[log] simplify: move EMPTY DataPack instance to the DataPack

platform/vcs-log/impl/src/com/intellij/vcs/log/data/DataPack.java

@@ -1,6 +1,7 @@
 package com.intellij.vcs.log.data;
 
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.util.ConstantFunction;
 import com.intellij.util.NotNullFunction;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.vcs.log.*;
@@ -12,15 +13,26 @@ import com.intellij.vcs.log.util.StopWatch;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.*;
-import java.util.List;
 
 public class DataPack {
 
+  public static final DataPack EMPTY = createEmptyInstance();
+
   @NotNull private final RefsModel myRefsModel;
   @NotNull private final PermanentGraph<Integer> myPermanentGraph;
   @NotNull private final Map<VirtualFile, VcsLogProvider> myLogProviders;
   private boolean myFull;
 
+  DataPack(@NotNull RefsModel refsModel,
+           @NotNull PermanentGraph<Integer> permanentGraph,
+           @NotNull Map<VirtualFile, VcsLogProvider> providers,
+           boolean full) {
+    myRefsModel = refsModel;
+    myPermanentGraph = permanentGraph;
+    myLogProviders = providers;
+    myFull = full;
+  }
+
   @NotNull
   static DataPack build(@NotNull List<? extends GraphCommit<Integer>> commits,
                         @NotNull Map<VirtualFile, Set<VcsRef>> refs,
@@ -69,14 +81,10 @@ public class DataPack {
     return map;
   }
 
-  DataPack(@NotNull RefsModel refsModel,
-           @NotNull PermanentGraph<Integer> permanentGraph,
-           @NotNull Map<VirtualFile, VcsLogProvider> providers,
-           boolean full) {
-    myRefsModel = refsModel;
-    myPermanentGraph = permanentGraph;
-    myLogProviders = providers;
-    myFull = full;
+  @NotNull
+  private static DataPack createEmptyInstance() {
+    RefsModel emptyModel = new RefsModel(Collections.<VirtualFile, Set<VcsRef>>emptyMap(), new ConstantFunction<Hash, Integer>(0));
+    return new DataPack(emptyModel, EmptyPermanentGraph.getInstance(), Collections.<VirtualFile, VcsLogProvider>emptyMap(), false);
   }
 
   @NotNull

platform/vcs-log/impl/src/com/intellij/vcs/log/data/EmptyDataPack.java

@@ -1,36 +0,0 @@
-/*
- * Copyright 2000-2014 JetBrains s.r.o.
- *
- * 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.intellij.vcs.log.data;
-
-import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.util.ConstantFunction;
-import com.intellij.vcs.log.Hash;
-import com.intellij.vcs.log.VcsLogProvider;
-import com.intellij.vcs.log.VcsRef;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collections;
-import java.util.Set;
-
-public class EmptyDataPack {
-
-  @NotNull
-  public static DataPack getInstance() {
-    RefsModel emptyModel = new RefsModel(Collections.<VirtualFile, Set<VcsRef>>emptyMap(), new ConstantFunction<Hash, Integer>(0));
-    return new DataPack(emptyModel, EmptyPermanentGraph.getInstance(), Collections.<VirtualFile, VcsLogProvider>emptyMap(), false);
-  }
-
-}

platform/vcs-log/impl/src/com/intellij/vcs/log/data/VcsLogRefresherImpl.java

@@ -55,7 +55,7 @@ public class VcsLogRefresherImpl implements VcsLogRefresher {
 
   @NotNull private final SingleTaskController<RefreshRequest, DataPack> mySingleTaskController;
 
-  @NotNull private DataPack myDataPack = EmptyDataPack.getInstance();
+  @NotNull private DataPack myDataPack = DataPack.EMPTY;
 
   public VcsLogRefresherImpl(@NotNull final Project project,
                              @NotNull VcsLogHashMap hashMap,
@@ -106,7 +106,7 @@ public class VcsLogRefresherImpl implements VcsLogRefresher {
     }
     catch (VcsException e) {
       myExceptionHandler.consume(e);
-      return EmptyDataPack.getInstance();
+      return DataPack.EMPTY;
     }
   }
 
@@ -214,7 +214,7 @@ public class VcsLogRefresherImpl implements VcsLogRefresher {
       Collection<VirtualFile> rootsToRefresh = ContainerUtil.newArrayList();
       for (RefreshRequest request : requests) {
         if (request == RefreshRequest.RELOAD_ALL) {
-          myCurrentDataPack = EmptyDataPack.getInstance();
+          myCurrentDataPack = DataPack.EMPTY;
           return myProviders.keySet();
         }
         rootsToRefresh.addAll(request.rootsToRefresh);
@@ -251,7 +251,7 @@ public class VcsLogRefresherImpl implements VcsLogRefresher {
       }
       catch (Exception e) {
         myExceptionHandler.consume(e);
-        return EmptyDataPack.getInstance();
+        return DataPack.EMPTY;
       }
       finally {
         sw.report();

platform/vcs-log/impl/src/com/intellij/vcs/log/data/VisiblePack.java

@@ -26,7 +26,7 @@ import java.util.Map;
 
 public class VisiblePack implements VcsLogDataPack {
 
-  public static final VisiblePack EMPTY = new VisiblePack(EmptyDataPack.getInstance(), EmptyVisibleGraph.getInstance(), false);
+  public static final VisiblePack EMPTY = new VisiblePack(DataPack.EMPTY, EmptyVisibleGraph.getInstance(), false);
 
   @NotNull private final DataPack myDataPack;
   @NotNull private final VisibleGraph<Integer> myVisibleGraph;