/*
 * Copyright (C) 2011 The Guava Authors
 *
 * 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.google.common.util.concurrent;

import static java.util.concurrent.TimeUnit.NANOSECONDS;

import com.google.common.annotations.Beta;
import com.google.common.base.Preconditions;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Utilities for treating interruptible operations as uninterruptible.
 * In all cases, if a thread is interrupted during such a call, the call
 * continues to block until the result is available or the timeout elapses,
 * and only then re-interrupts the thread.
 *
 * @author Anthony Zana
 * @since 10.0
 */
@Beta
public final class Uninterruptibles {

  // Implementation Note: As of 3-7-11, the logic for each blocking/timeout
  // methods is identical, save for method being invoked.

  /**
   * Invokes {@code latch.}{@link CountDownLatch#await() await()}
   * uninterruptibly.
   */
  public static void awaitUninterruptibly(CountDownLatch latch) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          latch.await();
          return;
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes
   * {@code latch.}{@link CountDownLatch#await(long, TimeUnit)
   * await(timeout, unit)} uninterruptibly.
   */
  public static boolean awaitUninterruptibly(CountDownLatch latch,
      long timeout, TimeUnit unit) {
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(timeout);
      long end = System.nanoTime() + remainingNanos;

      while (true) {
        try {
          // CountDownLatch treats negative timeouts just like zero.
          return latch.await(remainingNanos, NANOSECONDS);
        } catch (InterruptedException e) {
          interrupted = true;
          remainingNanos = end - System.nanoTime();
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes {@code toJoin.}{@link Thread#join() join()} uninterruptibly.
   */
  public static void joinUninterruptibly(Thread toJoin) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          toJoin.join();
          return;
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes {@code future.}{@link Future#get() get()} uninterruptibly.
   * To get uninterruptibility and remove checked exceptions, see
   * {@link Futures#getUnchecked}.
   *
   * <p>If instead, you wish to treat {@link InterruptedException} uniformly
   * with other exceptions, see {@link Futures#get(Future, Class) Futures.get}
   * or {@link Futures#makeChecked}.
   *
   * @throws ExecutionException if the computation threw an exception
   * @throws CancellationException if the computation was cancelled
   */
  public static <V> V getUninterruptibly(Future<V> future)
      throws ExecutionException {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          return future.get();
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes
   * {@code future.}{@link Future#get(long, TimeUnit) get(timeout, unit)}
   * uninterruptibly.
   *
   * <p>If instead, you wish to treat {@link InterruptedException} uniformly
   * with other exceptions, see {@link Futures#get(Future, Class) Futures.get}
   * or {@link Futures#makeChecked}.
   *
   * @throws ExecutionException if the computation threw an exception
   * @throws CancellationException if the computation was cancelled
   * @throws TimeoutException if the wait timed out
   */
  public static <V> V getUninterruptibly(
      Future<V> future, long timeout,  TimeUnit unit)
          throws ExecutionException, TimeoutException {
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(timeout);
      long end = System.nanoTime() + remainingNanos;

      while (true) {
        try {
          // Future treats negative timeouts just like zero.
          return future.get(remainingNanos, NANOSECONDS);
        } catch (InterruptedException e) {
          interrupted = true;
          remainingNanos = end - System.nanoTime();
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes
   * {@code unit.}{@link TimeUnit#timedJoin(Thread, long)
   * timedJoin(toJoin, timeout)} uninterruptibly.
   */
  public static void joinUninterruptibly(Thread toJoin,
      long timeout, TimeUnit unit) {
    Preconditions.checkNotNull(toJoin);
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(timeout);
      long end = System.nanoTime() + remainingNanos;
      while (true) {
        try {
          // TimeUnit.timedJoin() treats negative timeouts just like zero.
          NANOSECONDS.timedJoin(toJoin, remainingNanos);
          return;
        } catch (InterruptedException e) {
          interrupted = true;
          remainingNanos = end - System.nanoTime();
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes {@code queue.}{@link BlockingQueue#take() take()} uninterruptibly.
   */
  public static <E> E takeUninterruptibly(BlockingQueue<E> queue) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          return queue.take();
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes {@code queue.}{@link BlockingQueue#put(Object) put(element)}
   * uninterruptibly.
   *
   * @throws ClassCastException if the class of the specified element prevents
   *     it from being added to the given queue
   * @throws IllegalArgumentException if some property of the specified element
   *     prevents it from being added to the given queue
   */
  public static <E> void putUninterruptibly(BlockingQueue<E> queue, E element) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          queue.put(element);
          return;
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  // TODO(user): Support Sleeper somehow (wrapper or interface method)?
  /**
   * Invokes {@code unit.}{@link TimeUnit#sleep(long) sleep(sleepFor)}
   * uninterruptibly.
   */
  public static void sleepUninterruptibly(long sleepFor, TimeUnit unit) {
    boolean interrupted = false;
    try {
      long remainingNanos = unit.toNanos(sleepFor);
      long end = System.nanoTime() + remainingNanos;
      while (true) {
        try {
          // TimeUnit.sleep() treats negative timeouts just like zero.
          NANOSECONDS.sleep(remainingNanos);
          return;
        } catch (InterruptedException e) {
          interrupted = true;
          remainingNanos = end - System.nanoTime();
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  // TODO(user): Add support for waitUninterruptibly.

  private Uninterruptibles() {}
}