import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/** Forwarding wrapper around a {@code Lock}. */
@J2ktIncompatible
@GwtIncompatible
abstract class ForwardingLock implements Lock {
  abstract Lock delegate();

  @Override
  public void lock() {
    delegate().lock();
  }

  @Override

### Locks

We have 3 different things that we synchronize on.

#### Http2Connection

This lock guards internal state of each connection. This lock is never held for blocking operations. That means that we acquire the lock, read or write a few fields and release the lock. No I/O and no application-layer callbacks.

#### Http2Stream

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

/** Forwarding wrapper around a {@code Lock}. */
@J2ktIncompatible
@GwtIncompatible
abstract class ForwardingLock implements Lock {
  abstract Lock delegate();

  @Override
  public void lock() {
    delegate().lock();
  }

  @Override

import com.google.common.annotations.VisibleForTesting;
import com.google.j2objc.annotations.ReflectionSupport;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.AbstractOwnableSynchronizer;
import java.util.concurrent.locks.LockSupport;
import org.jspecify.annotations.Nullable;

@GwtCompatible
@ReflectionSupport(value = ReflectionSupport.Level.FULL)

 *   <li>It is easy for the user to ensure that listeners are never invoked while holding locks.
 * </ul>
 *
 * The last point is subtle. Often the observable object will be managing its own internal state
 * using a lock, however it is dangerous to dispatch listeners while holding a lock because they
 * might run on the {@code directExecutor()} or be otherwise re-entrant (call back into your

    }
    ReentrantLock lock = this.lock;
    lock.lock();

    boolean satisfied = false;
    try {
      return satisfied = guard.isSatisfied();
    } finally {
      if (!satisfied) {
        lock.unlock();
      }
    }
  }

  /**
   * Enters this monitor if the guard is satisfied. Blocks at most the given time acquiring the
   * lock, but does not wait for the guard to be satisfied.

  /**
   * Removes and returns the stream's received response headers, blocking if necessary until headers
   * have been received. If the returned list contains multiple blocks of headers the blocks will be
   * delimited by 'null'.
   *
   * @param callerIsIdle true if the caller isn't sending any more bytes until the peer responds.

  }

  /**
   * Invokes {@code lock.}{@link Lock#tryLock(long, TimeUnit) tryLock(timeout, unit)}
   * uninterruptibly.
   *
   * @since 30.0
   */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  public static boolean tryLockUninterruptibly(Lock lock, long timeout, TimeUnit unit) {

    }

    static TestCondition create() {
      Lock lock = new ReentrantLock();
      Condition condition = lock.newCondition();
      return new TestCondition(lock, condition);
    }

    @Override
    public void await() throws InterruptedException {
      lock.lock();
      try {
        condition.await();
      } finally {
        lock.unlock();
      }
    }

    @Override

    int added = 0;
    while (added < numElements) {
      // we could rely solely on #poll, but #drainTo might be more efficient when there are multiple
      // elements already available (e.g. LinkedBlockingQueue#drainTo locks only once)
      added += q.drainTo(buffer, numElements - added);
      if (added < numElements) { // not enough elements immediately available; will have to poll
        E e = q.poll(deadline - System.nanoTime(), NANOSECONDS);