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/*
 * 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.flink.streaming.api.functions;

import org.apache.flink.api.common.functions.Function;

/**
 * A {@code TimestampAssigner} assigns event time timestamps to elements. These timestamps are used
 * by all functions that operate on event time, for example event time windows.
 *
 * Timestamps are represented in milliseconds since the Epoch (midnight, January 1, 1970 UTC).
 *
 * @param  The type of the elements to which this assigner assigns timestamps.
 * @deprecated use {@link org.apache.flink.api.common.eventtime.TimestampAssigner}
 */
@Deprecated
public interface TimestampAssigner
        extends org.apache.flink.api.common.eventtime.TimestampAssigner, Function {

    /**
     * Assigns a timestamp to an element, in milliseconds since the Epoch.
     *
     * The method is passed the previously assigned timestamp of the element. That previous
     * timestamp may have been assigned from a previous assigner, by ingestion time. If the element
     * did not carry a timestamp before, this value is {@code Long.MIN_VALUE}.
     *
     * @param element The element that the timestamp will be assigned to.
     * @param recordTimestamp The previous internal timestamp of the element, or a negative value,
     *     if no timestamp has been assigned yet.
     * @return The new timestamp.
     */
    @Override
    long extractTimestamp(T element, long recordTimestamp);
}