com.google.api.gax.retrying.DirectRetryingExecutor Maven / Gradle / Ivy

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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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package com.google.api.gax.retrying;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.api.core.BetaApi;
import java.io.InterruptedIOException;
import java.nio.channels.ClosedByInterruptException;
import java.util.concurrent.Callable;
import org.threeten.bp.Duration;

/**
 * The retry executor which executes attempts in the current thread, potentially causing the current
 * thread to sleep for the specified amount of time before execution.
 *
 * This class is thread-safe.
 *
 * @param  response type
 */
public class DirectRetryingExecutor implements RetryingExecutorWithContext {

  private final RetryAlgorithm retryAlgorithm;

  /**
   * Creates a new direct retrying executor instance, which will be using {@code retryAlgorithm} to
   * determine retrying strategy.
   *
   * @param retryAlgorithm retry algorithm to use for attempts execution
   * @throws NullPointerException if {@code retryAlgorithm} is null
   */
  public DirectRetryingExecutor(RetryAlgorithm retryAlgorithm) {
    this.retryAlgorithm = checkNotNull(retryAlgorithm);
  }

  /**
   * Creates a {@link RetryingFuture}, which is a facade, returned to the client code to wait for
   * any retriable operation to complete. The future is bounded to {@code this} executor instance.
   *
   * @param callable the actual callable, which should be executed in a retriable context
   * @return retrying future facade
   */
  @Override
  public RetryingFuture createFuture(Callable callable) {
    return createFuture(callable, NoopRetryingContext.create());
  }

  /**
   * Creates a {@link RetryingFuture}, which is a facade, returned to the client code to wait for
   * any retriable operation to complete. The future is bounded to {@code this} executor instance.
   *
   * @param callable the actual callable, which should be executed in a retriable context
   * @return retrying future facade
   */
  @BetaApi("The surface for passing per operation state is not yet stable")
  @Override
  public RetryingFuture createFuture(
      Callable callable, RetryingContext context) {
    return new BasicRetryingFuture<>(callable, retryAlgorithm, context);
  }

  /**
   * Submits an attempt for execution in the current thread, causing the current thread to sleep for
   * the specified by the {@link RetryingFuture#getAttemptSettings()} amount of time. As result,
   * this method completes execution only after the specified {@code retryingFuture} completes.
   *
   * @param retryingFuture the future previously returned by {@link #createFuture(Callable,
   *     RetryingContext)}
   * @return returns completed {@code retryingFuture}
   */
  @Override
  public ApiFuture submit(RetryingFuture retryingFuture) {
    while (!retryingFuture.isDone()) {
      try {
        sleep(retryingFuture.getAttemptSettings().getRandomizedRetryDelay());
        ResponseT response = retryingFuture.getCallable().call();
        retryingFuture.setAttemptFuture(ApiFutures.immediateFuture(response));
      } catch (InterruptedException | InterruptedIOException | ClosedByInterruptException e) {
        Thread.currentThread().interrupt();
        retryingFuture.setAttemptFuture(ApiFutures.immediateFailedFuture(e));
      } catch (Exception e) {
        retryingFuture.setAttemptFuture(ApiFutures.immediateFailedFuture(e));
      }
    }
    return retryingFuture;
  }

  /**
   * This method simply calls {@link Thread#sleep(long)}.
   *
   * @param delay time to sleep
   * @throws InterruptedException if any thread has interrupted the current thread
   */
  protected void sleep(Duration delay) throws InterruptedException {
    if (Duration.ZERO.compareTo(delay) < 0) {
      Thread.sleep(delay.toMillis());
    }
  }
}