Change SetMapping signature to return the mapping's ID, not update (#14030)

Part of #14016

Author: dmathieu

.chloggen/setmapping-immutable.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: pdata/pprofile
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Update `SetMapping` to return the mapping's ID rather than update the Location
+
+# One or more tracking issues or pull requests related to the change
+issues: [14016, 14030]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

pdata/pprofile/mappings.go

@@ -5,43 +5,27 @@ package pprofile // import "go.opentelemetry.io/collector/pdata/pprofile"
 
 import (
 	"errors"
-	"fmt"
 	"math"
 )
 
 var errTooManyMappingTableEntries = errors.New("too many entries in MappingTable")
 
-// SetMapping updates a MappingTable and a Location's MappingIndex to
-// add or update a mapping.
-func SetMapping(table MappingSlice, record Location, ma Mapping) error {
-	idx := int(record.MappingIndex())
-	if idx > 0 {
-		if idx >= table.Len() {
-			return fmt.Errorf("index value %d out of range for MappingIndex", idx)
-		}
-		mapAt := table.At(idx)
-		if mapAt.Equal(ma) {
-			// Mapping already exists, nothing to do.
-			return nil
-		}
-	}
-
+// SetMapping updates a MappingTable, adding or providing a value and returns
+// its index.
+func SetMapping(table MappingSlice, ma Mapping) (int32, error) {
 	for j, m := range table.All() {
 		if m.Equal(ma) {
 			if j > math.MaxInt32 {
-				return errTooManyMappingTableEntries
+				return 0, errTooManyMappingTableEntries
 			}
-			// Add the index of the existing mapping to the indices.
-			record.SetMappingIndex(int32(j)) //nolint:gosec // G115 overflow checked
-			return nil
+			return int32(j), nil //nolint:gosec // G115 overflow checked
 		}
 	}
 
 	if table.Len() >= math.MaxInt32 {
-		return errTooManyMappingTableEntries
+		return 0, errTooManyMappingTableEntries
 	}
 
 	ma.CopyTo(table.AppendEmpty())
-	record.SetMappingIndex(int32(table.Len() - 1)) //nolint:gosec // G115 overflow checked
-	return nil
+	return int32(table.Len() - 1), nil //nolint:gosec // G115 overflow checked
 }

pdata/pprofile/mappings_test.go

@@ -16,52 +16,45 @@ func TestSetMapping(t *testing.T) {
 	m.SetMemoryLimit(1)
 	m2 := NewMapping()
 	m2.SetMemoryLimit(2)
-	loc := NewLocation()
 
 	// Put a first mapping
-	require.NoError(t, SetMapping(table, loc, m))
+	idx, err := SetMapping(table, m)
+	require.NoError(t, err)
 	assert.Equal(t, 1, table.Len())
-	assert.Equal(t, int32(0), loc.MappingIndex())
+	assert.Equal(t, int32(0), idx)
 
 	// Put the same mapping
 	// This should be a no-op.
-	require.NoError(t, SetMapping(table, loc, m))
+	idx, err = SetMapping(table, m)
+	require.NoError(t, err)
 	assert.Equal(t, 1, table.Len())
-	assert.Equal(t, int32(0), loc.MappingIndex())
+	assert.Equal(t, int32(0), idx)
 
 	// Set a new mapping
 	// This sets the index and adds to the table.
-	require.NoError(t, SetMapping(table, loc, m2))
+	idx, err = SetMapping(table, m2)
+	require.NoError(t, err)
 	assert.Equal(t, 2, table.Len())
-	assert.Equal(t, int32(table.Len()-1), loc.MappingIndex()) //nolint:gosec // G115
+	assert.Equal(t, int32(table.Len()-1), idx) //nolint:gosec // G115
 
 	// Set an existing mapping
-	require.NoError(t, SetMapping(table, loc, m))
+	idx, err = SetMapping(table, m)
+	require.NoError(t, err)
 	assert.Equal(t, 2, table.Len())
-	assert.Equal(t, int32(0), loc.MappingIndex())
+	assert.Equal(t, int32(0), idx)
 	// Set another existing mapping
-	require.NoError(t, SetMapping(table, loc, m2))
+	idx, err = SetMapping(table, m2)
+	require.NoError(t, err)
 	assert.Equal(t, 2, table.Len())
-	assert.Equal(t, int32(table.Len()-1), loc.MappingIndex()) //nolint:gosec // G115
-}
-
-func TestSetMappingCurrentTooHigh(t *testing.T) {
-	table := NewMappingSlice()
-	loc := NewLocation()
-	loc.SetMappingIndex(42)
-
-	err := SetMapping(table, loc, NewMapping())
-	require.Error(t, err)
-	assert.Equal(t, 0, table.Len())
-	assert.Equal(t, int32(42), loc.MappingIndex())
+	assert.Equal(t, int32(table.Len()-1), idx) //nolint:gosec // G115
 }
 
 func BenchmarkSetMapping(b *testing.B) {
 	for _, bb := range []struct {
 		name    string
 		mapping Mapping
 
-		runBefore func(*testing.B, MappingSlice, Location)
+		runBefore func(*testing.B, MappingSlice)
 	}{
 		{
 			name:    "with a new mapping",
@@ -75,7 +68,7 @@ func BenchmarkSetMapping(b *testing.B) {
 				return m
 			}(),
 
-			runBefore: func(_ *testing.B, table MappingSlice, _ Location) {
+			runBefore: func(_ *testing.B, table MappingSlice) {
 				m := table.AppendEmpty()
 				m.SetMemoryLimit(1)
 			},
@@ -84,8 +77,9 @@ func BenchmarkSetMapping(b *testing.B) {
 			name:    "with a duplicate mapping",
 			mapping: NewMapping(),
 
-			runBefore: func(_ *testing.B, table MappingSlice, obj Location) {
-				require.NoError(b, SetMapping(table, obj, NewMapping()))
+			runBefore: func(_ *testing.B, table MappingSlice) {
+				_, err := SetMapping(table, NewMapping())
+				require.NoError(b, err)
 			},
 		},
 		{
@@ -96,7 +90,7 @@ func BenchmarkSetMapping(b *testing.B) {
 				return m
 			}(),
 
-			runBefore: func(_ *testing.B, table MappingSlice, _ Location) {
+			runBefore: func(_ *testing.B, table MappingSlice) {
 				for i := range 100 {
 					m := table.AppendEmpty()
 					m.SetMemoryLimit(uint64(i)) //nolint:gosec // overflow checked
@@ -106,17 +100,16 @@ func BenchmarkSetMapping(b *testing.B) {
 	} {
 		b.Run(bb.name, func(b *testing.B) {
 			table := NewMappingSlice()
-			obj := NewLocation()
 
 			if bb.runBefore != nil {
-				bb.runBefore(b, table, obj)
+				bb.runBefore(b, table)
 			}
 
 			b.ResetTimer()
 			b.ReportAllocs()
 
 			for b.Loop() {
-				_ = SetMapping(table, obj, bb.mapping)
+				_, _ = SetMapping(table, bb.mapping)
 			}
 		})
 	}