[git] Optimize listening of VFS events: don't use VirtualFile#getFile(), use getPath() and getName() instead.

getFile() calls findChild for VFileCreateEvent, which may result in performance problems as in IDEA-87656.

platform/core-api/src/com/intellij/openapi/vfs/newvfs/events/VFileEvent.java

@@ -46,6 +46,9 @@ public abstract class VFileEvent {
   /**
    * Returns the VirtualFile which this event belongs to.
    * In some cases it may be null - it is not guaranteed that there is such file.
+   *
+   * NB: Use this method with caution, because {@link com.intellij.openapi.vfs.newvfs.events.VFileCreateEvent#getFile()} needs
+   * {@link VirtualFile#findChild(String)} which may be a performance leak.
    */
   @Nullable
   public abstract VirtualFile getFile();

plugins/git4idea/src/git4idea/repo/GitRepositoryUpdater.java

@@ -112,11 +112,11 @@ final class GitRepositoryUpdater implements Disposable, BulkFileListener {
     boolean rebaseFileChanged = false;
     boolean mergeFileChanged = false;
     for (VFileEvent event : events) {
-      final VirtualFile file = event.getFile();
-      if (file == null) {
+      String filePath = event.getPath();
+      if (filePath == null) {
         continue;
       }
-      String filePath = GitFileUtils.stripFileProtocolPrefix(file.getPath());
+      filePath = GitFileUtils.stripFileProtocolPrefix(filePath);
       if (myRepositoryFiles.isConfigFile(filePath)) {
         configChanged = true;
       } else if (myRepositoryFiles.isHeadFile(filePath)) {

plugins/git4idea/src/git4idea/repo/GitUntrackedFilesHolder.java

@@ -227,11 +227,10 @@ public class GitUntrackedFilesHolder implements Disposable, BulkFileListener {
       if (allChanged) {
         break;
       }
-      VirtualFile file = event.getFile();
-      if (file == null) {
+      String path = event.getPath();
+      if (path == null) {
         continue;
       }
-      String path = file.getPath();
       if (totalRefreshNeeded(path)) {
         allChanged = true;
       }

plugins/git4idea/src/git4idea/roots/GitRootScanner.java

@@ -25,7 +25,6 @@ import com.intellij.openapi.roots.ModuleRootListener;
 import com.intellij.openapi.startup.StartupManager;
 import com.intellij.openapi.vcs.ProjectLevelVcsManager;
 import com.intellij.openapi.vcs.VcsListener;
-import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.vfs.VirtualFileManager;
 import com.intellij.openapi.vfs.newvfs.BulkFileListener;
 import com.intellij.openapi.vfs.newvfs.events.VFileEvent;
@@ -79,8 +78,8 @@ public class GitRootScanner implements BulkFileListener, ModuleRootListener, Dis
   @Override
   public void after(@NotNull List<? extends VFileEvent> events) {
     for (VFileEvent event : events) {
-      VirtualFile file = event.getFile();
-      if (file != null && file.getName().equalsIgnoreCase(GitUtil.DOT_GIT) && file.isDirectory()) {
+      String filePath = event.getPath();
+      if (filePath != null && filePath.toLowerCase().endsWith(GitUtil.DOT_GIT)) {
         scanIfReady();
       }
     }