blob: fdbe37adf1e43efeecd9bab710768c1bd705eebf (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
//
// SpoolingTaskBase.cs
//
// <OWNER>[....]</OWNER>
//
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
using System.Collections.Generic;
using System.Threading;
using System.Diagnostics.Contracts;
namespace System.Linq.Parallel
{
/// <summary>
/// A spooling task handles marshaling data from a producer to a consumer. It simply
/// takes data from a producer and hands it off to a consumer. This class is the base
/// class from which other concrete spooling tasks derive, encapsulating some common
/// logic (such as capturing exceptions).
/// </summary>
internal abstract class SpoolingTaskBase : QueryTask
{
//-----------------------------------------------------------------------------------
// Constructs a new spooling task.
//
// Arguments:
// taskIndex - the unique index of this task
//
protected SpoolingTaskBase(int taskIndex, QueryTaskGroupState groupState) :
base(taskIndex, groupState)
{
}
//-----------------------------------------------------------------------------------
// The implementation of the Work API just enumerates the producer's data, and
// enqueues it into the consumer channel. Well, really, it just defers to extension
// points (below) implemented by subclasses to do these things.
//
protected override void Work()
{
try
{
// Defer to the base class for the actual work.
SpoolingWork();
}
catch (Exception ex)
{
OperationCanceledException oce = ex as OperationCanceledException;
if (oce != null &&
oce.CancellationToken == m_groupState.CancellationState.MergedCancellationToken
&& m_groupState.CancellationState.MergedCancellationToken.IsCancellationRequested)
{
//an expected internal cancellation has occurred. suppress this exception.
}
else
{
// TPL will catch and store the exception on the task object. We'll then later
// turn around and wait on it, having the effect of propagating it. In the meantime,
// we want to cooperative cancel all workers.
m_groupState.CancellationState.InternalCancellationTokenSource.Cancel();
// And then repropagate to let TPL catch it.
throw;
}
}
finally
{
SpoolingFinally(); //dispose resources etc.
}
}
//-----------------------------------------------------------------------------------
// This method is responsible for enumerating results and enqueueing them to
// the output channel(s) as appropriate. Each base class implements its own.
//
protected abstract void SpoolingWork();
//-----------------------------------------------------------------------------------
// If the subclass needs to do something in the finally block of the main work loop,
// it should override this and do it. Purely optional.
//
protected virtual void SpoolingFinally()
{
// (Intentionally left blank.)
}
}
}
|
