// TCP fallback doesn't support real RDMA read
        throw new UnsupportedOperationException("RDMA read not supported by TCP fallback");
    }

    @Override
    public void rdmaWrite(RdmaMemoryRegion localRegion, long remoteAddress, int remoteKey, int length) throws IOException {
        // TCP fallback doesn't support real RDMA write

     * potential NTLM fallback (if the server does not support kerberos).
     *
     * @param subject
     *            represents the user who perform Kerberos authentication. Should at least contain a TGT for the user.
     * @param domain
     *            domain for NTLM fallback
     * @param username
     *            user for NTLM fallback
     * @param password

        // Test fallback logic
        assertTrue(errorHandler.shouldFallbackToTcp(hardwareError), "Hardware errors should suggest TCP fallback");
        assertFalse(errorHandler.shouldFallbackToTcp(timeoutError), "Timeout errors should not immediately suggest TCP fallback");

        // Test error classification using public API

      Class<Throwable> exceptionType,
      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return (FluentFuture<V>) Futures.catching(this, exceptionType, fallback, executor);
  }

  public final FluentFuture<V> catchingAsync(
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {

      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return AbstractCatchingFuture.create(input, exceptionType, fallback, executor);
  }

  public static <V extends @Nullable Object> ListenableFuture<V> catchingAsync(
      ListenableFuture<? extends V> input,
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {

     * Execute a callable through the circuit breaker with fallback
     *
     * @param <T> return type
     * @param callable the callable to execute
     * @param fallback fallback supplier if circuit is open
     * @return the result or fallback value
     * @throws Exception if execution fails and no fallback provided
     */
    public <T> T call(Callable<T> callable, Callable<T> fallback) throws Exception {

### [Fast Fallback](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/fast-fallback/)

Since version 5.0, `OkHttpClient` supports fast fallback, which is our implementation of Happy Eyeballs [RFC 6555](https://datatracker.ietf.org/doc/html/rfc6555).

    }

    @Test
    @DisplayName("Test fallback used when circuit is open")
    void testFallbackWhenOpen() throws Exception {
        // Open the circuit
        circuitBreaker.tripBreaker();

        String result = circuitBreaker.call(() -> "primary", () -> "fallback");

        assertEquals("fallback", result);
    }

    @Test

 * selected in the static initializer of AbstractFuture. This is convenient and performant but
 * introduces some testing difficulties. This test exercises the fallback strategies.
 *
 * <p>To force selection of our fallback strategies, we load {@link AbstractFuture} (and all of
 * {@code com.google.common.util.concurrent}) in degenerate class loaders which make certain
 * platform classes unavailable. Then we construct a test suite so we can run the normal

import java.util.EnumSet;
import java.util.Set;

/**
 * Interface for RDMA provider implementations.
 *
 * This interface abstracts different RDMA implementations such as
 * InfiniBand, iWARP, RoCE, or TCP fallback providers.
 */
public interface RdmaProvider {

    /**
     * Check if RDMA is available on this system
     *
     * @return true if RDMA can be used, false otherwise
     */
    boolean isAvailable();