content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.sdk.state;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  import org.joda.time.Instant;
  
  /** Interface for interacting with time. */
  public interface Timers {
    /**
     * Sets a timer to fire when the event time watermark, the current processing time, or the
     * synchronized processing time watermark surpasses a given timestamp.
     *
     * <p>See {@link TimeDomain} for details on the time domains available.
     *
     * <p>Timers are not guaranteed to fire immediately, but will be delivered at some time
     * afterwards.
     *
     * <p>An implementation of {@link Timers} implicitly scopes timers that are set - they may be
     * scoped to a key and window, or a key, window, and trigger, etc.
     *
     * @param timestamp the time at which the timer should be delivered
     * @param timeDomain the domain that the {@code timestamp} applies to
     */
    void setTimer(Instant timestamp, TimeDomain timeDomain);
  
    /** Set a timer with outputTimestamp. */
    void setTimer(Instant timestamp, Instant outputTimestamp, TimeDomain timeDomain);
  
    /** Removes the timer set in this context for the {@code timestamp} and {@code timeDomain}. */
    void deleteTimer(Instant timestamp, TimeDomain timeDomain);
  
    /** Returns the current processing time. */
    Instant currentProcessingTime();
  
    /** Returns the current synchronized processing time or {@code null} if unknown. */
    @Nullable
    Instant currentSynchronizedProcessingTime();
  
    /** Returns the current event time. */
    Instant currentEventTime();
  }
  