/*
* 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 javax.annotation.Nullable;
import org.apache.beam.sdk.annotations.Experimental;
import org.joda.time.Instant;
/**
* Interface for interacting with time.
*/
@Experimental(Experimental.Kind.TIMERS)
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);
/** Removes the timer set in this context for the {@code timestmap} 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();
}