groovyx.gpars.extra166y
Class PAS.FJScan

java.lang.Object
  jsr166y.ForkJoinTask<java.lang.Void>
      groovyx.gpars.extra166y.PAS.FJScan

All Implemented Interfaces:

java.io.Serializable, java.util.concurrent.Future<java.lang.Void>

Direct Known Subclasses:

PAS.FJDScan, PAS.FJLScan, PAS.FJOScan

Enclosing class:

PAS

abstract static class PAS.FJScan
extends jsr166y.ForkJoinTask<java.lang.Void>

Cumulative scan A basic version of scan is straightforward. Keep dividing by two to threshold segment size, and then: Pass 1: Create tree of partial sums for each segment Pass 2: For each segment, cumulate with offset of left sibling See G. Blelloch's http://www.cs.cmu.edu/~scandal/alg/scan.html This version improves performance within FJ framework mainly by allowing second pass of ready left-hand sides to proceed even if some right-hand side first passes are still executing. It also combines first and second pass for leftmost segment, and for cumulate (not precumulate) also skips first pass for rightmost segment (whose result is not needed for second pass). To manage this, it relies on "phase" phase/state control field maintaining bits CUMULATE, SUMMED, and FINISHED. CUMULATE is main phase bit. When false, segments compute only their sum. When true, they cumulate array elements. CUMULATE is set at root at beginning of second pass and then propagated down. But it may also be set earlier for subtrees with lo==origin (the left spine of tree). SUMMED is a one bit join count. For leafs, set when summed. For internal nodes, becomes true when one child is summed. When second child finishes summing, it then moves up tree to trigger cumulate phase. FINISHED is also a one bit join count. For leafs, it is set when cumulated. For internal nodes, it becomes true when one child is cumulated. When second child finishes cumulating, it then moves up tree, executing complete() at the root. This class maintains only the basic control logic. Subclasses maintain the "in" and "out" fields, and *Ops classes perform computations

Field Summary

(package private) static short	CUMULATE
(package private) static short	FINISHED
(package private) int	hi
(package private) PAS.FJScan	left
(package private) int	lo
(package private) PAS.FJScanOp	op
(package private) PAS.FJScan	parent
(package private) int	phase
(package private) static java.util.concurrent.atomic.AtomicIntegerFieldUpdater<PAS.FJScan>	phaseUpdater
(package private) PAS.FJScan	right
(package private) static short	SUMMED

Constructor Summary

PAS.FJScan(PAS.FJScan parent, PAS.FJScanOp op, int lo, int hi)

Method Summary

(package private) double	dgetIn()
(package private) double	dgetOut()
(package private) void	dsetIn(double x)
(package private) void	dsetOut(double x)
boolean	exec()
java.lang.Void	getRawResult()
(package private) long	lgetIn()
(package private) long	lgetOut()
(package private) void	lsetIn(long x)
(package private) void	lsetOut(long x)
(package private) java.lang.Object	ogetIn()
(package private) java.lang.Object	ogetOut()
(package private) void	rsetIn(java.lang.Object x)
(package private) void	rsetOut(java.lang.Object x)
protected void	setRawResult(java.lang.Void mustBeNull)
(package private) boolean	transitionToCumulate() Returns true if can CAS CUMULATE bit true

Methods inherited from class jsr166y.ForkJoinTask

adapt, adapt, adapt, cancel, complete, completeExceptionally, fork, get, get, getException, getPool, getQueuedTaskCount, getSurplusQueuedTaskCount, helpQuiesce, inForkJoinPool, invoke, invokeAll, invokeAll, invokeAll, isCancelled, isCompletedAbnormally, isCompletedNormally, isDone, join, peekNextLocalTask, pollNextLocalTask, pollTask, quietlyInvoke, quietlyJoin, reinitialize, tryUnfork

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CUMULATE

static final short CUMULATE

See Also:

Constant Field Values

SUMMED

static final short SUMMED

See Also:

Constant Field Values

FINISHED

static final short FINISHED

See Also:

Constant Field Values

parent

final PAS.FJScan parent

op

final PAS.FJScanOp op

left

PAS.FJScan left

right

PAS.FJScan right

phase

volatile int phase

lo

final int lo

hi

final int hi

phaseUpdater

static final java.util.concurrent.atomic.AtomicIntegerFieldUpdater<PAS.FJScan> phaseUpdater

Constructor Detail

PAS.FJScan

PAS.FJScan(PAS.FJScan parent,
           PAS.FJScanOp op,
           int lo,
           int hi)

Method Detail

getRawResult

public final java.lang.Void getRawResult()

Specified by:

getRawResult in class jsr166y.ForkJoinTask<java.lang.Void>

setRawResult

protected final void setRawResult(java.lang.Void mustBeNull)

Specified by:

setRawResult in class jsr166y.ForkJoinTask<java.lang.Void>

transitionToCumulate

final boolean transitionToCumulate()

Returns true if can CAS CUMULATE bit true

exec

public final boolean exec()

Specified by:

exec in class jsr166y.ForkJoinTask<java.lang.Void>

ogetIn

java.lang.Object ogetIn()

ogetOut

java.lang.Object ogetOut()

rsetIn

void rsetIn(java.lang.Object x)

rsetOut

void rsetOut(java.lang.Object x)

dgetIn

double dgetIn()

dgetOut

double dgetOut()

dsetIn

void dsetIn(double x)

dsetOut

void dsetOut(double x)

lgetIn

long lgetIn()

lgetOut

long lgetOut()

lsetIn

void lsetIn(long x)

lsetOut

void lsetOut(long x)