From cd5b53db93d99b402ae09ba9968236a7a3c626ce Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Tue, 29 Jul 2014 11:01:20 +0200
Subject: [PATCH] RootIndex: cache non-existent packages (IDEA-127942)

---
 .../intellij/openapi/roots/impl/RootIndex.java   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/RootIndex.java b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/RootIndex.java
index 165a77b411af..eb04fb6c103e 100644
--- a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/RootIndex.java
+++ b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/RootIndex.java
@@ -25,13 +25,16 @@ import com.intellij.openapi.roots.*;
 import com.intellij.openapi.roots.impl.libraries.LibraryEx;
 import com.intellij.openapi.roots.libraries.Library;
 import com.intellij.openapi.util.Condition;
+import com.intellij.openapi.util.LowMemoryWatcher;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VfsUtilCore;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.vfs.newvfs.events.VFileEvent;
 import com.intellij.util.CollectionQuery;
+import com.intellij.util.EmptyQuery;
 import com.intellij.util.Query;
+import com.intellij.util.containers.ConcurrentHashSet;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.MultiMap;
 import gnu.trove.TObjectIntHashMap;
@@ -62,11 +65,20 @@ public class RootIndex {
   };
 
   private final Map<String, List<VirtualFile>> myDirectoriesByPackageNameCache = ContainerUtil.newConcurrentMap();
+  private final Set<String> myNonExistentPackages = new ConcurrentHashSet<String>();
   private final InfoCache myInfoCache;
   private final List<JpsModuleSourceRootType<?>> myRootTypes = ContainerUtil.newArrayList();
   private final TObjectIntHashMap<JpsModuleSourceRootType<?>> myRootTypeId = new TObjectIntHashMap<JpsModuleSourceRootType<?>>();
   @NotNull private final Project myProject;
   private volatile Map<VirtualFile, OrderEntry[]> myOrderEntries;
+  @SuppressWarnings("UnusedDeclaration")
+  private final LowMemoryWatcher myLowMemoryWatcher = LowMemoryWatcher.register(new Runnable() {
+    @Override
+    public void run() {
+      myNonExistentPackages.clear();
+    }
+  });
+
 
   // made public for Upsource
   public RootIndex(@NotNull Project project, @NotNull InfoCache cache) {
@@ -321,6 +333,8 @@ public class RootIndex {
   public Query<VirtualFile> getDirectoriesByPackageName(@NotNull final String packageName, final boolean includeLibrarySources) {
     List<VirtualFile> result = myDirectoriesByPackageNameCache.get(packageName);
     if (result == null) {
+      if (myNonExistentPackages.contains(packageName)) return EmptyQuery.getEmptyQuery();
+
       result = ContainerUtil.newSmartList();
 
       if (StringUtil.isNotEmpty(packageName) && !StringUtil.startsWithChar(packageName, '.')) {
@@ -348,6 +362,8 @@ public class RootIndex {
 
       if (!result.isEmpty()) {
         myDirectoriesByPackageNameCache.put(packageName, result);
+      } else {
+        myNonExistentPackages.add(packageName);
       }
     }