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daviwildaviwil
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Add intervallic buffering of OutputEvent messages
This change introduces a new AsyncDebouncer class which is able to gate invocation requests to only occur after a specified interval. This class is used to implement an OutputDebouncer which takes all output messages written from the PowerShell host and buffers them. This causes many lines of output written in a short time window to be sent as one OutputEvent rather than writing individual events for each line. Resolves #113.
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15 files changed

+672
-54
lines changed

15 files changed

+672
-54
lines changed

‎src/PowerShellEditorServices.Protocol/PowerShellEditorServices.Protocol.csproj

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@@ -124,6 +124,7 @@
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<Compile Include="Properties\AssemblyInfo.cs" />
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<Compile Include="LanguageServer\References.cs" />
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<Compile Include="Server\LanguageServerSettings.cs" />
127+
<Compile Include="Server\OutputDebouncer.cs" />
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<Compile Include="Server\PromptHandlers.cs" />
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</ItemGroup>
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<ItemGroup>

‎src/PowerShellEditorServices.Protocol/Properties/AssemblyInfo.cs

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@@ -41,3 +41,4 @@
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[assembly: AssemblyFileVersion("0.0.0.0")]
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[assembly: AssemblyInformationalVersion("0.0.0.0")]
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[assembly: InternalsVisibleTo("Microsoft.PowerShell.EditorServices.Test.Protocol")]

‎src/PowerShellEditorServices.Protocol/Server/DebugAdapter.cs

Lines changed: 12 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,6 @@
66
using Microsoft.PowerShell.EditorServices.Protocol.DebugAdapter;
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using Microsoft.PowerShell.EditorServices.Protocol.MessageProtocol;
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using Microsoft.PowerShell.EditorServices.Protocol.MessageProtocol.Channel;
9-
using Microsoft.PowerShell.EditorServices.Protocol.Server;
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using Microsoft.PowerShell.EditorServices.Utility;
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using System;
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using System.Collections.Generic;
@@ -19,6 +18,7 @@ namespace Microsoft.PowerShell.EditorServices.Protocol.Server
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public class DebugAdapter : DebugAdapterBase
2019
{
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private EditorSession editorSession;
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private OutputDebouncer outputDebouncer;
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public DebugAdapter() : this(new StdioServerChannel())
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{
@@ -30,6 +30,9 @@ public DebugAdapter(ChannelBase serverChannel) : base(serverChannel)
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this.editorSession.StartSession();
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this.editorSession.DebugService.DebuggerStopped += this.DebugService_DebuggerStopped;
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this.editorSession.ConsoleService.OutputWritten += this.powerShellContext_OutputWritten;
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// Set up the output debouncer to throttle output event writes
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this.outputDebouncer = new OutputDebouncer(this);
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}
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protected override void Initialize()
@@ -59,6 +62,9 @@ protected override void Initialize()
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protected override void Shutdown()
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{
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// Make sure remaining output is flushed before exiting
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this.outputDebouncer.Flush().Wait();
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6268
Logger.Write(LogLevel.Normal, "Debug adapter is shutting down...");
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if (this.editorSession != null)
@@ -359,6 +365,9 @@ await requestContext.SendResult(
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async void DebugService_DebuggerStopped(object sender, DebuggerStopEventArgs e)
361367
{
368+
// Flush pending output before sending the event
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await this.outputDebouncer.Flush();
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362371
await this.SendEvent(
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StoppedEvent.Type,
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new StoppedEventBody
@@ -376,13 +385,8 @@ await this.SendEvent(
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async void powerShellContext_OutputWritten(object sender, OutputWrittenEventArgs e)
378387
{
379-
await this.SendEvent(
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OutputEvent.Type,
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new OutputEventBody
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{
383-
Output = e.OutputText + (e.IncludeNewLine ? "\r\n" : string.Empty),
384-
Category = (e.OutputType == OutputType.Error) ? "stderr" : "stdout"
385-
});
388+
// Queue the output for writing
389+
await this.outputDebouncer.Invoke(e);
386390
}
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388392
#endregion

‎src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

Lines changed: 9 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -25,6 +25,7 @@ public class LanguageServer : LanguageServerBase
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private static CancellationTokenSource existingRequestCancellation;
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private EditorSession editorSession;
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private OutputDebouncer outputDebouncer;
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private LanguageServerSettings currentSettings = new LanguageServerSettings();
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public LanguageServer() : this(new StdioServerChannel())
@@ -44,6 +45,9 @@ public LanguageServer(ChannelBase serverChannel) : base(serverChannel)
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new ProtocolPromptHandlerContext(
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this,
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this.editorSession.ConsoleService));
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// Set up the output debouncer to throttle output event writes
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this.outputDebouncer = new OutputDebouncer(this);
4751
}
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4953
protected override void Initialize()
@@ -78,6 +82,9 @@ protected override void Initialize()
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7983
protected override void Shutdown()
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{
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// Make sure remaining output is flushed before exiting
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this.outputDebouncer.Flush().Wait();
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Logger.Write(LogLevel.Normal, "Language service is shutting down...");
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if (this.editorSession != null)
@@ -757,13 +764,8 @@ protected Task HandleEvaluateRequest(
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758765
async void powerShellContext_OutputWritten(object sender, OutputWrittenEventArgs e)
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{
760-
await this.SendEvent(
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DebugAdapterMessages.OutputEvent.Type,
762-
new DebugAdapterMessages.OutputEventBody
763-
{
764-
Output = e.OutputText + (e.IncludeNewLine ? "\r\n" : string.Empty),
765-
Category = (e.OutputType == OutputType.Error) ? "stderr" : "stdout"
766-
});
767+
// Queue the output for writing
768+
await this.outputDebouncer.Invoke(e);
767769
}
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769771
#endregion

‎src/PowerShellEditorServices.Protocol/Server/OutputDebouncer.cs

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,102 @@
1+
//
2+
// 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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6+
using Microsoft.PowerShell.EditorServices.Protocol.DebugAdapter;
7+
using Microsoft.PowerShell.EditorServices.Protocol.MessageProtocol;
8+
using Microsoft.PowerShell.EditorServices.Utility;
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using System.Threading.Tasks;
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namespace Microsoft.PowerShell.EditorServices.Protocol.Server
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{
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/// <summary>
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/// Throttles output written via OutputEvents by batching all output
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/// written within a short time window and writing it all out at once.
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/// </summary>
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internal class OutputDebouncer : AsyncDebouncer<OutputWrittenEventArgs>
18+
{
19+
#region Private Fields
20+
21+
private IMessageSender messageSender;
22+
private bool currentOutputIsError = false;
23+
private string currentOutputString = null;
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25+
#endregion
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27+
#region Constants
28+
29+
// Set a really short window for output flushes. This
30+
// gives the appearance of fast output without the crushing
31+
// overhead of sending an OutputEvent for every single line
32+
// written. At this point it seems that around 10-20 lines get
33+
// batched for each flush when Get-Process is called.
34+
public const int OutputFlushInterval = 200;
35+
36+
#endregion
37+
38+
#region Constructors
39+
40+
public OutputDebouncer(IMessageSender messageSender)
41+
: base(OutputFlushInterval, false)
42+
{
43+
this.messageSender = messageSender;
44+
}
45+
46+
#endregion
47+
48+
#region Private Methods
49+
50+
protected override async Task OnInvoke(OutputWrittenEventArgs output)
51+
{
52+
bool outputIsError = output.OutputType == OutputType.Error;
53+
54+
if (this.currentOutputIsError != outputIsError)
55+
{
56+
if (this.currentOutputString != null)
57+
{
58+
// Flush the output
59+
await this.OnFlush();
60+
}
61+
62+
this.currentOutputString = string.Empty;
63+
this.currentOutputIsError = outputIsError;
64+
}
65+
66+
// Output string could be null if the last output was already flushed
67+
if (this.currentOutputString == null)
68+
{
69+
this.currentOutputString = string.Empty;
70+
}
71+
72+
// Add to string (and include newline)
73+
this.currentOutputString +=
74+
output.OutputText +
75+
(output.IncludeNewLine ?
76+
System.Environment.NewLine :
77+
string.Empty);
78+
}
79+
80+
protected override async Task OnFlush()
81+
{
82+
// Only flush output if there is some to flush
83+
if (this.currentOutputString != null)
84+
{
85+
// Send an event for the current output
86+
await this.messageSender.SendEvent(
87+
OutputEvent.Type,
88+
new OutputEventBody
89+
{
90+
Output = this.currentOutputString,
91+
Category = (this.currentOutputIsError) ? "stderr" : "stdout"
92+
});
93+
94+
// Clear the output string for the next batch
95+
this.currentOutputString = null;
96+
}
97+
}
98+
99+
#endregion
100+
}
101+
}
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‎src/PowerShellEditorServices/PowerShellEditorServices.csproj

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@@ -101,6 +101,7 @@
101101
<Compile Include="Session\SessionPSHostUserInterface.cs" />
102102
<Compile Include="Session\SessionStateChangedEventArgs.cs" />
103103
<Compile Include="Utility\AsyncContextThread.cs" />
104+
<Compile Include="Utility\AsyncDebouncer.cs" />
104105
<Compile Include="Utility\AsyncLock.cs" />
105106
<Compile Include="Utility\AsyncQueue.cs" />
106107
<Compile Include="Utility\AsyncContext.cs" />

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