/
SCollectionSafeSyntax.scala
81 lines (75 loc) · 2.87 KB
/
SCollectionSafeSyntax.scala
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
/*
* Copyright 2020 Spotify AB
*
* Licensed 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 com.spotify.scio.transforms.syntax
import com.spotify.scio.values.SCollection
import com.spotify.scio.coders.{Coder, CoderMaterializer}
import com.spotify.scio.util.NamedDoFn
import com.twitter.chill.ClosureCleaner
import org.apache.beam.sdk.transforms.DoFn.{Element, MultiOutputReceiver, ProcessElement}
import org.apache.beam.sdk.transforms.ParDo
import org.apache.beam.sdk.values.{TupleTag, TupleTagList}
import scala.collection.compat._
trait SCollectionSafeSyntax {
/**
* Enhanced version of [[com.spotify.scio.values.SCollection SCollection]] with specialized
* versions of flatMap.
*/
implicit class SafeFlatMapSCollection[T](private val self: SCollection[T]) {
/**
* Latency optimized flavor of
* [[com.spotify.scio.values.SCollection.flatMap SCollection.flatMap]], it returns a new
* SCollection by first applying a function to all elements of this SCollection, and then
* flattening the results. If function throws an exception, instead of retrying, faulty element
* goes into given error side output.
*
* @group transform
*/
def safeFlatMap[U: Coder](
f: T => TraversableOnce[U]
): (SCollection[U], SCollection[(T, Throwable)]) = {
val (mainTag, errorTag) = (new TupleTag[U], new TupleTag[(T, Throwable)])
val doFn = new NamedDoFn[T, U] {
val g = ClosureCleaner.clean(f) // defeat closure
@ProcessElement
private[scio] def processElement(
@Element element: T,
out: MultiOutputReceiver
): Unit = {
val i =
try {
g(element).iterator
} catch {
case e: Throwable =>
out.get[(T, Throwable)](errorTag).output((element, e))
Iterator.empty
}
while (i.hasNext) out.get[U](mainTag).output(i.next())
}
}
val tuple =
self.applyInternal(ParDo.of(doFn).withOutputTags(mainTag, TupleTagList.of(errorTag)))
val main = tuple
.get(mainTag)
.setCoder(CoderMaterializer.beam(self.context, Coder[U]))
import self.coder
val errorPipe =
tuple
.get(errorTag)
.setCoder(CoderMaterializer.beam(self.context, Coder[(T, Throwable)]))
(self.context.wrap(main), self.context.wrap(errorPipe))
}
}
}