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@ladipro ladipro commented Oct 22, 2021

Context

Fixing a few places where we allocated objects unnecessarily. This is by no means exhaustive.

Changes Made

  • GetOrAdd should be given a delegate to a method that creates a new object, not the new object itself. Otherwise we allocate and throw away the object in the "Get" case.
  • When passing a callbacks to a method, a lambda expression should be used even if all arguments are passed-through. Otherwise a new delegate object is allocated on each invocation. Lambdas are cached in static fields by the compiler.

Testing

Existing unit tests.

return existenceCache.Value.GetOrAdd(directory, Directory.Exists);
}

public virtual bool FileExists(string file)
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This method was unused.

p => FileUtilities.DirectoryExistsNoThrow(p),
(p, searchPattern) => Directory.GetDirectories(p, searchPattern),
p => AssemblyNameExtension.GetAssemblyNameEx(p),
(string path, ConcurrentDictionary<string, AssemblyMetadata> assemblyMetadataCache, out AssemblyNameExtension[] dependencies, out string[] scatterFiles, out FrameworkNameVersioning frameworkName)
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I wonder if there's a more concise way of expressing this. My understanding is that if there is an out parameter then all parameters have to be listed complete with types.

@rainersigwald rainersigwald added this to the MSBuild 17.1 milestone Oct 25, 2021
@Forgind Forgind added the merge-when-branch-open PRs that are approved, except that there is a problem that means we are not merging stuff right now. label Oct 25, 2021
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5 participants