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comparison Implab/FuncChainTaskBase.cs @ 145:706fccb85524 v2

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RC: cancellation support for promises + tests
author cin
date Sun, 08 Mar 2015 02:52:27 +0300
parents
children eb793fbbe4ea
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144:8c0b95069066 145:706fccb85524
1 using System;
2 using System.Threading;
3
4 namespace Implab {
5 public class FuncChainTaskBase<TResult> : AbstractPromise<TResult> {
6 readonly Func<Exception, IPromise<TResult>> m_error;
7 readonly Func<Exception, IPromise<TResult>> m_cancel;
8
9 int m_cancelationLock;
10
11 protected FuncChainTaskBase( Func<Exception, IPromise<TResult>> error, Func<Exception, IPromise<TResult>> cancel) {
12 m_error = error;
13 m_cancel = cancel;
14 }
15
16 public void Reject(Exception error) {
17 if (LockCancelation())
18 HandleErrorInternal(error);
19 }
20
21 public override void CancelOperation(Exception reason) {
22 if (m_cancel != null && LockCancelation()) {
23 try {
24 Observe(m_cancel(reason));
25 } catch(Exception err) {
26 HandleErrorInternal(err);
27 }
28 }
29
30 }
31
32 protected void HandleErrorInternal(Exception error) {
33 if (m_error != null) {
34 try {
35 Observe(m_error(error));
36 } catch(Exception err) {
37 SetError(err);
38 }
39 } else {
40 SetError(error);
41 }
42 }
43
44 protected void Observe(IPromise<TResult> operation) {
45 if (operation == null)
46 throw new NullReferenceException("The task returned null promise");
47
48 // pass operation results to the current promise
49 operation.On(SetResult, SetError, SetCancelled);
50
51 // pass the cancelation request
52 CancellationRequested(operation.Cancel);
53 }
54
55 protected bool LockCancelation() {
56 return 0 == Interlocked.CompareExchange(ref m_cancelationLock, 1, 0);
57 }
58 }
59 }
60