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Restore caching in Helper.GetCommandInfo #1074

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Merged
merged 2 commits into from
Oct 3, 2018
Merged

Restore caching in Helper.GetCommandInfo #1074

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ae3c26c
Enable command lookup caching by name and filter
SeeminglyScience Oct 1, 2018
1217068
Moved CommandLookupKey to new file
SeeminglyScience Oct 1, 2018
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49 changes: 41 additions & 8 deletions Engine/Helper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ public class Helper
private readonly static Version minSupportedPSVersion = new Version(3, 0);
private Dictionary<string, Dictionary<string, object>> ruleArguments;
private PSVersionTable psVersionTable;
private Dictionary<string, CommandInfo> commandInfoCache;
private Dictionary<CommandLookupKey, CommandInfo> commandInfoCache;

#endregion

Expand Down Expand Up @@ -142,7 +142,7 @@ public void Initialize()
ruleArguments = new Dictionary<string, Dictionary<string, object>>(StringComparer.OrdinalIgnoreCase);
if (commandInfoCache == null)
{
commandInfoCache = new Dictionary<string, CommandInfo>(StringComparer.OrdinalIgnoreCase);
commandInfoCache = new Dictionary<CommandLookupKey, CommandInfo>();
}

IEnumerable<CommandInfo> aliases = this.invokeCommand.GetCommands("*", CommandTypes.Alias, true);
Expand Down Expand Up @@ -700,15 +700,16 @@ public CommandInfo GetCommandInfoLegacy(string name, CommandTypes? commandType =
cmdletName = name;
}

var key = new CommandLookupKey(name, commandType);
lock (getCommandLock)
{
if (commandInfoCache.ContainsKey(cmdletName))
if (commandInfoCache.ContainsKey(key))
{
return commandInfoCache[cmdletName];
return commandInfoCache[key];
}

var commandInfo = GetCommandInfoInternal(cmdletName, commandType);
commandInfoCache.Add(cmdletName, commandInfo);
commandInfoCache.Add(key, commandInfo);
return commandInfo;
}
}
Expand All @@ -726,15 +727,16 @@ public CommandInfo GetCommandInfo(string name, CommandTypes? commandType = null)
return null;
}

var key = new CommandLookupKey(name, commandType);
lock (getCommandLock)
{
if (commandInfoCache.ContainsKey(name))
if (commandInfoCache.ContainsKey(key))
{
return commandInfoCache[name];
return commandInfoCache[key];
}

var commandInfo = GetCommandInfoInternal(name, commandType);

commandInfoCache.Add(key, commandInfo);
return commandInfo;
}
}
Expand Down Expand Up @@ -1910,6 +1912,37 @@ public Version GetPSVersion()
}

#endregion Methods

private struct CommandLookupKey : IEquatable<CommandLookupKey>
{
private readonly string Name;

private readonly CommandTypes CommandTypes;

internal CommandLookupKey(string name, CommandTypes? commandTypes)
{
Name = name;
CommandTypes = commandTypes ?? CommandTypes.All;
}

public bool Equals(CommandLookupKey other)
{
return CommandTypes == other.CommandTypes
&& Name.Equals(other.Name, StringComparison.OrdinalIgnoreCase);
}

public override int GetHashCode()
{
// Algorithm from https://stackoverflow.com/questions/1646807/quick-and-simple-hash-code-combinations
unchecked
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On this part, worth reading through PowerShell/PowerShell#7134 and the comment it starts with. We discussed the hashcode stuff a bit, but not sure (1) how far we want to take the bikeshedding on hashcodes or (2) if there's a convenient function to do this in both .NET Core and .NET Framework

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PSSA already has many conditional compilation options for different version of powershell, therefore using a special, optimised version for .net core would be acceptable (the only restriction is that it should be part of .net standard 2.0 at the moment)

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Another option might be new Tuple(Name.ToUpperInvariant(), CommandTypes).GetHashCode(). I don't think older framework versions have System.ValueTuple, so this would be forced to allocate :(

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@bergmeister bergmeister Oct 1, 2018 •
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There is a NuGet package for System.ValueTuple that supports full .net and .net core

{
int hash = 17;
hash = hash * 31 + Name.ToUpperInvariant().GetHashCode();
hash = hash * 31 + CommandTypes.GetHashCode();
return hash;
}
}
}
}


Expand Down