private void InitializePartitions(IEnumerable <T> source, int partitionCount, bool useStriping)
{
ParallelEnumerableWrapper <T> wrapper = source as ParallelEnumerableWrapper <T>;
if (wrapper != null)
{
source = wrapper.WrappedEnumerable;
}
IList <T> data = source as IList <T>;
if (data != null)
{
QueryOperatorEnumerator <T, int>[] enumeratorArray = new QueryOperatorEnumerator <T, int> [partitionCount];
int count = data.Count;
T[] localArray = source as T[];
int maxChunkSize = -1;
if (useStriping)
{
maxChunkSize = Scheduling.GetDefaultChunkSize <T>();
if (maxChunkSize < 1)
{
maxChunkSize = 1;
}
}
for (int i = 0; i < partitionCount; i++)
{
if (localArray != null)
{
if (useStriping)
{
enumeratorArray[i] = new ArrayIndexRangeEnumerator <T>(localArray, partitionCount, i, maxChunkSize);
}
else
{
enumeratorArray[i] = new ArrayContiguousIndexRangeEnumerator <T>(localArray, partitionCount, i);
}
}
else if (useStriping)
{
enumeratorArray[i] = new ListIndexRangeEnumerator <T>(data, partitionCount, i, maxChunkSize);
}
else
{
enumeratorArray[i] = new ListContiguousIndexRangeEnumerator <T>(data, partitionCount, i);
}
}
base.m_partitions = enumeratorArray;
}
else
{
base.m_partitions = PartitionedDataSource <T> .MakePartitions(source.GetEnumerator(), partitionCount);
}
}
//-----------------------------------------------------------------------------------
// A factory method to construct a partitioned stream over a data source.
//
// Arguments:
// source - the data source to be partitioned
// partitionCount - the number of partitions desired
// useOrdinalOrderPreservation - whether ordinal position must be tracked
// useStriping - whether striped partitioning should be used instead of range partitioning
//
internal static PartitionedStream <T, int> PartitionDataSource <T>(IEnumerable <T> source, int partitionCount, bool useStriping)
{
// The partitioned stream to return.
PartitionedStream <T, int> returnValue;
IParallelPartitionable <T> sourceAsPartitionable = source as IParallelPartitionable <T>;
if (sourceAsPartitionable != null)
{
// The type overrides the partitioning algorithm, so we will use it instead of the default.
// The returned enumerator must be the same size that we requested, otherwise we throw.
QueryOperatorEnumerator <T, int>[] enumerators = sourceAsPartitionable.GetPartitions(partitionCount);
if (enumerators == null)
{
throw new InvalidOperationException(SR.GetString(SR.ParallelPartitionable_NullReturn));
}
else if (enumerators.Length != partitionCount)
{
throw new InvalidOperationException(SR.GetString(SR.ParallelPartitionable_IncorretElementCount));
}
// Now just copy the enumerators into the stream, validating that the result is non-null.
PartitionedStream <T, int> stream =
new PartitionedStream <T, int>(partitionCount, Util.GetDefaultComparer <int>(), OrdinalIndexState.Correct);
for (int i = 0; i < partitionCount; i++)
{
QueryOperatorEnumerator <T, int> currentEnumerator = enumerators[i];
if (currentEnumerator == null)
{
throw new InvalidOperationException(SR.GetString(SR.ParallelPartitionable_NullElement));
}
stream[i] = currentEnumerator;
}
returnValue = stream;
}
else
{
returnValue = new PartitionedDataSource <T>(source, partitionCount, useStriping);
}
Contract.Assert(returnValue.PartitionCount == partitionCount);
return(returnValue);
}
