Partitioner<TSource> 클래스

정의

네임스페이스:

System.Collections.Concurrent

어셈블리:

System.Collections.Concurrent.dll

Source:

Partitioner.cs

데이터 소스를 여러 개의 파티션으로 분할하는 특정 방법을 나타냅니다.

generic <typename TSource>
public ref class Partitioner abstract

public abstract class Partitioner<TSource>

type Partitioner<'Source> = class

Public MustInherit Class Partitioner(Of TSource)

형식 매개 변수

TSource

컬렉션에 있는 요소의 형식입니다.

상속

Object

Partitioner<TSource>

파생

System.Collections.Concurrent.OrderablePartitioner<TSource>

예제

다음 예제에서는 한 번에 단일 요소를 반환하는 파티셔너를 구현하는 방법을 보여줍니다.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

namespace PartitionerDemo
{
    // Simple partitioner that will extract one item at a time, in a thread-safe fashion,
    // from the underlying collection.
    class SingleElementPartitioner<T> : Partitioner<T>
    {
        // The collection being wrapped by this Partitioner
        IEnumerable<T> m_referenceEnumerable;

        // Internal class that serves as a shared enumerable for the
        // underlying collection.
        private class InternalEnumerable : IEnumerable<T>, IDisposable
        {
            IEnumerator<T> m_reader;
            bool m_disposed = false;

            // These two are used to implement Dispose() when static partitioning is being performed
            int m_activeEnumerators;
            bool m_downcountEnumerators;

            // "downcountEnumerators" will be true for static partitioning, false for
            // dynamic partitioning.
            public InternalEnumerable(IEnumerator<T> reader, bool downcountEnumerators)
            {
                m_reader = reader;
                m_activeEnumerators = 0;
                m_downcountEnumerators = downcountEnumerators;
            }

            public IEnumerator<T> GetEnumerator()
            {
                if (m_disposed)
                    throw new ObjectDisposedException("InternalEnumerable: Can't call GetEnumerator() after disposing");

                // For static partitioning, keep track of the number of active enumerators.
                if (m_downcountEnumerators) Interlocked.Increment(ref m_activeEnumerators);

                return new InternalEnumerator(m_reader, this);
            }

            IEnumerator IEnumerable.GetEnumerator()
            {
                return ((IEnumerable<T>)this).GetEnumerator();
            }

            public void Dispose()
            {
                if (!m_disposed)
                {
                    // Only dispose the source enumerator if you are doing dynamic partitioning
                    if (!m_downcountEnumerators)
                    {
                        m_reader.Dispose();
                    }
                    m_disposed = true;
                }
            }

            // Called from Dispose() method of spawned InternalEnumerator.  During
            // static partitioning, the source enumerator will be automatically
            // disposed once all requested InternalEnumerators have been disposed.
            public void DisposeEnumerator()
            {
                if (m_downcountEnumerators)
                {
                    if (Interlocked.Decrement(ref m_activeEnumerators) == 0)
                    {
                        m_reader.Dispose();
                    }
                }
            }
        }

        // Internal class that serves as a shared enumerator for
        // the underlying collection.
        private class InternalEnumerator : IEnumerator<T>
        {
            T m_current;
            IEnumerator<T> m_source;
            InternalEnumerable m_controllingEnumerable;
            bool m_disposed = false;

            public InternalEnumerator(IEnumerator<T> source, InternalEnumerable controllingEnumerable)
            {
                m_source = source;
                m_current = default(T);
                m_controllingEnumerable = controllingEnumerable;
            }

            object IEnumerator.Current
            {
                get { return m_current; }
            }

            T IEnumerator<T>.Current
            {
                get { return m_current; }
            }

            void IEnumerator.Reset()
            {
                throw new NotSupportedException("Reset() not supported");
            }

            // This method is the crux of this class.  Under lock, it calls
            // MoveNext() on the underlying enumerator and grabs Current.
            bool IEnumerator.MoveNext()
            {
                bool rval = false;
                lock (m_source)
                {
                    rval = m_source.MoveNext();
                    m_current = rval ? m_source.Current : default(T);
                }
                return rval;
            }

            void IDisposable.Dispose()
            {
                if (!m_disposed)
                {
                    // Delegate to parent enumerable's DisposeEnumerator() method
                    m_controllingEnumerable.DisposeEnumerator();
                    m_disposed = true;
                }
            }
        }

        // Constructor just grabs the collection to wrap
        public SingleElementPartitioner(IEnumerable<T> enumerable)
        {
            // Verify that the source IEnumerable is not null
            if (enumerable == null)
                throw new ArgumentNullException("enumerable");

            m_referenceEnumerable = enumerable;
        }

        // Produces a list of "numPartitions" IEnumerators that can each be
        // used to traverse the underlying collection in a thread-safe manner.
        // This will return a static number of enumerators, as opposed to
        // GetDynamicPartitions(), the result of which can be used to produce
        // any number of enumerators.
        public override IList<IEnumerator<T>> GetPartitions(int numPartitions)
        {
            if (numPartitions < 1)
                throw new ArgumentOutOfRangeException("NumPartitions");

            List<IEnumerator<T>> list = new List<IEnumerator<T>>(numPartitions);

            // Since we are doing static partitioning, create an InternalEnumerable with reference
            // counting of spawned InternalEnumerators turned on.  Once all of the spawned enumerators
            // are disposed, dynamicPartitions will be disposed.
            var dynamicPartitions = new InternalEnumerable(m_referenceEnumerable.GetEnumerator(), true);
            for (int i = 0; i < numPartitions; i++)
                list.Add(dynamicPartitions.GetEnumerator());

            return list;
        }

        // Returns an instance of our internal Enumerable class.  GetEnumerator()
        // can then be called on that (multiple times) to produce shared enumerators.
        public override IEnumerable<T> GetDynamicPartitions()
        {
            // Since we are doing dynamic partitioning, create an InternalEnumerable with reference
            // counting of spawned InternalEnumerators turned off.  This returned InternalEnumerable
            // will need to be explicitly disposed.
            return new InternalEnumerable(m_referenceEnumerable.GetEnumerator(), false);
        }

        // Must be set to true if GetDynamicPartitions() is supported.
        public override bool SupportsDynamicPartitions
        {
            get { return true; }
        }
    }

    class Program
    {
        // Test our SingleElementPartitioner(T) class
        static void Main()
        {
            // Our sample collection
            string[] collection = new string[] {"red", "orange", "yellow", "green", "blue", "indigo",
                "violet", "black", "white", "grey"};

            // Instantiate a partitioner for our collection
            SingleElementPartitioner<string> myPart = new SingleElementPartitioner<string>(collection);

            //
            // Simple test with ForEach
            //
            Console.WriteLine("Testing with Parallel.ForEach");
            Parallel.ForEach(myPart, item =>
            {
                Console.WriteLine("  item = {0}, thread id = {1}", item, Thread.CurrentThread.ManagedThreadId);
            });

            //
            //
            // Demonstrate the use of static partitioning, which really means
            // "using a static number of partitioners".  The partitioners themselves
            // may still be "dynamic" in the sense that their outputs may not be
            // deterministic.
            //
            //

            // Perform static partitioning of collection
            var staticPartitions = myPart.GetPartitions(2);
            int index = 0;

            Console.WriteLine("Static Partitioning, 2 partitions, 2 tasks:");

            // Action will consume from static partitions
            Action staticAction = () =>
            {
                int myIndex = Interlocked.Increment(ref index) - 1; // compute your index
                var myItems = staticPartitions[myIndex]; // grab your static partition
                int id = Thread.CurrentThread.ManagedThreadId; // cache your thread id

                // Enumerate through your static partition
                while (myItems.MoveNext())
                {
                    Thread.Sleep(50); // guarantees that multiple threads have a chance to run
                    Console.WriteLine("  item = {0}, thread id = {1}", myItems.Current, Thread.CurrentThread.ManagedThreadId);
                }

                myItems.Dispose();
            };

            // Spawn off 2 actions to consume 2 static partitions
            Parallel.Invoke(staticAction, staticAction);

            //
            //
            // Demonstrate the use of dynamic partitioning
            //
            //

            // Grab an IEnumerable which can then be used to generate multiple
            // shared IEnumerables.
            var dynamicPartitions = myPart.GetDynamicPartitions();

            Console.WriteLine("Dynamic Partitioning, 3 tasks:");

            // Action will consume from dynamic partitions
            Action dynamicAction = () =>
            {
                // Grab an enumerator from the dynamic partitions
                var enumerator = dynamicPartitions.GetEnumerator();
                int id = Thread.CurrentThread.ManagedThreadId; // cache our thread id

                // Enumerate through your dynamic enumerator
                while (enumerator.MoveNext())
                {
                    Thread.Sleep(50); // guarantees that multiple threads will have a chance to run
                    Console.WriteLine("  item = {0}, thread id = {1}", enumerator.Current, id);
                }

                enumerator.Dispose();
            };

            // Spawn 3 concurrent actions to consume the dynamic partitions
            Parallel.Invoke(dynamicAction, dynamicAction, dynamicAction);

            // Clean up
            if (dynamicPartitions is IDisposable)
                ((IDisposable)dynamicPartitions).Dispose();
        }
    }
}

Imports System.Collections.Concurrent
Imports System.Threading
Imports System.Threading.Tasks

Module PartitionerDemo
    ' Simple partitioner that will extract one item at a time, in a thread-safe fashion,
    ' from the underlying collection.
    Class SingleElementPartitioner(Of T)
        Inherits Partitioner(Of T)
        ' The collection being wrapped by this Partitioner
        Private m_referenceEnumerable As IEnumerable(Of T)

        ' Internal class that serves as a shared enumerable for the
        ' underlying collection.
        Private Class InternalEnumerable
            Implements IEnumerable(Of T)
            Implements IDisposable

            Private m_reader As IEnumerator(Of T)
            Private m_disposed As Boolean = False

            ' These two are used to implement Dispose() when static partitioning is being performed
            Private m_activeEnumerators As Integer
            Private m_downcountEnumerators As Boolean

            ' "downcountEnumerators" will be true for static partitioning, false for
            ' dynamic partitioning. 
            Public Sub New(ByVal reader As IEnumerator(Of T), ByVal downcountEnumerators As Boolean)
                m_reader = reader
                m_activeEnumerators = 0
                m_downcountEnumerators = downcountEnumerators
            End Sub

            Public Function GetEnumerator() As IEnumerator(Of T) Implements IEnumerable(Of T).GetEnumerator
                If m_disposed Then
                    Throw New ObjectDisposedException("InternalEnumerable: Can't call GetEnumerator() after disposing")
                End If

                ' For static partitioning, keep track of the number of active enumerators.
                If m_downcountEnumerators Then
                    Interlocked.Increment(m_activeEnumerators)
                End If

                Return New InternalEnumerator(m_reader, Me)
            End Function

            Private Function GetEnumerator2() As IEnumerator Implements IEnumerable.GetEnumerator
                Return DirectCast(Me, IEnumerable(Of T)).GetEnumerator()
            End Function

            Public Sub Dispose() Implements IDisposable.Dispose
                If Not m_disposed Then
                    ' Only dispose the source enumerator if you are doing dynamic partitioning
                    If Not m_downcountEnumerators Then
                        m_reader.Dispose()
                    End If
                    m_disposed = True
                End If
            End Sub

            ' Called from Dispose() method of spawned InternalEnumerator. During
            ' static partitioning, the source enumerator will be automatically
            ' disposed once all requested InternalEnumerators have been disposed.
            Public Sub DisposeEnumerator()
                If m_downcountEnumerators Then
                    If Interlocked.Decrement(m_activeEnumerators) = 0 Then
                        m_reader.Dispose()
                    End If
                End If
            End Sub
        End Class

        ' Internal class that serves as a shared enumerator for 
        ' the underlying collection.
        Private Class InternalEnumerator
            Implements IEnumerator(Of T)

            Private m_current As T
            Private m_source As IEnumerator(Of T)
            Private m_controllingEnumerable As InternalEnumerable
            Private m_disposed As Boolean = False

            Public Sub New(ByVal source As IEnumerator(Of T), ByVal controllingEnumerable As InternalEnumerable)
                m_source = source
                m_current = Nothing
                m_controllingEnumerable = controllingEnumerable
            End Sub

            Private ReadOnly Property Current2() As Object Implements IEnumerator.Current
                Get
                    Return m_current
                End Get
            End Property

            Private ReadOnly Property Current() As T Implements IEnumerator(Of T).Current
                Get
                    Return m_current
                End Get
            End Property

            Private Sub Reset() Implements IEnumerator.Reset
                Throw New NotSupportedException("Reset() not supported")
            End Sub

            ' This method is the crux of this class. Under lock, it calls
            ' MoveNext() on the underlying enumerator and grabs Current.
            Private Function MoveNext() As Boolean Implements IEnumerator.MoveNext
                Dim rval As Boolean = False
                SyncLock m_source
                    rval = m_source.MoveNext()
                    m_current = If(rval, m_source.Current, Nothing)
                End SyncLock
                Return rval
            End Function

            Private Sub Dispose() Implements IDisposable.Dispose
                If Not m_disposed Then
                    ' Delegate to parent enumerable's DisposeEnumerator() method
                    m_controllingEnumerable.DisposeEnumerator()
                    m_disposed = True
                End If
            End Sub

        End Class

        ' Constructor just grabs the collection to wrap
        Public Sub New(ByVal enumerable As IEnumerable(Of T))

            ' Verify that the source IEnumerable is not null
            If enumerable Is Nothing Then
                Throw New ArgumentNullException("enumerable")
            End If

            m_referenceEnumerable = enumerable
        End Sub

        ' Produces a list of "numPartitions" IEnumerators that can each be
        ' used to traverse the underlying collection in a thread-safe manner.
        ' This will return a static number of enumerators, as opposed to
        ' GetDynamicPartitions(), the result of which can be used to produce
        ' any number of enumerators.
        Public Overloads Overrides Function GetPartitions(ByVal numPartitions As Integer) As IList(Of IEnumerator(Of T))
            If numPartitions < 1 Then
                Throw New ArgumentOutOfRangeException("NumPartitions")
            End If

            Dim list As New List(Of IEnumerator(Of T))(numPartitions)

            ' Since we are doing static partitioning, create an InternalEnumerable with reference
            ' counting of spawned InternalEnumerators turned on. Once all of the spawned enumerators
            ' are disposed, dynamicPartitions will be disposed.
            Dim dynamicPartitions = New InternalEnumerable(m_referenceEnumerable.GetEnumerator(), True)
            For i As Integer = 0 To numPartitions - 1
                list.Add(dynamicPartitions.GetEnumerator())
            Next

            Return list
        End Function

        ' Returns an instance of our internal Enumerable class. GetEnumerator()
        ' can then be called on that (multiple times) to produce shared enumerators.
        Public Overloads Overrides Function GetDynamicPartitions() As IEnumerable(Of T)
            ' Since we are doing dynamic partitioning, create an InternalEnumerable with reference
            ' counting of spawned InternalEnumerators turned off. This returned InternalEnumerable
            ' will need to be explicitly disposed.
            Return New InternalEnumerable(m_referenceEnumerable.GetEnumerator(), False)
        End Function

        ' Must be set to true if GetDynamicPartitions() is supported.
        Public Overloads Overrides ReadOnly Property SupportsDynamicPartitions() As Boolean
            Get
                Return True
            End Get
        End Property
    End Class

    Class Program
        ' Test our SingleElementPartitioner(T) class
        Shared Sub Main()
            ' Our sample collection
            Dim collection As String() = New String() {"red", "orange", "yellow", "green", "blue", "indigo", _
            "violet", "black", "white", "grey"}

            ' Instantiate a partitioner for our collection
            Dim myPart As New SingleElementPartitioner(Of String)(Collection)

            '
            ' Simple test with ForEach
            '
            Console.WriteLine("Testing with Parallel.ForEach")
            Parallel.ForEach(myPart,
                             Sub(item)
                                 Console.WriteLine(" item = {0}, thread id = {1}", item, Thread.CurrentThread.ManagedThreadId)
                             End Sub)

            '
            '
            ' Demonstrate the use of static partitioning, which really means
            ' "using a static number of partitioners". The partitioners themselves
            ' may still be "dynamic" in the sense that their outputs may not be
            ' deterministic.
            '
            '

            ' Perform static partitioning of collection
            Dim staticPartitions = myPart.GetPartitions(2)
            Dim index As Integer = 0

            Console.WriteLine("Static Partitioning, 2 partitions, 2 tasks:")

            ' Action will consume from static partitions
            Dim staticAction As Action =
                Sub()
                    Dim myIndex As Integer = Interlocked.Increment(index) - 1
                    ' compute your index
                    Dim myItems = staticPartitions(myIndex)
                    ' grab your static partition
                    Dim id As Integer = Thread.CurrentThread.ManagedThreadId
                    ' cache your thread id
                    ' Enumerate through your static partition
                    While myItems.MoveNext()
                        Thread.Sleep(50)
                        ' guarantees that multiple threads have a chance to run
                        Console.WriteLine(" item = {0}, thread id = {1}", myItems.Current, Thread.CurrentThread.ManagedThreadId)
                    End While

                    myItems.Dispose()
                End Sub

            ' Spawn off 2 actions to consume 2 static partitions
            Parallel.Invoke(staticAction, staticAction)

            '
            '
            ' Demonstrate the use of dynamic partitioning
            '
            '

            ' Grab an IEnumerable which can then be used to generate multiple
            ' shared IEnumerables.
            Dim dynamicPartitions = myPart.GetDynamicPartitions()

            Console.WriteLine("Dynamic Partitioning, 3 tasks:")

            ' Action will consume from dynamic partitions
            Dim dynamicAction As Action =
                Sub()
                    ' Grab an enumerator from the dynamic partitioner
                    Dim enumerator = dynamicPartitions.GetEnumerator()
                    Dim id As Integer = Thread.CurrentThread.ManagedThreadId
                    ' cache our thread id
                    ' Enumerate through your dynamic enumerator
                    While enumerator.MoveNext()
                        Thread.Sleep(50)
                        ' guarantees that multiple threads will have a chance to run
                        Console.WriteLine(" item = {0}, thread id = {1}", enumerator.Current, id)
                    End While

                    enumerator.Dispose()
                End Sub

            ' Spawn 3 concurrent actions to consume the dynamic partitions
            Parallel.Invoke(dynamicAction, dynamicAction, dynamicAction)

            ' Clean up
            If TypeOf dynamicPartitions Is IDisposable Then
                DirectCast(dynamicPartitions, IDisposable).Dispose()
            End If
        End Sub
    End Class

End Module

설명

자세한 내용은 PLINQ 및 TPL에 대한 사용자 지정 파티셔너를 참조하세요.

생성자

Partitioner<TSource>()

새 파티셔너 인스턴스를 만듭니다.

속성

SupportsDynamicPartitions

추가 파티션을 동적으로 만들 수 있는지 여부를 가져옵니다.

메서드

Equals(Object)	지정된 개체가 현재 개체와 같은지 확인합니다. (다음에서 상속됨 Object)
GetDynamicPartitions()	기본 컬렉션을 여러 파티션으로 분할할 수 있는 개체를 만듭니다.
GetHashCode()	기본 해시 함수로 작동합니다. (다음에서 상속됨 Object)
GetPartitions(Int32)	기본 컬렉션을 지정된 개수의 파티션으로 분할합니다.
GetType()	현재 인스턴스의 Type을 가져옵니다. (다음에서 상속됨 Object)
MemberwiseClone()	현재 Object의 단순 복사본을 만듭니다. (다음에서 상속됨 Object)
ToString()	현재 개체를 나타내는 문자열을 반환합니다. (다음에서 상속됨 Object)

확장 메서드

AsParallel<TSource>(Partitioner<TSource>)

입력 시퀀스를 파티션으로 분할해야 하는 사용자 지정 파티셔너에 의해 발생한 쿼리를 병렬화할 수 있도록 합니다.

스레드 보안

의 Partitioner<TSource> 정적 메서드는 모두 스레드로부터 안전하며 여러 스레드에서 동시에 사용할 수 있습니다. 그러나 생성된 파티셔너를 사용하는 동안에는 파티셔너를 사용하는 동일한 스레드에서 또는 별도의 스레드에서 기본 데이터 원본을 수정해서는 안 됩니다.

추가 정보

• OrderablePartitioner<TSource>
• Partitioner