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CollectionsMarshal.GetValueRef(Dictionary) #49388

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merged 1 commit into from Mar 17, 2021

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benaadams
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@benaadams benaadams commented Mar 9, 2021

Implement the api

namespace System.Runtime.InteropServices
{
    public static class CollectionsMarshal
    {
        public ref TValue GetValueRefOrNullRef<TKey, TValue>(Dictionary<TKey, TValue> dictionary, TKey key);
    }
}

Contributes to #27062

/cc @layomia

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ghost commented Mar 9, 2021

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Issue Details

Still needs doc comments and tests

Resolves #27062

Author: benaadams
Assignees: -
Labels:

area-System.Collections

Milestone: -

@stephentoub
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Still needs doc comments and tests

Are there places outside of Dictionary we should be using the new method, too?

@benaadams
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Are there places outside of Dictionary we should be using the new method, too?

For GetValueRef the big wins are for struct TValues; either using in place or mutating which don't look to be a common pattern in CoreLib.

However GetValueRefOrAddDefault does look like it would have more applicability removing a double lookup from TryGet+Add; assuming it was implemented more efficiently. So is probably worth looping back and doing that as well.

@jkotas
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jkotas commented Mar 9, 2021

GetValueRefOrAddDefault does look like it would have more applicability removing a double lookup from TryGet+Add

It also needs to be something reasonably hot to make it worth the trouble.

@benaadams
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It also needs to be something reasonably hot to make it worth the trouble.

While CoreLib does create dictionaries, it doesn't really do much modifying of them and alas my search-fu isn't good enough to check all the other libs; though I definitely have uses further downstream

Looks like a ref enumerator

ref struct RefEnumerator
{
    (TKey key, ref TValue) Current { get; }
    bool MoveNext();
}

would be helpful too, but small steps 😉

@benaadams benaadams force-pushed the CollectionsMarshal-Dictionary branch from 310ad9b to 66feb3c Compare March 10, 2021 03:15
@benaadams benaadams closed this Mar 10, 2021
@benaadams benaadams reopened this Mar 10, 2021
@benaadams benaadams force-pushed the CollectionsMarshal-Dictionary branch 3 times, most recently from b45aaa5 to 8d37543 Compare March 10, 2021 13:24
@benaadams benaadams marked this pull request as ready for review March 10, 2021 13:42
@stephentoub
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Thanks, @benaadams.

@benaadams
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runtime (Libraries Test Run checked coreclr windows x64 Debug) Failure is #48236 though that's closed, and looks like the vm pool died for the rest

@benaadams benaadams closed this Mar 12, 2021
@benaadams benaadams reopened this Mar 12, 2021
@benaadams benaadams closed this Mar 17, 2021
@benaadams benaadams reopened this Mar 17, 2021
@benaadams benaadams force-pushed the CollectionsMarshal-Dictionary branch from 76c7749 to 4b9cc40 Compare March 17, 2021 02:26
@benaadams
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Rebased to reset CI

@benaadams
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🥳

@stephentoub stephentoub merged commit 46127ea into dotnet:main Mar 17, 2021
@benaadams benaadams deleted the CollectionsMarshal-Dictionary branch March 17, 2021 10:50
@ghost ghost locked as resolved and limited conversation to collaborators Apr 16, 2021
@karelz karelz added this to the 6.0.0 milestone May 20, 2021
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6 participants