/
RDD.scala
418 lines (347 loc) · 13.1 KB
/
RDD.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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
package spark
import java.util.concurrent.atomic.AtomicLong
import java.util.HashSet
import java.util.Random
import scala.collection.mutable.ArrayBuffer
import scala.collection.mutable.Map
import scala.collection.mutable.HashMap
import SparkContext._
import mesos._
@serializable
abstract class RDD[T: ClassManifest](@transient sc: SparkContext) {
def splits: Array[Split]
def iterator(split: Split): Iterator[T]
def preferredLocations(split: Split): Seq[String]
def taskStarted(split: Split, slot: SlaveOffer) {}
def sparkContext = sc
def map[U: ClassManifest](f: T => U) = new MappedRDD(this, sc.clean(f))
def filter(f: T => Boolean) = new FilteredRDD(this, sc.clean(f))
def cache() = new CachedRDD(this)
def sample(withReplacement: Boolean, frac: Double, seed: Int) =
new SampledRDD(this, withReplacement, frac, seed)
def flatMap[U: ClassManifest](f: T => Traversable[U]) =
new FlatMappedRDD(this, sc.clean(f))
def foreach(f: T => Unit) {
val cleanF = sc.clean(f)
val tasks = splits.map(s => new ForeachTask(this, s, cleanF)).toArray
sc.runTaskObjects(tasks)
}
def collect(): Array[T] = {
val tasks = splits.map(s => new CollectTask(this, s))
val results = sc.runTaskObjects(tasks)
Array.concat(results: _*)
}
def toArray(): Array[T] = collect()
def reduce(f: (T, T) => T): T = {
val cleanF = sc.clean(f)
val tasks = splits.map(s => new ReduceTask(this, s, f))
val results = new ArrayBuffer[T]
for (option <- sc.runTaskObjects(tasks); elem <- option)
results += elem
if (results.size == 0)
throw new UnsupportedOperationException("empty collection")
else
return results.reduceLeft(f)
}
def take(num: Int): Array[T] = {
if (num == 0)
return new Array[T](0)
val buf = new ArrayBuffer[T]
for (split <- splits; elem <- iterator(split)) {
buf += elem
if (buf.length == num)
return buf.toArray
}
return buf.toArray
}
def first: T = take(1) match {
case Array(t) => t
case _ => throw new UnsupportedOperationException("empty collection")
}
def count(): Long = {
try {
map(x => 1L).reduce(_+_)
} catch {
case e: UnsupportedOperationException => 0L // No elements in RDD
}
}
def union(other: RDD[T]) = new UnionRDD(sc, Array(this, other))
def ++(other: RDD[T]) = this.union(other)
def splitRdd() = new SplitRDD(this)
def cartesian[U: ClassManifest](other: RDD[U]) =
new CartesianRDD(sc, this, other)
def groupBy[K](func: T => K, numSplits: Int): RDD[(K, Seq[T])] =
this.map(t => (func(t), t)).groupByKey(numSplits)
def groupBy[K](func: T => K): RDD[(K, Seq[T])] =
groupBy[K](func, sc.numCores)
}
@serializable
abstract class RDDTask[U: ClassManifest, T: ClassManifest](
val rdd: RDD[T], val split: Split)
extends Task[U] {
override def preferredLocations() = rdd.preferredLocations(split)
override def markStarted(slot: SlaveOffer) { rdd.taskStarted(split, slot) }
}
class ForeachTask[T: ClassManifest](
rdd: RDD[T], split: Split, func: T => Unit)
extends RDDTask[Unit, T](rdd, split) with Logging {
override def run() {
logInfo("Processing " + split)
rdd.iterator(split).foreach(func)
}
}
class CollectTask[T](
rdd: RDD[T], split: Split)(implicit m: ClassManifest[T])
extends RDDTask[Array[T], T](rdd, split) with Logging {
override def run(): Array[T] = {
logInfo("Processing " + split)
rdd.iterator(split).toArray(m)
}
}
class ReduceTask[T: ClassManifest](
rdd: RDD[T], split: Split, f: (T, T) => T)
extends RDDTask[Option[T], T](rdd, split) with Logging {
override def run(): Option[T] = {
logInfo("Processing " + split)
val iter = rdd.iterator(split)
if (iter.hasNext)
Some(iter.reduceLeft(f))
else
None
}
}
class MappedRDD[U: ClassManifest, T: ClassManifest](
prev: RDD[T], f: T => U)
extends RDD[U](prev.sparkContext) {
override def splits = prev.splits
override def preferredLocations(split: Split) = prev.preferredLocations(split)
override def iterator(split: Split) = prev.iterator(split).map(f)
override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
}
class FilteredRDD[T: ClassManifest](
prev: RDD[T], f: T => Boolean)
extends RDD[T](prev.sparkContext) {
override def splits = prev.splits
override def preferredLocations(split: Split) = prev.preferredLocations(split)
override def iterator(split: Split) = prev.iterator(split).filter(f)
override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
}
class FlatMappedRDD[U: ClassManifest, T: ClassManifest](
prev: RDD[T], f: T => Traversable[U])
extends RDD[U](prev.sparkContext) {
override def splits = prev.splits
override def preferredLocations(split: Split) = prev.preferredLocations(split)
override def iterator(split: Split) =
prev.iterator(split).toStream.flatMap(f).iterator
override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
}
class SplitRDD[T: ClassManifest](prev: RDD[T])
extends RDD[Array[T]](prev.sparkContext) {
override def splits = prev.splits
override def preferredLocations(split: Split) = prev.preferredLocations(split)
override def iterator(split: Split) = Iterator.fromArray(Array(prev.iterator(split).toArray))
override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
}
@serializable class SeededSplit(val prev: Split, val seed: Int) extends Split {
override def getId() =
"SeededSplit(" + prev.getId() + ", seed " + seed + ")"
}
class SampledRDD[T: ClassManifest](
prev: RDD[T], withReplacement: Boolean, frac: Double, seed: Int)
extends RDD[T](prev.sparkContext) {
@transient val splits_ = { val rg = new Random(seed); prev.splits.map(x => new SeededSplit(x, rg.nextInt)) }
override def splits = splits_.asInstanceOf[Array[Split]]
override def preferredLocations(split: Split) = prev.preferredLocations(split.asInstanceOf[SeededSplit].prev)
override def iterator(splitIn: Split) = {
val split = splitIn.asInstanceOf[SeededSplit]
val rg = new Random(split.seed);
// Sampling with replacement (TODO: use reservoir sampling to make this more efficient?)
if (withReplacement) {
val oldData = prev.iterator(split.prev).toArray
val sampleSize = (oldData.size * frac).ceil.toInt
val sampledData = for (i <- 1 to sampleSize) yield oldData(rg.nextInt(oldData.size)) // all of oldData's indices are candidates, even if sampleSize < oldData.size
sampledData.iterator
}
// Sampling without replacement
else {
prev.iterator(split.prev).filter(x => (rg.nextDouble <= frac))
}
}
override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split.asInstanceOf[SeededSplit].prev, slot)
}
class CachedRDD[T](
prev: RDD[T])(implicit m: ClassManifest[T])
extends RDD[T](prev.sparkContext) with Logging {
val id = CachedRDD.newId()
@transient val cacheLocs = Map[Split, List[String]]()
override def splits = prev.splits
override def preferredLocations(split: Split) = {
if (cacheLocs.contains(split))
cacheLocs(split)
else
prev.preferredLocations(split)
}
override def iterator(split: Split): Iterator[T] = {
val key = id + "::" + split.getId()
logInfo("CachedRDD split key is " + key)
val cache = CachedRDD.cache
val loading = CachedRDD.loading
val cachedVal = cache.get(key)
if (cachedVal != null) {
// Split is in cache, so just return its values
return Iterator.fromArray(cachedVal.asInstanceOf[Array[T]])
} else {
// Mark the split as loading (unless someone else marks it first)
loading.synchronized {
if (loading.contains(key)) {
while (loading.contains(key)) {
try {loading.wait()} catch {case _ =>}
}
return Iterator.fromArray(cache.get(key).asInstanceOf[Array[T]])
} else {
loading.add(key)
}
}
// If we got here, we have to load the split
logInfo("Loading and caching " + split)
val array = prev.iterator(split).toArray(m)
cache.put(key, array)
loading.synchronized {
loading.remove(key)
loading.notifyAll()
}
return Iterator.fromArray(array)
}
}
override def taskStarted(split: Split, slot: SlaveOffer) {
val oldList = cacheLocs.getOrElse(split, Nil)
val host = slot.getHost
if (!oldList.contains(host))
cacheLocs(split) = host :: oldList
}
}
private object CachedRDD {
val nextId = new AtomicLong(0) // Generates IDs for cached RDDs (on master)
def newId() = nextId.getAndIncrement()
// Stores map results for various splits locally (on workers)
val cache = Cache.newKeySpace()
// Remembers which splits are currently being loaded (on workers)
val loading = new HashSet[String]
}
@serializable
class UnionSplit[T: ClassManifest](rdd: RDD[T], split: Split)
extends Split {
def iterator() = rdd.iterator(split)
def preferredLocations() = rdd.preferredLocations(split)
override def getId() = "UnionSplit(" + split.getId() + ")"
}
@serializable
class UnionRDD[T: ClassManifest](sc: SparkContext, rdds: Seq[RDD[T]])
extends RDD[T](sc) {
@transient val splits_ : Array[Split] = {
val splits: Seq[Split] =
for (rdd <- rdds; split <- rdd.splits)
yield new UnionSplit(rdd, split)
splits.toArray
}
override def splits = splits_
override def iterator(s: Split): Iterator[T] =
s.asInstanceOf[UnionSplit[T]].iterator()
override def preferredLocations(s: Split): Seq[String] =
s.asInstanceOf[UnionSplit[T]].preferredLocations()
}
@serializable class CartesianSplit(val s1: Split, val s2: Split) extends Split {
override def getId() =
"CartesianSplit(" + s1.getId() + ", " + s2.getId() + ")"
}
@serializable
class CartesianRDD[T: ClassManifest, U:ClassManifest](
sc: SparkContext, rdd1: RDD[T], rdd2: RDD[U])
extends RDD[Pair[T, U]](sc) {
@transient val splits_ = {
// create the cross product split
rdd2.splits.map(y => rdd1.splits.map(x => new CartesianSplit(x, y))).flatten
}
override def splits = splits_.asInstanceOf[Array[Split]]
override def preferredLocations(split: Split) = {
val currSplit = split.asInstanceOf[CartesianSplit]
rdd1.preferredLocations(currSplit.s1) ++ rdd2.preferredLocations(currSplit.s2)
}
override def iterator(split: Split) = {
val currSplit = split.asInstanceOf[CartesianSplit]
for (x <- rdd1.iterator(currSplit.s1); y <- rdd2.iterator(currSplit.s2)) yield (x, y)
}
override def taskStarted(split: Split, slot: SlaveOffer) = {
val currSplit = split.asInstanceOf[CartesianSplit]
rdd1.taskStarted(currSplit.s1, slot)
rdd2.taskStarted(currSplit.s2, slot)
}
}
@serializable class PairRDDExtras[K, V](self: RDD[(K, V)]) {
def reduceByKeyToDriver(func: (V, V) => V): Map[K, V] = {
def mergeMaps(m1: HashMap[K, V], m2: HashMap[K, V]): HashMap[K, V] = {
for ((k, v) <- m2) {
m1.get(k) match {
case None => m1(k) = v
case Some(w) => m1(k) = func(w, v)
}
}
return m1
}
self.map(pair => HashMap(pair)).reduce(mergeMaps)
}
def combineByKey[C](createCombiner: V => C,
mergeValue: (C, V) => C,
mergeCombiners: (C, C) => C,
numSplits: Int)
: RDD[(K, C)] =
{
val shufClass = Class.forName(System.getProperty(
"spark.shuffle.class", "spark.LocalFileShuffle"))
val shuf = shufClass.newInstance().asInstanceOf[Shuffle[K, V, C]]
shuf.compute(self, numSplits, createCombiner, mergeValue, mergeCombiners)
}
def reduceByKey(func: (V, V) => V, numSplits: Int): RDD[(K, V)] = {
combineByKey[V]((v: V) => v, func, func, numSplits)
}
def groupByKey(numSplits: Int): RDD[(K, Seq[V])] = {
def createCombiner(v: V) = ArrayBuffer(v)
def mergeValue(buf: ArrayBuffer[V], v: V) = buf += v
def mergeCombiners(b1: ArrayBuffer[V], b2: ArrayBuffer[V]) = b1 ++= b2
val bufs = combineByKey[ArrayBuffer[V]](
createCombiner _, mergeValue _, mergeCombiners _, numSplits)
bufs.asInstanceOf[RDD[(K, Seq[V])]]
}
def join[W](other: RDD[(K, W)], numSplits: Int): RDD[(K, (V, W))] = {
val vs: RDD[(K, Either[V, W])] = self.map { case (k, v) => (k, Left(v)) }
val ws: RDD[(K, Either[V, W])] = other.map { case (k, w) => (k, Right(w)) }
(vs ++ ws).groupByKey(numSplits).flatMap {
case (k, seq) => {
val vbuf = new ArrayBuffer[V]
val wbuf = new ArrayBuffer[W]
seq.foreach(_ match {
case Left(v) => vbuf += v
case Right(w) => wbuf += w
})
for (v <- vbuf; w <- wbuf) yield (k, (v, w))
}
}
}
def combineByKey[C](createCombiner: V => C,
mergeValue: (C, V) => C,
mergeCombiners: (C, C) => C)
: RDD[(K, C)] = {
combineByKey(createCombiner, mergeValue, mergeCombiners, numCores)
}
def reduceByKey(func: (V, V) => V): RDD[(K, V)] = {
reduceByKey(func, numCores)
}
def groupByKey(): RDD[(K, Seq[V])] = {
groupByKey(numCores)
}
def join[W](other: RDD[(K, W)]): RDD[(K, (V, W))] = {
join(other, numCores)
}
def numCores = self.sparkContext.numCores
def collectAsMap(): Map[K, V] = HashMap(self.collect(): _*)
}