low contention counter

platform/platform-impl/src/com/intellij/openapi/editor/impl/RangeMarkerImpl.java

@@ -21,12 +21,11 @@ import com.intellij.openapi.editor.ex.DocumentEx;
 import com.intellij.openapi.editor.ex.RangeMarkerEx;
 import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.UserDataHolderBase;
+import com.intellij.util.DistributedCounter;
 import com.intellij.util.Processor;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.concurrent.atomic.AtomicLong;
-
 public class RangeMarkerImpl extends UserDataHolderBase implements RangeMarkerEx, MutableInterval {
   private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.editor.impl.RangeMarkerImpl");
 
@@ -34,8 +33,7 @@ public class RangeMarkerImpl extends UserDataHolderBase implements RangeMarkerEx
   protected RangeMarkerTree.RMNode myNode;
 
   private final long myId;
-  //private static long counter;
-  private static final AtomicLong counter = new AtomicLong();
+  private static final DistributedCounter counter = new DistributedCounter();
 
   protected RangeMarkerImpl(@NotNull DocumentEx document, int start, int end, boolean register) {
     this(document, start, end, register, false, false);
@@ -52,7 +50,7 @@ public class RangeMarkerImpl extends UserDataHolderBase implements RangeMarkerEx
     }
 
     myDocument = document;
-    myId = counter.getAndIncrement();
+    myId = counter.next();
     if (register) {
       registerInTree(start, end, greedyToLeft, greedyToRight, 0);
     }

platform/util/src/com/intellij/util/DistributedCounter.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2000-2011 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.util;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * Low-contention counter.
+ * Repeated calls to {@link #next()} return increasing numbers unique across all calling threads.
+ */
+public class DistributedCounter {
+  private static final int CHUNK_SIZE = 1000;
+  private final AtomicLong nextChunkStart = new AtomicLong();
+  // must not ne static
+  private final ThreadLocal<NextPair> localCounter = new ThreadLocal<NextPair>();
+  private static class NextPair {
+    long nextId;
+    final long limit;
+
+    private NextPair(long nextId, long limit) {
+      this.nextId = nextId;
+      this.limit = limit;
+    }
+  }
+
+  public long next() {
+    NextPair nextPair = localCounter.get();
+    if (nextPair == null || nextPair.nextId == nextPair.limit) {
+      long start = nextChunkStart.getAndAdd(CHUNK_SIZE);
+      nextPair = new NextPair(start, start + CHUNK_SIZE);
+      localCounter.set(nextPair);
+    }
+    long result = nextPair.nextId;
+    nextPair.nextId++;
+    return result;
+  }
+}