/*
* 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.transforms.windowing;
import java.util.concurrent.TimeUnit;
import org.joda.time.Instant;
/**
* A {@code BoundedWindow} represents a finite grouping of elements, with an
* upper bound (larger timestamps represent more recent data) on the timestamps
* of elements that can be placed in the window. This finiteness means that for
* every window, at some point in time, all data for that window will have
* arrived and can be processed together.
*
* <p>Windows must also implement {@link Object#equals} and
* {@link Object#hashCode} such that windows that are logically equal will
* be treated as equal by {@code equals()} and {@code hashCode()}.
*/
public abstract class BoundedWindow {
// The min and max timestamps that won't overflow when they are converted to
// usec.
/**
* The minimum value for any Beam timestamp. Often referred to as "-infinity".
*
* <p>This value and {@link #TIMESTAMP_MAX_VALUE} are chosen so that their
* microseconds-since-epoch can be safely represented with a {@code long}.
*/
public static final Instant TIMESTAMP_MIN_VALUE =
new Instant(TimeUnit.MICROSECONDS.toMillis(Long.MIN_VALUE));
/**
* The maximum value for any Beam timestamp. Often referred to as "+infinity".
*
* <p>This value and {@link #TIMESTAMP_MIN_VALUE} are chosen so that their
* microseconds-since-epoch can be safely represented with a {@code long}.
*/
public static final Instant TIMESTAMP_MAX_VALUE =
new Instant(TimeUnit.MICROSECONDS.toMillis(Long.MAX_VALUE));
/**
* Formats a {@link Instant} timestamp with additional Beam-specific metadata, such as indicating
* whether the timestamp is the end of the global window or one of the distinguished values {@link
* #TIMESTAMP_MIN_VALUE} or {@link #TIMESTAMP_MIN_VALUE}.
*/
public static String formatTimestamp(Instant timestamp) {
if (timestamp.equals(TIMESTAMP_MIN_VALUE)) {
return timestamp.toString() + " (TIMESTAMP_MIN_VALUE)";
} else if (timestamp.equals(TIMESTAMP_MAX_VALUE)) {
return timestamp.toString() + " (TIMESTAMP_MAX_VALUE)";
} else if (timestamp.equals(GlobalWindow.INSTANCE.maxTimestamp())) {
return timestamp.toString() + " (end of global window)";
} else {
return timestamp.toString();
}
}
/**
* Returns the inclusive upper bound of timestamps for values in this window.
*/
public abstract Instant maxTimestamp();
}