From 13b380716682691f911fe955aebf4c5f4b2cabc1 Mon Sep 17 00:00:00 2001
From: Dmitry Avdeev <Dmitry.Avdeev@jetbrains.com>
Date: Tue, 27 Oct 2015 16:01:00 +0300
Subject: [PATCH] IDEA-146849 IntelliJ hangs for 30+ seconds with large Android
 project after leaving and returning...

---
 .../com/intellij/roots/ModuleGraphTest.java   | 54 +++++++++++++++++++
 .../intellij/util/graph/GraphAlgorithms.java  |  9 ++++
 .../util/graph/impl/GraphAlgorithmsImpl.java  | 12 +++++
 3 files changed, 75 insertions(+)
 create mode 100644 java/java-tests/testSrc/com/intellij/roots/ModuleGraphTest.java

diff --git a/java/java-tests/testSrc/com/intellij/roots/ModuleGraphTest.java b/java/java-tests/testSrc/com/intellij/roots/ModuleGraphTest.java
new file mode 100644
index 000000000000..c1aadc0092bc
--- /dev/null
+++ b/java/java-tests/testSrc/com/intellij/roots/ModuleGraphTest.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2000-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.roots;
+
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.module.ModuleManager;
+import com.intellij.openapi.roots.DependencyScope;
+import com.intellij.openapi.roots.ModuleRootModificationUtil;
+import com.intellij.util.containers.ContainerUtil;
+import com.intellij.util.graph.Graph;
+import com.intellij.util.graph.GraphAlgorithms;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * @author Dmitry Avdeev
+ */
+public class ModuleGraphTest extends ModuleRootManagerTestCase {
+
+  public void testOuts() throws Exception {
+
+    Module a = createModule("a");
+    Module b = createModule("b");
+    addDependency(myModule, a);
+    addDependency(a, b);
+
+    Graph<Module> graph = ModuleManager.getInstance(getProject()).moduleGraph();
+    List<Module> outs = ContainerUtil.collect(graph.getOut(a));
+    assertEquals(1, outs.size());
+
+    Set<Module> set = new HashSet<>();
+    GraphAlgorithms.getInstance().collectOutsRecursively(graph, b, set);
+    assertEquals(3, set.size());
+  }
+
+  protected void addDependency(Module module, Module a) {
+    ModuleRootModificationUtil.addDependency(module, a, DependencyScope.COMPILE, true);
+  }
+}
diff --git a/platform/platform-api/src/com/intellij/util/graph/GraphAlgorithms.java b/platform/platform-api/src/com/intellij/util/graph/GraphAlgorithms.java
index 6ae9d4491844..b5cf7835d89b 100644
--- a/platform/platform-api/src/com/intellij/util/graph/GraphAlgorithms.java
+++ b/platform/platform-api/src/com/intellij/util/graph/GraphAlgorithms.java
@@ -54,4 +54,13 @@ public abstract class GraphAlgorithms {
 
   @NotNull
   public abstract <Node> Graph<Chunk<Node>> computeSCCGraph(@NotNull Graph<Node> graph);
+
+  /**
+   * Adds start node and all its outs to given set recursively.
+   * If start node is in set already, returns immediately.
+   *
+   * @param start node to start from
+   * @param set set to be populated
+   */
+  public abstract <Node> void collectOutsRecursively(@NotNull Graph<Node> graph, Node start, Set<Node> set);
 }
diff --git a/platform/platform-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java b/platform/platform-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
index 7fe41a92f864..9beb9a49db57 100644
--- a/platform/platform-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
+++ b/platform/platform-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
@@ -111,6 +111,18 @@ public class GraphAlgorithmsImpl extends GraphAlgorithms {
     }));
   }
 
+  @Override
+  public <Node> void collectOutsRecursively(@NotNull Graph<Node> graph, Node start, Set<Node> set) {
+    if (!set.add(start)) {
+      return;
+    }
+    Iterator<Node> iterator = graph.getOut(start);
+    while (iterator.hasNext()) {
+      Node node = iterator.next();
+      collectOutsRecursively(graph, node, set);
+    }
+  }
+
   @NotNull
   @Override
   public <Node> Collection<Chunk<Node>> computeStronglyConnectedComponents(@NotNull Graph<Node> graph) {