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Avoid Regex in DscClassCache.CreateKeywordFromCimClass #26306

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Merged
daxian-dbw merged 1 commit into from
Oct 28, 2025
Merged

Avoid Regex in DscClassCache.CreateKeywordFromCimClass #26306

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38 changes: 25 additions & 13 deletions src/System.Management.Automation/DscSupport/CimDSCParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -525,9 +525,6 @@ public DscClassCacheEntry(DSCResourceRunAsCredential aDSCResourceRunAsCredential
public static class DscClassCache
{
private const string InboxDscResourceModulePath = "WindowsPowershell\\v1.0\\Modules\\PsDesiredStateConfiguration";
private const string reservedDynamicKeywords = "^(Synchronization|Certificate|IIS|SQL)$";

private const string reservedProperties = "^(Require|Trigger|Notify|Before|After|Subscribe)$";

private static readonly PSTraceSource s_tracer = PSTraceSource.GetTracer("DSC", "DSC Class Cache");

Expand Down Expand Up @@ -1264,13 +1261,6 @@ public static void ValidateInstanceText(string instanceText)
parser.ValidateInstanceText(instanceText);
}

private static bool IsMagicProperty(string propertyName)
{
return System.Text.RegularExpressions.Regex.Match(propertyName,
"^(ResourceId|SourceInfo|ModuleName|ModuleVersion|ConfigurationName)$",
System.Text.RegularExpressions.RegexOptions.IgnoreCase).Success;
}

private static string GetFriendlyName(CimClass cimClass)
{
try
Expand Down Expand Up @@ -1367,7 +1357,8 @@ private static DynamicKeyword CreateKeywordFromCimClass(string moduleName, Versi
//
// Skip all of the base, meta, registration and other classes that are not intended to be used directly by a script author
//
if (System.Text.RegularExpressions.Regex.Match(keywordString, "^OMI_Base|^OMI_.*Registration", System.Text.RegularExpressions.RegexOptions.IgnoreCase).Success)
if (keywordString.StartsWith("OMI_Base", StringComparison.OrdinalIgnoreCase) ||
(keywordString.StartsWith("OMI_", StringComparison.OrdinalIgnoreCase) && keywordString.IndexOf("Registration", 4, StringComparison.OrdinalIgnoreCase) >= 0))
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{
return null;
}
Expand All @@ -1383,7 +1374,7 @@ private static DynamicKeyword CreateKeywordFromCimClass(string moduleName, Versi
};

// If it's one of reserved dynamic keyword, mark it
if (System.Text.RegularExpressions.Regex.Match(keywordString, reservedDynamicKeywords, System.Text.RegularExpressions.RegexOptions.IgnoreCase).Success)
if (IsReservedDynamicKeyword(keywordString))
{
keyword.IsReservedKeyword = true;
}
Expand Down Expand Up @@ -1441,7 +1432,7 @@ private static DynamicKeyword CreateKeywordFromCimClass(string moduleName, Versi
}
}
// If it's one of our reserved properties, save it for error reporting
if (System.Text.RegularExpressions.Regex.Match(prop.Name, reservedProperties, System.Text.RegularExpressions.RegexOptions.IgnoreCase).Success)
if (IsReservedProperty(prop.Name))
{
keyword.HasReservedProperties = true;
continue;
Expand Down Expand Up @@ -1540,6 +1531,27 @@ private static DynamicKeyword CreateKeywordFromCimClass(string moduleName, Versi
UpdateKnownRestriction(keyword);

return keyword;

static bool IsMagicProperty(string propertyName) =>
string.Equals(propertyName, "ResourceId", StringComparison.OrdinalIgnoreCase) ||
string.Equals(propertyName, "SourceInfo", StringComparison.OrdinalIgnoreCase) ||
string.Equals(propertyName, "ModuleName", StringComparison.OrdinalIgnoreCase) ||
string.Equals(propertyName, "ModuleVersion", StringComparison.OrdinalIgnoreCase) ||
string.Equals(propertyName, "ConfigurationName", StringComparison.OrdinalIgnoreCase);
Comment on lines +1535 to +1540
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@iSazonov iSazonov Oct 27, 2025

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If this change is just to get rid of the Regex, then it doesn't make sense.
If it's about performance, then I suspect that Regex makes better optimizations than this change. And we need measurements to prove that there is a significant increase in parser performance.

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@xtqqczze xtqqczze Oct 27, 2025 •
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Avoiding Regex can make significant improvement:

Method propertyName Mean Error Median Ratio
IsMagicProperty_GeneratedRegex ConfigurationName 17.068 ns 0.0866 ns 17.056 ns 9.66
IsMagicProperty_StringEquals ConfigurationName 1.768 ns 0.0382 ns 1.772 ns 1.00
IsMagicProperty_CompiledRegex ConfigurationName 66.315 ns 1.3416 ns 65.370 ns 37.52
IsMagicProperty_RegexIsMatch ConfigurationName 127.821 ns 1.7693 ns 127.007 ns 72.32
IsMagicProperty_Regex ConfigurationName 157.995 ns 3.1062 ns 156.249 ns 89.40


static bool IsReservedDynamicKeyword(string keyword) =>
string.Equals(keyword, "Synchronization", StringComparison.OrdinalIgnoreCase) ||
string.Equals(keyword, "Certificate", StringComparison.OrdinalIgnoreCase) ||
string.Equals(keyword, "IIS", StringComparison.OrdinalIgnoreCase) ||
string.Equals(keyword, "SQL", StringComparison.OrdinalIgnoreCase);

static bool IsReservedProperty(string name) =>
string.Equals(name, "Require", StringComparison.OrdinalIgnoreCase) ||
string.Equals(name, "Trigger", StringComparison.OrdinalIgnoreCase) ||
string.Equals(name, "Notify", StringComparison.OrdinalIgnoreCase) ||
string.Equals(name, "Before", StringComparison.OrdinalIgnoreCase) ||
string.Equals(name, "After", StringComparison.OrdinalIgnoreCase) ||
string.Equals(name, "Subscribe", StringComparison.OrdinalIgnoreCase);
}

/// <summary>
Expand Down
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