From 71e7e41b7cea8cb257e34adbdbaf7e095909cd9a Mon Sep 17 00:00:00 2001
From: Maxim Shafirov <max@jetbrains.com>
Date: Mon, 6 Feb 2012 19:42:48 +0400
Subject: [PATCH] Don't check .isFile() too often, don't call .list() too often

---
 .../intellij/core/CoreJavaFileManager.java    | 26 ++++++++++++-------
 .../vfs/local/CoreLocalVirtualFile.java       | 17 ++++++++----
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/java/java-psi-impl/src/com/intellij/core/CoreJavaFileManager.java b/java/java-psi-impl/src/com/intellij/core/CoreJavaFileManager.java
index 845339e66d7a..06b1eb6a65f5 100644
--- a/java/java-psi-impl/src/com/intellij/core/CoreJavaFileManager.java
+++ b/java/java-psi-impl/src/com/intellij/core/CoreJavaFileManager.java
@@ -27,14 +27,12 @@ import com.intellij.psi.impl.file.impl.JavaFileManager;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.util.CollectionQuery;
 import com.intellij.util.Query;
+import com.intellij.util.containers.ConcurrentFactoryMap;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.List;
+import java.util.*;
 
 /**
  * @author yole
@@ -45,6 +43,19 @@ public class CoreJavaFileManager extends PackageIndex implements JavaFileManager
   private final CoreLocalFileSystem myLocalFileSystem;
   private final CoreJarFileSystem myJarFileSystem;
   private final List<File> myClasspath = new ArrayList<File>();
+
+  private final Map<File, VirtualFile> myClasspathRoots = new ConcurrentFactoryMap<File, VirtualFile>() {
+    @Override
+    protected VirtualFile create(File key) {
+      if (key.isFile()) {
+         return myJarFileSystem.findFileByPath(key.getPath() + "!/");
+      }
+      else {
+        return myLocalFileSystem.findFileByPath(key.getPath());
+      }
+    }
+  };
+
   private final PsiManager myPsiManager;
 
   public CoreJavaFileManager(PsiManager psiManager, CoreLocalFileSystem localFileSystem, CoreJarFileSystem jarFileSystem) {
@@ -94,12 +105,7 @@ public class CoreJavaFileManager extends PackageIndex implements JavaFileManager
 
   @Nullable
   private VirtualFile findRootInClassPathEntry(File classpathEntry) {
-    if (classpathEntry.isFile()) {
-       return myJarFileSystem.findFileByPath(classpathEntry.getPath() + "!/");
-    }
-    else {
-      return myLocalFileSystem.findFileByPath(classpathEntry.getPath());
-    }
+    return myClasspathRoots.get(classpathEntry);
   }
 
   @Override
diff --git a/platform/core-impl/src/com/intellij/openapi/vfs/local/CoreLocalVirtualFile.java b/platform/core-impl/src/com/intellij/openapi/vfs/local/CoreLocalVirtualFile.java
index 067fe61a8266..5b330f4c3772 100644
--- a/platform/core-impl/src/com/intellij/openapi/vfs/local/CoreLocalVirtualFile.java
+++ b/platform/core-impl/src/com/intellij/openapi/vfs/local/CoreLocalVirtualFile.java
@@ -31,6 +31,7 @@ import java.util.List;
 public class CoreLocalVirtualFile extends VirtualFile {
   private final CoreLocalFileSystem myFileSystem;
   private final File myIoFile;
+  private VirtualFile[] myChildren;
 
   public CoreLocalVirtualFile(CoreLocalFileSystem fileSystem, File ioFile) {
     myFileSystem = fileSystem;
@@ -77,12 +78,18 @@ public class CoreLocalVirtualFile extends VirtualFile {
 
   @Override
   public VirtualFile[] getChildren() {
-    List<VirtualFile> result = new ArrayList<VirtualFile>();
-    final File[] files = myIoFile.listFiles();
-    for (File file : files) {
-      result.add(new CoreLocalVirtualFile(myFileSystem, file));
+    VirtualFile[] answer = myChildren;
+    if (answer == null) {
+      List<VirtualFile> result = new ArrayList<VirtualFile>();
+      final File[] files = myIoFile.listFiles();
+      for (File file : files) {
+        result.add(new CoreLocalVirtualFile(myFileSystem, file));
+      }
+      answer = result.toArray(new VirtualFile[result.size()]);
+
+      myChildren = answer;
     }
-    return result.toArray(new VirtualFile[result.size()]);
+    return answer;
   }
 
   @NotNull