public Collection <R, T> FixedPoint <K>(
Func <Naiad.Dataflow.Iteration.LoopContext <T>,
Collection <R, IterationIn <T> >, Collection <R, IterationIn <T> > > f, Expression <Func <R, K> > consolidateFunction, int maxIterations)
{
if (f == null)
{
throw new ArgumentNullException("f");
}
var compiled = consolidateFunction.ConvertToWeightedFuncAndHashCode();
var fp = new Naiad.Dataflow.Iteration.LoopContext <T>(this.Statistics, "FixedPoint");
var delay = fp.Delay <Weighted <R> >(compiled, maxIterations);
var ingress = fp.EnterLoop <Weighted <R> >(this.Output).ToCollection()
.PartitionBy(consolidateFunction); // add coordinate and ensure partitioned appropriately.
var source = ingress.Concat(delay.Output.ToCollection()); // merge input with feedback data.
var iteration = f(fp, source); // apply the body of the logic.
var fixedpoint = iteration.Except(ingress) // subtract starting point.
.Consolidate(consolidateFunction); // consolidate, to ensure cancellation.
delay.Input = fixedpoint.Output; // attach the result to the delayVertex source.
return(fp.ExitLoop(iteration.Output).ToCollection()); // return the loop body as output.
}
public Collection <R, T> GeneralFixedPoint <K>(
Func <Naiad.Dataflow.Iteration.LoopContext <T>, Collection <R, IterationIn <T> >, Collection <R, IterationIn <T> > > f, // (lc, x) => f(x)
Func <R, int> priorityFunction,
Expression <Func <R, K> > partitionedBy,
int maxIterations)
{
if (priorityFunction == null)
{
throw new ArgumentNullException("priorityFunction");
}
var compiled = partitionedBy.ConvertToWeightedFuncAndHashCode();
var fp = new Naiad.Dataflow.Iteration.LoopContext <T>(this.Statistics, "FixedPointSequence");
// probably doesn't work correctly when max + pri >= 2^31. Fix!
var delayVertex = fp.Delay(compiled, maxIterations);
// consider partitioning first, to ensure even boring work is distributed
var ingress = fp.EnterLoop(this.Output, x => priorityFunction(x.record))
.ToCollection()
.PartitionBy(partitionedBy);
var source = ingress.Concat(delayVertex.Output.ToCollection());
var iteration = f(fp, source);
var fixedpoint = iteration.Except(ingress)
.Consolidate(partitionedBy);
delayVertex.Input = fixedpoint.Output;
var egress = fp.ExitLoop(iteration.Output).ToCollection();
return(egress);
}
/// <summary>
/// Adds a temporal dimension to each record.
/// </summary>
/// <param name="name">an identifier, for purposes of printing and reading</param>
/// <returns></returns>
public Collection <R, IterationIn <T> > EnterLoop(Naiad.Dataflow.Iteration.LoopContext <T> helper, Func <R, int> initialIteration)
{
return(helper.EnterLoop(this.Output, x => initialIteration(x.record)).ToCollection(this.Immutable));
}
/// <summary>
/// Adds a temporal dimension to each record.
/// </summary>
/// <param name="name">an identifier, for purposes of printing and reading</param>
/// <returns></returns>
public Collection <R, IterationIn <T> > EnterLoop(Naiad.Dataflow.Iteration.LoopContext <T> helper)
{
return(helper.EnterLoop(this.Output).ToCollection(this.Immutable));
}
