chore: add switchDictionary benchmarks (#14201)

This adds benchmarks for the `switchDictionary` method within pprofile.
None of them should emit allocs ever.

```
goos: darwin
goarch: arm64
pkg: go.opentelemetry.io/collector/pdata/pprofile
cpu: Apple M1 Max
BenchmarkFunctionSwitchDictionary-10                    87434488                13.44 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueAndUnitSwitchDictionary-10             584721352                2.047 ns/op           0 B/op          0 allocs/op
BenchmarkLineSwitchDictionary-10                        577840999                2.073 ns/op           0 B/op          0 allocs/op
BenchmarkLocationSwitchDictionary-10                    55512399                21.56 ns/op            0 B/op          0 allocs/op
BenchmarkMappingSwitchDictionary-10                     26952688                44.67 ns/op            0 B/op          0 allocs/op
BenchmarkProfileSwitchDictionary-10                     24649387                48.70 ns/op            0 B/op          0 allocs/op
BenchmarkProfilesSwitchDictionary-10                    58513749                20.36 ns/op            0 B/op          0 allocs/op
BenchmarkResourceProfilesSwitchDictionary-10            67610554                16.99 ns/op            0 B/op          0 allocs/op
BenchmarkSampleSwitchDictionary-10                      468034540                2.573 ns/op           0 B/op          0 allocs/op
BenchmarkScopeProfilesSwitchDictionary-10               90358615                13.13 ns/op            0 B/op          0 allocs/op
BenchmarkStackSwitchDictionary-10                       35702508                33.42 ns/op            0 B/op          0 allocs/op
BenchmarkValueTypeSwitchDictionary-10                   91959018                12.88 ns/op            0 B/op          0 allocs/op
```

Author: dmathieu

connector/connectortest/go.mod

@@ -69,3 +69,5 @@ replace go.opentelemetry.io/collector/pipeline/xpipeline => ../../pipeline/xpipe
 replace go.opentelemetry.io/collector/internal/fanoutconsumer => ../../internal/fanoutconsumer
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../internal/testutil

connector/go.mod

@@ -51,3 +51,5 @@ replace go.opentelemetry.io/collector/pipeline => ../pipeline
 replace go.opentelemetry.io/collector/internal/fanoutconsumer => ../internal/fanoutconsumer
 
 replace go.opentelemetry.io/collector/featuregate => ../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../internal/testutil

connector/xconnector/go.mod

@@ -56,3 +56,5 @@ replace go.opentelemetry.io/collector/pipeline/xpipeline => ../../pipeline/xpipe
 replace go.opentelemetry.io/collector/internal/fanoutconsumer => ../../internal/fanoutconsumer
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../internal/testutil

consumer/consumererror/go.mod

@@ -33,3 +33,5 @@ replace go.opentelemetry.io/collector/pdata => ../../pdata
 replace go.opentelemetry.io/collector/pdata/testdata => ../../pdata/testdata
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../internal/testutil

consumer/consumererror/xconsumererror/go.mod

@@ -31,3 +31,5 @@ replace go.opentelemetry.io/collector/pdata/pprofile => ../../../pdata/pprofile
 replace go.opentelemetry.io/collector/consumer/consumererror => ../../consumererror
 
 replace go.opentelemetry.io/collector/featuregate => ../../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../../internal/testutil

consumer/consumertest/go.mod

@@ -35,3 +35,5 @@ replace go.opentelemetry.io/collector/consumer/xconsumer => ../xconsumer
 replace go.opentelemetry.io/collector/pdata/testdata => ../../pdata/testdata
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../internal/testutil

consumer/xconsumer/go.mod

@@ -28,3 +28,5 @@ replace go.opentelemetry.io/collector/pdata/pprofile => ../../pdata/pprofile
 replace go.opentelemetry.io/collector/consumer => ../
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../../internal/testutil

internal/fanoutconsumer/go.mod

@@ -38,3 +38,5 @@ replace go.opentelemetry.io/collector/consumer/consumertest => ../../consumer/co
 replace go.opentelemetry.io/collector/consumer/xconsumer => ../../consumer/xconsumer
 
 replace go.opentelemetry.io/collector/featuregate => ../../featuregate
+
+replace go.opentelemetry.io/collector/internal/testutil => ../testutil

internal/testutil/benchmarks.go

@@ -0,0 +1,17 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package testutil // import "go.opentelemetry.io/collector/internal/testutil"
+
+import (
+	"os"
+	"testing"
+)
+
+// SkipMemoryBench will skip memory benchmarks on CI, as we currently only
+// monitor duration.
+func SkipMemoryBench(b *testing.B) {
+	if os.Getenv("MEMBENCH") == "" {
+		b.Skip("Skipping since the 'MEMBENCH' environment variable was not set")
+	}
+}

pdata/pprofile/function_test.go

@@ -9,6 +9,8 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"go.opentelemetry.io/collector/internal/testutil"
 )
 
 func TestFunctionEqual(t *testing.T) {
@@ -252,6 +254,28 @@ func TestFunctionSwitchDictionary(t *testing.T) {
 	}
 }
 
+func BenchmarkFunctionSwitchDictionary(b *testing.B) {
+	testutil.SkipMemoryBench(b)
+
+	fn := NewFunction()
+	fn.SetNameStrindex(1)
+	fn.SetSystemNameStrindex(2)
+
+	src := NewProfilesDictionary()
+	src.StringTable().Append("", "test", "foo")
+
+	b.ReportAllocs()
+
+	for b.Loop() {
+		b.StopTimer()
+		dst := NewProfilesDictionary()
+		dst.StringTable().Append("", "foo")
+		b.StartTimer()
+
+		_ = fn.switchDictionary(src, dst)
+	}
+}
+
 func buildFunction(name, sName, fileName int32, startLine int64) Function {
 	f := NewFunction()
 	f.SetNameStrindex(name)