InstantiatingWatchdogProvider.java

/*
 * Copyright 2018 Google LLC
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package com.google.api.gax.rpc;

import com.google.api.core.ApiClock;
import com.google.api.core.BetaApi;
import com.google.api.core.InternalApi;
import com.google.common.base.Preconditions;
import java.util.concurrent.ScheduledExecutorService;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import org.threeten.bp.Duration;

/**
 * A watchdog provider which instantiates a new provider on every request.
 *
 * <p>This is the internal class and is public only for technical reasons. It may change any time
 * without notice, please do not depend on it explicitly.
 */
@BetaApi("The surface for streaming is not stable yet and may change in the future.")
@InternalApi
public final class InstantiatingWatchdogProvider implements WatchdogProvider {
  @Nullable private final ApiClock clock;
  @Nullable private final ScheduledExecutorService executor;
  @Nullable private final Duration checkInterval;

  public static WatchdogProvider create() {
    return new InstantiatingWatchdogProvider(null, null, null);
  }

  private InstantiatingWatchdogProvider(
      @Nullable ApiClock clock,
      @Nullable ScheduledExecutorService executor,
      @Nullable Duration checkInterval) {
    this.clock = clock;
    this.executor = executor;
    this.checkInterval = checkInterval;
  }

  @Override
  public boolean needsClock() {
    return clock == null;
  }

  @Override
  public WatchdogProvider withClock(@Nonnull ApiClock clock) {
    return new InstantiatingWatchdogProvider(
        Preconditions.checkNotNull(clock), executor, checkInterval);
  }

  @Override
  public boolean needsCheckInterval() {
    return checkInterval == null;
  }

  @Override
  public WatchdogProvider withCheckInterval(@Nonnull Duration checkInterval) {
    return new InstantiatingWatchdogProvider(
        clock, executor, Preconditions.checkNotNull(checkInterval));
  }

  @Override
  public boolean needsExecutor() {
    return executor == null;
  }

  @Override
  public WatchdogProvider withExecutor(ScheduledExecutorService executor) {
    return new InstantiatingWatchdogProvider(
        clock, Preconditions.checkNotNull(executor), checkInterval);
  }

  @SuppressWarnings("ConstantConditions")
  @Nullable
  @Override
  public Watchdog getWatchdog() {
    Preconditions.checkState(!needsClock(), "A clock is needed");
    Preconditions.checkState(!needsCheckInterval(), "A check interval is needed");
    Preconditions.checkState(!needsExecutor(), "An executor is needed");

    // Watchdog is disabled
    if (checkInterval.isZero()) {
      return null;
    }

    return Watchdog.create(clock, checkInterval, executor);
  }

  @Override
  public boolean shouldAutoClose() {
    return true;
  }
}