* tasks. Second, the returned list will always be empty, as any submitted task is considered to
   * have started execution. This applies also to tasks given to {@code invokeAll} or {@code
   * invokeAny} which are pending serial execution, even the subset of the tasks that have not yet
   * started execution. It is unclear from the {@code ExecutorService} specification if these should

# Build execution model

At the highest level, Gradle's execution model is quite simple:

Below is the protocol in some more detail:

1. The client looks for a compatible idle daemon. If there isn't one, it starts a new daemon.
2. The client connects to the idle daemon and sends it a request to do some work. If the daemon is no longer running, the client starts again.

  /**
   * Returns an {@link Executor} that runs each task executed sequentially, such that no two tasks
   * are running concurrently.
   *
   * <p>{@linkplain Executor#execute executed} tasks have a happens-before order as defined in the
   * Java Language Specification. Tasks execute with the same happens-before order that the function
   * calls to {@link Executor#execute execute()} that submitted those tasks had.
   *

  /**
   * Returns a snapshot of tasks currently scheduled for execution. Does not include the
   * currently-executing task unless it is also scheduled for future execution.
   */
  val scheduledTasks: List<Task>
    get() = taskRunner.withLock { futureTasks.toList() }

  /**
   * Schedules [task] for execution in [delayNanos]. A task may only have one future execution

package okhttp3.internal.concurrent

/**
 * A unit of work that can be executed one or more times.
 *
 * Recurrence
 * ----------
 *
 * Tasks control their recurrence schedule. The [runOnce] function returns -1L to signify that the
 * task should not be executed again. Otherwise it returns a delay until the next execution.
 *
 * A task has at most one next execution. If the same task instance is scheduled multiple times, the

 * that every {@code Runnable} that is {@linkplain #add added} will be executed after {@link
 * #execute()} is called. Any {@code Runnable} added after the call to {@code execute} is still
 * guaranteed to execute. There is no guarantee, however, that listeners will be executed in the
 * order that they are added.
 *

import org.jspecify.annotations.Nullable;

/**
 * Executor ensuring that all Runnables submitted are executed in order, using the provided
 * Executor, and sequentially such that no two will ever be running at the same time.
 *
 * <p>Tasks submitted to {@link #execute(Runnable)} are executed in FIFO order.
 *
 * <p>The execution of tasks is done by one thread as long as there are tasks left in the queue.

import org.jspecify.annotations.Nullable;

/**
 * Executor ensuring that all Runnables submitted are executed in order, using the provided
 * Executor, and sequentially such that no two will ever be running at the same time.
 *
 * <p>Tasks submitted to {@link #execute(Runnable)} are executed in FIFO order.
 *
 * <p>The execution of tasks is done by one thread as long as there are tasks left in the queue.

      if (executeImmediate) {
        new RunnableExecutorPair(runnable, executor).execute();
      }
    }

    void execute() {
      synchronized (runnables) {
        if (executed) {
          return;
        }
        executed = true;
      }

      while (!runnables.isEmpty()) {
        runnables.poll().execute();
      }
    }

    private static class RunnableExecutorPair {

   *
   * @throws IOException if the request could not be executed due to cancellation, a connectivity
   *     problem or timeout. Because networks can fail during an exchange, it is possible that the
   *     remote server accepted the request before the failure.
   * @throws IllegalStateException when the call has already been executed.
   */
  @Throws(IOException::class)
  fun execute(): Response

  /**