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   /*
    * Copyright 2013 The Netty Project
    *
    * The Netty Project licenses this file to you 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 io.netty.util.concurrent;
  
  import java.util.Queue;
  import java.util.concurrent.Callable;
  import java.util.concurrent.Delayed;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicLong;
  
  @SuppressWarnings("ComparableImplementedButEqualsNotOverridden")
  final class ScheduledFutureTask<V> extends PromiseTask<V> implements ScheduledFuture<V> {
      private static final AtomicLong nextTaskId = new AtomicLong();
      private static final long START_TIME = System.nanoTime();
  
      static long nanoTime() {
          return System.nanoTime() - START_TIME;
      }
  
      static long deadlineNanos(long delay) {
          return nanoTime() + delay;
      }
  
      private final long id = nextTaskId.getAndIncrement();
      private long deadlineNanos;
      /* 0 - no repeat, >0 - repeat at fixed rate, <0 - repeat with fixed delay */
      private final long periodNanos;
  
      ScheduledFutureTask(
              AbstractScheduledEventExecutor executor,
              Runnable runnable, V result, long nanoTime) {
  
          this(executor, toCallable(runnable, result), nanoTime);
      }
  
      ScheduledFutureTask(
              AbstractScheduledEventExecutor executor,
              Callable<V> callable, long nanoTime, long period) {
  
          super(executor, callable);
          if (period == 0) {
              throw new IllegalArgumentException("period: 0 (expected: != 0)");
          }
          deadlineNanos = nanoTime;
          periodNanos = period;
      }
  
      ScheduledFutureTask(
              AbstractScheduledEventExecutor executor,
              Callable<V> callable, long nanoTime) {
  
          super(executor, callable);
          deadlineNanos = nanoTime;
          periodNanos = 0;
      }
  
      @Override
      protected EventExecutor executor() {
          return super.executor();
      }
  
      public long deadlineNanos() {
          return deadlineNanos;
      }
  
      public long delayNanos() {
          return Math.max(0, deadlineNanos() - nanoTime());
      }
  
      public long delayNanos(long currentTimeNanos) {
          return Math.max(0, deadlineNanos() - (currentTimeNanos - START_TIME));
      }
  
      @Override
      public long getDelay(TimeUnit unit) {
          return unit.convert(delayNanos(), TimeUnit.NANOSECONDS);
      }
  
      @Override
      public int compareTo(Delayed o) {
          if (this == o) {
              return 0;
          }
  
          ScheduledFutureTask<?> that = (ScheduledFutureTask<?>) o;
         long d = deadlineNanos() - that.deadlineNanos();
         if (d < 0) {
             return -1;
         } else if (d > 0) {
             return 1;
         } else if (id < that.id) {
             return -1;
         } else if (id == that.id) {
             throw new Error();
         } else {
             return 1;
         }
     }
 
     @Override
     public void run() {
         assert executor().inEventLoop();
         try {
             if (periodNanos == 0) {
                 if (setUncancellableInternal()) {
                     V result = task.call();
                     setSuccessInternal(result);
                 }
             } else {
                 // check if is done as it may was cancelled
                 if (!isCancelled()) {
                     task.call();
                     if (!executor().isShutdown()) {
                         long p = periodNanos;
                         if (p > 0) {
                             deadlineNanos += p;
                         } else {
                             deadlineNanos = nanoTime() - p;
                         }
                         if (!isCancelled()) {
                             // scheduledTaskQueue can never be null as we lazy init it before submit the task!
                             Queue<ScheduledFutureTask<?>> scheduledTaskQueue =
                                     ((AbstractScheduledEventExecutor) executor()).scheduledTaskQueue;
                             assert scheduledTaskQueue != null;
                             scheduledTaskQueue.add(this);
                         }
                     }
                 }
             }
         } catch (Throwable cause) {
             setFailureInternal(cause);
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @param mayInterruptIfRunning this value has no effect in this implementation.
      */
     @Override
     public boolean cancel(boolean mayInterruptIfRunning) {
         boolean canceled = super.cancel(mayInterruptIfRunning);
         if (canceled) {
             ((AbstractScheduledEventExecutor) executor()).removeScheduled(this);
         }
         return canceled;
     }
 
     boolean cancelWithoutRemove(boolean mayInterruptIfRunning) {
         return super.cancel(mayInterruptIfRunning);
     }
 
     @Override
     protected StringBuilder toStringBuilder() {
         StringBuilder buf = super.toStringBuilder();
         buf.setCharAt(buf.length() - 1, ',');
 
         return buf.append(" id: ")
                   .append(id)
                   .append(", deadline: ")
                   .append(deadlineNanos)
                   .append(", period: ")
                   .append(periodNanos)
                   .append(')');
     }
 }