From 86df77cf40f5361da0b10be78ef938ef6bc4854a Mon Sep 17 00:00:00 2001
From: Kirill Likhodedov <Kirill.Likhodedov@jetbrains.com>
Date: Tue, 11 Dec 2018 15:47:56 +0300
Subject: [PATCH] git: optimize checking if a directory is a Git or Hg root

Checking the File is expensive. If the file is already inside the VFS, checking it via the VFS is more efficient.

IDEA-201588
---
 .../src/com/intellij/openapi/vcs/VcsRootChecker.java       | 7 +++++++
 .../intellij/openapi/vcs/roots/VcsRootDetectorImpl.java    | 3 +--
 plugins/git4idea/src/git4idea/roots/GitRootChecker.java    | 5 +++++
 .../hg4idea/src/org/zmlx/hg4idea/roots/HgRootChecker.java  | 7 +++++++
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/platform/vcs-api/src/com/intellij/openapi/vcs/VcsRootChecker.java b/platform/vcs-api/src/com/intellij/openapi/vcs/VcsRootChecker.java
index 930edfd06f00..23a965b2549b 100644
--- a/platform/vcs-api/src/com/intellij/openapi/vcs/VcsRootChecker.java
+++ b/platform/vcs-api/src/com/intellij/openapi/vcs/VcsRootChecker.java
@@ -36,6 +36,13 @@ public abstract class VcsRootChecker {
     return false;
   }
 
+  /**
+   * Checks if the given directory is a root of the supported VCS.
+   */
+  public boolean isRoot(@NotNull VirtualFile maybeRoot) {
+    return isRoot(maybeRoot.getPath());
+  }
+
   /**
    * Returns the VCS supported by this checker.
    */
diff --git a/platform/vcs-impl/src/com/intellij/openapi/vcs/roots/VcsRootDetectorImpl.java b/platform/vcs-impl/src/com/intellij/openapi/vcs/roots/VcsRootDetectorImpl.java
index fc4b1a6ec7fe..6b83d7a6146d 100644
--- a/platform/vcs-impl/src/com/intellij/openapi/vcs/roots/VcsRootDetectorImpl.java
+++ b/platform/vcs-impl/src/com/intellij/openapi/vcs/roots/VcsRootDetectorImpl.java
@@ -143,9 +143,8 @@ public class VcsRootDetectorImpl implements VcsRootDetector {
 
   @Nullable
   private AbstractVcs getVcsFor(@NotNull VirtualFile maybeRoot, @Nullable VirtualFile dirToCheckForIgnore) {
-    String path = maybeRoot.getPath();
     for (VcsRootChecker checker : myCheckers) {
-      if (checker.isRoot(path) && (dirToCheckForIgnore == null || !checker.isIgnored(maybeRoot, dirToCheckForIgnore))) {
+      if (checker.isRoot(maybeRoot) && (dirToCheckForIgnore == null || !checker.isIgnored(maybeRoot, dirToCheckForIgnore))) {
         return myVcsManager.findVcsByName(checker.getSupportedVcs().getName());
       }
     }
diff --git a/plugins/git4idea/src/git4idea/roots/GitRootChecker.java b/plugins/git4idea/src/git4idea/roots/GitRootChecker.java
index 5d40640511d1..8f91dac7c68d 100644
--- a/plugins/git4idea/src/git4idea/roots/GitRootChecker.java
+++ b/plugins/git4idea/src/git4idea/roots/GitRootChecker.java
@@ -39,6 +39,11 @@ public class GitRootChecker extends VcsRootChecker {
     return GitUtil.isGitRoot(path);
   }
 
+  @Override
+  public boolean isRoot(@NotNull VirtualFile maybeRoot) {
+    return GitUtil.findGitDir(maybeRoot) != null;
+  }
+
   @Override
   @NotNull
   public VcsKey getSupportedVcs() {
diff --git a/plugins/hg4idea/src/org/zmlx/hg4idea/roots/HgRootChecker.java b/plugins/hg4idea/src/org/zmlx/hg4idea/roots/HgRootChecker.java
index 887568a6a15d..fb2143d01c4d 100644
--- a/plugins/hg4idea/src/org/zmlx/hg4idea/roots/HgRootChecker.java
+++ b/plugins/hg4idea/src/org/zmlx/hg4idea/roots/HgRootChecker.java
@@ -17,6 +17,8 @@ package org.zmlx.hg4idea.roots;
 
 import com.intellij.openapi.vcs.VcsKey;
 import com.intellij.openapi.vcs.VcsRootChecker;
+import com.intellij.openapi.vfs.VfsUtil;
+import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 import org.zmlx.hg4idea.HgVcs;
 import org.zmlx.hg4idea.util.HgUtil;
@@ -33,6 +35,11 @@ public class HgRootChecker extends VcsRootChecker {
     return new File(path, HgUtil.DOT_HG).exists();
   }
 
+  @Override
+  public boolean isRoot(@NotNull VirtualFile maybeRoot) {
+    return VfsUtil.refreshAndFindChild(maybeRoot, HgUtil.DOT_HG) != null;
+  }
+
   @NotNull
   @Override
   public VcsKey getSupportedVcs() {