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/*
* Copyright (C) 2015 Google Inc.
*
* Licensed 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 com.google.cloud.dataflow.sdk.util;
import com.google.cloud.dataflow.sdk.annotations.Experimental;
import org.joda.time.Instant;
import javax.annotation.Nullable;
/**
* 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.
*
* See {@link TimeDomain} for details on the time domains available.
*
*
Timers are not guaranteed to fire immediately, but will be delivered at some time
* afterwards.
*
*
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
*/
public abstract void setTimer(Instant timestamp, TimeDomain timeDomain);
/** Removes the timer set in this context for the {@code timestmap} and {@code timeDomain}. */
public abstract void deleteTimer(Instant timestamp, TimeDomain timeDomain);
/** Returns the current processing time. */
public abstract Instant currentProcessingTime();
/** Returns the current synchronized processing time or {@code null} if unknown. */
@Nullable
public abstract Instant currentSynchronizedProcessingTime();
/** Returns the current event time or {@code null} if unknown. */
@Nullable
public abstract Instant currentEventTime();
}