Introduce FromLocationIndices and PutLocation (#13150)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This introduces the `FromLocationIndices` and `PutLocation` methods, as
we have for attributes.

https://github.com/open-telemetry/opentelemetry-collector/blob/main/pdata/pprofile/attributes.go

The intent is to be able to use this to perform merging/batching of
profiles.
I will be adding similar methods for the other tables once the concept
of this first PR is validated.

## Benchmark Results

```
goos: darwin
goarch: arm64
pkg: go.opentelemetry.io/collector/pdata/pprofile
cpu: Apple M1 Max
BenchmarkFromLocationIndices-10                                                  7058838               171.7 ns/op           308 B/op          7 allocs/op
BenchmarkPutLocation/with_a_new_location-10                                     47819084                24.13 ns/op           16 B/op          1 allocs/op
BenchmarkPutLocation/with_an_existing_location-10                               47871942                23.71 ns/op           16 B/op          1 allocs/op
BenchmarkPutLocation/with_a_duplicate_location-10                               49755453                23.80 ns/op           16 B/op          1 allocs/op
BenchmarkPutLocation/with_a_hundred_locations_to_loop_through-10                47431298                24.13 ns/op           16 B/op          1 allocs/op
```

---------

Co-authored-by: Tim Rühsen <tim.ruehsen@gmx.de>

Author: dmathieu

.chloggen/locations-read-write-table.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: enhancement
+
+# 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: Add new helper methods `FromLocationIndices` and `PutLocation` to read and modify the content of locations.
+
+# One or more tracking issues or pull requests related to the change
+issues: [13150]
+
+# (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: []

.chloggen/pprofile-equal.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: enhancement
+
+# 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: Introduce `Equal` methods on the `Line` and `Location` types
+
+# One or more tracking issues or pull requests related to the change
+issues: [13150]
+
+# (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/json_test.go

@@ -4,8 +4,6 @@
 package pprofile
 
 import (
-	"fmt"
-	"os"
 	"testing"
 
 	jsoniter "github.com/json-iterator/go"
@@ -133,7 +131,6 @@ func TestJSONUnmarshal(t *testing.T) {
 func TestJSONMarshal(t *testing.T) {
 	encoder := &JSONMarshaler{}
 	jsonBuf, err := encoder.MarshalProfiles(profilesOTLP)
-	fmt.Fprintf(os.Stdout, "=================\n%#v\n----------------", string(jsonBuf))
 	require.NoError(t, err)
 	assert.JSONEq(t, profilesJSON, string(jsonBuf))
 }

pdata/pprofile/line.go

@@ -0,0 +1,26 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package pprofile // import "go.opentelemetry.io/collector/pdata/pprofile"
+
+// Equal checks equality with another LineSlice
+func (l LineSlice) Equal(val LineSlice) bool {
+	if l.Len() != val.Len() {
+		return false
+	}
+
+	for i := range l.Len() {
+		if !l.At(i).Equal(val.At(i)) {
+			return false
+		}
+	}
+
+	return true
+}
+
+// Equal checks equality with another Line
+func (l Line) Equal(val Line) bool {
+	return l.Column() == val.Column() &&
+		l.FunctionIndex() == val.FunctionIndex() &&
+		l.Line() == val.Line()
+}

pdata/pprofile/line_test.go

@@ -0,0 +1,129 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package pprofile
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLineSliceEqual(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		orig LineSlice
+		dest LineSlice
+		want bool
+	}{
+		{
+			name: "with empty slices",
+			orig: NewLineSlice(),
+			dest: NewLineSlice(),
+			want: true,
+		},
+		{
+			name: "with non-empty equal slices",
+			orig: func() LineSlice {
+				ls := NewLineSlice()
+				ls.AppendEmpty().SetLine(1)
+				return ls
+			}(),
+			dest: func() LineSlice {
+				ls := NewLineSlice()
+				ls.AppendEmpty().SetLine(1)
+				return ls
+			}(),
+			want: true,
+		},
+		{
+			name: "with different lengths",
+			orig: func() LineSlice {
+				ls := NewLineSlice()
+				ls.AppendEmpty()
+				return ls
+			}(),
+			dest: NewLineSlice(),
+			want: false,
+		},
+		{
+			name: "with non-equal slices",
+			orig: func() LineSlice {
+				ls := NewLineSlice()
+				ls.AppendEmpty().SetLine(2)
+				return ls
+			}(),
+			dest: func() LineSlice {
+				ls := NewLineSlice()
+				ls.AppendEmpty().SetLine(1)
+				return ls
+			}(),
+			want: false,
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.want {
+				assert.True(t, tt.orig.Equal(tt.dest))
+			} else {
+				assert.False(t, tt.orig.Equal(tt.dest))
+			}
+		})
+	}
+}
+
+func TestLineEqual(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		orig Line
+		dest Line
+		want bool
+	}{
+		{
+			name: "with empty lines",
+			orig: NewLine(),
+			dest: NewLine(),
+			want: true,
+		},
+		{
+			name: "with non-empty lines",
+			orig: buildLine(1, 2, 3),
+			dest: buildLine(1, 2, 3),
+			want: true,
+		},
+		{
+			name: "with non-equal column",
+			orig: buildLine(1, 2, 3),
+			dest: buildLine(2, 2, 3),
+			want: false,
+		},
+		{
+			name: "with non-equal function index",
+			orig: buildLine(1, 2, 3),
+			dest: buildLine(1, 3, 3),
+			want: false,
+		},
+		{
+			name: "with non-equal line",
+			orig: buildLine(1, 2, 3),
+			dest: buildLine(1, 2, 4),
+			want: false,
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.want {
+				assert.True(t, tt.orig.Equal(tt.dest))
+			} else {
+				assert.False(t, tt.orig.Equal(tt.dest))
+			}
+		})
+	}
+}
+
+func buildLine(col int64, funcIdx int32, line int64) Line {
+	l := NewLine()
+	l.SetColumn(col)
+	l.SetFunctionIndex(funcIdx)
+	l.SetLine(line)
+
+	return l
+}

pdata/pprofile/location.go

@@ -0,0 +1,13 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package pprofile // import "go.opentelemetry.io/collector/pdata/pprofile"
+
+// Equal checks equality with another Location
+func (l Location) Equal(val Location) bool {
+	return l.MappingIndex() == val.MappingIndex() &&
+		l.Address() == val.Address() &&
+		l.AttributeIndices().Equal(val.AttributeIndices()) &&
+		l.IsFolded() == val.IsFolded() &&
+		l.Line().Equal(val.Line())
+}

pdata/pprofile/location_test.go

@@ -0,0 +1,80 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package pprofile
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLocationEqual(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		orig Location
+		dest Location
+		want bool
+	}{
+		{
+			name: "empty locations",
+			orig: NewLocation(),
+			dest: NewLocation(),
+			want: true,
+		},
+		{
+			name: "non-empty locations",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			dest: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			want: true,
+		},
+		{
+			name: "with non-equal mapping index",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			dest: buildLocation(2, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			want: false,
+		},
+		{
+			name: "with non-equal address",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			dest: buildLocation(1, 3, []int32{3}, true, buildLine(1, 2, 3)),
+			want: false,
+		},
+		{
+			name: "with non-equal attribute indices",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			dest: buildLocation(1, 2, []int32{5}, true, buildLine(1, 2, 3)),
+			want: false,
+		},
+		{
+			name: "with non-equal is folded",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			dest: buildLocation(1, 2, []int32{3}, false, buildLine(1, 2, 3)),
+			want: false,
+		},
+		{
+			name: "with non-equal lines",
+			orig: buildLocation(1, 2, []int32{3}, true, buildLine(4, 5, 6)),
+			dest: buildLocation(1, 2, []int32{3}, true, buildLine(1, 2, 3)),
+			want: false,
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.want {
+				assert.True(t, tt.orig.Equal(tt.dest))
+			} else {
+				assert.False(t, tt.orig.Equal(tt.dest))
+			}
+		})
+	}
+}
+
+func buildLocation(mapIdx int32, addr uint64, attrIdxs []int32, isFolded bool, line Line) Location {
+	l := NewLocation()
+	l.SetMappingIndex(mapIdx)
+	l.SetAddress(addr)
+	l.AttributeIndices().FromRaw(attrIdxs)
+	l.SetIsFolded(isFolded)
+	line.MoveTo(l.Line().AppendEmpty())
+	return l
+}

pdata/pprofile/locations.go

@@ -0,0 +1,68 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package pprofile // import "go.opentelemetry.io/collector/pdata/pprofile"
+
+import (
+	"errors"
+	"fmt"
+	"math"
+)
+
+// FromLocationIndices builds a slice containing all the locations of a Profile.
+// Updates made to the returned map will not be applied back to the Profile.
+func FromLocationIndices(table LocationSlice, record Profile) LocationSlice {
+	m := NewLocationSlice()
+	m.EnsureCapacity(record.LocationIndices().Len())
+
+	for _, idx := range record.LocationIndices().All() {
+		l := table.At(int(idx))
+		l.CopyTo(m.AppendEmpty())
+	}
+
+	return m
+}
+
+var (
+	errTooManyLocationTableEntries   = errors.New("too many entries in LocationTable")
+	errTooManyLocationIndicesEntries = errors.New("too many entries in LocationIndices")
+)
+
+// PutLocation updates a LocationTable and a Profile's LocationIndices to
+// add or update a location.
+func PutLocation(table LocationSlice, record Profile, loc Location) error {
+	for i, locIdx := range record.LocationIndices().All() {
+		idx := int(locIdx)
+		if idx < 0 || idx >= table.Len() {
+			return fmt.Errorf("index value %d out of range in LocationIndices[%d]", idx, i)
+		}
+		locAt := table.At(idx)
+		if locAt.Equal(loc) {
+			// Location already exists, nothing to do.
+			return nil
+		}
+	}
+
+	if record.LocationIndices().Len() >= math.MaxInt32 {
+		return errTooManyLocationIndicesEntries
+	}
+
+	for j, a := range table.All() {
+		if a.Equal(loc) {
+			if j > math.MaxInt32 {
+				return errTooManyLocationTableEntries
+			}
+			// Add the index of the existing location to the indices.
+			record.LocationIndices().Append(int32(j)) //nolint:gosec // G115 overflow checked
+			return nil
+		}
+	}
+
+	if table.Len() >= math.MaxInt32 {
+		return errTooManyLocationTableEntries
+	}
+
+	loc.CopyTo(table.AppendEmpty())
+	record.LocationIndices().Append(int32(table.Len() - 1)) //nolint:gosec // G115 overflow checked
+	return nil
+}