Optimize AddPropertyIfAbsent

[sungam3r]

No actual API changes, only a few fixes for NRT annotations.
Eliminates allocation of LogEventProperty wrapper for LogEventPropertyValue.

dotnet test -c Release -f net7.0 --filter "FullyQualifiedName=Serilog.PerformanceTests.Harness.LogContextEnrichment"

BenchmarkDotNet=v0.13.5, OS=Windows 11 (10.0.22621.1265/22H2/2022Update/SunValley2)
AMD Ryzen 7 6800H with Radeon Graphics, 1 CPU, 16 logical and 8 physical cores
.NET SDK=7.0.201
  [Host]     : .NET 7.0.3 (7.0.323.6910), X64 RyuJIT AVX2
  DefaultJob : .NET 7.0.3 (7.0.323.6910), X64 RyuJIT AVX2

before

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
Bare	6.864 ns	0.1439 ns	0.1346 ns	1.00	0.00	-	-	NA
PushProperty	61.231 ns	1.2249 ns	1.3107 ns	8.94	0.28	0.0296	248 B	NA
PushPropertyNested	118.867 ns	2.4084 ns	2.6769 ns	17.34	0.62	0.0591	496 B	NA
PushPropertyEnriched	106.414 ns	1.7542 ns	1.6409 ns	15.51	0.36	0.0362	304 B	NA

after

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
Bare	6.810 ns	0.0722 ns	0.0603 ns	1.00	0.00	-	-	NA
PushProperty	62.395 ns	1.2570 ns	2.5393 ns	9.52	0.26	0.0296	248 B	NA
PushPropertyNested	128.455 ns	2.5705 ns	4.6351 ns	19.13	0.87	0.0591	496 B	NA
PushPropertyEnriched	93.311 ns	1.8405 ns	2.1909 ns	13.74	0.41	0.0296	248 B	NA

See Allocated column - 18% less heap allocation for case when event is logged with some pushed property.

[sungam3r]

I think this interface was just missed.

[sungam3r]

@nblumhardt For now it's internal but it may be changed to public for use in dependent packages. For example, in serilog-extensions-logging, see EnrichAndCreateScopeItem:

var property = propertyFactory.CreateProperty(key, value, destructureObject);
logEvent.AddPropertyIfAbsent(property);

[nblumhardt]

Since we already end up adding an internal property to LogEvent, we could just skip that and make this overload of AddPropertyIfAbsent an internal method on LogEvent itself, for now?

I can see how dependent libraries would benefit from making this accessible, but in that case we'd have to expose something on LogEvent anyway, so we might as well keep everything tight/encapsulated for now.

[sungam3r]

done