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Add improved prompt cancellation handling
This change improves the current handling of PSHostUserInterface prompt cancellation so that cancelled prompts are cleaned up effectively and don't block further command execution.
1 parent 8589a61 commit b37ad4f

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10 files changed

+212
-103
lines changed

10 files changed

+212
-103
lines changed

‎src/PowerShellEditorServices.Protocol/MessageProtocol/MessageDispatcher.cs‎

Lines changed: 26 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -234,12 +234,14 @@ protected async Task DispatchMessage(
234234
Message messageToDispatch,
235235
MessageWriter messageWriter)
236236
{
237+
Task handlerToAwait = null;
238+
237239
if (messageToDispatch.MessageType == MessageType.Request)
238240
{
239241
Func<Message, MessageWriter, Task> requestHandler = null;
240242
if (this.requestHandlers.TryGetValue(messageToDispatch.Method, out requestHandler))
241243
{
242-
await requestHandler(messageToDispatch, messageWriter);
244+
handlerToAwait = requestHandler(messageToDispatch, messageWriter);
243245
}
244246
else
245247
{
@@ -258,7 +260,7 @@ protected async Task DispatchMessage(
258260
Func<Message, MessageWriter, Task> eventHandler = null;
259261
if (this.eventHandlers.TryGetValue(messageToDispatch.Method, out eventHandler))
260262
{
261-
await eventHandler(messageToDispatch, messageWriter);
263+
handlerToAwait = eventHandler(messageToDispatch, messageWriter);
262264
}
263265
else
264266
{
@@ -269,6 +271,28 @@ protected async Task DispatchMessage(
269271
{
270272
// TODO: Return message not supported
271273
}
274+
275+
if (handlerToAwait != null)
276+
{
277+
try
278+
{
279+
await handlerToAwait;
280+
}
281+
catch (TaskCanceledException)
282+
{
283+
// Some tasks may be cancelled due to legitimate
284+
// timeouts so don't let those exceptions go higher.
285+
}
286+
catch (AggregateException e)
287+
{
288+
if (!(e.InnerExceptions[0] is TaskCanceledException))
289+
{
290+
// Cancelled tasks aren't a problem, so rethrow
291+
// anything that isn't a TaskCanceledException
292+
throw e;
293+
}
294+
}
295+
}
272296
}
273297

274298
private void OnListenTaskCompleted(Task listenTask)

‎src/PowerShellEditorServices/Console/ChoicePromptHandler.cs‎

Lines changed: 12 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,7 @@
44
//
55

66
using System;
7+
using System.Threading;
78
using System.Threading.Tasks;
89

910
namespace Microsoft.PowerShell.EditorServices.Console
@@ -32,7 +33,7 @@ public enum PromptStyle
3233
/// that present the user a set of options from which a selection
3334
/// should be made.
3435
/// </summary>
35-
public abstract class ChoicePromptHandler : IPromptHandler
36+
public abstract class ChoicePromptHandler : PromptHandler
3637
{
3738
#region Private Fields
3839

@@ -82,6 +83,9 @@ public abstract class ChoicePromptHandler : IPromptHandler
8283
/// <param name="defaultChoice">
8384
/// The default choice to highlight for the user.
8485
/// </param>
86+
/// <param name="cancellationToken">
87+
/// A CancellationToken that can be used to cancel the prompt.
88+
/// </param>
8589
/// <returns>
8690
/// A Task instance that can be monitored for completion to get
8791
/// the user's choice.
@@ -90,7 +94,8 @@ public Task<int> PromptForChoice(
9094
string promptCaption,
9195
string promptMessage,
9296
ChoiceDetails[] choices,
93-
int defaultChoice)
97+
int defaultChoice,
98+
CancellationToken cancellationToken)
9499
{
95100
// TODO: Guard against multiple calls
96101

@@ -100,6 +105,9 @@ public Task<int> PromptForChoice(
100105
this.DefaultChoice = defaultChoice;
101106
this.promptTask = new TaskCompletionSource<int>();
102107

108+
// Cancel the TaskCompletionSource if the caller cancels the task
109+
cancellationToken.Register(this.CancelPrompt, true);
110+
103111
// Show the prompt to the user
104112
this.ShowPrompt(PromptStyle.Full);
105113

@@ -114,7 +122,7 @@ public Task<int> PromptForChoice(
114122
/// True if the prompt is complete, false if the prompt is
115123
/// still waiting for a valid response.
116124
/// </returns>
117-
public virtual bool HandleResponse(string responseString)
125+
public override bool HandleResponse(string responseString)
118126
{
119127
int choiceIndex = -1;
120128

@@ -145,7 +153,7 @@ public virtual bool HandleResponse(string responseString)
145153
/// <summary>
146154
/// Called when the active prompt should be cancelled.
147155
/// </summary>
148-
public void CancelPrompt()
156+
protected override void OnPromptCancelled()
149157
{
150158
// Cancel the prompt task
151159
this.promptTask.TrySetCanceled();

‎src/PowerShellEditorServices/Console/ConsoleService.cs‎

Lines changed: 15 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,6 @@
66
using Microsoft.PowerShell.EditorServices.Utility;
77
using System;
88
using System.Collections.Generic;
9-
using System.Threading.Tasks;
109

1110
namespace Microsoft.PowerShell.EditorServices.Console
1211
{
@@ -20,7 +19,7 @@ public class ConsoleService : IConsoleHost
2019

2120
private PowerShellContext powerShellContext;
2221

23-
private IPromptHandler activePromptHandler;
22+
private PromptHandler activePromptHandler;
2423
private Stack<IPromptHandlerContext> promptHandlerContextStack =
2524
new Stack<IPromptHandlerContext>();
2625

@@ -193,7 +192,7 @@ void IConsoleHost.UpdateProgress(long sourceId, ProgressDetails progressDetails)
193192

194193
void IConsoleHost.ExitSession(int exitCode)
195194
{
196-
throw new NotImplementedException();
195+
//throw new NotImplementedException();
197196
}
198197

199198
ChoicePromptHandler IConsoleHost.GetChoicePromptHandler()
@@ -210,7 +209,7 @@ InputPromptHandler IConsoleHost.GetInputPromptHandler()
210209

211210
private TPromptHandler GetPromptHandler<TPromptHandler>(
212211
Func<IPromptHandlerContext, TPromptHandler> factoryInvoker)
213-
where TPromptHandler : IPromptHandler
212+
where TPromptHandler : PromptHandler
214213
{
215214
if (this.activePromptHandler != null)
216215
{
@@ -225,11 +224,23 @@ private TPromptHandler GetPromptHandler<TPromptHandler>(
225224

226225
TPromptHandler promptHandler = factoryInvoker(promptHandlerContext);
227226
this.activePromptHandler = promptHandler;
227+
this.activePromptHandler.PromptCancelled += activePromptHandler_PromptCancelled;
228228

229229
return promptHandler;
230230
}
231231

232232
#endregion
233+
234+
#region Event Handlers
235+
236+
private void activePromptHandler_PromptCancelled(object sender, EventArgs e)
237+
{
238+
// Clean up the existing prompt
239+
this.activePromptHandler.PromptCancelled -= activePromptHandler_PromptCancelled;
240+
this.activePromptHandler = null;
241+
}
242+
243+
#endregion
233244
}
234245
}
235246

‎src/PowerShellEditorServices/Console/IPromptHandler.cs‎

Lines changed: 0 additions & 29 deletions
This file was deleted.

‎src/PowerShellEditorServices/Console/InputPromptHandler.cs‎

Lines changed: 20 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@
99
using System.Globalization;
1010
using System.Linq;
1111
using System.Management.Automation;
12+
using System.Threading;
1213
using System.Threading.Tasks;
1314

1415
namespace Microsoft.PowerShell.EditorServices.Console
@@ -18,7 +19,7 @@ namespace Microsoft.PowerShell.EditorServices.Console
1819
/// that present the user a set of fields for which values
1920
/// should be entered.
2021
/// </summary>
21-
public abstract class InputPromptHandler : IPromptHandler
22+
public abstract class InputPromptHandler : PromptHandler
2223
{
2324
#region Private Fields
2425

@@ -51,13 +52,15 @@ public abstract class InputPromptHandler : IPromptHandler
5152
/// A Task instance that can be monitored for completion to get
5253
/// the user's input.
5354
/// </returns>
54-
public Task<string> PromptForInput()
55+
public Task<string> PromptForInput(
56+
CancellationToken cancellationToken)
5557
{
5658
Task<Dictionary<string, object>> innerTask =
5759
this.PromptForInput(
5860
null,
5961
null,
60-
new FieldDetails[] { new FieldDetails("", "", typeof(string), false, "") });
62+
new FieldDetails[] { new FieldDetails("", "", typeof(string), false, "") },
63+
cancellationToken);
6164

6265
return
6366
innerTask.ContinueWith<string>(
@@ -67,6 +70,10 @@ public Task<string> PromptForInput()
6770
{
6871
throw task.Exception;
6972
}
73+
else if (task.IsCanceled)
74+
{
75+
throw new TaskCanceledException(task);
76+
}
7077

7178
// Return the value of the sole field
7279
return (string)task.Result[""];
@@ -86,17 +93,24 @@ public Task<string> PromptForInput()
8693
/// An array of FieldDetails items to be displayed which prompt the
8794
/// user for input of a specific type.
8895
/// </param>
96+
/// <param name="cancellationToken">
97+
/// A CancellationToken that can be used to cancel the prompt.
98+
/// </param>
8999
/// <returns>
90100
/// A Task instance that can be monitored for completion to get
91101
/// the user's input.
92102
/// </returns>
93103
public Task<Dictionary<string, object>> PromptForInput(
94104
string promptCaption,
95105
string promptMessage,
96-
FieldDetails[] fields)
106+
FieldDetails[] fields,
107+
CancellationToken cancellationToken)
97108
{
98109
this.promptTask = new TaskCompletionSource<Dictionary<string, object>>();
99110

111+
// Cancel the TaskCompletionSource if the caller cancels the task
112+
cancellationToken.Register(this.CancelPrompt, true);
113+
100114
this.Fields = fields;
101115

102116
this.ShowPromptMessage(promptCaption, promptMessage);
@@ -113,7 +127,7 @@ public Task<Dictionary<string, object>> PromptForInput(
113127
/// True if the prompt is complete, false if the prompt is
114128
/// still waiting for a valid response.
115129
/// </returns>
116-
public bool HandleResponse(string responseString)
130+
public override bool HandleResponse(string responseString)
117131
{
118132
if (this.currentField == null)
119133
{
@@ -188,7 +202,7 @@ public bool HandleResponse(string responseString)
188202
/// <summary>
189203
/// Called when the active prompt should be cancelled.
190204
/// </summary>
191-
public void CancelPrompt()
205+
protected override void OnPromptCancelled()
192206
{
193207
// Cancel the prompt task
194208
this.promptTask.TrySetCanceled();

‎src/PowerShellEditorServices/Console/PromptHandler.cs‎

Lines changed: 54 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,54 @@
1+
//
2+
// Copyright (c) Microsoft. All rights reserved.
3+
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
4+
//
5+
6+
using System;
7+
8+
namespace Microsoft.PowerShell.EditorServices.Console
9+
{
10+
/// <summary>
11+
/// Defines an abstract base class for prompt handler implementations.
12+
/// </summary>
13+
public abstract class PromptHandler
14+
{
15+
/// <summary>
16+
/// Implements behavior to handle the user's response.
17+
/// </summary>
18+
/// <param name="responseString">The string representing the user's response.</param>
19+
/// <returns>
20+
/// True if the prompt is complete, false if the prompt is
21+
/// still waiting for a valid response.
22+
/// </returns>
23+
public abstract bool HandleResponse(string responseString);
24+
25+
/// <summary>
26+
/// Called when the active prompt should be cancelled.
27+
/// </summary>
28+
public void CancelPrompt()
29+
{
30+
// Allow the implementation to clean itself up
31+
this.OnPromptCancelled();
32+
33+
if (this.PromptCancelled != null)
34+
{
35+
this.PromptCancelled(this, new EventArgs());
36+
}
37+
}
38+
39+
/// <summary>
40+
/// An event that gets raised if the prompt is cancelled, either
41+
/// by the user or due to a timeout.
42+
/// </summary>
43+
public event EventHandler PromptCancelled;
44+
45+
/// <summary>
46+
/// Implementation classes may override this method to perform
47+
/// cleanup when the CancelPrompt method gets called.
48+
/// </summary>
49+
protected virtual void OnPromptCancelled()
50+
{
51+
}
52+
}
53+
}
54+

‎src/PowerShellEditorServices/PowerShellEditorServices.csproj‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -57,8 +57,8 @@
5757
<Compile Include="Console\ConsoleService.cs" />
5858
<Compile Include="Console\FieldDetails.cs" />
5959
<Compile Include="Console\InputPromptHandler.cs" />
60-
<Compile Include="Console\IPromptHandler.cs" />
6160
<Compile Include="Console\IPromptHandlerContext.cs" />
61+
<Compile Include="Console\PromptHandler.cs" />
6262
<Compile Include="Debugging\BreakpointDetails.cs" />
6363
<Compile Include="Debugging\DebugService.cs" />
6464
<Compile Include="Debugging\StackFrameDetails.cs" />

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