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Standard library for the Scala Programming Language
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection.parallel.immutable
import scala.collection.parallel.ParMapLike
import scala.collection.parallel.Combiner
import scala.collection.parallel.IterableSplitter
import scala.collection.mutable.UnrolledBuffer.Unrolled
import scala.collection.mutable.UnrolledBuffer
import scala.collection.generic.ParMapFactory
import scala.collection.generic.CanCombineFrom
import scala.collection.generic.GenericParMapTemplate
import scala.collection.generic.GenericParMapCompanion
import scala.collection.immutable.{ HashMap, TrieIterator }
import scala.annotation.unchecked.uncheckedVariance
import scala.collection.parallel.Task
/** Immutable parallel hash map, based on hash tries.
*
* $paralleliterableinfo
*
* $sideeffects
*
* @tparam K the key type of the map
* @tparam V the value type of the map
*
* @author Aleksandar Prokopec
* @since 2.9
* @see [[http://docs.scala-lang.org/overviews/parallel-collections/concrete-parallel-collections.html#parallel_hash_tries Scala's Parallel Collections Library overview]]
* section on Parallel Hash Tries for more information.
*
* @define Coll `immutable.ParHashMap`
* @define coll immutable parallel hash map
*/
@SerialVersionUID(1L)
class ParHashMap[K, +V] private[immutable] (private[this] val trie: HashMap[K, V])
extends ParMap[K, V]
with GenericParMapTemplate[K, V, ParHashMap]
with ParMapLike[K, V, ParHashMap[K, V], HashMap[K, V]]
with Serializable
{
self =>
def this() = this(HashMap.empty[K, V])
override def mapCompanion: GenericParMapCompanion[ParHashMap] = ParHashMap
override def empty: ParHashMap[K, V] = new ParHashMap[K, V]
protected[this] override def newCombiner = HashMapCombiner[K, V]
def splitter: IterableSplitter[(K, V)] = new ParHashMapIterator(trie.iterator, trie.size)
override def seq = trie
def -(k: K) = new ParHashMap(trie - k)
def +[U >: V](kv: (K, U)) = new ParHashMap(trie + kv)
def get(k: K) = trie.get(k)
override def size = trie.size
protected override def reuse[S, That](oldc: Option[Combiner[S, That]], newc: Combiner[S, That]) = oldc match {
case Some(old) => old
case None => newc
}
class ParHashMapIterator(var triter: Iterator[(K, V @uncheckedVariance)], val sz: Int)
extends IterableSplitter[(K, V)] {
var i = 0
def dup = triter match {
case t: TrieIterator[_] =>
dupFromIterator(t.dupIterator)
case _ =>
val buff = triter.toBuffer
triter = buff.iterator
dupFromIterator(buff.iterator)
}
private def dupFromIterator(it: Iterator[(K, V @uncheckedVariance)]) = {
val phit = new ParHashMapIterator(it, sz)
phit.i = i
phit
}
def split: Seq[IterableSplitter[(K, V)]] = if (remaining < 2) Seq(this) else triter match {
case t: TrieIterator[_] =>
val previousRemaining = remaining
val ((fst, fstlength), snd) = t.split
val sndlength = previousRemaining - fstlength
Seq(
new ParHashMapIterator(fst, fstlength),
new ParHashMapIterator(snd, sndlength)
)
case _ =>
// iterator of the collision map case
val buff = triter.toBuffer
val (fp, sp) = buff.splitAt(buff.length / 2)
Seq(fp, sp) map { b => new ParHashMapIterator(b.iterator, b.length) }
}
def next(): (K, V) = {
i += 1
val r = triter.next
r
}
def hasNext: Boolean = {
i < sz
}
def remaining = sz - i
override def toString = "HashTrieIterator(" + sz + ")"
}
/* debug */
private[parallel] def printDebugInfo() {
println("Parallel hash trie")
println("Top level inner trie type: " + trie.getClass)
trie match {
case hm: HashMap.HashMap1[k, v] =>
println("single node type")
println("key stored: " + hm.getKey)
println("hash of key: " + hm.getHash)
println("computed hash of " + hm.getKey + ": " + hm.computeHashFor(hm.getKey))
println("trie.get(key): " + hm.get(hm.getKey))
case _ =>
println("other kind of node")
}
}
}
/** $factoryInfo
* @define Coll `immutable.ParHashMap`
* @define coll immutable parallel hash map
*/
object ParHashMap extends ParMapFactory[ParHashMap] {
def empty[K, V]: ParHashMap[K, V] = new ParHashMap[K, V]
def newCombiner[K, V]: Combiner[(K, V), ParHashMap[K, V]] = HashMapCombiner[K, V]
implicit def canBuildFrom[K, V]: CanCombineFrom[Coll, (K, V), ParHashMap[K, V]] = {
new CanCombineFromMap[K, V]
}
def fromTrie[K, V](t: HashMap[K, V]) = new ParHashMap(t)
var totalcombines = new java.util.concurrent.atomic.AtomicInteger(0)
}
private[parallel] abstract class HashMapCombiner[K, V]
extends scala.collection.parallel.BucketCombiner[(K, V), ParHashMap[K, V], (K, V), HashMapCombiner[K, V]](HashMapCombiner.rootsize) {
//self: EnvironmentPassingCombiner[(K, V), ParHashMap[K, V]] =>
import HashMapCombiner._
val emptyTrie = HashMap.empty[K, V]
def +=(elem: (K, V)) = {
sz += 1
val hc = emptyTrie.computeHash(elem._1)
val pos = hc & 0x1f
if (buckets(pos) eq null) {
// initialize bucket
buckets(pos) = new UnrolledBuffer[(K, V)]
}
// add to bucket
buckets(pos) += elem
this
}
def result = {
val bucks = buckets.filter(_ != null).map(_.headPtr)
val root = new Array[HashMap[K, V]](bucks.length)
combinerTaskSupport.executeAndWaitResult(new CreateTrie(bucks, root, 0, bucks.length))
var bitmap = 0
var i = 0
while (i < rootsize) {
if (buckets(i) ne null) bitmap |= 1 << i
i += 1
}
val sz = root.foldLeft(0)(_ + _.size)
if (sz == 0) new ParHashMap[K, V]
else if (sz == 1) new ParHashMap[K, V](root(0))
else {
val trie = new HashMap.HashTrieMap(bitmap, root, sz)
new ParHashMap[K, V](trie)
}
}
def groupByKey[Repr](cbf: () => Combiner[V, Repr]): ParHashMap[K, Repr] = {
val bucks = buckets.filter(_ != null).map(_.headPtr)
val root = new Array[HashMap[K, AnyRef]](bucks.length)
combinerTaskSupport.executeAndWaitResult(new CreateGroupedTrie(cbf, bucks, root, 0, bucks.length))
var bitmap = 0
var i = 0
while (i < rootsize) {
if (buckets(i) ne null) bitmap |= 1 << i
i += 1
}
val sz = root.foldLeft(0)(_ + _.size)
if (sz == 0) new ParHashMap[K, Repr]
else if (sz == 1) new ParHashMap[K, Repr](root(0).asInstanceOf[HashMap[K, Repr]])
else {
val trie = new HashMap.HashTrieMap(bitmap, root.asInstanceOf[Array[HashMap[K, Repr]]], sz)
new ParHashMap[K, Repr](trie)
}
}
override def toString = {
"HashTrieCombiner(sz: " + size + ")"
//"HashTrieCombiner(buckets:\n\t" + buckets.filter(_ != null).mkString("\n\t") + ")\n"
}
/* tasks */
class CreateTrie(bucks: Array[Unrolled[(K, V)]], root: Array[HashMap[K, V]], offset: Int, howmany: Int)
extends Task[Unit, CreateTrie] {
@volatile var result = ()
def leaf(prev: Option[Unit]) = {
var i = offset
val until = offset + howmany
while (i < until) {
root(i) = createTrie(bucks(i))
i += 1
}
result = result
}
private def createTrie(elems: Unrolled[(K, V)]): HashMap[K, V] = {
var trie = new HashMap[K, V]
var unrolled = elems
var i = 0
while (unrolled ne null) {
val chunkarr = unrolled.array
val chunksz = unrolled.size
while (i < chunksz) {
val kv = chunkarr(i)
val hc = trie.computeHash(kv._1)
trie = trie.updated0(kv._1, hc, rootbits, kv._2, kv, null)
i += 1
}
i = 0
unrolled = unrolled.next
}
trie
}
def split = {
val fp = howmany / 2
List(new CreateTrie(bucks, root, offset, fp), new CreateTrie(bucks, root, offset + fp, howmany - fp))
}
def shouldSplitFurther = howmany > scala.collection.parallel.thresholdFromSize(root.length, combinerTaskSupport.parallelismLevel)
}
class CreateGroupedTrie[Repr](cbf: () => Combiner[V, Repr], bucks: Array[Unrolled[(K, V)]], root: Array[HashMap[K, AnyRef]], offset: Int, howmany: Int)
extends Task[Unit, CreateGroupedTrie[Repr]] {
@volatile var result = ()
def leaf(prev: Option[Unit]) = {
var i = offset
val until = offset + howmany
while (i < until) {
root(i) = createGroupedTrie(bucks(i)).asInstanceOf[HashMap[K, AnyRef]]
i += 1
}
result = result
}
private def createGroupedTrie(elems: Unrolled[(K, V)]): HashMap[K, Repr] = {
var trie = new HashMap[K, Combiner[V, Repr]]
var unrolled = elems
var i = 0
while (unrolled ne null) {
val chunkarr = unrolled.array
val chunksz = unrolled.size
while (i < chunksz) {
val kv = chunkarr(i)
val hc = trie.computeHash(kv._1)
// check to see if already present
val cmb: Combiner[V, Repr] = trie.get0(kv._1, hc, rootbits) match {
case Some(cmb) => cmb
case None =>
val cmb: Combiner[V, Repr] = cbf()
trie = trie.updated0[Combiner[V, Repr]](kv._1, hc, rootbits, cmb, null, null)
cmb
}
cmb += kv._2
i += 1
}
i = 0
unrolled = unrolled.next
}
evaluateCombiners(trie).asInstanceOf[HashMap[K, Repr]]
}
private def evaluateCombiners(trie: HashMap[K, Combiner[V, Repr]]): HashMap[K, Repr] = trie match {
case hm1: HashMap.HashMap1[_, _] =>
val evaledvalue = hm1.value.result
new HashMap.HashMap1[K, Repr](hm1.key, hm1.hash, evaledvalue, null)
case hmc: HashMap.HashMapCollision1[_, _] =>
val evaledkvs = hmc.kvs map { p => (p._1, p._2.result) }
new HashMap.HashMapCollision1[K, Repr](hmc.hash, evaledkvs)
case htm: HashMap.HashTrieMap[k, v] =>
var i = 0
while (i < htm.elems.length) {
htm.elems(i) = evaluateCombiners(htm.elems(i)).asInstanceOf[HashMap[k, v]]
i += 1
}
htm.asInstanceOf[HashMap[K, Repr]]
case empty => empty.asInstanceOf[HashMap[K, Repr]]
}
def split = {
val fp = howmany / 2
List(new CreateGroupedTrie(cbf, bucks, root, offset, fp), new CreateGroupedTrie(cbf, bucks, root, offset + fp, howmany - fp))
}
def shouldSplitFurther = howmany > scala.collection.parallel.thresholdFromSize(root.length, combinerTaskSupport.parallelismLevel)
}
}
private[parallel] object HashMapCombiner {
def apply[K, V] = new HashMapCombiner[K, V] {} // was: with EnvironmentPassingCombiner[(K, V), ParHashMap[K, V]]
private[immutable] val rootbits = 5
private[immutable] val rootsize = 1 << 5
}