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Add Breakpoint Label frame to optimize debug stepping performance (#2190
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* Add Breakpoint label frame to optimize debug stepping performance
* Incorporate PR Review Feedback
* Add Tests

Co-authored-by: Patrick Meinecke <[email protected]>
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JustinGrote and SeeminglyScience authored Dec 3, 2024
1 parent 42d1399 commit a5aaad8
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Showing 6 changed files with 241 additions and 145 deletions.
1 change: 1 addition & 0 deletions src/PowerShellEditorServices/Server/PsesDebugServer.cs
Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ public async Task StartAsync()
response.SupportsHitConditionalBreakpoints = true;
response.SupportsLogPoints = true;
response.SupportsSetVariable = true;
response.SupportsDelayedStackTraceLoading = true;

return Task.CompletedTask;
});
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65 changes: 7 additions & 58 deletions src/PowerShellEditorServices/Services/DebugAdapter/DebugService.cs
Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,6 @@
using System.Collections.Generic;
using System.Linq;
using System.Management.Automation;
using System.Management.Automation.Language;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
Expand Down Expand Up @@ -50,7 +48,6 @@ internal class DebugService
private VariableContainerDetails scriptScopeVariables;
private VariableContainerDetails localScopeVariables;
private StackFrameDetails[] stackFrameDetails;
private readonly PropertyInfo invocationTypeScriptPositionProperty;

private readonly SemaphoreSlim debugInfoHandle = AsyncUtils.CreateSimpleLockingSemaphore();
#endregion
Expand All @@ -75,6 +72,11 @@ internal class DebugService
/// </summary>
public DebuggerStoppedEventArgs CurrentDebuggerStoppedEventArgs { get; private set; }

/// <summary>
/// Returns a task that completes when script frames and variables have completed population
/// </summary>
public Task StackFramesAndVariablesFetched { get; private set; }

/// <summary>
/// Tracks whether we are running <c>Debug-Runspace</c> in an out-of-process runspace.
/// </summary>
Expand Down Expand Up @@ -111,12 +113,6 @@ public DebugService(
_debugContext.DebuggerResuming += OnDebuggerResuming;
_debugContext.BreakpointUpdated += OnBreakpointUpdated;
_remoteFileManager = remoteFileManager;

invocationTypeScriptPositionProperty =
typeof(InvocationInfo)
.GetProperty(
"ScriptPosition",
BindingFlags.NonPublic | BindingFlags.Instance);
}

#endregion
Expand Down Expand Up @@ -981,8 +977,8 @@ await _executionService.ExecutePSCommandAsync<PSObject>(
}
}

// Get call stack and variables.
await FetchStackFramesAndVariablesAsync(noScriptName ? localScriptPath : null).ConfigureAwait(false);
// Begin call stack and variables fetch. We don't need to block here.
StackFramesAndVariablesFetched = FetchStackFramesAndVariablesAsync(noScriptName ? localScriptPath : null);

// If this is a remote connection and the debugger stopped at a line
// in a script file, get the file contents
Expand All @@ -996,53 +992,6 @@ await _remoteFileManager.FetchRemoteFileAsync(
_psesHost.CurrentRunspace).ConfigureAwait(false);
}

if (stackFrameDetails.Length > 0)
{
// Augment the top stack frame with details from the stop event
if (invocationTypeScriptPositionProperty.GetValue(e.InvocationInfo) is IScriptExtent scriptExtent)
{
StackFrameDetails targetFrame = stackFrameDetails[0];

// Certain context changes (like stepping into the default value expression
// of a parameter) do not create a call stack frame. In order to represent
// this context change we create a fake call stack frame.
if (!string.IsNullOrEmpty(scriptExtent.File)
&& !PathUtils.IsPathEqual(scriptExtent.File, targetFrame.ScriptPath))
{
await debugInfoHandle.WaitAsync().ConfigureAwait(false);
try
{
targetFrame = new StackFrameDetails
{
ScriptPath = scriptExtent.File,
// Just use the last frame's variables since we don't have a
// good way to get real values.
AutoVariables = targetFrame.AutoVariables,
CommandVariables = targetFrame.CommandVariables,
// Ideally we'd get a real value here but since there's no real
// call stack frame for this, we'd need to replicate a lot of
// engine code.
FunctionName = "<ScriptBlock>",
};

StackFrameDetails[] newFrames = new StackFrameDetails[stackFrameDetails.Length + 1];
newFrames[0] = targetFrame;
stackFrameDetails.CopyTo(newFrames, 1);
stackFrameDetails = newFrames;
}
finally
{
debugInfoHandle.Release();
}
}

targetFrame.StartLineNumber = scriptExtent.StartLineNumber;
targetFrame.EndLineNumber = scriptExtent.EndLineNumber;
targetFrame.StartColumnNumber = scriptExtent.StartColumnNumber;
targetFrame.EndColumnNumber = scriptExtent.EndColumnNumber;
}
}

CurrentDebuggerStoppedEventArgs =
new DebuggerStoppedEventArgs(
e,
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Original file line number Diff line number Diff line change
Expand Up @@ -18,16 +18,27 @@ internal class ScopesHandler : IScopesHandler

public ScopesHandler(DebugService debugService) => _debugService = debugService;

/// <summary>
/// Retrieves the variable scopes (containers) for the currently selected stack frame. Variables details are fetched via a separate request.
/// </summary>
public Task<ScopesResponse> Handle(ScopesArguments request, CancellationToken cancellationToken)
{
VariableScope[] variableScopes =
_debugService.GetVariableScopes(
(int)request.FrameId);
// HACK: The StackTraceHandler injects an artificial label frame as the first frame as a performance optimization, so when scopes are requested by the client, we need to adjust the frame index accordingly to match the underlying PowerShell frame, so when the client clicks on the label (or hit the default breakpoint), they get variables populated from the top of the PowerShell stackframe. If the client dives deeper, we need to reflect that as well (though 90% of debug users don't actually investigate this)
// VSCode Frame 0 (Label) -> PowerShell StackFrame 0 (for convenience)
// VSCode Frame 1 (First Real PS Frame) -> Also PowerShell StackFrame 0
// VSCode Frame 2 -> PowerShell StackFrame 1
// VSCode Frame 3 -> PowerShell StackFrame 2
// etc.
int powershellFrameId = request.FrameId == 0 ? 0 : (int)request.FrameId - 1;

VariableScope[] variableScopes = _debugService.GetVariableScopes(powershellFrameId);

return Task.FromResult(new ScopesResponse
{
Scopes = new Container<Scope>(variableScopes
.Select(LspDebugUtils.CreateScope))
Scopes = new Container<Scope>(
variableScopes
.Select(LspDebugUtils.CreateScope)
)
});
}
}
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Original file line number Diff line number Diff line change
@@ -1,64 +1,133 @@
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
#nullable enable

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Management.Automation;
using Microsoft.PowerShell.EditorServices.Services;
using Microsoft.PowerShell.EditorServices.Services.DebugAdapter;
using Microsoft.PowerShell.EditorServices.Utility;
using OmniSharp.Extensions.DebugAdapter.Protocol.Models;
using OmniSharp.Extensions.DebugAdapter.Protocol.Requests;
using Microsoft.PowerShell.EditorServices.Services.DebugAdapter;
using System.Linq;
using OmniSharp.Extensions.JsonRpc;

namespace Microsoft.PowerShell.EditorServices.Handlers;

namespace Microsoft.PowerShell.EditorServices.Handlers
internal class StackTraceHandler(DebugService debugService) : IStackTraceHandler
{
internal class StackTraceHandler : IStackTraceHandler
/// <summary>
/// Because we don't know the size of the stacktrace beforehand, we will tell the client that there are more frames available, this is effectively a paging size, as the client should request this many frames after the first one.
/// </summary>
private const int INITIAL_PAGE_SIZE = 20;

public async Task<StackTraceResponse> Handle(StackTraceArguments request, CancellationToken cancellationToken)
{
private readonly DebugService _debugService;
if (!debugService.IsDebuggerStopped)
{
throw new RpcErrorException(0, null!, "Stacktrace was requested while we are not stopped at a breakpoint. This is a violation of the DAP protocol, and is probably a bug.");
}

public StackTraceHandler(DebugService debugService) => _debugService = debugService;
// Adapting to int to let us use LINQ, realistically if you have a stacktrace larger than this that the client is requesting, you have bigger problems...
int skip = Convert.ToInt32(request.StartFrame ?? 0);
int take = Convert.ToInt32(request.Levels ?? 0);

public async Task<StackTraceResponse> Handle(StackTraceArguments request, CancellationToken cancellationToken)
{
StackFrameDetails[] stackFrameDetails = await _debugService.GetStackFramesAsync(cancellationToken).ConfigureAwait(false);
// We generate a label for the breakpoint and can return that immediately if the client is supporting DelayedStackTraceLoading.
InvocationInfo invocationInfo = debugService.CurrentDebuggerStoppedEventArgs?.OriginalEvent?.InvocationInfo
?? throw new RpcErrorException(0, null!, "InvocationInfo was not available on CurrentDebuggerStoppedEvent args. This is a bug and you should report it.");

// Handle a rare race condition where the adapter requests stack frames before they've
// begun building.
if (stackFrameDetails is null)
{
return new StackTraceResponse
{
StackFrames = Array.Empty<StackFrame>(),
TotalFrames = 0
};
}

List<StackFrame> newStackFrames = new();

long startFrameIndex = request.StartFrame ?? 0;
long maxFrameCount = stackFrameDetails.Length;

// If the number of requested levels == 0 (or null), that means get all stack frames
// after the specified startFrame index. Otherwise get all the stack frames.
long requestedFrameCount = request.Levels ?? 0;
if (requestedFrameCount > 0)
{
maxFrameCount = Math.Min(maxFrameCount, startFrameIndex + requestedFrameCount);
}
StackFrame breakpointLabel = CreateBreakpointLabel(invocationInfo);

for (long i = startFrameIndex; i < maxFrameCount; i++)
if (skip == 0 && take == 1) // This indicates the client is doing an initial fetch, so we want to return quickly to unblock the UI and wait on the remaining stack frames for the subsequent requests.
{
return new StackTraceResponse()
{
// Create the new StackFrame object with an ID that can
// be referenced back to the current list of stack frames
newStackFrames.Add(LspDebugUtils.CreateStackFrame(stackFrameDetails[i], id: i));
}
StackFrames = new StackFrame[] { breakpointLabel },
TotalFrames = INITIAL_PAGE_SIZE //Indicate to the client that there are more frames available
};
}

// Wait until the stack frames and variables have been fetched.
await debugService.StackFramesAndVariablesFetched.ConfigureAwait(false);

StackFrameDetails[] stackFrameDetails = await debugService.GetStackFramesAsync(cancellationToken)
.ConfigureAwait(false);

// Handle a rare race condition where the adapter requests stack frames before they've
// begun building.
if (stackFrameDetails is null)
{
return new StackTraceResponse
{
StackFrames = newStackFrames,
TotalFrames = newStackFrames.Count
StackFrames = Array.Empty<StackFrame>(),
TotalFrames = 0
};
}

List<StackFrame> newStackFrames = new();
if (skip == 0)
{
newStackFrames.Add(breakpointLabel);
}

newStackFrames.AddRange(
stackFrameDetails
.Skip(skip != 0 ? skip - 1 : skip)
.Take(take != 0 ? take - 1 : take)
.Select((frame, index) => CreateStackFrame(frame, index + 1))
);

return new StackTraceResponse
{
StackFrames = newStackFrames,
TotalFrames = newStackFrames.Count
};
}

public static StackFrame CreateStackFrame(StackFrameDetails stackFrame, long id)
{
SourcePresentationHint sourcePresentationHint =
stackFrame.IsExternalCode ? SourcePresentationHint.Deemphasize : SourcePresentationHint.Normal;

// When debugging an interactive session, the ScriptPath is <No File> which is not a valid source file.
// We need to make sure the user can't open the file associated with this stack frame.
// It will generate a VSCode error in this case.
Source? source = null;
if (!stackFrame.ScriptPath.Contains("<No File>"))
{
source = new Source
{
Path = stackFrame.ScriptPath,
PresentationHint = sourcePresentationHint
};
}

return new StackFrame
{
Id = id,
Name = (source is not null) ? stackFrame.FunctionName : "Interactive Session",
Line = (source is not null) ? stackFrame.StartLineNumber : 0,
EndLine = stackFrame.EndLineNumber,
Column = (source is not null) ? stackFrame.StartColumnNumber : 0,
EndColumn = stackFrame.EndColumnNumber,
Source = source
};
}

public static StackFrame CreateBreakpointLabel(InvocationInfo invocationInfo, int id = 0) => new()
{
Name = "<Breakpoint>",
Id = id,
Source = new()
{
Path = invocationInfo.ScriptName
},
Line = invocationInfo.ScriptLineNumber,
Column = invocationInfo.OffsetInLine,
PresentationHint = StackFramePresentationHint.Label
};

}

32 changes: 0 additions & 32 deletions src/PowerShellEditorServices/Utility/LspDebugUtils.cs
Original file line number Diff line number Diff line change
Expand Up @@ -56,38 +56,6 @@ public static Breakpoint CreateBreakpoint(
};
}

public static StackFrame CreateStackFrame(
StackFrameDetails stackFrame,
long id)
{
SourcePresentationHint sourcePresentationHint =
stackFrame.IsExternalCode ? SourcePresentationHint.Deemphasize : SourcePresentationHint.Normal;

// When debugging an interactive session, the ScriptPath is <No File> which is not a valid source file.
// We need to make sure the user can't open the file associated with this stack frame.
// It will generate a VSCode error in this case.
Source source = null;
if (!stackFrame.ScriptPath.Contains("<"))
{
source = new Source
{
Path = stackFrame.ScriptPath,
PresentationHint = sourcePresentationHint
};
}

return new StackFrame
{
Id = id,
Name = (source != null) ? stackFrame.FunctionName : "Interactive Session",
Line = (source != null) ? stackFrame.StartLineNumber : 0,
EndLine = stackFrame.EndLineNumber,
Column = (source != null) ? stackFrame.StartColumnNumber : 0,
EndColumn = stackFrame.EndColumnNumber,
Source = source
};
}

public static Scope CreateScope(VariableScope scope)
{
return new Scope
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