public RowCursor(IChannelProvider provider, int poolRows, IRowCursor input, IRandom rand)
: base(provider)
{
Ch.AssertValue(input);
Ch.AssertValue(rand);
Ch.Assert(_blockSize > 0);
Ch.Assert(_bufferDepth > 0);
Ch.Assert(poolRows > 0);
_poolRows = poolRows;
_input = input;
_rand = rand;
_pipeIndices = Utils.GetIdentityPermutation(_poolRows - 1 + _bufferDepth * _blockSize);
int colLim = Schema.ColumnCount;
int numActive = 0;
_colToActivesIndex = new int[colLim];
for (int c = 0; c < colLim; ++c)
{
_colToActivesIndex[c] = _input.IsColumnActive(c) ? numActive++ : -1;
}
_pipes = new ShufflePipe[numActive + (int)ExtraIndex.Lim];
_getters = new Delegate[numActive];
for (int c = 0; c < colLim; ++c)
{
int ia = _colToActivesIndex[c];
if (ia < 0)
{
continue;
}
_pipes[ia] = ShufflePipe.Create(_pipeIndices.Length,
input.Schema.GetColumnType(c), RowCursorUtils.GetGetterAsDelegate(input, c));
_getters[ia] = CreateGetterDelegate(c);
}
var idPipe = _pipes[numActive + (int)ExtraIndex.Id] = ShufflePipe.Create(_pipeIndices.Length, NumberType.UG, input.GetIdGetter());
_idGetter = CreateGetterDelegate <UInt128>(idPipe);
// Initially, after the preamble to MoveNextCore, we want:
// liveCount=0, deadCount=0, circularIndex=0. So we set these
// funky values accordingly.
_pipeIndex = _circularIndex = _pipeIndices.Length - 1;
_deadCount = -1;
_liveCount = 1;
// Set up the producer worker.
_toConsume = new BufferBlock <int>();
_toProduce = new BufferBlock <int>();
// First request the pool - 1 + block size rows, to get us going.
PostAssert(_toProduce, _poolRows - 1 + _blockSize);
// Queue up the remaining capacity.
for (int i = 1; i < _bufferDepth; ++i)
{
PostAssert(_toProduce, _blockSize);
}
_producerTask = LoopProducerWorker();
}
private ValueGetter <TValue> CreateGetterDelegate <TValue>(ShufflePipe pipe)
{
Ch.AssertValue(pipe);
Ch.Assert(pipe is ShufflePipe <TValue>);
var pipe2 = (ShufflePipe <TValue>)pipe;
ValueGetter <TValue> getter =
(ref TValue value) =>
{
Ch.Assert(_pipeIndex == _pipeIndices[_circularIndex]);
pipe2.Fetch(_pipeIndex, ref value);
};
return(getter);
}
