.error(String.format( |
| "Cannot fetch %s (%s) from %s", //$NON-NLS-1$ |
| remoteId.abbreviate(8).name(), refName, |
| replica.describeForLog()), fetchErr); |
| throw new MissingObjectException(remoteId, OBJ_COMMIT); |
| } |
| |
| Map<String, Ref> adv = fetch.getRefs(); |
| if (adv == null) { |
| throw new MissingObjectException(remoteId, OBJ_COMMIT); |
| } |
| |
| Ref ref = adv.get(refName); |
| if (ref == null || ref.getObjectId() == null) { |
| throw new RefGoneException(); |
| } |
| |
| initRevWalk(); |
| remoteId = ref.getObjectId(); |
| return rw.parseCommit(remoteId); |
| } |
| |
| private static class RefGoneException extends Exception { |
| private static final long serialVersionUID = 1L; |
| } |
| } |