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https://issues.apache.org/jira/browse/BEAM-2939?focusedWorklogId=393889&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393889
]
ASF GitHub Bot logged work on BEAM-2939:
----------------------------------------
Author: ASF GitHub Bot
Created on: 27/Feb/20 01:30
Start Date: 27/Feb/20 01:30
Worklog Time Spent: 10m
Work Description: lukecwik commented on pull request #10897: [BEAM-2939]
Java UnboundedSource SDF wrapper
URL: https://github.com/apache/beam/pull/10897#discussion_r384866125
##########
File path: sdks/java/core/src/main/java/org/apache/beam/sdk/io/Read.java
##########
@@ -375,4 +422,361 @@ public void checkDone() throws IllegalStateException {
}
}
}
+
+ /**
+ * A splittable {@link DoFn} which executes an {@link UnboundedSource}.
+ *
+ * <p>We model the element as the original source and the restriction as a
pair of the sub-source
+ * and its {@link CheckpointMark}. This allows us to split the sub-source
over and over as long as
+ * the checkpoint mark is {@code null} or the {@link NoopCheckpointMark}
since it does not
+ * maintain any state.
+ */
+ // TODO: Support reporting the watermark, currently the watermark never
advances.
+ @UnboundedPerElement
+ static class UnboundedSourceAsSDFWrapperFn<OutputT, CheckpointT extends
CheckpointMark>
+ extends DoFn<UnboundedSource<OutputT, CheckpointT>,
ValueWithRecordId<OutputT>> {
+
+ private static final int DEFAULT_DESIRED_NUM_SPLITS = 20;
+ private static final int DEFAULT_BUNDLE_FINALIZATION_LIMIT_MINS = 10;
+ private final Coder<CheckpointT> restrictionCoder;
+
+ private UnboundedSourceAsSDFWrapperFn(Coder<CheckpointT> restrictionCoder)
{
+ this.restrictionCoder = restrictionCoder;
+ }
+
+ @GetInitialRestriction
+ public KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>
initialRestriction(
+ @Element UnboundedSource<OutputT, CheckpointT> element) {
+ return KV.of(element, null);
+ }
+
+ @GetSize
+ public double getSize(
+ @Restriction KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>
restriction,
+ PipelineOptions pipelineOptions)
+ throws Exception {
+ if (restriction.getKey() instanceof EmptyUnboundedSource) {
+ return 1;
+ }
+
+ UnboundedReader<OutputT> reader =
+ restriction.getKey().createReader(pipelineOptions,
restriction.getValue());
+ long size = reader.getSplitBacklogBytes();
+ if (size != UnboundedReader.BACKLOG_UNKNOWN) {
+ return size;
+ }
+ // TODO: Support "global" backlog reporting
+ // size = reader.getTotalBacklogBytes();
+ // if (size != UnboundedReader.BACKLOG_UNKNOWN) {
+ // return size;
+ // }
+ return 1;
+ }
+
+ @SplitRestriction
+ public void splitRestriction(
+ @Restriction KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>
restriction,
+ OutputReceiver<KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>>
receiver,
+ PipelineOptions pipelineOptions)
+ throws Exception {
+ // The empty unbounded source is trivially done and hence we don't need
to output any splits
+ // for it.
+ if (restriction.getKey() instanceof EmptyUnboundedSource) {
+ return;
+ }
+
+ // The UnboundedSource API does not support splitting after a meaningful
checkpoint mark has
+ // been created.
+ if (restriction.getValue() != null
+ && !(restriction.getValue()
+ instanceof UnboundedSource.CheckpointMark.NoopCheckpointMark)) {
+ receiver.output(restriction);
+ }
+
+ try {
+ for (UnboundedSource<OutputT, CheckpointT> split :
+ restriction.getKey().split(DEFAULT_DESIRED_NUM_SPLITS,
pipelineOptions)) {
+ receiver.output(KV.of(split, null));
+ }
+ } catch (Exception e) {
+ receiver.output(restriction);
+ }
+ }
+
+ @NewTracker
+ public RestrictionTracker<
+ KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>,
UnboundedSourceValue<OutputT>[]>
+ restrictionTracker(
+ @Restriction KV<UnboundedSource<OutputT, CheckpointT>,
CheckpointT> restriction,
+ PipelineOptions pipelineOptions) {
+ return new UnboundedSourceAsSDFRestrictionTracker(restriction,
pipelineOptions);
+ }
+
+ @ProcessElement
+ public ProcessContinuation processElement(
+ RestrictionTracker<
+ KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>,
UnboundedSourceValue[]>
+ tracker,
+ OutputReceiver<ValueWithRecordId<OutputT>> receiver,
+ BundleFinalizer bundleFinalizer)
+ throws IOException {
+ UnboundedSourceValue<OutputT>[] out = new UnboundedSourceValue[1];
+ while (tracker.tryClaim(out)) {
+ receiver.outputWithTimestamp(
+ new ValueWithRecordId<>(out[0].getValue(), out[0].getId()),
out[0].getTimestamp());
+ }
+
+ // Add the checkpoint mark to be finalized if the checkpoint mark isn't
trivial.
+ KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>
currentRestriction =
+ tracker.currentRestriction();
+ if (currentRestriction.getValue() != null
+ && !(tracker.currentRestriction().getValue() instanceof
NoopCheckpointMark)) {
+ bundleFinalizer.afterBundleCommit(
+
Instant.now().plus(Duration.standardMinutes(DEFAULT_BUNDLE_FINALIZATION_LIMIT_MINS)),
+ currentRestriction.getValue()::finalizeCheckpoint);
+ }
+
+ // If we have been split/checkpoint by a runner, the tracker will have
been updated to the
+ // empty source and we will return stop. Otherwise the unbounded source
has only temporarily
+ // run out of work.
+ if (tracker.currentRestriction().getKey() instanceof
EmptyUnboundedSource) {
+ return ProcessContinuation.stop();
+ }
+ return ProcessContinuation.resume();
+ }
+
+ @GetRestrictionCoder
+ public Coder<KV<UnboundedSource<OutputT, CheckpointT>, CheckpointT>>
restrictionCoder() {
+ return KvCoder.of(
+ SerializableCoder.of(new TypeDescriptor<UnboundedSource<OutputT,
CheckpointT>>() {}),
+ NullableCoder.of(restrictionCoder));
+ }
+
+ /**
+ * A named tuple representing all the values we need to pass between the
{@link UnboundedReader}
+ * and the {@link org.apache.beam.sdk.transforms.DoFn.ProcessElement
@ProcessElement} method of
+ * the splittable DoFn.
+ */
+ @AutoValue
+ abstract static class UnboundedSourceValue<T> {
+ public static <T> UnboundedSourceValue<T> create(
+ byte[] id, T value, Instant timestamp, Instant watermark) {
+ return new
AutoValue_Read_UnboundedSourceAsSDFWrapperFn_UnboundedSourceValue<T>(
+ id, value, timestamp, watermark);
+ }
+
+ @SuppressWarnings("mutable")
+ public abstract byte[] getId();
+
+ public abstract T getValue();
+
+ public abstract Instant getTimestamp();
+
+ public abstract Instant getWatermark();
Review comment:
The UnboundedSource can report a watermark that is reported separately from
the element timestamp.
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Issue Time Tracking
-------------------
Worklog Id: (was: 393889)
Time Spent: 21h 10m (was: 21h)
> Fn API SDF support
> ------------------
>
> Key: BEAM-2939
> URL: https://issues.apache.org/jira/browse/BEAM-2939
> Project: Beam
> Issue Type: Improvement
> Components: beam-model
> Reporter: Henning Rohde
> Assignee: Luke Cwik
> Priority: Major
> Labels: portability
> Time Spent: 21h 10m
> Remaining Estimate: 0h
>
> The Fn API should support streaming SDF. Detailed design TBD.
> Once design is ready, expand subtasks similarly to BEAM-2822.
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