opendev/gerrit
Code Issues Proposed changes

Split intraline differences into their own cache

Browse Source 
The bulk of the running time for loading a PatchList entry from the
PatchListCache is actually within the intraline difference code.
Assuming no bugs, running JGit's DiffFormatter and converting the
results is typically sub-second, even for a very large change that
has renames.

By deferring the intraline difference logic until its actually
required to display a particular file allows file lists to load
very quickly, and doesn't penalize users who have disabled the
intraline difference setting in their account preferences.

This also offers a work around for the dreaded "patch of death"
situation.  When a bad file is encountered and it won't load,
users can temporarily switch off intraline difference and open the
file anyway.  Unfortunately the server will still have at least
one worker thread stuck generating the intraline difference cache
record, but at least the change is still viewable.

Change-Id: I61bbd3d068bd9b3da9d1018c0f66969a5b6ff58e
Signed-off-by: Shawn O. Pearce <sop@google.com>
This commit is contained in:
Shawn O. Pearce
2010-11-11 16:54:35 -08:00
parent a3d260a3e1
commit 3ea1d5567c
9 changed files with 371 additions and 169 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListEntry.java
View File

@@ -29,7 +29,6 @@ import com.google.gerrit.reviewdb.Patch.ChangeType;
import com.google.gerrit.reviewdb.Patch.PatchType;
import org.eclipse.jgit.diff.Edit;
import org.eclipse.jgit.diff.ReplaceEdit;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.patch.CombinedFileHeader;
@@ -183,27 +182,13 @@ public class PatchListEntry {
writeVarInt32(out, edits.size());
for (final Edit e : edits) {
write(out, e);
if (e instanceof ReplaceEdit) {
ReplaceEdit r = (ReplaceEdit) e;
writeVarInt32(out, r.getInternalEdits().size());
for (Edit i : r.getInternalEdits()) {
write(out, i);
}
} else {
writeVarInt32(out, 0);
}
writeVarInt32(out, e.getBeginA());
writeVarInt32(out, e.getEndA());
writeVarInt32(out, e.getBeginB());
writeVarInt32(out, e.getEndB());
}
}
private void write(final OutputStream out, final Edit e) throws IOException {
writeVarInt32(out, e.getBeginA());
writeVarInt32(out, e.getEndA());
writeVarInt32(out, e.getBeginB());
writeVarInt32(out, e.getEndB());
}
static PatchListEntry readFrom(final InputStream in) throws IOException {
final ChangeType changeType = readEnum(in, ChangeType.values());
final PatchType patchType = readEnum(in, PatchType.values());
@@ -216,16 +201,11 @@ public class PatchListEntry {
final int editCount = readVarInt32(in);
final Edit[] editArray = new Edit[editCount];
for (int i = 0; i < editCount; i++) {
editArray[i] = readEdit(in);
int innerCount = readVarInt32(in);
if (0 < innerCount) {
Edit[] inner = new Edit[innerCount];
for (int innerIdx = 0; innerIdx < innerCount; innerIdx++) {
inner[innerIdx] = readEdit(in);
}
editArray[i] = new ReplaceEdit(editArray[i], toList(inner));
}
int beginA = readVarInt32(in);
int endA = readVarInt32(in);
int beginB = readVarInt32(in);
int endB = readVarInt32(in);
editArray[i] = new Edit(beginA, endA, beginB, endB);
}
return new PatchListEntry(changeType, patchType, oldName, newName, hdr,
@@ -236,14 +216,6 @@ public class PatchListEntry {
return Collections.unmodifiableList(Arrays.asList(l));
}
private static Edit readEdit(final InputStream in) throws IOException {
final int beginA = readVarInt32(in);
final int endA = readVarInt32(in);
final int beginB = readVarInt32(in);
final int endB = readVarInt32(in);
return new Edit(beginA, endA, beginB, endB);
}
private static byte[] compact(final FileHeader h) {
final int end = end(h);
if (h.getStartOffset() == 0 && end == h.getBuffer().length) {