// unmeasurable (comparing done AbstractFutures with immediateFuture)
    if (obj instanceof Cancellation) {
      Cancellation cancellation = (Cancellation) obj;
      Throwable cause = cancellation.cause;
      throw cancellationExceptionWithCause("Task was cancelled.", cause);
    } else if (obj instanceof Failure) {
      Failure failure = (Failure) obj;

 *
 * <p>This class has limited support for cancellation and other "early completions":
 *
 * <ul>
 *   <li>While calls to {@code submit} and {@code submitAsync} return a {@code Future} that can be
 *       cancelled, cancellation never propagates to a task that has started to run -- neither to
 *       the callable itself nor to any {@code Future} returned by an {@code AsyncCallable}.

    """Call the ASGI app for *path* and cancel after *timeout* seconds.

    Returns `True` if the cancellation was delivered (i.e. it did not hang).
    """
    chunks: list[bytes] = []

    async def receive():  # type: ignore[no-untyped-def]
        # Simulate a client that never disconnects, rely on cancellation
        await anyio.sleep(float("inf"))
        return {"type": "http.disconnect"}  # pragma: no cover

  /**
   * Tests that a canceled future throws a cancellation exception.
   *
   * <p>This method checks the cancel, isCancelled, and isDone methods.
   */
  public void testCanceledFutureThrowsCancellation() throws Exception {

    assertFalse(future.isDone());
    assertFalse(future.isCancelled());

    CountDownLatch successLatch = new CountDownLatch(1);

    // Run cancellation in a separate thread as an extra thread-safety test.

Context timeouts are propagated, and a default timeout of 1 minute is added if none is specified.

There is no cancellation propagation for single payload requests.
When the context is canceled, the request will return at once with an appropriate error.
However, the remote call will not see the cancellation - as can be seen from the 'missing' context on the handler.
The result will be discarded.

### Typed handlers

import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/** Tests for {@link AbstractFuture} with the cancellation cause system property set */
@AndroidIncompatible // custom classloading

@NullUnmarked
@GwtIncompatible
@J2ktIncompatible
public class AbstractFutureCancellationCauseTest extends TestCase {

import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/** Tests for {@link AbstractFuture} with the cancellation cause system property set */
@AndroidIncompatible // custom classloading

@NullUnmarked
@GwtIncompatible
@J2ktIncompatible
public class AbstractFutureCancellationCauseTest extends TestCase {

  /**
   * Tests that a canceled future throws a cancellation exception.
   *
   * <p>This method checks the cancel, isCancelled, and isDone methods.
   */
  public void testCanceledFutureThrowsCancellation() throws Exception {

    assertFalse(future.isDone());
    assertFalse(future.isCancelled());

    CountDownLatch successLatch = new CountDownLatch(1);

    // Run cancellation in a separate thread as an extra thread-safety test.

type Store interface {
	// New creates a new Stmt object and caches it.
	// Parameters:
	//   ctx: The context for the request, which can carry deadlines, cancellation signals, etc.
	//   key: The key representing the SQL query, used for caching and preparing the statement.
	//   isTransaction: Indicates whether this operation is part of a transaction, which may affect the caching strategy.

Since this small example does not need any `await` statements, we add an `await anyio.sleep(0)` to give the event loop a chance to handle cancellation.

This would be even more important with large or infinite streams.

///

/// tip