reuse common user data maps in VFS to save memory

platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/UserDataInterner.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2000-2014 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.openapi.vfs.newvfs.impl;
+
+import com.intellij.util.ConcurrencyUtil;
+import com.intellij.util.containers.ConcurrentWeakHashMap;
+import com.intellij.util.keyFMap.KeyFMap;
+import com.intellij.util.keyFMap.OneElementFMap;
+import org.jetbrains.annotations.NotNull;
+
+import java.nio.charset.Charset;
+
+/**
+ * @author peter
+ */
+class UserDataInterner {
+  private static final ConcurrentWeakHashMap<OneElementFMap, OneElementFMap> ourCache = new ConcurrentWeakHashMap<OneElementFMap, OneElementFMap>();
+
+  static KeyFMap internUserData(@NotNull KeyFMap map) {
+    if (map instanceof OneElementFMap && shouldIntern((OneElementFMap)map)) {
+      return ConcurrencyUtil.cacheOrGet(ourCache, (OneElementFMap)map, (OneElementFMap)map);
+    }
+    return map;
+  }
+
+  private static boolean shouldIntern(OneElementFMap map) {
+    Object value = map.getValue();
+    return value instanceof Enum || value instanceof Boolean || value instanceof Charset;
+  }
+}

platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/VirtualDirectoryImpl.java

@@ -536,7 +536,7 @@ public class VirtualDirectoryImpl extends VirtualFileSystemEntry {
 
   @Override
   protected boolean changeUserMap(KeyFMap oldMap, KeyFMap newMap) {
-    return myData.changeUserMap(oldMap, newMap);
+    return myData.changeUserMap(oldMap, UserDataInterner.internUserData(newMap));
   }
 
 }

platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/impl/VirtualFileImpl.java

@@ -142,7 +142,7 @@ public class VirtualFileImpl extends VirtualFileSystemEntry {
 
   @Override
   protected boolean changeUserMap(KeyFMap oldMap, KeyFMap newMap) {
-    return mySegment.changeUserMap(Math.abs(getId()), oldMap, newMap);
+    return mySegment.changeUserMap(Math.abs(getId()), oldMap, UserDataInterner.internUserData(newMap));
   }
 
 }

platform/util/src/com/intellij/util/keyFMap/ArrayBackedFMap.java

@@ -78,7 +78,7 @@ class ArrayBackedFMap implements KeyFMap {
         if (oldSize == 3) {
           int i1 = (2-i)/2;
           int i2 = 3 - (i+2)/2;
-          return new PairElementsFMap(keys[i1], values[i1], keys[i2], values[i2]);
+          return new PairElementsFMap(Key.getKeyByIndex(keys[i1]), values[i1], Key.getKeyByIndex(keys[i2]), values[i2]);
         }
         int newSize = oldSize - 1;
         int[] newKeys = new int[newSize];

platform/util/src/com/intellij/util/keyFMap/EmptyFMap.java

@@ -25,7 +25,7 @@ class EmptyFMap implements KeyFMap {
   @NotNull
   @Override
   public <V> KeyFMap plus(@NotNull Key<V> key, @NotNull V value) {
-    return new OneElementFMap<V>(key.hashCode(), value);
+    return new OneElementFMap<V>(key, value);
   }
 
   @NotNull

platform/util/src/com/intellij/util/keyFMap/OneElementFMap.java

@@ -18,45 +18,69 @@ package com.intellij.util.keyFMap;
 import com.intellij.openapi.util.Key;
 import org.jetbrains.annotations.NotNull;
 
-class OneElementFMap<V> implements KeyFMap {
-  private final int myKeyCode;
+public class OneElementFMap<V> implements KeyFMap {
+  private final Key myKey;
   private final V myValue;
 
-  OneElementFMap(int keyCode, @NotNull V value) {
-    myKeyCode = keyCode;
+  public OneElementFMap(Key key, @NotNull V value) {
+    myKey = key;
     myValue = value;
   }
 
   @NotNull
   @Override
   public <V> KeyFMap plus(@NotNull Key<V> key, @NotNull V value) {
-    int keyCode = key.hashCode();
-    if (myKeyCode == keyCode) return new OneElementFMap<V>(keyCode, value);
-    return new PairElementsFMap(myKeyCode, myValue, keyCode, value);
+    if (myKey == key) return new OneElementFMap<V>(key, value);
+    return new PairElementsFMap(myKey, myValue, key, value);
   }
 
   @NotNull
   @Override
   public KeyFMap minus(@NotNull Key<?> key) {
-    if (key.hashCode() == myKeyCode) {
-      return KeyFMap.EMPTY_MAP;
-    }
-    return this;
+    return key == myKey ? KeyFMap.EMPTY_MAP : this;
   }
 
   @Override
   public <V> V get(@NotNull Key<V> key) {
     //noinspection unchecked
-    return myKeyCode == key.hashCode() ? (V)myValue : null;
+    return myKey == key ? (V)myValue : null;
   }
 
   @Override
   public String toString() {
-    return "<"+Key.getKeyByIndex(myKeyCode) + " -> " + myValue+">";
+    return "<" + myKey + " -> " + myValue+">";
   }
 
   @Override
   public boolean isEmpty() {
     return false;
   }
+
+  public Key getKey() {
+    return myKey;
+  }
+
+  public V getValue() {
+    return myValue;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (!(o instanceof OneElementFMap)) return false;
+
+    OneElementFMap map = (OneElementFMap)o;
+
+    if (!myKey.equals(map.myKey)) return false;
+    if (!myValue.equals(map.myValue)) return false;
+
+    return true;
+  }
+
+  @Override
+  public int hashCode() {
+    int result = myKey.hashCode();
+    result = 31 * result + myValue.hashCode();
+    return result;
+  }
 }

platform/util/src/com/intellij/util/keyFMap/PairElementsFMap.java

@@ -19,12 +19,12 @@ import com.intellij.openapi.util.Key;
 import org.jetbrains.annotations.NotNull;
 
 class PairElementsFMap implements KeyFMap {
-  private final int key1;
-  private final int key2;
+  private final Key key1;
+  private final Key key2;
   private final Object value1;
   private final Object value2;
 
-  PairElementsFMap(int key1, @NotNull Object value1, int key2, @NotNull Object value2) {
+  PairElementsFMap(Key key1, @NotNull Object value1, Key key2, @NotNull Object value2) {
     this.key1 = key1;
     this.value1 = value1;
     this.key2 = key2;
@@ -35,31 +35,28 @@ class PairElementsFMap implements KeyFMap {
   @NotNull
   @Override
   public <V> KeyFMap plus(@NotNull Key<V> key, @NotNull V value) {
-    int keyCode = key.hashCode();
-    if (keyCode == key1) return new PairElementsFMap(keyCode, value, key2, value2);
-    if (keyCode == key2) return new PairElementsFMap(keyCode, value, key1, value1);
-    return new ArrayBackedFMap(new int[]{key1, key2, keyCode}, new Object[]{value1, value2, value});
+    if (key == key1) return new PairElementsFMap(key, value, key2, value2);
+    if (key == key2) return new PairElementsFMap(key, value, key1, value1);
+    return new ArrayBackedFMap(new int[]{key1.hashCode(), key2.hashCode(), key.hashCode()}, new Object[]{value1, value2, value});
   }
 
   @NotNull
   @Override
   public KeyFMap minus(@NotNull Key<?> key) {
-    int keyCode = key.hashCode();
-    if (keyCode == key1) return new OneElementFMap<Object>(key2, value2);
-    if (keyCode == key2) return new OneElementFMap<Object>(key1, value1);
+    if (key == key1) return new OneElementFMap<Object>(key2, value2);
+    if (key == key2) return new OneElementFMap<Object>(key1, value1);
     return this;
   }
 
   @Override
   public <V> V get(@NotNull Key<V> key) {
-    int keyCode = key.hashCode();
     //noinspection unchecked
-    return keyCode == key1 ? (V)value1 : keyCode == key2 ? (V)value2 : null;
+    return key == key1 ? (V)value1 : key == key2 ? (V)value2 : null;
   }
 
   @Override
   public String toString() {
-    return "Pair: ("+ Key.getKeyByIndex(key1) + " -> " + value1+"; "+Key.getKeyByIndex(key2) + " -> " + value2 + ")";
+    return "Pair: (" + key1 + " -> " + value1 + "; " + key2 + " -> " + value2 + ")";
   }
 
   @Override