content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF 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 org.apache.cassandra.simulator.systems;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.function.Consumer;
  
  import org.apache.cassandra.simulator.systems.InterceptedWait.InterceptedConditionWait;
  import org.apache.cassandra.simulator.systems.InterceptedWait.TriggerListener;
  import org.apache.cassandra.utils.concurrent.Awaitable;
  import org.apache.cassandra.utils.concurrent.Condition;
  import org.apache.cassandra.utils.concurrent.CountDownLatch;
  import org.apache.cassandra.utils.concurrent.UncheckedInterruptedException;
  import org.apache.cassandra.utils.concurrent.WaitQueue;
  
  import static org.apache.cassandra.simulator.systems.InterceptedWait.Kind.WAIT_UNTIL;
  import static org.apache.cassandra.simulator.systems.InterceptedWait.Kind.UNBOUNDED_WAIT;
  import static org.apache.cassandra.simulator.systems.InterceptedWait.Trigger.SIGNAL;
  import static org.apache.cassandra.simulator.systems.InterceptorOfGlobalMethods.Global.captureWaitSite;
  import static org.apache.cassandra.simulator.systems.InterceptorOfGlobalMethods.Global.ifIntercepted;
  import static org.apache.cassandra.simulator.systems.SimulatedTime.Global.localToGlobalNanos;
  import static org.apache.cassandra.simulator.systems.SimulatedTime.Global.relativeToLocalNanos;
  
  @PerClassLoader
  abstract class InterceptingAwaitable implements Awaitable
  {
      abstract boolean isSignalled();
      abstract Condition maybeIntercept(InterceptedWait.Kind kind, long waitNanos);
  
      Condition maybeInterceptThrowChecked(InterceptedWait.Kind kind, long waitNanos) throws InterruptedException
      {
          if (Thread.interrupted())
              throw new InterruptedException();
  
          return maybeIntercept(kind, waitNanos);
      }
  
      Condition maybeInterceptThrowUnchecked(InterceptedWait.Kind kind, long waitNanos)
      {
          if (Thread.interrupted())
              throw new UncheckedInterruptedException();
  
          return maybeIntercept(kind, waitNanos);
      }
  
      public boolean awaitUntil(long deadline) throws InterruptedException
      {
          maybeInterceptThrowChecked(WAIT_UNTIL, deadline).awaitUntil(deadline);
          return isSignalled();
      }
  
      public boolean awaitUntilThrowUncheckedOnInterrupt(long deadline)
      {
          maybeInterceptThrowUnchecked(WAIT_UNTIL, deadline).awaitUntilThrowUncheckedOnInterrupt(deadline);
          return isSignalled();
      }
  
      public boolean awaitUntilUninterruptibly(long deadline)
      {
          maybeIntercept(WAIT_UNTIL, deadline).awaitUntilUninterruptibly(deadline);
          return isSignalled();
      }
  
      public Awaitable await() throws InterruptedException
      {
          maybeInterceptThrowChecked(UNBOUNDED_WAIT, 0).await();
          return this;
      }
  
      public Awaitable awaitThrowUncheckedOnInterrupt()
      {
          maybeInterceptThrowUnchecked(UNBOUNDED_WAIT, 0).awaitThrowUncheckedOnInterrupt();
          return this;
      }
  
      public Awaitable awaitUninterruptibly()
      {
          maybeIntercept(UNBOUNDED_WAIT, 0).awaitUninterruptibly();
          return this;
      }
  
      public boolean await(long time, TimeUnit units) throws InterruptedException
      {
          long deadline = relativeToLocalNanos(units.toNanos(time));
          maybeInterceptThrowChecked(WAIT_UNTIL, localToGlobalNanos(deadline)).awaitUntil(deadline);
          return isSignalled();
      }
  
      public boolean awaitThrowUncheckedOnInterrupt(long time, TimeUnit units)
      {
          long deadline = relativeToLocalNanos(units.toNanos(time));
          maybeInterceptThrowUnchecked(WAIT_UNTIL, localToGlobalNanos(deadline)).awaitUntilThrowUncheckedOnInterrupt(deadline);
          return isSignalled();
      }
  
      public boolean awaitUninterruptibly(long time, TimeUnit units)
      {
          long deadline = relativeToLocalNanos(units.toNanos(time));
          maybeIntercept(WAIT_UNTIL, localToGlobalNanos(deadline)).awaitUntilUninterruptibly(deadline);
          return isSignalled();
      }
  
      @PerClassLoader
      static class InterceptingCondition extends InterceptingAwaitable implements Condition, TriggerListener
      {
          final Condition inner = new NotInterceptedSyncCondition();
          private List<InterceptedConditionWait> intercepted;
  
          public InterceptingCondition()
          {
          }
  
          Condition maybeIntercept(InterceptedWait.Kind kind, long waitNanos)
          {
              if (inner.isSignalled())
                  return inner;
  
              InterceptibleThread thread = ifIntercepted();
              if (thread == null)
                  return inner;
  
              InterceptedConditionWait signal = new InterceptedConditionWait(kind, waitNanos, thread, captureWaitSite(thread), inner);
              synchronized (this)
              {
                  if (intercepted == null)
                      intercepted = new ArrayList<>(2);
                  intercepted.add(signal);
              }
              signal.addListener(this);
              thread.interceptWait(signal);
              return signal;
          }
  
          public boolean isSignalled()
          {
              return inner.isSignalled();
          }
  
          public void signal()
          {
              if (isSignalled())
                  return;
  
              inner.signal();
              synchronized (this)
              {
                  if (intercepted != null)
                  {
                      Thread signalledBy = Thread.currentThread();
                      intercepted.forEach(signal -> signal.interceptWakeup(SIGNAL, signalledBy));
                  }
              }
          }
  
          @Override
          public synchronized void onTrigger(InterceptedWait triggered)
          {
              intercepted.remove(triggered);
          }
      }
  
      @PerClassLoader
      static class InterceptingCountDownLatch extends InterceptingCondition implements CountDownLatch
      {
          private final AtomicInteger count;
  
          public InterceptingCountDownLatch(int count)
          {
              super();
              this.count = new AtomicInteger(count);
          }
  
          public void decrement()
          {
              if (count.decrementAndGet() == 0)
                  signal();
          }
  
          public int count()
          {
              return count.get();
          }
      }
  
      @PerClassLoader
      static class InterceptingSignal<V> extends InterceptingAwaitable implements WaitQueue.Signal
      {
          final Condition inner = new NotInterceptedSyncCondition();
          final V supplyOnDone;
          final Consumer<V> receiveOnDone;
  
          InterceptedConditionWait intercepted;
  
          boolean isSignalled;
          boolean isCancelled;
  
          InterceptingSignal()
          {
              this(null, ignore -> {});
          }
  
          InterceptingSignal(V supplyOnDone, Consumer<V> receiveOnDone)
          {
              this.supplyOnDone = supplyOnDone;
              this.receiveOnDone = receiveOnDone;
          }
  
          public boolean isSignalled()
          {
              return isSignalled;
          }
  
          public synchronized boolean isCancelled()
          {
              return isCancelled;
          }
  
          public synchronized boolean isSet()
          {
              return isCancelled | isSignalled;
          }
  
          public void signal()
          {
              doSignal();
          }
  
          synchronized boolean doSignal()
          {
              if (isSet())
                  return false;
  
              isSignalled = true;
              receiveOnDone.accept(supplyOnDone);
              inner.signal();
              if (intercepted != null && !intercepted.isTriggered())
                  intercepted.interceptWakeup(SIGNAL, Thread.currentThread());
              return true;
          }
  
          public synchronized boolean checkAndClear()
          {
              if (isSet())
                  return isSignalled;
              isCancelled = true;
              receiveOnDone.accept(supplyOnDone);
              inner.signal();
              return false;
          }
  
          public synchronized void cancel()
          {
              checkAndClear();
          }
  
          Condition maybeIntercept(InterceptedWait.Kind kind, long waitNanos)
          {
              assert intercepted == null;
  
              // It is possible that by the time we call `await` on a signal, it will already have been
              // signalled, so we do not have to intercept or wait here.
              if (inner.isSignalled())
                  return inner;
  
              InterceptibleThread thread = ifIntercepted();
              if (thread == null)
                  return inner;
  
              intercepted = new InterceptedConditionWait(kind, waitNanos, thread, captureWaitSite(thread), inner);
              thread.interceptWait(intercepted);
              return intercepted;
          }
      }
  }
  