* See the License for the specific language governing permissions and
 * limitations under the License.
 */
@file:OptIn(ExperimentalContracts::class)

package okhttp3.internal.connection

import kotlin.concurrent.withLock
import kotlin.contracts.ExperimentalContracts
import kotlin.contracts.InvocationKind
import kotlin.contracts.contract
import okhttp3.Dispatcher
import okhttp3.internal.http2.Http2Connection

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeoutException;

/**
 * Testing utilities relating to garbage collection finalization.
 *
 * <p>Use this class to test code triggered by finalization, that is, one of the following
 * actions taken by the java garbage collection system:
 *
 * <ul>
 *   <li>invoking the {@code finalize} methods of unreachable objects

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.LongBinaryOperator;
import java.util.function.LongUnaryOperator;
import javax.annotation.CheckForNull;

/**
 * A map containing {@code long} values that can be atomically updated. While writes to a

  // priority level that may be exeucting at a given time.  ACS must
  // be a positive number. The server's concurrency limit (SCL) is
  // divided among the concurrency-controlled priority levels in
  // proportion to their assured concurrency shares. This produces
  // the assured concurrency value (ACV) --- the number of requests
  // that may be executing at a time --- for each such priority
  // level:
  //

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.Serializable;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.CheckForNull;

/**

    printEvent("callStart");
  }

  @Override public void callEnd(Call call) {
    printEvent("callEnd");
  }

  ...
}
```

We can use this listener to race a pair of concurrent HTTP requests:

```java
Request washingtonPostRequest = new Request.Builder()
    .url("https://www.washingtonpost.com/")
    .build();
client.newCall(washingtonPostRequest).enqueue(new Callback() {
  ...

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeoutException;

/**
 * Testing utilities relating to garbage collection finalization.
 *
 * <p>Use this class to test code triggered by finalization, that is, one of the following
 * actions taken by the java garbage collection system:
 *
 * <ul>
 *   <li>invoking the {@code finalize} methods of unreachable objects

import java.lang.ref.WeakReference
import java.net.Socket
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.ExecutorService
import java.util.concurrent.RejectedExecutionException
import java.util.concurrent.TimeUnit.MILLISECONDS
import java.util.concurrent.atomic.AtomicBoolean
import java.util.concurrent.atomic.AtomicInteger
import java.util.concurrent.locks.ReentrantLock
import okhttp3.Call
import okhttp3.Callback

import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A multiset that supports concurrent modifications and that provides atomic versions of most

import java.time.Duration;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import junit.framework.TestCase;

/** Unit tests for CacheBuilder. */