聊聊flink的Tumbling Window

<pre class="brush:php;toolbar:false;">@PublicEvolvingpublic abstract class WindowAssigner<T, W extends Window> implements Serializable {    private static final long serialVersionUID = 1L;​    /**     * Returns a {@code Collection} of windows that should be assigned to the element.     *     * @param element The element to which windows should be assigned.     * @param timestamp The timestamp of the element.     * @param context The {@link WindowAssignerContext} in which the assigner operates.     */    public abstract Collection<W> assignWindows(T element, long timestamp, WindowAssignerContext context);​    /**     * Returns the default trigger associated with this {@code WindowAssigner}.     */    public abstract Trigger<T, W> getDefaultTrigger(StreamExecutionEnvironment env);​    /**     * Returns a {@link TypeSerializer} for serializing windows that are assigned by     * this {@code WindowAssigner}.     */    public abstract TypeSerializer<W> getWindowSerializer(ExecutionConfig executionConfig);​    /**     * Returns {@code true} if elements are assigned to windows based on event time,     * {@code false} otherwise.     */    public abstract boolean isEventTime();​    /**     * A context provided to the {@link WindowAssigner} that allows it to query the     * current processing time.     *     * <p>This is provided to the assigner by its containing     * {@link org.apache.flink.streaming.runtime.operators.windowing.WindowOperator},     * which, in turn, gets it from the containing     * {@link org.apache.flink.streaming.runtime.tasks.StreamTask}.     */    public abstract static class WindowAssignerContext {​        /**         * Returns the current processing time.         */        public abstract long getCurrentProcessingTime();​    }}

<pre class="brush:php;toolbar:false;">@PublicEvolvingpublic abstract class Window {​    /**     * Gets the largest timestamp that still belongs to this window.     *     * @return The largest timestamp that still belongs to this window.     */    public abstract long maxTimestamp();}

<pre class="brush:php;toolbar:false;">@PublicEvolvingpublic class TimeWindow extends Window {​    private final long start;    private final long end;​    public TimeWindow(long start, long end) {        this.start = start;        this.end = end;    }​    /**     * Gets the starting timestamp of the window. This is the first timestamp that belongs     * to this window.     *     * @return The starting timestamp of this window.     */    public long getStart() {        return start;    }​    /**     * Gets the end timestamp of this window. The end timestamp is exclusive, meaning it     * is the first timestamp that does not belong to this window any more.     *     * @return The exclusive end timestamp of this window.     */    public long getEnd() {        return end;    }​    /**     * Gets the largest timestamp that still belongs to this window.     *     * <p>This timestamp is identical to {@code getEnd() - 1}.     *     * @return The largest timestamp that still belongs to this window.     *     * @see #getEnd()     */    @Override    public long maxTimestamp() {        return end - 1;    }​    @Override    public boolean equals(Object o) {        if (this == o) {            return true;        }        if (o == null || getClass() != o.getClass()) {            return false;        }​        TimeWindow window = (TimeWindow) o;​        return end == window.end && start == window.start;    }​    @Override    public int hashCode() {        return MathUtils.longToIntWithBitMixing(start + end);    }​    @Override    public String toString() {        return "TimeWindow{" +                "start=" + start +                ", end=" + end +                '}';    }​    /**     * Returns {@code true} if this window intersects the given window.     */    public boolean intersects(TimeWindow other) {        return this.start <= other.end && this.end >= other.start;    }​    /**     * Returns the minimal window covers both this window and the given window.     */    public TimeWindow cover(TimeWindow other) {        return new TimeWindow(Math.min(start, other.start), Math.max(end, other.end));    }​    // ------------------------------------------------------------------------    // Serializer    // ------------------------------------------------------------------------​    //......​    // ------------------------------------------------------------------------    //  Utilities    // ------------------------------------------------------------------------​    /**     * Merge overlapping {@link TimeWindow}s. For use by merging     * {@link org.apache.flink.streaming.api.windowing.assigners.WindowAssigner WindowAssigners}.     */    public static void mergeWindows(Collection<TimeWindow> windows, MergingWindowAssigner.MergeCallback<TimeWindow> c) {​        // sort the windows by the start time and then merge overlapping windows​        List<TimeWindow> sortedWindows = new ArrayList<>(windows);​        Collections.sort(sortedWindows, new Comparator<TimeWindow>() {            @Override            public int compare(TimeWindow o1, TimeWindow o2) {                return Long.compare(o1.getStart(), o2.getStart());            }        });​        List<Tuple2<TimeWindow, Set<TimeWindow>>> merged = new ArrayList<>();        Tuple2<TimeWindow, Set<TimeWindow>> currentMerge = null;​        for (TimeWindow candidate: sortedWindows) {            if (currentMerge == null) {                currentMerge = new Tuple2<>();                currentMerge.f0 = candidate;                currentMerge.f1 = new HashSet<>();                currentMerge.f1.add(candidate);            } else if (currentMerge.f0.intersects(candidate)) {                currentMerge.f0 = currentMerge.f0.cover(candidate);                currentMerge.f1.add(candidate);            } else {                merged.add(currentMerge);                currentMerge = new Tuple2<>();                currentMerge.f0 = candidate;                currentMerge.f1 = new HashSet<>();                currentMerge.f1.add(candidate);            }        }​        if (currentMerge != null) {            merged.add(currentMerge);        }​        for (Tuple2<TimeWindow, Set<TimeWindow>> m: merged) {            if (m.f1.size() > 1) {                c.merge(m.f1, m.f0);            }        }    }​    /**     * Method to get the window start for a timestamp.     *     * @param timestamp epoch millisecond to get the window start.     * @param offset The offset which window start would be shifted by.     * @param windowSize The size of the generated windows.     * @return window start     */    public static long getWindowStartWithOffset(long timestamp, long offset, long windowSize) {        return timestamp - (timestamp - offset + windowSize) % windowSize;    }}

<pre class="brush:php;toolbar:false;">@PublicEvolvingpublic class TumblingEventTimeWindows extends WindowAssigner<Object, TimeWindow> {    private static final long serialVersionUID = 1L;​    private final long size;​    private final long offset;​    protected TumblingEventTimeWindows(long size, long offset) {        if (offset < 0 || offset >= size) {            throw new IllegalArgumentException("TumblingEventTimeWindows parameters must satisfy 0 <= offset < size");        }​        this.size = size;        this.offset = offset;    }​    @Override    public Collection<TimeWindow> assignWindows(Object element, long timestamp, WindowAssignerContext context) {        if (timestamp > Long.MIN_VALUE) {            // Long.MIN_VALUE is currently assigned when no timestamp is present            long start = TimeWindow.getWindowStartWithOffset(timestamp, offset, size);            return Collections.singletonList(new TimeWindow(start, start + size));        } else {            throw new RuntimeException("Record has Long.MIN_VALUE timestamp (= no timestamp marker). " +                    "Is the time characteristic set to 'ProcessingTime', or did you forget to call " +                    "'DataStream.assignTimestampsAndWatermarks(...)'?");        }    }​    @Override    public Trigger<Object, TimeWindow> getDefaultTrigger(StreamExecutionEnvironment env) {        return EventTimeTrigger.create();    }​    @Override    public String toString() {        return "TumblingEventTimeWindows(" + size + ")";    }​    public static TumblingEventTimeWindows of(Time size) {        return new TumblingEventTimeWindows(size.toMilliseconds(), 0);    }​    public static TumblingEventTimeWindows of(Time size, Time offset) {        return new TumblingEventTimeWindows(size.toMilliseconds(), offset.toMilliseconds());    }​    @Override    public TypeSerializer<TimeWindow> getWindowSerializer(ExecutionConfig executionConfig) {        return new TimeWindow.Serializer();    }​    @Override    public boolean isEventTime() {        return true;    }}

<pre class="brush:php;toolbar:false;">public class TumblingProcessingTimeWindows extends WindowAssigner<Object, TimeWindow> {    private static final long serialVersionUID = 1L;​    private final long size;​    private final long offset;​    private TumblingProcessingTimeWindows(long size, long offset) {        if (offset < 0 || offset >= size) {            throw new IllegalArgumentException("TumblingProcessingTimeWindows parameters must satisfy  0 <= offset < size");        }​        this.size = size;        this.offset = offset;    }​    @Override    public Collection<TimeWindow> assignWindows(Object element, long timestamp, WindowAssignerContext context) {        final long now = context.getCurrentProcessingTime();        long start = TimeWindow.getWindowStartWithOffset(now, offset, size);        return Collections.singletonList(new TimeWindow(start, start + size));    }​    public long getSize() {        return size;    }​    @Override    public Trigger<Object, TimeWindow> getDefaultTrigger(StreamExecutionEnvironment env) {        return ProcessingTimeTrigger.create();    }​    @Override    public String toString() {        return "TumblingProcessingTimeWindows(" + size + ")";    }​    public static TumblingProcessingTimeWindows of(Time size) {        return new TumblingProcessingTimeWindows(size.toMilliseconds(), 0);    }​    public static TumblingProcessingTimeWindows of(Time size, Time offset) {        return new TumblingProcessingTimeWindows(size.toMilliseconds(), offset.toMilliseconds());    }​    @Override    public TypeSerializer<TimeWindow> getWindowSerializer(ExecutionConfig executionConfig) {        return new TimeWindow.Serializer();    }​    @Override    public boolean isEventTime() {        return false;    }}