start dumb mode more often

When number of updated files is small also
count their size and start dumb mode if the size is large enough,
currently 1M (configurable)

platform/lang-impl/src/com/intellij/util/indexing/FileBasedIndexImpl.java

@@ -105,10 +105,12 @@ import java.util.concurrent.Phaser;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.Consumer;
 import java.util.stream.Stream;
 
 /**
@@ -287,6 +289,20 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
     }
   }
 
+  long getChangedFilesSize() {
+    Set<VirtualFile> changed = new THashSet<>();
+    AtomicLong changedFilesSize = new AtomicLong();
+
+    Consumer<VirtualFile> consumer = file -> {
+      if (file.isValid() && changed.add(file)) {
+        changedFilesSize.addAndGet(file.getLength());
+      }
+    };
+    myChangedFilesCollector.myVfsEventsMerger.getChangedFiles().forEach(consumer);
+    myChangedFilesCollector.myFilesToUpdate.values().forEach(consumer);
+    return changedFilesSize.get();
+  }
+
   public static boolean isProjectOrWorkspaceFile(@NotNull VirtualFile file, @Nullable FileType fileType) {
     return ProjectCoreUtil.isProjectOrWorkspaceFile(file, fileType);
   }
@@ -383,6 +399,7 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
           ContentHashesSupport.initContentHashesEnumerator();
           contentHashesEnumeratorOk = true;
         }
+        long started = System.currentTimeMillis();
         storage = new VfsAwareMapIndexStorage<>(
           IndexInfrastructure.getStorageFile(name),
           extension.getKeyDescriptor(),
@@ -391,6 +408,7 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
           extension.keyIsUniqueForIndexedFile(),
           extension.traceKeyHashToVirtualFileMapping()
         );
+        LOG.info("Initialized index " + (System.currentTimeMillis() - started) + " for " + name);
 
         final InputFilter inputFilter = extension.getInputFilter();
         final Set<FileType> addedTypes = new THashSet<>();

platform/lang-impl/src/com/intellij/util/indexing/FileBasedIndexProjectHandler.java

@@ -30,6 +30,7 @@ import com.intellij.openapi.project.*;
 import com.intellij.openapi.roots.ContentIterator;
 import com.intellij.openapi.roots.impl.PushedFilePropertiesUpdater;
 import com.intellij.openapi.startup.StartupManager;
+import com.intellij.openapi.util.registry.Registry;
 import com.intellij.openapi.vfs.VfsUtilCore;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.vfs.VirtualFileVisitor;
@@ -113,6 +114,9 @@ public class FileBasedIndexProjectHandler implements IndexableFileSet, Disposabl
     myIndex.removeIndexableSet(this);
   }
 
+  private static final int ourMinFilesToStartDumMode = Registry.intValue("ide.dumb.mode.minFilesToStart", 20);
+  private static final int ourMinFilesSizeToStartDumMode = Registry.intValue("ide.dumb.mode.minFilesSizeToStart", 1048576);
+  
   @Nullable
   public static DumbModeTask createChangedFilesIndexingTask(final Project project) {
     final FileBasedIndex i = FileBasedIndex.getInstance();
@@ -121,8 +125,8 @@ public class FileBasedIndexProjectHandler implements IndexableFileSet, Disposabl
     }
 
     final FileBasedIndexImpl index = (FileBasedIndexImpl)i;
-    if (index.getChangedFileCount() < 20) {
-      return null;
+    if (index.getChangedFileCount() < ourMinFilesToStartDumMode) {
+      if (index.getChangedFilesSize() < ourMinFilesSizeToStartDumMode) return null;
     }
 
     return new DumbModeTask(project.getComponent(FileBasedIndexProjectHandler.class)) {

platform/util/resources/misc/registry.properties

@@ -191,6 +191,11 @@ editor.virtual.lines.description=Number of virtual empty lines displayed at the
 
 ide.showIndexRebuildMessage=false
 
+ide.dumb.mode.minFilesToStart=20
+ide.dumb.mode.minFilesToStart.description=How many files should be changed for IDE to start dumb mode
+ide.dumb.mode.minFilesSizeToStart=1048576
+ide.dumb.mode.minFilesSizeToStart.description=How large should be updated files's size to start dumb mode in case there are a few of them
+
 ide.tabbedPane.bufferedPaint=true
 ide.tabbedPane.dragOutMultiplier=1.2