Limit file list to files that were touched in new patch set

When comparing two patch sets only files that were touched in the new
patch set should be listed. At the moment the file list contains all
files that were changed between the commits of the compared patch sets.

E.g. if a rebase was done which touched many files this made the patch
set comparison pretty useless since the file list grew way too big.

Change-Id: I6c512a69d8632a4ce57ef23928411bf0829aeb70
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/change/PatchListCacheIT.java

@@ -149,16 +149,11 @@ public class PatchListCacheIT extends AbstractDaemonTest {
     pushHead(git, "refs/for/master", false);
     ObjectId b = getCurrentRevisionId(c.getChangeId());
 
-    // Compare Change 1,1 with Change 1,2
+    // Compare Change 1,1 with Change 1,2 (+FILE_B)
-    // expected: +FILE_B
-    // actual: +FILE_B, -FILE_C
-    // -FILE_C is wrongly returned, it is not contained in Change 1,2
-    //         but was only added in Change 1,1
     List<PatchListEntry>  entries = getPatches(a, b);
-    assertEquals(3, entries.size());
+    assertEquals(2, entries.size());
     assertModified(Patch.COMMIT_MSG, entries.get(0));
     assertAdded(FILE_B, entries.get(1));
-    assertDeleted(FILE_C, entries.get(2));
   }
 
   @Test
@@ -189,17 +184,11 @@ public class PatchListCacheIT extends AbstractDaemonTest {
     pushHead(git, "refs/for/master", false);
     ObjectId b = getCurrentRevisionId(c.getChangeId());
 
-    // Compare Change 1,1 with Change 1,2
+    // Compare Change 1,1 with Change 1,2 (+FILE_C)
-    // expected: +FILE_C
-    // actual: +FILE_B, +FILE_C
-    // +FILE_B is wrongly returned, it is neither contained in Change 1,1
-    //         nor in Change 1,2, but was only changed due to the rebase
-    //         on Change 2,1
     List<PatchListEntry>  entries = getPatches(a, b);
-    assertEquals(3, entries.size());
+    assertEquals(2, entries.size());
     assertModified(Patch.COMMIT_MSG, entries.get(0));
-    assertAdded(FILE_B, entries.get(1));
+    assertAdded(FILE_C, entries.get(1));
-    assertAdded(FILE_C, entries.get(2));
   }
 
   private static void assertAdded(String expectedNewName, PatchListEntry e) {

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListKey.java

@@ -34,7 +34,7 @@ import java.io.ObjectOutputStream;
 import java.io.Serializable;
 
 public class PatchListKey implements Serializable {
-  static final long serialVersionUID = 16L;
+  static final long serialVersionUID = 17L;
 
   private transient ObjectId oldId;
   private transient ObjectId newId;

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListLoader.java

@@ -15,7 +15,9 @@
 
 package com.google.gerrit.server.patch;
 
+import com.google.common.base.Function;
 import com.google.common.cache.CacheLoader;
+import com.google.common.collect.FluentIterable;
 import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.RefNames;
@@ -58,23 +60,28 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 public class PatchListLoader extends CacheLoader<PatchListKey, PatchList> {
   static final Logger log = LoggerFactory.getLogger(PatchListLoader.class);
 
   private final GitRepositoryManager repoManager;
+  private final PatchListCache patchListCache;
 
   @Inject
-  PatchListLoader(GitRepositoryManager mgr) {
+  PatchListLoader(GitRepositoryManager mgr, PatchListCache plc) {
     repoManager = mgr;
+    patchListCache = plc;
   }
 
   @Override
-  public PatchList load(final PatchListKey key) throws Exception {
+  public PatchList load(final PatchListKey key) throws IOException,
+      PatchListNotAvailableException {
     final Repository repo = repoManager.openRepository(key.projectKey);
     try {
       return readPatchList(key, repo);
@@ -100,8 +107,8 @@ public class PatchListLoader extends CacheLoader<PatchListKey, PatchList> {
     }
   }
 
-  private PatchList readPatchList(final PatchListKey key,
+  private PatchList readPatchList(final PatchListKey key, final Repository repo)
-      final Repository repo) throws IOException {
+      throws IOException, PatchListNotAvailableException {
     final RawTextComparator cmp = comparatorFor(key.getWhitespace());
     final ObjectReader reader = repo.newObjectReader();
     try {
@@ -121,18 +128,8 @@ public class PatchListLoader extends CacheLoader<PatchListKey, PatchList> {
       final boolean againstParent =
           b.getParentCount() > 0 && b.getParent(0) == a;
 
-      RevCommit aCommit;
+      RevCommit aCommit = a instanceof RevCommit ? (RevCommit) a : null;
-      RevTree aTree;
+      RevTree aTree = rw.parseTree(a);
-      if (a instanceof RevCommit) {
-        aCommit = (RevCommit) a;
-        aTree = aCommit.getTree();
-      } else if (a instanceof RevTree) {
-        aCommit = null;
-        aTree = (RevTree) a;
-      } else {
-        throw new IOException("Unexpected type: " + a.getClass());
-      }
-
       RevTree bTree = b.getTree();
 
       DiffFormatter df = new DiffFormatter(DisabledOutputStream.INSTANCE);
@@ -141,15 +138,32 @@ public class PatchListLoader extends CacheLoader<PatchListKey, PatchList> {
       df.setDetectRenames(true);
       List<DiffEntry> diffEntries = df.scan(aTree, bTree);
 
-      final int cnt = diffEntries.size();
+      Set<String> paths = key.getOldId() != null
-      final PatchListEntry[] entries = new PatchListEntry[1 + cnt];
+          ? FluentIterable.from(patchListCache.get(
-      entries[0] = newCommitMessage(cmp, repo, reader, //
+                  new PatchListKey(key.projectKey, null, key.getNewId(),
-          againstParent ? null : aCommit, b);
+                  key.getWhitespace())).getPatches())
+              .transform(new Function<PatchListEntry, String>() {
+                @Override
+                public String apply(PatchListEntry entry) {
+                  return entry.getNewName();
+                }
+              })
+          .toSet()
+          : null;
+      int cnt = diffEntries.size();
+      List<PatchListEntry> entries = new ArrayList<>();
+      entries.add(newCommitMessage(cmp, repo, reader, //
+          againstParent ? null : aCommit, b));
       for (int i = 0; i < cnt; i++) {
-        FileHeader fh = df.toFileHeader(diffEntries.get(i));
+        DiffEntry diffEntry = diffEntries.get(i);
-        entries[1 + i] = newEntry(aTree, fh);
+        if (paths == null || paths.contains(diffEntry.getNewPath())
+            || paths.contains(diffEntry.getOldPath())) {
+          FileHeader fh = df.toFileHeader(diffEntry);
+          entries.add(newEntry(aTree, fh));
+        }
       }
-      return new PatchList(a, b, againstParent, entries);
+      return new PatchList(a, b, againstParent,
+          entries.toArray(new PatchListEntry[entries.size()]));
     } finally {
       reader.release();
     }