lukecwik commented on a change in pull request #12924:
URL: https://github.com/apache/beam/pull/12924#discussion_r498425569
##########
File path:
sdks/java/io/contextualtextio/src/main/java/org/apache/beam/sdk/io/contextualtextio/ContextualTextIO.java
##########
@@ -637,4 +619,68 @@ private CreateTextSourceFn(byte[] delimiter, boolean
hasMultilineCSVRecords) {
/** Disable construction of utility class. */
private ContextualTextIO() {}
+
+ private static class ProcessRecordNumbers extends
PTransform<PCollection<Row>, PCollection<Row>> {
+
+ @Override
+ public PCollection<Row> expand(PCollection<Row> records) {
+ /*
+ * At this point the line number in RecordWithMetadata contains the
relative line offset from the beginning of the read range.
+ *
+ * To compute the absolute position from the beginning of the input we
group the lines within the same ranges, and evaluate the size of each range.
+ */
+
+ // This algorithm only works with triggers that fire once, for now only
default trigger is
+ // supported.
+ Trigger currentTrigger = records.getWindowingStrategy().getTrigger();
+
+ Set<Trigger> allowedTriggers =
+ ImmutableSet.of(
+ Repeatedly.forever(AfterWatermark.pastEndOfWindow()),
DefaultTrigger.of());
+
+ Preconditions.checkArgument(
+ allowedTriggers.contains(currentTrigger),
+ String.format(
+ "getWithRecordNumMetadata only support the default trigger not.
%s", currentTrigger));
Review comment:
```suggestion
"getWithRecordNumMetadata(true) only supports the default
trigger not: %s", currentTrigger));
```
##########
File path:
sdks/java/io/contextualtextio/src/main/java/org/apache/beam/sdk/io/contextualtextio/ContextualTextIO.java
##########
@@ -167,26 +177,26 @@
* .apply(ContextualTextIO.readFiles());
* }</pre>
*
- * <p>Example 6: reading without recordNum metadata, or only fileName
associated Metadata. (the
- * Objects would still contain recordNums, but these recordNums would
correspond to their positions
- * in their respective offsets rather than their positions within the entire
file).
+ * <p>Example 6: reading with recordNum metadata. (the Objects still contain
recordNums, but these
+ * recordNums would correspond to their positions in their respective offsets
rather than their
+ * positions within the entire file).
*
* <pre>{@code
* Pipeline p = ...;
*
* PCollection<Row> records = p.apply(ContextualTextIO.read()
* .from("/local/path/to/files/*.csv")
- * .setWithoutRecordNumMetadata(true));
+ * .setWithRecordNumMetadata(true));
* }</pre>
*
* <p>NOTE: When using {@link
ContextualTextIO.Read#withHasMultilineCSVRecords(Boolean)} this
* option, a single reader will be used to process the file, rather than
multiple readers which can
* read from different offsets. For a large file this can result in lower
performance.
*
- * <p>NOTE: Use {@link Read#withoutRecordNumMetadata()} when recordNum
metadata is not required, for
- * example, when when only filename metadata is required. Computing record
positions currently
- * introduces a shuffle step, which increases the resources used by the
pipeline. <b> By default
- * withoutRecordNumMetadata is set to false, so the shuffle step is
performed.</b>
+ * <p>NOTE: Use {@link Read#withRecordNumMetadata()} when recordNum metadata
is required. Computing
+ * record positions currently introduces a shuffle step, which increases the
resources used by the
Review comment:
```suggestion
* record positions currently introduces a grouping step, which increases
the resources used by the
```
##########
File path:
sdks/java/io/contextualtextio/src/main/java/org/apache/beam/sdk/io/contextualtextio/ContextualTextIO.java
##########
@@ -637,4 +619,68 @@ private CreateTextSourceFn(byte[] delimiter, boolean
hasMultilineCSVRecords) {
/** Disable construction of utility class. */
private ContextualTextIO() {}
+
+ private static class ProcessRecordNumbers extends
PTransform<PCollection<Row>, PCollection<Row>> {
+
+ @Override
+ public PCollection<Row> expand(PCollection<Row> records) {
+ /*
+ * At this point the line number in RecordWithMetadata contains the
relative line offset from the beginning of the read range.
+ *
+ * To compute the absolute position from the beginning of the input we
group the lines within the same ranges, and evaluate the size of each range.
+ */
+
+ // This algorithm only works with triggers that fire once, for now only
default trigger is
+ // supported.
+ Trigger currentTrigger = records.getWindowingStrategy().getTrigger();
+
+ Set<Trigger> allowedTriggers =
+ ImmutableSet.of(
+ Repeatedly.forever(AfterWatermark.pastEndOfWindow()),
DefaultTrigger.of());
+
+ Preconditions.checkArgument(
+ allowedTriggers.contains(currentTrigger),
+ String.format(
+ "getWithRecordNumMetadata only support the default trigger not.
%s", currentTrigger));
+
+ PCollection<KV<KV<String, Long>, Row>> recordsGroupedByFileAndRange =
+ records
+ .apply("AddFileNameAndRange", ParDo.of(new
AddFileNameAndRange()))
+ .setCoder(
+ KvCoder.of(
+ KvCoder.of(StringUtf8Coder.of(),
BigEndianLongCoder.of()),
+ RowCoder.of(RecordWithMetadata.getSchema())));
+
+ PCollectionView<Map<KV<String, Long>, Long>> rangeSizes =
+ recordsGroupedByFileAndRange
+ .apply("CountRecordsForEachFileRange", Count.perKey())
+ .apply("SizesAsView", View.asMap());
+
+ // Get Pipeline to create a dummy PCollection with one element to help
compute the lines
+ // before each Range
+ PCollection<Integer> singletonPcoll =
+ records.getPipeline().apply("CreateSingletonPcoll",
Create.of(Arrays.asList(1)));
+
+ /*
+ * For each (File, Offset) pair, calculate the number of lines occurring
before the Range for each file
+ *
+ * After computing the number of lines before each range, we can find
the line number in original file as numLiesBeforeOffset + lineNumInCurrentOffset
Review comment:
```suggestion
* After computing the number of lines before each range, we can find
the line number in original file as numLinesBeforeOffset +
lineNumInCurrentOffset
```
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