opendev/gerrit
Code Issues Proposed changes

MergeSuperSet: Avoid quadratic behavior by walking once per target ref

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When multiple changes in a line of history are already part of the
ChangeSet, Gerrit repeats work by walking history for each of the
changes separately. For example, suppose a linear sequence of n changes
are discovered as part of a topic; then we visit O(n^2) revisions that
we already knew.

Speed it up by using a single RevWalk per target branch.

Change-Id: I8d27f36bb508a06c4bdb6fe5c51bc666c0088096
Helped-By: Jonathan Nieder <jrn@google.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
This commit is contained in:
Stefan Beller
2016-09-15 12:31:43 -07:00
committed by Dave Borowitz
parent 9b152d9901
commit 04748738ae
2 changed files with 120 additions and 70 deletions
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112
gerrit-server/src/main/java/com/google/gerrit/server/git/MergeSuperSet.java
View File

@@ -18,6 +18,8 @@ import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.base.Strings;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.gerrit.common.data.SubmitTypeRecord;
@@ -51,6 +53,8 @@ import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
@@ -149,17 +153,61 @@ public class MergeSuperSet {
return str.type;
}
private static ImmutableListMultimap<Branch.NameKey, ChangeData>
byBranch(Iterable<ChangeData> changes) throws OrmException {
ImmutableListMultimap.Builder<Branch.NameKey, ChangeData> builder =
ImmutableListMultimap.builder();
for (ChangeData cd : changes) {
builder.put(cd.change().getDest(), cd);
}
return builder.build();
}
private Set<String> walkChangesByHashes(Collection<RevCommit> sourceCommits,
Set<String> ignoreHashes, OpenRepo or, Optional<RevCommit> head)
throws IOException {
Set<String> destHashes = new HashSet<>();
or.rw.reset();
if (head.isPresent()) {
or.rw.markUninteresting(head.get());
}
for (RevCommit c : sourceCommits) {
String name = c.name();
if (ignoreHashes.contains(name)) {
continue;
}
destHashes.add(name);
or.rw.markStart(c);
}
for (RevCommit c : or.rw) {
String name = c.name();
if (ignoreHashes.contains(name)) {
continue;
}
destHashes.add(name);
}
return destHashes;
}
private ChangeSet completeChangeSetWithoutTopic(ReviewDb db,
ChangeSet changes, CurrentUser user) throws IOException, OrmException {
List<ChangeData> visibleChanges = new ArrayList<>();
List<ChangeData> nonVisibleChanges = new ArrayList<>();
Collection<ChangeData> visibleChanges = new ArrayList<>();
Collection<ChangeData> nonVisibleChanges = new ArrayList<>();
for (ChangeData cd :
Iterables.concat(changes.changes(), changes.nonVisibleChanges())) {
// For each target branch we run a separate rev walk to find open changes
// reachable from changes already in the merge super set.
ImmutableListMultimap<Branch.NameKey, ChangeData> bc = byBranch(
Iterables.concat(changes.changes(), changes.nonVisibleChanges()));
for (Branch.NameKey b : bc.keySet()) {
OpenRepo or = getRepo(b.getParentKey());
List<RevCommit> visibleCommits = new ArrayList<>();
List<RevCommit> nonVisibleCommits = new ArrayList<>();
for (ChangeData cd : bc.get(b)) {
checkState(cd.hasChangeControl(),
"completeChangeSet forgot to set changeControl for current user"
+ " at ChangeData creation time");
OpenRepo or = getRepo(cd.change().getProject());
boolean visible = changes.ids().contains(cd.getId());
if (visible && !cd.changeControl().isVisible(db, cd)) {
// We thought the change was visible, but it isn't.
@@ -167,7 +215,8 @@ public class MergeSuperSet {
// completeChangeSet computation, for example.
visible = false;
}
List<ChangeData> dest = visible ? visibleChanges : nonVisibleChanges;
Collection<RevCommit> toWalk = visible ?
visibleCommits : nonVisibleCommits;
// Pick a revision to use for traversal. If any of the patch sets
// is visible, we use the most recent one. Otherwise, use the current
@@ -184,7 +233,12 @@ public class MergeSuperSet {
}
if (submitType(cd, ps, visiblePatchSet) == SubmitType.CHERRY_PICK) {
dest.add(cd);
if (visible) {
visibleChanges.add(cd);
} else {
nonVisibleChanges.add(cd);
}
continue;
}
@@ -192,37 +246,33 @@ public class MergeSuperSet {
String objIdStr = ps.getRevision().get();
RevCommit commit = or.rw.parseCommit(ObjectId.fromString(objIdStr));
// Collect unmerged ancestors
Branch.NameKey destBranch = cd.change().getDest();
Ref ref = or.repo.getRefDatabase().getRef(destBranch.get());
or.rw.reset();
or.rw.markStart(commit);
if (ref != null) {
RevCommit head = or.rw.parseCommit(ref.getObjectId());
or.rw.markUninteresting(head);
}
List<String> hashes = new ArrayList<>();
// Always include the input, even if merged. This allows
// SubmitStrategyOp to correct the situation later, assuming it gets
// returned by byCommitsOnBranchNotMerged below.
hashes.add(objIdStr);
for (RevCommit c : or.rw) {
if (!c.equals(commit)) {
hashes.add(c.name());
}
toWalk.add(commit);
}
if (!hashes.isEmpty()) {
Iterable<ChangeData> destChanges = query()
.byCommitsOnBranchNotMerged(
or.repo, db, cd.change().getDest(), hashes);
for (ChangeData chd : destChanges) {
Ref ref = or.repo.getRefDatabase().getRef(b.get());
Optional<RevCommit> head =
ref != null
? Optional.<RevCommit>of(or.rw.parseCommit(ref.getObjectId()))
: Optional.<RevCommit>absent();
Set<String> emptySet = Collections.emptySet();
Set<String> visibleHashes = walkChangesByHashes(visibleCommits,
emptySet, or, head);
Iterable<ChangeData> cds = query()
.byCommitsOnBranchNotMerged(or.repo, db, b, visibleHashes);
for (ChangeData chd : cds) {
chd.changeControl(user);
dest.add(chd);
}
visibleChanges.add(chd);
}
Set<String> nonVisibleHashes = walkChangesByHashes(nonVisibleCommits,
visibleHashes, or, head);
Iterables.addAll(nonVisibleChanges,
query().byCommitsOnBranchNotMerged(or.repo, db, b, nonVisibleHashes));
}
return new ChangeSet(visibleChanges, nonVisibleChanges);

10
gerrit-server/src/main/java/com/google/gerrit/server/query/change/InternalChangeQuery.java
View File

@@ -153,7 +153,7 @@ public class InternalChangeQuery extends InternalQuery<ChangeData> {
}
public Iterable<ChangeData> byCommitsOnBranchNotMerged(Repository repo,
ReviewDb db, Branch.NameKey branch, List<String> hashes)
ReviewDb db, Branch.NameKey branch, Collection<String> hashes)
throws OrmException, IOException {
return byCommitsOnBranchNotMerged(repo, db, branch, hashes,
// Account for all commit predicates plus ref, project, status.
@@ -162,7 +162,7 @@ public class InternalChangeQuery extends InternalQuery<ChangeData> {
@VisibleForTesting
Iterable<ChangeData> byCommitsOnBranchNotMerged(Repository repo, ReviewDb db,
Branch.NameKey branch, List<String> hashes, int indexLimit)
Branch.NameKey branch, Collection<String> hashes, int indexLimit)
throws OrmException, IOException {
if (hashes.size() > indexLimit) {
return byCommitsOnBranchNotMergedFromDatabase(repo, db, branch, hashes);
@@ -172,7 +172,7 @@ public class InternalChangeQuery extends InternalQuery<ChangeData> {
private Iterable<ChangeData> byCommitsOnBranchNotMergedFromDatabase(
Repository repo, final ReviewDb db, final Branch.NameKey branch,
List<String> hashes) throws OrmException, IOException {
Collection<String> hashes) throws OrmException, IOException {
Set<Change.Id> changeIds = Sets.newHashSetWithExpectedSize(hashes.size());
String lastPrefix = null;
for (Ref ref :
@@ -208,7 +208,7 @@ public class InternalChangeQuery extends InternalQuery<ChangeData> {
}
private Iterable<ChangeData> byCommitsOnBranchNotMergedFromIndex(
Branch.NameKey branch, List<String> hashes) throws OrmException {
Branch.NameKey branch, Collection<String> hashes) throws OrmException {
return query(and(
ref(branch),
project(branch.getParentKey()),
@@ -216,7 +216,7 @@ public class InternalChangeQuery extends InternalQuery<ChangeData> {
or(commits(hashes))));
}
private static List<Predicate<ChangeData>> commits(List<String> hashes) {
private static List<Predicate<ChangeData>> commits(Collection<String> hashes) {
List<Predicate<ChangeData>> commits = new ArrayList<>(hashes.size());
for (String s : hashes) {
commits.add(commit(s));