S1450 Improve performance: PrivateFieldUsedAsLocalVariable

[pavel-mikula-sonarsource]

Split of #4483, originally reported by @pfeigl into separate issues per rule:

Description

We have a single assembly which takes very long when beeing analyzed. /p:reportanalyzer=true shows the following result

Total analyzer execution time: 15420.471 seconds. (TaskId:263)
NOTE: Elapsed time may be less than analyzer execution time because analyzers can run concurrently. (TaskId:263)
Time (s)    %   Analyzer (TaskId:263)
15420.471  100   SonarAnalyzer.CSharp, Version=8.23.0.0, Culture=neutral, PublicKeyToken=c5b62af9de6d7244 (TaskId:263)
8089.488   52      SonarAnalyzer.Rules.CSharp.XmlExternalEntityShouldNotBeParsed (TaskId:263)
6958.701   45      SonarAnalyzer.Rules.CSharp.PrivateFieldUsedAsLocalVariable (TaskId:263)
355.733    2      SonarAnalyzer.Rules.CSharp.HardcodedIpAddress (TaskId:263)
2.563   <1      SonarAnalyzer.Rules.SymbolicExecution.SymbolicExecutionRunner (TaskId:263)
1.689   <1      SonarAnalyzer.Rules.CSharp.CreatingHashAlgorithms (TaskId:263)
...

Repro steps

For now I'm unable to share the source code :-( Some things that might stand out and give you some hints:

• The project contains XML and XSD files as embedded resources
• However we actually exclude them from sonar completely by using <Property Name="sonar.exclusions">**/*.xml,**/*.xsd</Property>
• One of the files has a very big Dictionary (around 4k lines), so we suspected a connection to Reduce the number of symbols retrieved by SymbolReferenceAnalyzer #4220. While this might also have been a problem (we already applied 8.23 with the respective fix), it doesn't seem to be the root problem

Known workarounds

We didn't find one (except ofcourse excluding the whole project, but that shouldn't be an option ;-) )

Related information

• 8.23 (but we started off with 8.19)
• Visual Studio version: Only msbuild tools, no VS installation on build machines
• MSBuild / dotnet version: Microsoft (R) Build Engine version 16.8.2+25e4d540b for .NET Framework
• SonarScanner for .NET version (if used): 5.21
• Operating System: Windows Server 2016

[pavel-mikula-sonarsource]

Snippet from original issue, might not be related:

Thanks for the feedback. We also suspected that the dictionary might still be somehow connected.

We meanwhile changed the huge dictionary to IList<string> and Lazy-converted this into a static dictionary field. Not the best of solutions, because we now have runtime code were we previously had a compiled dictionary, but well - with ~4k entries and not many iterations on our side, not too big of a deal.
This also fixed the build problems.

To answer the open question: Yes, integrating 8.23 actually brought the build times down from ~3h to ~2h.

Also find a anaonymized and shortened version of the file in question below (in reality its 4200 lines):

using System.Collections.Generic;
using System.Linq;

public class InformationContainer
{
    public InformationContainer(string identifier, int x, int y)
    {
        Identifier = identifier;
        X = x;
        Y = y;
    }

    public string Identifier { get; }
    public int X { get; }
    public int Y { get; }
}

public static class LongDictionaryContainer
{
    public static IDictionary<string, IList<InformationContainer>> LongDictionary = new Dictionary<string, IList<InformationContainer>>
    {
        {"1", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"2", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"3", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"4", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"5", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1) } },
        {"6", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"7", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"8", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"9", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"10", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"11", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"12", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"13", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"14", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"15", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"16", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"17", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"18", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"19", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"20", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"21", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"22", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"23", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"24", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"25", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"26", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } },
        {"27", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"28", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,1), new InformationContainer("Lorem Ipsum", 0,0) } },
        {"29", new List<InformationContainer> { new InformationContainer("Lorem Ipsum", 0,0) } }
    };
}

Thanks for a great product and the rapid help!

One final question from our side: We actually excluded the whole file using sonar.exclusions and this didn't help at all. Does this mean, that analyzers even run for excluded files and that they are just not reported?

If yes, is there a way to exclude certain analyzers for a specific file?

[pavel-mikula-sonarsource]

Might be related to #4350

[pavel-mikula-sonarsource]

FieldAccessCollector.VisitIdentifierName / GetTopmostSyntaxWithTheSameSymbol: Don't request all symbols. Filter them by good candidates first privateFields.Keys - Name

[pavel-mikula-sonarsource]

It's not clear why is the GetEnclosingSymbol call needed - reconsider why it's there and if it's necessary