Read action doesn't need to be in EDT

plugins/git4idea/src/git4idea/PlatformFacade.java

@@ -18,6 +18,7 @@ package git4idea;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.ProjectRootManager;
 import com.intellij.openapi.ui.DialogWrapper;
+import com.intellij.openapi.util.Computable;
 import com.intellij.openapi.vcs.AbstractVcs;
 import com.intellij.openapi.vcs.ProjectLevelVcsManager;
 import org.jetbrains.annotations.NotNull;
@@ -55,7 +56,7 @@ public interface PlatformFacade {
   ProjectRootManager getProjectRootManager(@NotNull Project project);
 
   /**
-   * Invokes {@link com.intellij.openapi.application.Application#runReadAction(Runnable)} in AWT and waits if needed.
+   * Invokes {@link com.intellij.openapi.application.Application#runReadAction(Computable)}.
    */
-  void runReadActionAndWaitIfNeeded(@NotNull Runnable runnable);
+  <T> T runReadAction(@NotNull Computable<T> computable);
 }

plugins/git4idea/src/git4idea/PlatformFacadeImpl.java

@@ -19,9 +19,9 @@ import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.ProjectRootManager;
 import com.intellij.openapi.ui.DialogWrapper;
+import com.intellij.openapi.util.Computable;
 import com.intellij.openapi.vcs.AbstractVcs;
 import com.intellij.openapi.vcs.ProjectLevelVcsManager;
-import com.intellij.util.ui.UIUtil;
 import org.jetbrains.annotations.NotNull;
 
 /**
@@ -53,12 +53,8 @@ public class PlatformFacadeImpl implements PlatformFacade {
   }
 
   @Override
-  public void runReadActionAndWaitIfNeeded(@NotNull final Runnable runnable) {
-    UIUtil.invokeAndWaitIfNeeded(new Runnable() {
-      @Override public void run() {
-        ApplicationManager.getApplication().runReadAction(runnable);
-      }
-    });
+  public <T> T runReadAction(@NotNull Computable<T> computable) {
+    return ApplicationManager.getApplication().runReadAction(computable);
   }
 
   @NotNull

plugins/git4idea/src/git4idea/roots/GitRootDetector.java

@@ -16,6 +16,7 @@
 package git4idea.roots;
 
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.Computable;
 import com.intellij.openapi.vfs.VirtualFile;
 import git4idea.PlatformFacade;
 import org.jetbrains.annotations.NotNull;
@@ -24,7 +25,6 @@ import org.jetbrains.annotations.Nullable;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * <p>
@@ -94,10 +94,10 @@ public class GitRootDetector {
       return roots;
     }
 
-    myPlatformFacade.runReadActionAndWaitIfNeeded(new Runnable() {
-      @Override public void run() {
+    myPlatformFacade.runReadAction(new Computable<Object>() {
+      @Nullable @Override public Object compute() {
         if (myProject.isDisposed() || !dir.isDirectory()) {
-          return;
+          return null;
         }
         if (hasGitDir(dir)) {
           roots.add(dir);
@@ -105,6 +105,7 @@ public class GitRootDetector {
         for (VirtualFile child : dir.getChildren()) {
           roots.addAll(scanForRootsInsideDir(child, depth + 1));
         }
+        return null;
       }
     });
 
@@ -118,24 +119,22 @@ public class GitRootDetector {
 
   @Nullable
   private VirtualFile scanForSingleRootAboveDir(@NotNull final VirtualFile projectDir) {
-    final AtomicReference<VirtualFile> parent = new AtomicReference<VirtualFile>();
-    myPlatformFacade.runReadActionAndWaitIfNeeded(new Runnable() {
-      @Override public void run() {
+    return myPlatformFacade.runReadAction(new Computable<VirtualFile>() {
+      @Nullable @Override public VirtualFile compute() {
         if (myProject.isDisposed()) {
-          return;
+          return null;
         }
 
         VirtualFile par = projectDir.getParent();
         while (par != null) {
           if (hasGitDir(par)) {
-            parent.set(par);
-            return;
+            return par;
           }
           par = par.getParent();
         }
+        return null;
       }
     });
-    return parent.get();
   }
 
   private static boolean hasGitDir(@NotNull VirtualFile dir) {

plugins/git4idea/tests/git4idea/test/GitTestPlatformFacade.groovy

@@ -24,6 +24,7 @@ import git4idea.PlatformFacade
 import git4idea.tests.TestDialogManager
 import org.jetbrains.annotations.NotNull
 import com.intellij.openapi.roots.ProjectRootManager
+import com.intellij.openapi.util.Computable
 
 /**
  * 
@@ -72,8 +73,8 @@ public class GitTestPlatformFacade implements PlatformFacade {
   }
 
   @Override
-  void runReadActionAndWaitIfNeeded(Runnable runnable) {
-    runnable.run()
+  <T> T runReadAction(@NotNull Computable<T> computable) {
+    computable.compute()
   }
 
   @NotNull