Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Unary / DistinctQueryOperator.cs / 1305376 / DistinctQueryOperator.cs
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//
// DistinctQueryOperator.cs
//
// [....]
//
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Threading;
namespace System.Linq.Parallel
{
///
/// This operator yields all of the distinct elements in a single data set. It works quite
/// like the above set operations, with the obvious difference being that it only accepts
/// a single data source as input.
///
/// : UnaryQueryOperator
{
private readonly IEqualityComparer m_comparer; // An (optional) equality comparer.
//----------------------------------------------------------------------------------------
// Constructs a new distinction operator.
//
internal DistinctQueryOperator(IEnumerable source, IEqualityComparer comparer)
:base(source)
{
Contract.Assert(source != null, "child data source cannot be null");
m_comparer = comparer;
SetOrdinalIndexState(OrdinalIndexState.Shuffled);
}
//---------------------------------------------------------------------------------------
// Just opens the current operator, including opening the child and wrapping it with
// partitions as needed.
//
internal override QueryResults Open(QuerySettings settings, bool preferStriping)
{
// We just open our child operator. Do not propagate the preferStriping value, but
// instead explicitly set it to false. Regardless of whether the parent prefers striping or range
// partitioning, the output will be hash-partititioned.
QueryResults childResults = Child.Open(settings, false);
return new UnaryQueryOperatorResults(childResults, this, settings, false);
}
internal override void WrapPartitionedStream(
PartitionedStream inputStream, IPartitionedStreamRecipient recipient, bool preferStriping, QuerySettings settings)
{
// Hash-repartion the source stream
if (OutputOrdered)
{
WrapPartitionedStreamHelper(
ExchangeUtilities.HashRepartitionOrdered(
inputStream, null, null, m_comparer, settings.CancellationState.MergedCancellationToken),
recipient, settings.CancellationState.MergedCancellationToken);
}
else
{
WrapPartitionedStreamHelper(
ExchangeUtilities.HashRepartition(
inputStream, null, null, m_comparer, settings.CancellationState.MergedCancellationToken),
recipient, settings.CancellationState.MergedCancellationToken);
}
}
//---------------------------------------------------------------------------------------
// This is a helper method. WrapPartitionedStream decides what type TKey is going
// to be, and then call this method with that key as a generic parameter.
//
private void WrapPartitionedStreamHelper(
PartitionedStream, TKey> hashStream,
IPartitionedStreamRecipient recipient, CancellationToken cancellationToken)
{
int partitionCount = hashStream.PartitionCount;
PartitionedStream outputStream =
new PartitionedStream(partitionCount, hashStream.KeyComparer, OrdinalIndexState.Shuffled);
for (int i = 0; i < partitionCount; i++)
{
if (OutputOrdered)
{
outputStream[i] =
new OrderedDistinctQueryOperatorEnumerator(hashStream[i], m_comparer, hashStream.KeyComparer, cancellationToken);
}
else
{
outputStream[i] = (QueryOperatorEnumerator)(object)
new DistinctQueryOperatorEnumerator(hashStream[i], m_comparer, cancellationToken);
}
}
recipient.Receive(outputStream);
}
//---------------------------------------------------------------------------------------
// Whether this operator performs a premature merge.
//
internal override bool LimitsParallelism
{
get { return false; }
}
//----------------------------------------------------------------------------------------
// This enumerator performs the distinct operation incrementally. It does this by
// maintaining a history -- in the form of a set -- of all data already seen. It simply
// then doesn't return elements it has already seen before.
//
class DistinctQueryOperatorEnumerator : QueryOperatorEnumerator
{
private QueryOperatorEnumerator, TKey> m_source; // The data source.
private Set m_hashLookup; // The hash lookup, used to produce the distinct set.
private CancellationToken m_cancellationToken;
private Shared m_outputLoopCount; // Allocated in MoveNext to avoid false sharing.
//---------------------------------------------------------------------------------------
// Instantiates a new distinction operator.
//
internal DistinctQueryOperatorEnumerator(
QueryOperatorEnumerator, TKey> source, IEqualityComparer comparer,
CancellationToken cancellationToken)
{
Contract.Assert(source != null);
m_source = source;
// @
m_hashLookup = new Set(comparer);
m_cancellationToken = cancellationToken;
}
//----------------------------------------------------------------------------------------
// Walks the single data source, skipping elements it has already seen.
//
internal override bool MoveNext(ref TInputOutput currentElement, ref int currentKey)
{
Contract.Assert(m_source != null);
Contract.Assert(m_hashLookup != null);
// Iterate over this set's elements until we find a unique element.
TKey keyUnused = default(TKey);
Pair current = default(Pair);
if (m_outputLoopCount == null)
m_outputLoopCount = new Shared(0);
while (m_source.MoveNext(ref current, ref keyUnused))
{
if ((m_outputLoopCount.Value++ & CancellationState.POLL_INTERVAL) == 0)
CancellationState.ThrowIfCanceled(m_cancellationToken);
// We ensure we never return duplicates by tracking them in our set.
if (m_hashLookup.Add(current.First))
{
#if DEBUG
currentKey = unchecked((int)0xdeadbeef);
#endif
currentElement = current.First;
return true;
}
}
return false;
}
protected override void Dispose(bool disposing)
{
Contract.Assert(m_source != null);
m_source.Dispose();
}
}
//----------------------------------------------------------------------------------------
// Returns an enumerable that represents the query executing sequentially.
//
internal override IEnumerable AsSequentialQuery(CancellationToken token)
{
IEnumerable wrappedChild = CancellableEnumerable.Wrap(Child.AsSequentialQuery(token), token);
return wrappedChild.Distinct(m_comparer);
}
class OrderedDistinctQueryOperatorEnumerator : QueryOperatorEnumerator
{
private QueryOperatorEnumerator, TKey> m_source; // The data source.
private Dictionary, TKey> m_hashLookup; // The hash lookup, used to produce the distinct set.
private IComparer m_keyComparer; // Comparer to decide the key order.
private IEnumerator, TKey>> m_hashLookupEnumerator; // Enumerates over m_hashLookup.
private CancellationToken m_cancellationToken;
//---------------------------------------------------------------------------------------
// Instantiates a new distinction operator.
//
internal OrderedDistinctQueryOperatorEnumerator(
QueryOperatorEnumerator, TKey> source,
IEqualityComparer comparer, IComparer keyComparer,
CancellationToken cancellationToken)
{
Contract.Assert(source != null);
m_source = source;
m_keyComparer = keyComparer;
// @
m_hashLookup = new Dictionary, TKey>(
new WrapperEqualityComparer(comparer));
m_cancellationToken = cancellationToken;
}
//----------------------------------------------------------------------------------------
// Walks the single data source, skipping elements it has already seen.
//
internal override bool MoveNext(ref TInputOutput currentElement, ref TKey currentKey)
{
Contract.Assert(m_source != null);
Contract.Assert(m_hashLookup != null);
if (m_hashLookupEnumerator == null)
{
Pair elem = default(Pair);
TKey orderKey = default(TKey);
int i = 0;
while (m_source.MoveNext(ref elem, ref orderKey))
{
if ((i++ & CancellationState.POLL_INTERVAL) == 0)
CancellationState.ThrowIfCanceled(m_cancellationToken);
// For each element, we track the smallest order key for that element that we saw so far
TKey oldEntry;
Wrapper wrappedElem = new Wrapper(elem.First);
// If this is the first occurence of this element, or the order key is lower than all keys we saw previously,
// update the order key for this element.
if (!m_hashLookup.TryGetValue(wrappedElem, out oldEntry) || m_keyComparer.Compare(orderKey, oldEntry) < 0)
{
// For each "elem" value, we store the smallest key, and the element value that had that key.
// Note that even though two element values are "equal" according to the EqualityComparer,
// we still cannot choose arbitrarily which of the two to yield.
m_hashLookup[wrappedElem] = orderKey;
}
}
m_hashLookupEnumerator = m_hashLookup.GetEnumerator();
}
if (m_hashLookupEnumerator.MoveNext())
{
KeyValuePair, TKey> currentPair = m_hashLookupEnumerator.Current;
currentElement = currentPair.Key.Value;
currentKey = currentPair.Value;
return true;
}
return false;
}
protected override void Dispose(bool disposing)
{
Contract.Assert(m_source != null);
m_source.Dispose();
if (m_hashLookupEnumerator != null)
{
m_hashLookupEnumerator.Dispose();
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//
// DistinctQueryOperator.cs
//
// [....]
//
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Threading;
namespace System.Linq.Parallel
{
///
/// This operator yields all of the distinct elements in a single data set. It works quite
/// like the above set operations, with the obvious difference being that it only accepts
/// a single data source as input.
///
/// : UnaryQueryOperator
{
private readonly IEqualityComparer m_comparer; // An (optional) equality comparer.
//----------------------------------------------------------------------------------------
// Constructs a new distinction operator.
//
internal DistinctQueryOperator(IEnumerable source, IEqualityComparer comparer)
:base(source)
{
Contract.Assert(source != null, "child data source cannot be null");
m_comparer = comparer;
SetOrdinalIndexState(OrdinalIndexState.Shuffled);
}
//---------------------------------------------------------------------------------------
// Just opens the current operator, including opening the child and wrapping it with
// partitions as needed.
//
internal override QueryResults Open(QuerySettings settings, bool preferStriping)
{
// We just open our child operator. Do not propagate the preferStriping value, but
// instead explicitly set it to false. Regardless of whether the parent prefers striping or range
// partitioning, the output will be hash-partititioned.
QueryResults childResults = Child.Open(settings, false);
return new UnaryQueryOperatorResults(childResults, this, settings, false);
}
internal override void WrapPartitionedStream(
PartitionedStream inputStream, IPartitionedStreamRecipient recipient, bool preferStriping, QuerySettings settings)
{
// Hash-repartion the source stream
if (OutputOrdered)
{
WrapPartitionedStreamHelper(
ExchangeUtilities.HashRepartitionOrdered(
inputStream, null, null, m_comparer, settings.CancellationState.MergedCancellationToken),
recipient, settings.CancellationState.MergedCancellationToken);
}
else
{
WrapPartitionedStreamHelper(
ExchangeUtilities.HashRepartition(
inputStream, null, null, m_comparer, settings.CancellationState.MergedCancellationToken),
recipient, settings.CancellationState.MergedCancellationToken);
}
}
//---------------------------------------------------------------------------------------
// This is a helper method. WrapPartitionedStream decides what type TKey is going
// to be, and then call this method with that key as a generic parameter.
//
private void WrapPartitionedStreamHelper(
PartitionedStream, TKey> hashStream,
IPartitionedStreamRecipient recipient, CancellationToken cancellationToken)
{
int partitionCount = hashStream.PartitionCount;
PartitionedStream outputStream =
new PartitionedStream(partitionCount, hashStream.KeyComparer, OrdinalIndexState.Shuffled);
for (int i = 0; i < partitionCount; i++)
{
if (OutputOrdered)
{
outputStream[i] =
new OrderedDistinctQueryOperatorEnumerator(hashStream[i], m_comparer, hashStream.KeyComparer, cancellationToken);
}
else
{
outputStream[i] = (QueryOperatorEnumerator)(object)
new DistinctQueryOperatorEnumerator(hashStream[i], m_comparer, cancellationToken);
}
}
recipient.Receive(outputStream);
}
//---------------------------------------------------------------------------------------
// Whether this operator performs a premature merge.
//
internal override bool LimitsParallelism
{
get { return false; }
}
//----------------------------------------------------------------------------------------
// This enumerator performs the distinct operation incrementally. It does this by
// maintaining a history -- in the form of a set -- of all data already seen. It simply
// then doesn't return elements it has already seen before.
//
class DistinctQueryOperatorEnumerator : QueryOperatorEnumerator
{
private QueryOperatorEnumerator, TKey> m_source; // The data source.
private Set m_hashLookup; // The hash lookup, used to produce the distinct set.
private CancellationToken m_cancellationToken;
private Shared m_outputLoopCount; // Allocated in MoveNext to avoid false sharing.
//---------------------------------------------------------------------------------------
// Instantiates a new distinction operator.
//
internal DistinctQueryOperatorEnumerator(
QueryOperatorEnumerator, TKey> source, IEqualityComparer comparer,
CancellationToken cancellationToken)
{
Contract.Assert(source != null);
m_source = source;
// @
m_hashLookup = new Set(comparer);
m_cancellationToken = cancellationToken;
}
//----------------------------------------------------------------------------------------
// Walks the single data source, skipping elements it has already seen.
//
internal override bool MoveNext(ref TInputOutput currentElement, ref int currentKey)
{
Contract.Assert(m_source != null);
Contract.Assert(m_hashLookup != null);
// Iterate over this set's elements until we find a unique element.
TKey keyUnused = default(TKey);
Pair current = default(Pair);
if (m_outputLoopCount == null)
m_outputLoopCount = new Shared(0);
while (m_source.MoveNext(ref current, ref keyUnused))
{
if ((m_outputLoopCount.Value++ & CancellationState.POLL_INTERVAL) == 0)
CancellationState.ThrowIfCanceled(m_cancellationToken);
// We ensure we never return duplicates by tracking them in our set.
if (m_hashLookup.Add(current.First))
{
#if DEBUG
currentKey = unchecked((int)0xdeadbeef);
#endif
currentElement = current.First;
return true;
}
}
return false;
}
protected override void Dispose(bool disposing)
{
Contract.Assert(m_source != null);
m_source.Dispose();
}
}
//----------------------------------------------------------------------------------------
// Returns an enumerable that represents the query executing sequentially.
//
internal override IEnumerable AsSequentialQuery(CancellationToken token)
{
IEnumerable wrappedChild = CancellableEnumerable.Wrap(Child.AsSequentialQuery(token), token);
return wrappedChild.Distinct(m_comparer);
}
class OrderedDistinctQueryOperatorEnumerator : QueryOperatorEnumerator
{
private QueryOperatorEnumerator, TKey> m_source; // The data source.
private Dictionary, TKey> m_hashLookup; // The hash lookup, used to produce the distinct set.
private IComparer m_keyComparer; // Comparer to decide the key order.
private IEnumerator, TKey>> m_hashLookupEnumerator; // Enumerates over m_hashLookup.
private CancellationToken m_cancellationToken;
//---------------------------------------------------------------------------------------
// Instantiates a new distinction operator.
//
internal OrderedDistinctQueryOperatorEnumerator(
QueryOperatorEnumerator, TKey> source,
IEqualityComparer comparer, IComparer keyComparer,
CancellationToken cancellationToken)
{
Contract.Assert(source != null);
m_source = source;
m_keyComparer = keyComparer;
// @
m_hashLookup = new Dictionary, TKey>(
new WrapperEqualityComparer(comparer));
m_cancellationToken = cancellationToken;
}
//----------------------------------------------------------------------------------------
// Walks the single data source, skipping elements it has already seen.
//
internal override bool MoveNext(ref TInputOutput currentElement, ref TKey currentKey)
{
Contract.Assert(m_source != null);
Contract.Assert(m_hashLookup != null);
if (m_hashLookupEnumerator == null)
{
Pair elem = default(Pair);
TKey orderKey = default(TKey);
int i = 0;
while (m_source.MoveNext(ref elem, ref orderKey))
{
if ((i++ & CancellationState.POLL_INTERVAL) == 0)
CancellationState.ThrowIfCanceled(m_cancellationToken);
// For each element, we track the smallest order key for that element that we saw so far
TKey oldEntry;
Wrapper wrappedElem = new Wrapper(elem.First);
// If this is the first occurence of this element, or the order key is lower than all keys we saw previously,
// update the order key for this element.
if (!m_hashLookup.TryGetValue(wrappedElem, out oldEntry) || m_keyComparer.Compare(orderKey, oldEntry) < 0)
{
// For each "elem" value, we store the smallest key, and the element value that had that key.
// Note that even though two element values are "equal" according to the EqualityComparer,
// we still cannot choose arbitrarily which of the two to yield.
m_hashLookup[wrappedElem] = orderKey;
}
}
m_hashLookupEnumerator = m_hashLookup.GetEnumerator();
}
if (m_hashLookupEnumerator.MoveNext())
{
KeyValuePair, TKey> currentPair = m_hashLookupEnumerator.Current;
currentElement = currentPair.Key.Value;
currentKey = currentPair.Value;
return true;
}
return false;
}
protected override void Dispose(bool disposing)
{
Contract.Assert(m_source != null);
m_source.Dispose();
if (m_hashLookupEnumerator != null)
{
m_hashLookupEnumerator.Dispose();
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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