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A packaging of the IntelliJ Community Edition core-api library. This is release number 1 of trunk branch 142.
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/*
 * 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.util;

import com.intellij.util.SmartList;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

class ExecutionCallback {
  private int myCurrentCount;
  private final int myCountToExecution;
  private List myRunnables;

  ExecutionCallback() {
    this(1);
  }

  ExecutionCallback(int executedCount) {
    myCountToExecution = executedCount;
    assert executedCount >= 1 : executedCount;
  }

  /**
   * @return true if was executed, false if specified executed count is not yet done
   */
  boolean setExecuted() {
    if (!signalExecution()) {
      return false;
    }

    List all;
    synchronized (this) {
      if (myRunnables == null) {
        return true;
      }
      else {
        all = myRunnables;
        myRunnables = null;
      }
    }
    for (Runnable each : all) {
      each.run();
    }
    return true;
  }

  private static class CompositeRunnable extends ArrayList implements Runnable {
    private CompositeRunnable(@NotNull Collection c) {
      super(c);
    }

    @Override
    public void run() {
      for (Runnable runnable : this) {
        runnable.run();
      }
    }
  }

  final void doWhenExecuted(@NotNull final Runnable runnable) {
    Runnable toRun;
    synchronized (this) {
      if (isExecuted()) {
        if (myRunnables == null) {
          toRun = runnable;
        }
        else {
          CompositeRunnable composite = new CompositeRunnable(myRunnables);
          composite.add(runnable);
          toRun = composite;
          myRunnables = null;
        }
      }
      else {
        if (myRunnables == null) {
          myRunnables = new SmartList();
        }

        myRunnables.add(runnable);
        return;
      }
    }

    toRun.run();
  }

  /**
   * Avoid memory leak in case: myDone executed but myRejected still keep doWhenRejected listeners (and vice versa)
   */
  synchronized void clear() {
    myRunnables = null;
  }

  private synchronized boolean signalExecution() {
    return ++myCurrentCount >= myCountToExecution;
  }

  synchronized boolean isExecuted() {
    return myCurrentCount >= myCountToExecution;
  }

  @NonNls
  @Override
  public synchronized String toString() {
    return "current=" + myCurrentCount + " countToExecution=" + myCountToExecution;
  }
}