scala.actors.MQueue.scala Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of scala-actors Show documentation
Show all versions of scala-actors Show documentation
Deprecated Actors Library for Scala
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2005-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.actors
private[actors] class MQueueElement[Msg >: Null](val msg: Msg, val session: OutputChannel[Any], var next: MQueueElement[Msg]) {
def this() = this(null, null, null)
def this(msg: Msg, session: OutputChannel[Any]) = this(msg, session, null)
}
private[actors] class MQueue[Msg >: Null](protected val label: String) {
protected var first: MQueueElement[Msg] = null
protected var last: MQueueElement[Msg] = null // last eq null iff list is empty
private var _size = 0
def size = _size
final def isEmpty = last eq null
protected def changeSize(diff: Int) {
_size += diff
}
def prepend(other: MQueue[Msg]) {
if (!other.isEmpty) {
other.last.next = first
first = other.first
}
}
def clear() {
first = null
last = null
_size = 0
}
def append(msg: Msg, session: OutputChannel[Any]) {
changeSize(1) // size always increases by 1
val el = new MQueueElement(msg, session)
if (isEmpty) first = el
else last.next = el
last = el
}
def append(el: MQueueElement[Msg]) {
changeSize(1) // size always increases by 1
if (isEmpty) first = el
else last.next = el
last = el
}
def foreach(f: (Msg, OutputChannel[Any]) => Unit) {
var curr = first
while (curr != null) {
f(curr.msg, curr.session)
curr = curr.next
}
}
def foreachAppend(target: MQueue[Msg]) {
var curr = first
while (curr != null) {
target.append(curr)
curr = curr.next
}
}
def foreachDequeue(target: MQueue[Msg]) {
var curr = first
while (curr != null) {
target.append(curr)
curr = curr.next
}
first = null
last = null
_size = 0
}
def foldLeft[B](z: B)(f: (B, Msg) => B): B = {
var acc = z
var curr = first
while (curr != null) {
acc = f(acc, curr.msg)
curr = curr.next
}
acc
}
/** Returns the n-th message that satisfies the predicate `p`
* without removing it.
*/
def get(n: Int)(p: Msg => Boolean): Option[Msg] = {
var pos = 0
def test(msg: Msg): Boolean =
p(msg) && (pos == n || { pos += 1; false })
var curr = first
while (curr != null)
if (test(curr.msg)) return Some(curr.msg) // early return
else curr = curr.next
None
}
/** Removes the n-th message that satisfies the predicate p.
*/
def remove(n: Int)(p: (Msg, OutputChannel[Any]) => Boolean): Option[(Msg, OutputChannel[Any])] =
removeInternal(n)(p) map (x => (x.msg, x.session))
/** Extracts the first message that satisfies the predicate `p`
* or `'''null'''` if `p` fails for all of them.
*/
def extractFirst(p: (Msg, OutputChannel[Any]) => Boolean): MQueueElement[Msg] =
removeInternal(0)(p).orNull
def extractFirst(pf: PartialFunction[Msg, Any]): MQueueElement[Msg] = {
if (isEmpty) // early return
return null
// special handling if returning the head
if (pf.isDefinedAt(first.msg)) {
val res = first
first = first.next
if (res eq last)
last = null
changeSize(-1)
res
}
else {
var curr = first.next // init to element #2
var prev = first
while (curr != null) {
if (pf.isDefinedAt(curr.msg)) {
prev.next = curr.next
if (curr eq last)
last = prev
changeSize(-1)
return curr // early return
}
else {
prev = curr
curr = curr.next
}
}
// not found
null
}
}
private def removeInternal(n: Int)(p: (Msg, OutputChannel[Any]) => Boolean): Option[MQueueElement[Msg]] = {
var pos = 0
def foundMsg(x: MQueueElement[Msg]) = {
changeSize(-1)
Some(x)
}
def test(msg: Msg, session: OutputChannel[Any]): Boolean =
p(msg, session) && (pos == n || { pos += 1 ; false })
if (isEmpty) // early return
return None
// special handling if returning the head
if (test(first.msg, first.session)) {
val res = first
first = first.next
if (res eq last)
last = null
foundMsg(res)
}
else {
var curr = first.next // init to element #2
var prev = first
while (curr != null) {
if (test(curr.msg, curr.session)) {
prev.next = curr.next
if (curr eq last)
last = prev
return foundMsg(curr) // early return
}
else {
prev = curr
curr = curr.next
}
}
// not found
None
}
}
}
/** Debugging trait.
*/
private[actors] trait MessageQueueTracer extends MQueue[Any]
{
private val queueNumber = MessageQueueTracer.getQueueNumber
override def append(msg: Any, session: OutputChannel[Any]) {
super.append(msg, session)
printQueue("APPEND %s" format msg)
}
override def get(n: Int)(p: Any => Boolean): Option[Any] = {
val res = super.get(n)(p)
printQueue("GET %s" format res)
res
}
override def remove(n: Int)(p: (Any, OutputChannel[Any]) => Boolean): Option[(Any, OutputChannel[Any])] = {
val res = super.remove(n)(p)
printQueue("REMOVE %s" format res)
res
}
override def extractFirst(p: (Any, OutputChannel[Any]) => Boolean): MQueueElement[Any] = {
val res = super.extractFirst(p)
printQueue("EXTRACT_FIRST %s" format res)
res
}
private def printQueue(msg: String) = {
def firstMsg = if (first eq null) "null" else first.msg
def lastMsg = if (last eq null) "null" else last.msg
println("[%s size=%d] [%s] first = %s, last = %s".format(this, size, msg, firstMsg, lastMsg))
}
override def toString() = "%s:%d".format(label, queueNumber)
}
private[actors] object MessageQueueTracer {
// for tracing purposes
private var queueNumberAssigner = 0
private def getQueueNumber = synchronized {
queueNumberAssigner += 1
queueNumberAssigner
}
}