Avoid delegate allocation in TraceSourceLoggerProvider.GetOrAddTraceSource (dotnet#71134)

stephentoub · web-flow · commit de078d1d078d · 2022-06-22T14:53:40.000-04:00
Every call to GetOrAddTraceSource was allocating a new delegate instance.
diff --git a/src/libraries/Microsoft.Extensions.Logging.TraceSource/src/TraceSourceLoggerProvider.cs b/src/libraries/Microsoft.Extensions.Logging.TraceSource/src/TraceSourceLoggerProvider.cs
@@ -53,10 +53,9 @@ public ILogger CreateLogger(string name)
             return new TraceSourceLogger(GetOrAddTraceSource(name));
         }
 
-        private DiagnosticsTraceSource GetOrAddTraceSource(string name)
-        {
-            return _sources.GetOrAdd(name, InitializeTraceSource);
-        }
+        private DiagnosticsTraceSource GetOrAddTraceSource(string name) =>
+            _sources.TryGetValue(name, out DiagnosticsTraceSource? source) ? source :
+            _sources.GetOrAdd(name, InitializeTraceSource(name));
 
         private DiagnosticsTraceSource InitializeTraceSource(string traceSourceName)
         {

Original file line number	Diff line number	Diff line change
`@@ -53,10 +53,9 @@ public ILogger CreateLogger(string name)`
`53`	`53`	`return new TraceSourceLogger(GetOrAddTraceSource(name));`
`54`	`54`	`}`
`55`	`55`
`56`		`- private DiagnosticsTraceSource GetOrAddTraceSource(string name)`
`57`		`- {`
`58`		`- return _sources.GetOrAdd(name, InitializeTraceSource);`
`59`		`- }`
	`56`	`+ private DiagnosticsTraceSource GetOrAddTraceSource(string name) =>`
	`57`	`+ _sources.TryGetValue(name, out DiagnosticsTraceSource? source) ? source :`
	`58`	`+ _sources.GetOrAdd(name, InitializeTraceSource(name));`
`60`	`59`
`61`	`60`	`private DiagnosticsTraceSource InitializeTraceSource(string traceSourceName)`
`62`	`61`	`{`