114 lines
5.2 KiB
C#
114 lines
5.2 KiB
C#
// Copyright (c) Microsoft. All rights reserved.
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// Licensed under the MIT license. See LICENSE file in the project root for full license information.
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// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
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//
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// DataflowLinkOptions.cs
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//
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//
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// DataflowLinkOptions type for configuring links between dataflow blocks
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//
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// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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using System;
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using System.Diagnostics;
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using System.Threading.Tasks;
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namespace System.Threading.Tasks.Dataflow
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{
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/// <summary>
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/// Provides options used to configure a link between dataflow blocks.
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/// </summary>
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/// <remarks>
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/// <see cref="DataflowLinkOptions"/> is mutable and can be configured through its properties.
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/// When specific configuration options are not set, the following defaults are used:
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/// <list type="table">
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/// <listheader>
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/// <term>Options</term>
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/// <description>Default</description>
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/// </listheader>
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/// <item>
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/// <term>PropagateCompletion</term>
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/// <description>False</description>
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/// </item>
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/// <item>
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/// <term>MaxMessages</term>
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/// <description>DataflowBlockOptions.Unbounded (-1)</description>
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/// </item>
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/// <item>
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/// <term>Append</term>
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/// <description>True</description>
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/// </item>
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/// </list>
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/// Dataflow blocks capture the state of the options at linking. Subsequent changes to the provided
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/// <see cref="DataflowLinkOptions"/> instance should not affect the behavior of a link.
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/// </remarks>
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[DebuggerDisplay("PropagateCompletion = {PropagateCompletion}, MaxMessages = {MaxMessages}, Append = {Append}")]
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public class DataflowLinkOptions
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{
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/// <summary>
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/// A constant used to specify an unlimited quantity for <see cref="DataflowLinkOptions"/> members
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/// that provide an upper bound. This field is a constant tied to <see cref="DataflowLinkOptions.Unbounded"/>.
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/// </summary>
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internal const Int32 Unbounded = DataflowBlockOptions.Unbounded;
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/// <summary>Whether the linked target will have completion and faulting notification propagated to it automatically.</summary>
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private Boolean _propagateCompletion = false;
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/// <summary>The maximum number of messages that may be consumed across the link.</summary>
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private Int32 _maxNumberOfMessages = Unbounded;
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/// <summary>Whether the link should be appended to the source’s list of links, or whether it should be prepended.</summary>
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private Boolean _append = true;
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/// <summary>A default instance of <see cref="DataflowLinkOptions"/>.</summary>
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/// <remarks>
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/// Do not change the values of this instance. It is shared by all of our blocks when no options are provided by the user.
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/// </remarks>
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internal static readonly DataflowLinkOptions Default = new DataflowLinkOptions();
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/// <summary>A cached instance of <see cref="DataflowLinkOptions"/>.</summary>
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/// <remarks>
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/// Do not change the values of this instance. It is shared by all of our blocks that need to unlink after one message has been consumed.
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/// </remarks>
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internal static readonly DataflowLinkOptions UnlinkAfterOneAndPropagateCompletion = new DataflowLinkOptions() { MaxMessages = 1, PropagateCompletion = true };
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/// <summary>Initializes the <see cref="DataflowLinkOptions"/>.</summary>
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public DataflowLinkOptions()
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{
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}
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/// <summary>Gets or sets whether the linked target will have completion and faulting notification propagated to it automatically.</summary>
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public Boolean PropagateCompletion
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{
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get { return _propagateCompletion; }
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set
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{
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Debug.Assert(this != Default && this != UnlinkAfterOneAndPropagateCompletion, "Default and UnlinkAfterOneAndPropagateCompletion instances are supposed to be immutable.");
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_propagateCompletion = value;
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}
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}
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/// <summary>Gets or sets the maximum number of messages that may be consumed across the link.</summary>
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public Int32 MaxMessages
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{
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get { return _maxNumberOfMessages; }
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set
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{
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Debug.Assert(this != Default && this != UnlinkAfterOneAndPropagateCompletion, "Default and UnlinkAfterOneAndPropagateCompletion instances are supposed to be immutable.");
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if (value < 1 && value != Unbounded) throw new ArgumentOutOfRangeException("value");
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_maxNumberOfMessages = value;
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}
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}
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/// <summary>Gets or sets whether the link should be appended to the source’s list of links, or whether it should be prepended.</summary>
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public Boolean Append
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{
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get { return _append; }
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set
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{
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Debug.Assert(this != Default && this != UnlinkAfterOneAndPropagateCompletion, "Default and UnlinkAfterOneAndPropagateCompletion instances are supposed to be immutable.");
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_append = value;
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}
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}
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}
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}
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