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);
}
}
//---------------------------------------------------------------------------------------
// This method just creates the individual partitions given a data source.
//
// Notes:
// We check whether the data source is an IList<T> and, if so, we can partition
// "in place" by calculating a set of indexes. Otherwise, we return an enumerator that
// performs partitioning lazily. Depending on which case it is, the enumerator may
// contain synchronization (i.e. the latter case), meaning callers may occ----ionally
// block when enumerating it.
//
private void InitializePartitions(IEnumerable <T> source, int partitionCount, bool useStriping)
{
Contract.Assert(source != null);
Contract.Assert(partitionCount > 0);
// If this is a wrapper, grab the internal wrapped data source so we can uncover its real type.
ParallelEnumerableWrapper <T> wrapper = source as ParallelEnumerableWrapper <T>;
if (wrapper != null)
{
source = wrapper.WrappedEnumerable;
Contract.Assert(source != null);
}
// Check whether we have an indexable data source.
IList <T> sourceAsList = source as IList <T>;
if (sourceAsList != null)
{
QueryOperatorEnumerator <T, int>[] partitions = new QueryOperatorEnumerator <T, int> [partitionCount];
int listCount = sourceAsList.Count;
// We use this below to specialize enumerators when possible.
T[] sourceAsArray = source as T[];
// If range partitioning is used, chunk size will be unlimited, i.e. -1.
int maxChunkSize = -1;
if (useStriping)
{
maxChunkSize = Scheduling.GetDefaultChunkSize <T>();
// The minimum chunk size is 1.
if (maxChunkSize < 1)
{
maxChunkSize = 1;
}
}
// Calculate indexes and construct enumerators that walk a subset of the input.
for (int i = 0; i < partitionCount; i++)
{
if (sourceAsArray != null)
{
// If the source is an array, we can use a fast path below to index using
// 'ldelem' instructions rather than making interface method calls.
if (useStriping)
{
partitions[i] = new ArrayIndexRangeEnumerator(sourceAsArray, partitionCount, i, maxChunkSize);
}
else
{
partitions[i] = new ArrayContiguousIndexRangeEnumerator(sourceAsArray, partitionCount, i);
}
TraceHelpers.TraceInfo("ContigousRangePartitionExchangeStream::MakePartitions - (array) #{0} {1}", i, maxChunkSize);
}
else
{
// Create a general purpose list enumerator object.
if (useStriping)
{
partitions[i] = new ListIndexRangeEnumerator(sourceAsList, partitionCount, i, maxChunkSize);
}
else
{
partitions[i] = new ListContiguousIndexRangeEnumerator(sourceAsList, partitionCount, i);
}
TraceHelpers.TraceInfo("ContigousRangePartitionExchangeStream::MakePartitions - (list) #{0} {1})", i, maxChunkSize);
}
}
Contract.Assert(partitions.Length == partitionCount);
m_partitions = partitions;
}
else
{
// We couldn't use an in-place partition. Shucks. Defer to the other overload which
// accepts an enumerator as input instead.
m_partitions = MakePartitions(source.GetEnumerator(), partitionCount);
}
}
