Eliminate potential NPEs with ChangeData.getChange()

Callers were supposed to be calling hasChange() to determine whether
getChange() would return null, but none were. Remove this error-prone
pair of methods and just use change(), which includes lazy loading.
There are a few places where we need to catch an additional
OrmException but these are easy enough to fix.

Change-Id: I23335e362715f59e2c093ffec88427739ff0cffc

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneChangeIndex.java

@@ -234,7 +234,7 @@ public class LuceneChangeIndex implements ChangeIndex {
     Term id = QueryBuilder.idTerm(cd);
     Document doc = toDocument(cd);
     try {
-      if (cd.getChange().getStatus().isOpen()) {
+      if (cd.change().getStatus().isOpen()) {
         Futures.allAsList(
             closedIndex.delete(id),
             openIndex.insert(doc)).get();
@@ -243,9 +243,7 @@ public class LuceneChangeIndex implements ChangeIndex {
             openIndex.delete(id),
             closedIndex.insert(doc)).get();
       }
-    } catch (ExecutionException e) {
+    } catch (OrmException | ExecutionException | InterruptedException e) {
-      throw new IOException(e);
-    } catch (InterruptedException e) {
       throw new IOException(e);
     }
   }
@@ -256,7 +254,7 @@ public class LuceneChangeIndex implements ChangeIndex {
     Term id = QueryBuilder.idTerm(cd);
     Document doc = toDocument(cd);
     try {
-      if (cd.getChange().getStatus().isOpen()) {
+      if (cd.change().getStatus().isOpen()) {
         Futures.allAsList(
             closedIndex.delete(id),
             openIndex.replace(id, doc)).get();
@@ -265,9 +263,7 @@ public class LuceneChangeIndex implements ChangeIndex {
             openIndex.delete(id),
             closedIndex.replace(id, doc)).get();
       }
-    } catch (ExecutionException e) {
+    } catch (OrmException | ExecutionException | InterruptedException e) {
-      throw new IOException(e);
-    } catch (InterruptedException e) {
       throw new IOException(e);
     }
   }
@@ -280,9 +276,7 @@ public class LuceneChangeIndex implements ChangeIndex {
       Futures.allAsList(
           openIndex.delete(id),
           closedIndex.delete(id)).get();
-    } catch (ExecutionException e) {
+    } catch (ExecutionException | InterruptedException e) {
-      throw new IOException(e);
-    } catch (InterruptedException e) {
       throw new IOException(e);
     }
   }

gerrit-server/src/main/java/com/google/gerrit/rules/StoredValues.java

@@ -35,11 +35,11 @@ import com.google.gerrit.server.patch.PatchSetInfoFactory;
 import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
 import com.google.gerrit.server.project.ChangeControl;
 import com.google.gerrit.server.query.change.ChangeData;
+import com.google.gwtorm.server.OrmException;
 
 import com.googlecode.prolog_cafe.lang.Prolog;
 import com.googlecode.prolog_cafe.lang.SystemException;
 
-import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
 
@@ -52,10 +52,19 @@ public final class StoredValues {
   public static final StoredValue<PatchSet> PATCH_SET = create(PatchSet.class);
   public static final StoredValue<ChangeControl> CHANGE_CONTROL = create(ChangeControl.class);
 
+  public static Change getChange(Prolog engine) throws SystemException {
+    ChangeData cd = CHANGE_DATA.get(engine);
+    try {
+      return cd.change();
+    } catch (OrmException e) {
+      throw new SystemException("Cannot load change " + cd.getId());
+    }
+  }
+
   public static final StoredValue<PatchSetInfo> PATCH_SET_INFO = new StoredValue<PatchSetInfo>() {
     @Override
     public PatchSetInfo createValue(Prolog engine) {
-      Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+      Change change = getChange(engine);
       PatchSet ps = StoredValues.PATCH_SET.get(engine);
       PrologEnvironment env = (PrologEnvironment) engine.control;
       PatchSetInfoFactory patchInfoFactory =
@@ -74,7 +83,7 @@ public final class StoredValues {
       PrologEnvironment env = (PrologEnvironment) engine.control;
       PatchSetInfo psInfo = StoredValues.PATCH_SET_INFO.get(engine);
       PatchListCache plCache = env.getArgs().getPatchListCache();
-      Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+      Change change = getChange(engine);
       Project.NameKey projectKey = change.getProject();
       ObjectId a = null;
       ObjectId b = ObjectId.fromString(psInfo.getRevId());
@@ -95,13 +104,11 @@ public final class StoredValues {
     public Repository createValue(Prolog engine) {
       PrologEnvironment env = (PrologEnvironment) engine.control;
       GitRepositoryManager gitMgr = env.getArgs().getGitRepositoryManager();
-      Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+      Change change = getChange(engine);
       Project.NameKey projectKey = change.getProject();
       final Repository repo;
       try {
         repo = gitMgr.openRepository(projectKey);
-      } catch (RepositoryNotFoundException e) {
-        throw new SystemException(e.getMessage());
       } catch (IOException e) {
         throw new SystemException(e.getMessage());
       }

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeJson.java

@@ -384,7 +384,7 @@ public class ChangeJson {
     }
 
     LabelTypes labelTypes = ctl.getLabelTypes();
-    if (cd.getChange().getStatus().isOpen()) {
+    if (cd.change().getStatus().isOpen()) {
       return labelsForOpenChange(cd, labelTypes, standard, detailed);
     } else {
       return labelsForClosedChange(cd, labelTypes, standard, detailed);

gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeData.java

@@ -295,14 +295,6 @@ public class ChangeData {
     return legacyId;
   }
 
-  public Change getChange() {
-    return change;
-  }
-
-  public boolean hasChange() {
-    return change != null;
-  }
-
   boolean fastIsVisibleTo(CurrentUser user) {
     return visibleTo == user;
   }
@@ -323,10 +315,6 @@ public class ChangeData {
     return change;
   }
 
-  void setChange(Change c) {
-    change = c;
-  }
-
   public PatchSet currentPatchSet() throws OrmException {
     if (currentPatchSet == null) {
       Change c = change();
@@ -385,7 +373,7 @@ public class ChangeData {
       IncorrectObjectTypeException {
     PatchSet.Id psId = change().currentPatchSetId();
     String sha1 = db.patchSets().get(psId).getRevision().get();
-    Repository repo = repoManager.openRepository(change.getProject());
+    Repository repo = repoManager.openRepository(change().getProject());
     try {
       RevWalk walk = new RevWalk(repo);
       try {

gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryProcessor.java

@@ -308,8 +308,8 @@ public class QueryProcessor {
           }
 
           LabelTypes labelTypes = cc.getLabelTypes();
-          c = eventFactory.asChangeAttribute(d.getChange());
+          c = eventFactory.asChangeAttribute(d.change());
-          eventFactory.extend(c, d.getChange());
+          eventFactory.extend(c, d.change());
 
           if (!trackingFooters.isEmpty()) {
             eventFactory.addTrackingIds(c,
@@ -317,11 +317,11 @@ public class QueryProcessor {
           }
 
           if (includeAllReviewers) {
-            eventFactory.addAllReviewers(c, d.getChange());
+            eventFactory.addAllReviewers(c, d.change());
           }
 
           if (includeSubmitRecords) {
-            PatchSet.Id psId = d.getChange().currentPatchSetId();
+            PatchSet.Id psId = d.change().currentPatchSetId();
             PatchSet patchSet = db.get().patchSets().get(psId);
             List<SubmitRecord> submitResult = cc.canSubmit( //
                 db.get(), patchSet, null, false, true, true);
@@ -368,7 +368,7 @@ public class QueryProcessor {
           }
 
           if (includeDependencies) {
-            eventFactory.addDependencies(c, d.getChange());
+            eventFactory.addDependencies(c, d.change());
           }
 
           show(c);

gerrit-server/src/main/java/gerrit/PRED_change_branch_1.java

@@ -15,7 +15,6 @@
 package gerrit;
 
 import com.google.gerrit.reviewdb.client.Branch;
-import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.rules.StoredValues;
 
 import com.googlecode.prolog_cafe.lang.Operation;
@@ -36,8 +35,7 @@ public class PRED_change_branch_1 extends Predicate.P1 {
     engine.setB0();
     Term a1 = arg1.dereference();
 
-    Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+    Branch.NameKey name = StoredValues.getChange(engine).getDest();
-    Branch.NameKey name = change.getDest();
 
     if (!a1.unify(SymbolTerm.create(name.get()), engine.trail)) {
       return engine.fail();

gerrit-server/src/main/java/gerrit/PRED_change_owner_1.java

@@ -15,7 +15,6 @@
 package gerrit;
 
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.rules.StoredValues;
 
 import com.googlecode.prolog_cafe.lang.IntegerTerm;
@@ -40,8 +39,7 @@ public class PRED_change_owner_1 extends Predicate.P1 {
     engine.setB0();
     Term a1 = arg1.dereference();
 
-    Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+    Account.Id ownerId = StoredValues.getChange(engine).getOwner();
-    Account.Id ownerId = change.getOwner();
 
     if (!a1.unify(new StructureTerm(user, new IntegerTerm(ownerId.get())), engine.trail)) {
       return engine.fail();

gerrit-server/src/main/java/gerrit/PRED_change_project_1.java

@@ -14,7 +14,6 @@
 
 package gerrit;
 
-import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.rules.StoredValues;
 
@@ -36,8 +35,7 @@ public class PRED_change_project_1 extends Predicate.P1 {
     engine.setB0();
     Term a1 = arg1.dereference();
 
-    Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+    Project.NameKey name = StoredValues.getChange(engine).getProject();
-    Project.NameKey name = change.getProject();
 
     if (!a1.unify(SymbolTerm.create(name.get()), engine.trail)) {
       return engine.fail();

gerrit-server/src/main/java/gerrit/PRED_change_topic_1.java

@@ -36,7 +36,7 @@ public class PRED_change_topic_1 extends Predicate.P1 {
     Term a1 = arg1.dereference();
 
     Term topicTerm = Prolog.Nil;
-    Change change = StoredValues.CHANGE_DATA.get(engine).getChange();
+    Change change = StoredValues.getChange(engine);
     String topic = change.getTopic();
     if (topic != null) {
       topicTerm = SymbolTerm.create(topic);

gerrit-solr/src/main/java/com/google/gerrit/solr/SolrChangeIndex.java

@@ -148,14 +148,14 @@ class SolrChangeIndex implements ChangeIndex, LifecycleListener {
     String id = cd.getId().toString();
     SolrInputDocument doc = toDocument(cd);
     try {
-      if (cd.getChange().getStatus().isOpen()) {
+      if (cd.change().getStatus().isOpen()) {
         closedIndex.deleteById(id);
         openIndex.add(doc);
       } else {
         openIndex.deleteById(id);
         closedIndex.add(doc);
       }
-    } catch (SolrServerException e) {
+    } catch (OrmException | SolrServerException e) {
       throw new IOException(e);
     }
     commit(openIndex);
@@ -167,14 +167,14 @@ class SolrChangeIndex implements ChangeIndex, LifecycleListener {
     String id = cd.getId().toString();
     SolrInputDocument doc = toDocument(cd);
     try {
-      if (cd.getChange().getStatus().isOpen()) {
+      if (cd.change().getStatus().isOpen()) {
         closedIndex.deleteById(id);
         openIndex.add(doc);
       } else {
         openIndex.deleteById(id);
         closedIndex.add(doc);
       }
-    } catch (SolrServerException e) {
+    } catch (OrmException | SolrServerException e) {
       throw new IOException(e);
     }
     commit(openIndex);
@@ -185,14 +185,14 @@ class SolrChangeIndex implements ChangeIndex, LifecycleListener {
   public void delete(ChangeData cd) throws IOException {
     String id = cd.getId().toString();
     try {
-      if (cd.getChange().getStatus().isOpen()) {
+      if (cd.change().getStatus().isOpen()) {
         openIndex.deleteById(id);
         commit(openIndex);
       } else {
         closedIndex.deleteById(id);
         commit(closedIndex);
       }
-    } catch (SolrServerException e) {
+    } catch (OrmException | SolrServerException e) {
       throw new IOException(e);
     }
   }