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Implement OnIdle engine events #1581

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Merged
merged 4 commits into from
Oct 13, 2021
Merged

Implement OnIdle engine events #1581

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ec85f59
Implement PowerShell engine OnIdle events
rjmholt Oct 12, 2021
e4730a1
Improve artificial idle event comment
rjmholt Oct 13, 2021
fe6a142
Fix typo
rjmholt Oct 13, 2021
08df557
Change BlockingConcurrentDequeue to provide IsEmpty property
rjmholt Oct 13, 2021
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52 changes: 44 additions & 8 deletions src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,8 @@ internal class PsesInternalHost : PSHost, IHostSupportsInteractiveSession, IRuns

private readonly IdempotentLatch _isRunningLatch = new();

private EngineIntrinsics _mainRunspaceEngineIntrinsics;

private bool _shouldExit = false;

private string _localComputerName;
Expand Down Expand Up @@ -345,17 +347,18 @@ public Task SetInitialWorkingDirectoryAsync(string path, CancellationToken cance

private void Run()
{
(PowerShell pwsh, RunspaceInfo localRunspaceInfo) = CreateInitialPowerShellSession();
(PowerShell pwsh, RunspaceInfo localRunspaceInfo, EngineIntrinsics engineIntrinsics) = CreateInitialPowerShellSession();
_mainRunspaceEngineIntrinsics = engineIntrinsics;
_localComputerName = localRunspaceInfo.SessionDetails.ComputerName;
_runspaceStack.Push(new RunspaceFrame(pwsh.Runspace, localRunspaceInfo));
PushPowerShellAndRunLoop(pwsh, PowerShellFrameType.Normal, localRunspaceInfo);
}

private (PowerShell, RunspaceInfo) CreateInitialPowerShellSession()
private (PowerShell, RunspaceInfo, EngineIntrinsics) CreateInitialPowerShellSession()
{
PowerShell pwsh = CreateInitialPowerShell(_hostInfo, _readLineProvider);
(PowerShell pwsh, EngineIntrinsics engineIntrinsics) = CreateInitialPowerShell(_hostInfo, _readLineProvider);
RunspaceInfo localRunspaceInfo = RunspaceInfo.CreateFromLocalPowerShell(_logger, pwsh);
return (pwsh, localRunspaceInfo);
return (pwsh, localRunspaceInfo, engineIntrinsics);
}

private void PushPowerShellAndRunLoop(SMA.PowerShell pwsh, PowerShellFrameType frameType, RunspaceInfo newRunspaceInfo = null)
Expand Down Expand Up @@ -611,7 +614,7 @@ private static PowerShell CreatePowerShellForRunspace(Runspace runspace)
return pwsh;
}

public PowerShell CreateInitialPowerShell(
public (PowerShell, EngineIntrinsics) CreateInitialPowerShell(
HostStartupInfo hostStartupInfo,
ReadLineProvider readLineProvider)
{
Expand Down Expand Up @@ -647,7 +650,7 @@ public PowerShell CreateInitialPowerShell(
}
}

return pwsh;
return (pwsh, engineIntrinsics);
}

private Runspace CreateInitialRunspace(InitialSessionState initialSessionState)
Expand All @@ -666,7 +669,27 @@ private Runspace CreateInitialRunspace(InitialSessionState initialSessionState)

private void OnPowerShellIdle()
{
if (_taskQueue.Count == 0)
IReadOnlyList<PSEventSubscriber> eventSubscribers = _mainRunspaceEngineIntrinsics.Events.Subscribers;

// Go through pending event subscribers and:
// - if we have any subscribers, ensure we process any events
// - if we have any idle events, generate an idle event and process that
bool runPipelineForEventProcessing = false;
foreach (PSEventSubscriber subscriber in eventSubscribers)
{
runPipelineForEventProcessing = true;

if (string.Equals(subscriber.SourceIdentifier, PSEngineEvent.OnIdle, StringComparison.OrdinalIgnoreCase))
{
// PowerShell thinks we're in a call (the ReadLine call) rather than idle,
// but we know we're sitting in the prompt.
// So we need to generate the idle event ourselves
_mainRunspaceEngineIntrinsics.Events.GenerateEvent(PSEngineEvent.OnIdle, sender: null, args: null, extraData: null);
break;
}
}

if (!runPipelineForEventProcessing && _taskQueue.Count == 0)
{
return;
}
Expand All @@ -686,9 +709,21 @@ private void OnPowerShellIdle()
return;
}

// If we're executing a task, we don't need to run an extra pipeline later for events
// TODO: This may not be a PowerShell task, so ideally we can differentiate that here.
// For now it's mostly true and an easy assumption to make.
runPipelineForEventProcessing = false;
task.ExecuteSynchronously(cancellationScope.CancellationToken);
}
}

// We didn't end up executinng anything in the background,
// so we need to run a small artificial pipeline instead
// to force event processing
if (runPipelineForEventProcessing)
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I think it'd be worth explaining why, architecturally, we have to do this.

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I got it from here, but @daxian-dbw might know more

{
InvokePSCommand(new PSCommand().AddScript("0", useLocalScope: true), PowerShellExecutionOptions.Default, CancellationToken.None);
}
}

private void OnCancelKeyPress(object sender, ConsoleCancelEventArgs args)
Expand Down Expand Up @@ -769,7 +804,8 @@ private Task PopOrReinitializeRunspaceAsync()
// If our main runspace was corrupted,
// we must re-initialize our state.
// TODO: Use runspace.ResetRunspaceState() here instead
(PowerShell pwsh, RunspaceInfo runspaceInfo) = CreateInitialPowerShellSession();
(PowerShell pwsh, RunspaceInfo runspaceInfo, EngineIntrinsics engineIntrinsics) = CreateInitialPowerShellSession();
_mainRunspaceEngineIntrinsics = engineIntrinsics;
PushPowerShell(new PowerShellContextFrame(pwsh, runspaceInfo, PowerShellFrameType.Normal));

_logger.LogError($"Top level runspace entered state '{oldRunspaceState.State}' for reason '{oldRunspaceState.Reason}' and was reinitialized."
Expand Down