Java tutorial
// Copyright (C) 2012 The Android Open Source Project // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.google.gerrit.server.git; import static com.google.common.base.Preconditions.checkArgument; import com.google.common.base.Function; import com.google.common.base.Joiner; import com.google.common.base.Strings; import com.google.common.collect.Iterables; import com.google.gerrit.common.FooterConstants; import com.google.gerrit.common.Nullable; import com.google.gerrit.common.data.LabelType; import com.google.gerrit.reviewdb.client.Account; import com.google.gerrit.reviewdb.client.Branch; import com.google.gerrit.reviewdb.client.Change; import com.google.gerrit.reviewdb.client.LabelId; import com.google.gerrit.reviewdb.client.PatchSet; import com.google.gerrit.reviewdb.client.PatchSetApproval; import com.google.gerrit.reviewdb.server.ReviewDb; import com.google.gerrit.server.ApprovalsUtil; import com.google.gerrit.server.IdentifiedUser; import com.google.gerrit.server.config.CanonicalWebUrl; import com.google.gerrit.server.config.GerritServerConfig; import com.google.gerrit.server.git.CodeReviewCommit.CodeReviewRevWalk; import com.google.gerrit.server.project.ChangeControl; import com.google.gerrit.server.project.ProjectState; import com.google.gwtorm.server.OrmException; import com.google.inject.Provider; import com.google.inject.assistedinject.Assisted; import com.google.inject.assistedinject.AssistedInject; import org.eclipse.jgit.errors.IncorrectObjectTypeException; import org.eclipse.jgit.errors.LargeObjectException; import org.eclipse.jgit.errors.MissingObjectException; import org.eclipse.jgit.errors.NoMergeBaseException; import org.eclipse.jgit.errors.NoMergeBaseException.MergeBaseFailureReason; import org.eclipse.jgit.lib.AnyObjectId; import org.eclipse.jgit.lib.CommitBuilder; import org.eclipse.jgit.lib.Config; import org.eclipse.jgit.lib.Constants; import org.eclipse.jgit.lib.ObjectId; import org.eclipse.jgit.lib.ObjectInserter; import org.eclipse.jgit.lib.PersonIdent; import org.eclipse.jgit.lib.Repository; import org.eclipse.jgit.merge.MergeStrategy; import org.eclipse.jgit.merge.Merger; import org.eclipse.jgit.merge.ThreeWayMergeStrategy; import org.eclipse.jgit.merge.ThreeWayMerger; import org.eclipse.jgit.revwalk.FooterKey; import org.eclipse.jgit.revwalk.FooterLine; import org.eclipse.jgit.revwalk.RevCommit; import org.eclipse.jgit.revwalk.RevFlag; import org.eclipse.jgit.revwalk.RevSort; import org.eclipse.jgit.revwalk.RevWalk; import org.eclipse.jgit.transport.PackParser; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Iterator; import java.util.LinkedHashSet; import java.util.List; import java.util.Set; public class MergeUtil { private static final Logger log = LoggerFactory.getLogger(MergeUtil.class); private static final String R_HEADS_MASTER = Constants.R_HEADS + Constants.MASTER; public static boolean useRecursiveMerge(Config cfg) { return cfg.getBoolean("core", null, "useRecursiveMerge", true); } public static ThreeWayMergeStrategy getMergeStrategy(Config cfg) { return useRecursiveMerge(cfg) ? MergeStrategy.RECURSIVE : MergeStrategy.RESOLVE; } public static interface Factory { MergeUtil create(ProjectState project); MergeUtil create(ProjectState project, boolean useContentMerge); } private final Provider<ReviewDb> db; private final IdentifiedUser.GenericFactory identifiedUserFactory; private final Provider<String> urlProvider; private final ApprovalsUtil approvalsUtil; private final ProjectState project; private final boolean useContentMerge; private final boolean useRecursiveMerge; @AssistedInject MergeUtil(@GerritServerConfig Config serverConfig, final Provider<ReviewDb> db, final IdentifiedUser.GenericFactory identifiedUserFactory, @CanonicalWebUrl @Nullable final Provider<String> urlProvider, final ApprovalsUtil approvalsUtil, @Assisted final ProjectState project) { this(serverConfig, db, identifiedUserFactory, urlProvider, approvalsUtil, project, project.isUseContentMerge()); } @AssistedInject MergeUtil(@GerritServerConfig Config serverConfig, final Provider<ReviewDb> db, final IdentifiedUser.GenericFactory identifiedUserFactory, @CanonicalWebUrl @Nullable final Provider<String> urlProvider, final ApprovalsUtil approvalsUtil, @Assisted final ProjectState project, @Assisted boolean useContentMerge) { this.db = db; this.identifiedUserFactory = identifiedUserFactory; this.urlProvider = urlProvider; this.approvalsUtil = approvalsUtil; this.project = project; this.useContentMerge = useContentMerge; this.useRecursiveMerge = useRecursiveMerge(serverConfig); } public CodeReviewCommit getFirstFastForward(final CodeReviewCommit mergeTip, final RevWalk rw, final List<CodeReviewCommit> toMerge) throws MergeException { for (final Iterator<CodeReviewCommit> i = toMerge.iterator(); i.hasNext();) { try { final CodeReviewCommit n = i.next(); if (mergeTip == null || rw.isMergedInto(mergeTip, n)) { i.remove(); return n; } } catch (IOException e) { throw new MergeException("Cannot fast-forward test during merge", e); } } return mergeTip; } public List<CodeReviewCommit> reduceToMinimalMerge(MergeSorter mergeSorter, Collection<CodeReviewCommit> toSort) throws MergeException { List<CodeReviewCommit> result = new ArrayList<>(); try { result.addAll(mergeSorter.sort(toSort)); } catch (IOException e) { throw new MergeException("Branch head sorting failed", e); } Collections.sort(result, CodeReviewCommit.ORDER); return result; } public CodeReviewCommit createCherryPickFromCommit(Repository repo, ObjectInserter inserter, RevCommit mergeTip, RevCommit originalCommit, PersonIdent cherryPickCommitterIdent, String commitMsg, CodeReviewRevWalk rw) throws MissingObjectException, IncorrectObjectTypeException, IOException, MergeIdenticalTreeException, MergeConflictException { final ThreeWayMerger m = newThreeWayMerger(repo, inserter); m.setBase(originalCommit.getParent(0)); if (m.merge(mergeTip, originalCommit)) { ObjectId tree = m.getResultTreeId(); if (tree.equals(mergeTip.getTree())) { throw new MergeIdenticalTreeException("identical tree"); } CommitBuilder mergeCommit = new CommitBuilder(); mergeCommit.setTreeId(tree); mergeCommit.setParentId(mergeTip); mergeCommit.setAuthor(originalCommit.getAuthorIdent()); mergeCommit.setCommitter(cherryPickCommitterIdent); mergeCommit.setMessage(commitMsg); return rw.parseCommit(commit(inserter, mergeCommit)); } else { throw new MergeConflictException("merge conflict"); } } public String createCherryPickCommitMessage(RevCommit n, ChangeControl ctl, PatchSet.Id psId) { Change c = ctl.getChange(); final List<FooterLine> footers = n.getFooterLines(); final StringBuilder msgbuf = new StringBuilder(); msgbuf.append(n.getFullMessage()); if (msgbuf.length() == 0) { // WTF, an empty commit message? msgbuf.append("<no commit message provided>"); } if (msgbuf.charAt(msgbuf.length() - 1) != '\n') { // Missing a trailing LF? Correct it (perhaps the editor was broken). msgbuf.append('\n'); } if (footers.isEmpty()) { // Doesn't end in a "Signed-off-by: ..." style line? Add another line // break to start a new paragraph for the reviewed-by tag lines. // msgbuf.append('\n'); } if (!contains(footers, FooterConstants.CHANGE_ID, c.getKey().get())) { msgbuf.append(FooterConstants.CHANGE_ID.getName()); msgbuf.append(": "); msgbuf.append(c.getKey().get()); msgbuf.append('\n'); } final String siteUrl = urlProvider.get(); if (siteUrl != null) { final String url = siteUrl + c.getId().get(); if (!contains(footers, FooterConstants.REVIEWED_ON, url)) { msgbuf.append(FooterConstants.REVIEWED_ON.getName()); msgbuf.append(": "); msgbuf.append(url); msgbuf.append('\n'); } } PatchSetApproval submitAudit = null; for (final PatchSetApproval a : safeGetApprovals(ctl, psId)) { if (a.getValue() <= 0) { // Negative votes aren't counted. continue; } if (a.isSubmit()) { // Submit is treated specially, below (becomes committer) // if (submitAudit == null || a.getGranted().compareTo(submitAudit.getGranted()) > 0) { submitAudit = a; } continue; } final Account acc = identifiedUserFactory.create(a.getAccountId()).getAccount(); final StringBuilder identbuf = new StringBuilder(); if (acc.getFullName() != null && acc.getFullName().length() > 0) { if (identbuf.length() > 0) { identbuf.append(' '); } identbuf.append(acc.getFullName()); } if (acc.getPreferredEmail() != null && acc.getPreferredEmail().length() > 0) { if (isSignedOffBy(footers, acc.getPreferredEmail())) { continue; } if (identbuf.length() > 0) { identbuf.append(' '); } identbuf.append('<'); identbuf.append(acc.getPreferredEmail()); identbuf.append('>'); } if (identbuf.length() == 0) { // Nothing reasonable to describe them by? Ignore them. continue; } final String tag; if (isCodeReview(a.getLabelId())) { tag = "Reviewed-by"; } else if (isVerified(a.getLabelId())) { tag = "Tested-by"; } else { final LabelType lt = project.getLabelTypes().byLabel(a.getLabelId()); if (lt == null) { continue; } tag = lt.getName(); } if (!contains(footers, new FooterKey(tag), identbuf.toString())) { msgbuf.append(tag); msgbuf.append(": "); msgbuf.append(identbuf); msgbuf.append('\n'); } } return msgbuf.toString(); } public String createCherryPickCommitMessage(final CodeReviewCommit n) { return createCherryPickCommitMessage(n, n.getControl(), n.getPatchsetId()); } private static boolean isCodeReview(LabelId id) { return "Code-Review".equalsIgnoreCase(id.get()); } private static boolean isVerified(LabelId id) { return "Verified".equalsIgnoreCase(id.get()); } private Iterable<PatchSetApproval> safeGetApprovals(ChangeControl ctl, PatchSet.Id psId) { try { return approvalsUtil.byPatchSet(db.get(), ctl, psId); } catch (OrmException e) { log.error("Can't read approval records for " + psId, e); return Collections.emptyList(); } } private static boolean contains(List<FooterLine> footers, FooterKey key, String val) { for (final FooterLine line : footers) { if (line.matches(key) && val.equals(line.getValue())) { return true; } } return false; } private static boolean isSignedOffBy(List<FooterLine> footers, String email) { for (final FooterLine line : footers) { if (line.matches(FooterKey.SIGNED_OFF_BY) && email.equals(line.getEmailAddress())) { return true; } } return false; } public boolean canMerge(final MergeSorter mergeSorter, final Repository repo, final CodeReviewCommit mergeTip, final CodeReviewCommit toMerge) throws MergeException { if (hasMissingDependencies(mergeSorter, toMerge)) { return false; } ThreeWayMerger m = newThreeWayMerger(repo, createDryRunInserter(repo)); try { return m.merge(new AnyObjectId[] { mergeTip, toMerge }); } catch (LargeObjectException e) { log.warn("Cannot merge due to LargeObjectException: " + toMerge.name()); return false; } catch (NoMergeBaseException e) { return false; } catch (IOException e) { throw new MergeException("Cannot merge " + toMerge.name(), e); } } public boolean canFastForward(MergeSorter mergeSorter, CodeReviewCommit mergeTip, CodeReviewRevWalk rw, CodeReviewCommit toMerge) throws MergeException { if (hasMissingDependencies(mergeSorter, toMerge)) { return false; } try { return mergeTip == null || rw.isMergedInto(mergeTip, toMerge); } catch (IOException e) { throw new MergeException("Cannot fast-forward test during merge", e); } } public boolean canCherryPick(MergeSorter mergeSorter, Repository repo, CodeReviewCommit mergeTip, CodeReviewRevWalk rw, CodeReviewCommit toMerge) throws MergeException { if (mergeTip == null) { // The branch is unborn. Fast-forward is possible. // return true; } if (toMerge.getParentCount() == 0) { // Refuse to merge a root commit into an existing branch, // we cannot obtain a delta for the cherry-pick to apply. // return false; } if (toMerge.getParentCount() == 1) { // If there is only one parent, a cherry-pick can be done by // taking the delta relative to that one parent and redoing // that on the current merge tip. // try { ThreeWayMerger m = newThreeWayMerger(repo, createDryRunInserter(repo)); m.setBase(toMerge.getParent(0)); return m.merge(mergeTip, toMerge); } catch (IOException e) { throw new MergeException("Cannot merge " + toMerge.name(), e); } } // There are multiple parents, so this is a merge commit. We // don't want to cherry-pick the merge as clients can't easily // rebase their history with that merge present and replaced // by an equivalent merge with a different first parent. So // instead behave as though MERGE_IF_NECESSARY was configured. // return canFastForward(mergeSorter, mergeTip, rw, toMerge) || canMerge(mergeSorter, repo, mergeTip, toMerge); } public boolean hasMissingDependencies(final MergeSorter mergeSorter, final CodeReviewCommit toMerge) throws MergeException { try { return !mergeSorter.sort(Collections.singleton(toMerge)).contains(toMerge); } catch (IOException e) { throw new MergeException("Branch head sorting failed", e); } } public static ObjectInserter createDryRunInserter(Repository db) { final ObjectInserter delegate = db.newObjectInserter(); return new ObjectInserter.Filter() { @Override protected ObjectInserter delegate() { return delegate; } @Override public PackParser newPackParser(InputStream in) throws IOException { throw new UnsupportedOperationException(); } @Override public void flush() throws IOException { // Do nothing. } }; } public CodeReviewCommit mergeOneCommit(PersonIdent author, PersonIdent committer, Repository repo, CodeReviewRevWalk rw, ObjectInserter inserter, RevFlag canMergeFlag, Branch.NameKey destBranch, CodeReviewCommit mergeTip, CodeReviewCommit n) throws MergeException { final ThreeWayMerger m = newThreeWayMerger(repo, inserter); try { if (m.merge(new AnyObjectId[] { mergeTip, n })) { return writeMergeCommit(author, committer, rw, inserter, canMergeFlag, destBranch, mergeTip, m.getResultTreeId(), n); } else { failed(rw, canMergeFlag, mergeTip, n, CommitMergeStatus.PATH_CONFLICT); } } catch (NoMergeBaseException e) { try { failed(rw, canMergeFlag, mergeTip, n, getCommitMergeStatus(e.getReason())); } catch (IOException e2) { throw new MergeException("Cannot merge " + n.name(), e); } } catch (IOException e) { throw new MergeException("Cannot merge " + n.name(), e); } return mergeTip; } private static CommitMergeStatus getCommitMergeStatus(MergeBaseFailureReason reason) { switch (reason) { case MULTIPLE_MERGE_BASES_NOT_SUPPORTED: case TOO_MANY_MERGE_BASES: default: return CommitMergeStatus.MANUAL_RECURSIVE_MERGE; case CONFLICTS_DURING_MERGE_BASE_CALCULATION: return CommitMergeStatus.PATH_CONFLICT; } } private static CodeReviewCommit failed(CodeReviewRevWalk rw, RevFlag canMergeFlag, CodeReviewCommit mergeTip, CodeReviewCommit n, CommitMergeStatus failure) throws MissingObjectException, IncorrectObjectTypeException, IOException { rw.resetRetain(canMergeFlag); rw.markStart(n); rw.markUninteresting(mergeTip); CodeReviewCommit failed; while ((failed = rw.next()) != null) { failed.setStatusCode(failure); } return failed; } public CodeReviewCommit writeMergeCommit(PersonIdent author, PersonIdent committer, CodeReviewRevWalk rw, ObjectInserter inserter, RevFlag canMergeFlag, Branch.NameKey destBranch, CodeReviewCommit mergeTip, ObjectId treeId, CodeReviewCommit n) throws IOException, MissingObjectException, IncorrectObjectTypeException { final List<CodeReviewCommit> merged = new ArrayList<>(); rw.resetRetain(canMergeFlag); rw.markStart(n); rw.markUninteresting(mergeTip); CodeReviewCommit crc; while ((crc = rw.next()) != null) { if (crc.getPatchsetId() != null) { merged.add(crc); } } StringBuilder msgbuf = new StringBuilder().append(summarize(rw, merged)); if (!R_HEADS_MASTER.equals(destBranch.get())) { msgbuf.append(" into "); msgbuf.append(destBranch.getShortName()); } if (merged.size() > 1) { msgbuf.append("\n\n* changes:\n"); for (final CodeReviewCommit c : merged) { rw.parseBody(c); msgbuf.append(" "); msgbuf.append(c.getShortMessage()); msgbuf.append("\n"); } } final CommitBuilder mergeCommit = new CommitBuilder(); mergeCommit.setTreeId(treeId); mergeCommit.setParentIds(mergeTip, n); mergeCommit.setAuthor(author); mergeCommit.setCommitter(committer); mergeCommit.setMessage(msgbuf.toString()); CodeReviewCommit mergeResult = rw.parseCommit(commit(inserter, mergeCommit)); mergeResult.setControl(n.getControl()); return mergeResult; } private String summarize(RevWalk rw, List<CodeReviewCommit> merged) throws IOException { if (merged.size() == 1) { CodeReviewCommit c = merged.get(0); rw.parseBody(c); return String.format("Merge \"%s\"", c.getShortMessage()); } LinkedHashSet<String> topics = new LinkedHashSet<>(4); for (CodeReviewCommit c : merged) { if (!Strings.isNullOrEmpty(c.change().getTopic())) { topics.add(c.change().getTopic()); } } if (topics.size() == 1) { return String.format("Merge changes from topic '%s'", Iterables.getFirst(topics, null)); } else if (topics.size() > 1) { return String.format("Merge changes from topics '%s'", Joiner.on("', '").join(topics)); } else { return String.format("Merge changes %s%s", Joiner.on(',') .join(Iterables.transform(Iterables.limit(merged, 5), new Function<CodeReviewCommit, String>() { @Override public String apply(CodeReviewCommit in) { return in.change().getKey().abbreviate(); } })), merged.size() > 5 ? ", ..." : ""); } } public ThreeWayMerger newThreeWayMerger(final Repository repo, final ObjectInserter inserter) { return newThreeWayMerger(repo, inserter, mergeStrategyName()); } public String mergeStrategyName() { return mergeStrategyName(useContentMerge, useRecursiveMerge); } public static String mergeStrategyName(boolean useContentMerge, boolean useRecursiveMerge) { if (useContentMerge) { // Settings for this project allow us to try and automatically resolve // conflicts within files if needed. Use either the old resolve merger or // new recursive merger, and instruct to operate in core. if (useRecursiveMerge) { return MergeStrategy.RECURSIVE.getName(); } else { return MergeStrategy.RESOLVE.getName(); } } else { // No auto conflict resolving allowed. If any of the // affected files was modified, merge will fail. return MergeStrategy.SIMPLE_TWO_WAY_IN_CORE.getName(); } } public static ThreeWayMerger newThreeWayMerger(Repository repo, final ObjectInserter inserter, String strategyName) { MergeStrategy strategy = MergeStrategy.get(strategyName); checkArgument(strategy != null, "invalid merge strategy: %s", strategyName); Merger m = strategy.newMerger(repo, true); checkArgument(m instanceof ThreeWayMerger, "merge strategy %s does not support three-way merging", strategyName); m.setObjectInserter(new ObjectInserter.Filter() { @Override protected ObjectInserter delegate() { return inserter; } @Override public void flush() { } @Override public void close() { } }); return (ThreeWayMerger) m; } public ObjectId commit(final ObjectInserter inserter, final CommitBuilder mergeCommit) throws IOException, UnsupportedEncodingException { ObjectId id = inserter.insert(mergeCommit); inserter.flush(); return id; } public void markCleanMerges(final RevWalk rw, final RevFlag canMergeFlag, final CodeReviewCommit mergeTip, final Set<RevCommit> alreadyAccepted) throws MergeException { if (mergeTip == null) { // If mergeTip is null here, branchTip was null, indicating a new branch // at the start of the merge process. We also elected to merge nothing, // probably due to missing dependencies. Nothing was cleanly merged. // return; } try { rw.resetRetain(canMergeFlag); rw.sort(RevSort.TOPO); rw.sort(RevSort.REVERSE, true); rw.markStart(mergeTip); for (RevCommit c : alreadyAccepted) { rw.markUninteresting(c); } CodeReviewCommit c; while ((c = (CodeReviewCommit) rw.next()) != null) { if (c.getPatchsetId() != null) { c.setStatusCode(CommitMergeStatus.CLEAN_MERGE); } } } catch (IOException e) { throw new MergeException("Cannot mark clean merges", e); } } }