private static void SetupCursor(TextLoader parent, bool[] active, int n,
out int srcNeeded, out int cthd)
{
// Note that files is allowed to be empty.
Contracts.AssertValue(parent);
Contracts.AssertValue(parent._files);
Contracts.Assert(active == null || active.Length == parent._bindings.Infos.Length);
var bindings = parent._bindings;
// This ensures _srcNeeded is >= 0.
int srcLim = 1;
for (int i = 0; i < bindings.Infos.Length; i++)
{
if (active != null && !active[i])
{
continue;
}
var info = bindings.Infos[i];
foreach (var seg in info.Segments)
{
if (srcLim < seg.Lim)
{
srcLim = seg.Lim;
}
}
}
if (srcLim > parent._inputSize && parent._inputSize > 0)
{
srcLim = parent._inputSize;
}
srcNeeded = srcLim - 1;
Contracts.Assert(srcNeeded >= 0);
// Determine the number of threads to use.
cthd = DataViewUtils.GetThreadCount(parent._host, n, !parent._useThreads);
long cblkMax = parent._maxRows / BatchSize;
if (cthd > cblkMax)
{
cthd = Math.Max(1, (int)cblkMax);
}
}
public IRowCursor[] GetRowCursorSet(out IRowCursorConsolidator consolidator, Func <int, bool> predicate, int n, IRandom rand = null)
{
var host = new ConsoleEnvironment().Register("Estimate n threads");
n = DataViewUtils.GetThreadCount(host, n);
if (n <= 1)
{
consolidator = null;
return(new IRowCursor[] { GetRowCursor(predicate, rand) });
}
else
{
var cursors = Source.GetRowCursorSet(out consolidator, i => predicate(i) || predicate(SchemaHelper.NeedColumn(_columnMapping, i)),
n, rand);
for (int i = 0; i < cursors.Length; ++i)
{
cursors[i] = new AddRandomCursor(this, cursors[i]);
}
return(cursors);
}
}
public DataViewRowCursor[] GetRowCursorSet(IEnumerable <DataViewSchema.Column> columnsNeeded, int n, Random rand = null)
{
n = DataViewUtils.GetThreadCount(n);
if (n <= 1)
{
return new DataViewRowCursor[] { GetRowCursor(columnsNeeded, rand) }
}
;
else
{
//var cols = SchemaHelper.ColumnsNeeded(columnsNeeded, Schema, _args.columns);
var cols = SchemaHelper.ColumnsNeeded(columnsNeeded, Source.Schema);
var cursors = Source.GetRowCursorSet(cols, n, rand);
for (int i = 0; i < cursors.Length; ++i)
{
cursors[i] = new AddRandomCursor(this, cursors[i]);
}
return(cursors);
}
}