Add an auto-instrumentable no-op implementation to the trace package (

#6203)

This copes the `go.opentelemetry.io/auto/sdk` package into the
`go.opentelemetry.io/otel/trace` package. This is done to avoid package
import cycles and still provide an auto-instrumentable SDK (see
open-telemetry/opentelemetry-go-instrumentation#974).

## Overview of changes

The code copied is updated with the following changes. The over-all goal
is to ensure none of this is exported and follows the `auto/sdk` as
close as possible to help maintenance.

### `trace/auto.go`

Consolidation of the following into a single file:

-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/tracer_provider.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/tracer.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/span.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/limit.go

Has the following changes:

- `func TracerProvider()` renamed to `newAutoTracerProvider`
- `type tracerProvider struct` renamed to `autoTracerProvider`
- `type tracer struct` renamed to `autoTracer`
- `type span struct` renamed to `autoSpan`
- Lint issues addressed based on this repositories configuration (these
changes are being back-ported upstream)

### `trace/auto_test.go`

Consolidation of the following into a single file:

-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/tracer_provider_test.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/tracer_test.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/span_test.go
-
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/limit_test.go

Has the following changes:

- Renames in `trace/auto.go` are applied here
- Lint issues addressed based on this repositories configuration (these
changes are being back-ported upstream)

### `trace/internal/telemetry`

Copied from
https://github.com/open-telemetry/opentelemetry-go-instrumentation/tree/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/internal/telemetry

- Pacakge vanity URLs added
- Lint issues addressed based on this repositories configuration (these
changes are being back-ported upstream)
- Use of the package name has been updated

#### `trace/internal/telemetry/test`

Copied from
https://github.com/open-telemetry/opentelemetry-go-instrumentation/tree/aea085dd2a3640630ac07a2187cbda9d15d2dd00/sdk/internal/telemetry/test

- Module name updated
- Documentation updated with new package name
- Testing values updated with new package name

---------

Co-authored-by: Ron Federman <[email protected]>

trace/internal/telemetry/attr.go

@@ -0,0 +1,58 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package telemetry // import "go.opentelemetry.io/otel/trace/internal/telemetry"
+
+// Attr is a key-value pair.
+type Attr struct {
+	Key   string `json:"key,omitempty"`
+	Value Value  `json:"value,omitempty"`
+}
+
+// String returns an Attr for a string value.
+func String(key, value string) Attr {
+	return Attr{key, StringValue(value)}
+}
+
+// Int64 returns an Attr for an int64 value.
+func Int64(key string, value int64) Attr {
+	return Attr{key, Int64Value(value)}
+}
+
+// Int returns an Attr for an int value.
+func Int(key string, value int) Attr {
+	return Int64(key, int64(value))
+}
+
+// Float64 returns an Attr for a float64 value.
+func Float64(key string, value float64) Attr {
+	return Attr{key, Float64Value(value)}
+}
+
+// Bool returns an Attr for a bool value.
+func Bool(key string, value bool) Attr {
+	return Attr{key, BoolValue(value)}
+}
+
+// Bytes returns an Attr for a []byte value.
+// The passed slice must not be changed after it is passed.
+func Bytes(key string, value []byte) Attr {
+	return Attr{key, BytesValue(value)}
+}
+
+// Slice returns an Attr for a []Value value.
+// The passed slice must not be changed after it is passed.
+func Slice(key string, value ...Value) Attr {
+	return Attr{key, SliceValue(value...)}
+}
+
+// Map returns an Attr for a map value.
+// The passed slice must not be changed after it is passed.
+func Map(key string, value ...Attr) Attr {
+	return Attr{key, MapValue(value...)}
+}
+
+// Equal returns if a is equal to b.
+func (a Attr) Equal(b Attr) bool {
+	return a.Key == b.Key && a.Value.Equal(b.Value)
+}

trace/internal/telemetry/attr_test.go

@@ -0,0 +1,156 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package telemetry
+
+import "testing"
+
+func TestAttrEncoding(t *testing.T) {
+	attrs := []Attr{
+		String("user", "Alice"),
+		Bool("admin", true),
+		Int64("floor", -2),
+		Float64("impact", 0.21362),
+		Slice("reports", StringValue("Bob"), StringValue("Dave")),
+		Map("favorites", String("food", "hot dog"), Int("number", 13)),
+		Bytes("secret", []byte("NUI4RUZGRjc5ODAzODEwM0QyNjlCNjMzODEzRkM2MEM=")),
+	}
+
+	t.Run("CamelCase", runJSONEncodingTests(attrs, []byte(`[
+		{
+			"key": "user",
+			"value": {
+				"stringValue": "Alice"
+			}
+		},
+		{
+			"key": "admin",
+			"value": {
+				"boolValue": true
+			}
+		},
+		{
+			"key": "floor",
+			"value": {
+				"intValue": "-2"
+			}
+		},
+		{
+			"key": "impact",
+			"value": {
+				"doubleValue": 0.21362
+			}
+		},
+		{
+			"key": "reports",
+			"value": {
+				"arrayValue": {
+					"values": [
+						{
+							"stringValue": "Bob"
+						},
+						{
+							"stringValue": "Dave"
+						}
+					]
+				}
+			}
+		},
+		{
+			"key": "favorites",
+			"value": {
+				"kvlistValue": {
+					"values": [
+						{
+							"key": "food",
+							"value": {
+								"stringValue": "hot dog"
+							}
+						},
+						{
+							"key": "number",
+							"value": {
+								"intValue": "13"
+							}
+						}
+					]
+				}
+			}
+		},
+		{
+			"key": "secret",
+			"value": {
+				"bytesValue": "TlVJNFJVWkdSamM1T0RBek9ERXdNMFF5TmpsQ05qTXpPREV6UmtNMk1FTT0="
+			}
+		}
+	]`)))
+
+	t.Run("SnakeCase/Unmarshal", runJSONUnmarshalTest(attrs, []byte(`[
+		{
+			"key": "user",
+			"value": {
+				"string_value": "Alice"
+			}
+		},
+		{
+			"key": "admin",
+			"value": {
+				"bool_value": true
+			}
+		},
+		{
+			"key": "floor",
+			"value": {
+				"int_value": "-2"
+			}
+		},
+		{
+			"key": "impact",
+			"value": {
+				"double_value": 0.21362
+			}
+		},
+		{
+			"key": "reports",
+			"value": {
+				"array_value": {
+					"values": [
+						{
+							"string_value": "Bob"
+						},
+						{
+							"string_value": "Dave"
+						}
+					]
+				}
+			}
+		},
+		{
+			"key": "favorites",
+			"value": {
+				"kvlist_value": {
+					"values": [
+						{
+							"key": "food",
+							"value": {
+								"string_value": "hot dog"
+							}
+						},
+						{
+							"key": "number",
+							"value": {
+								"int_value": "13"
+							}
+						}
+					]
+				}
+			}
+		},
+		{
+			"key": "secret",
+			"value": {
+				"bytes_value": "TlVJNFJVWkdSamM1T0RBek9ERXdNMFF5TmpsQ05qTXpPREV6UmtNMk1FTT0="
+			}
+		}
+	]`)))
+}

trace/internal/telemetry/bench_test.go

@@ -0,0 +1,70 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package telemetry
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+	"time"
+)
+
+var (
+	traceID = [16]byte{0x1}
+
+	spanID1 = [8]byte{0x1}
+	spanID2 = [8]byte{0x2}
+
+	now      = time.Now()
+	nowPlus1 = now.Add(1 * time.Second)
+
+	spanA = &Span{
+		TraceID:      traceID,
+		SpanID:       spanID2,
+		ParentSpanID: spanID1,
+		Flags:        1,
+		Name:         "span-a",
+		StartTime:    now,
+		EndTime:      nowPlus1,
+		Status: &Status{
+			Message: "test status",
+			Code:    StatusCodeOK,
+		},
+	}
+
+	spanB = &Span{}
+
+	scopeSpans = &ScopeSpans{
+		Scope: &Scope{
+			Name:    "TestTracer",
+			Version: "v0.1.0",
+		},
+		SchemaURL: "http://go.opentelemetry.io/test",
+		Spans:     []*Span{spanA, spanB},
+	}
+)
+
+func BenchmarkJSONMarshalUnmarshal(b *testing.B) {
+	var out ScopeSpans
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		var inBuf bytes.Buffer
+		enc := json.NewEncoder(&inBuf)
+		err := enc.Encode(scopeSpans)
+		if err != nil {
+			b.Fatal(err)
+		}
+
+		payload := inBuf.Bytes()
+
+		dec := json.NewDecoder(bytes.NewReader(payload))
+		err = dec.Decode(&out)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+	_ = out
+}

trace/internal/telemetry/conv_test.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package telemetry
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const schema100 = "http://go.opentelemetry.io/schema/v1.0.0"
+
+var y2k = time.Unix(0, time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC).UnixNano()) // No location.
+
+func runJSONEncodingTests[T any](decoded T, encoded []byte) func(*testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+
+		t.Run("Unmarshal", runJSONUnmarshalTest(decoded, encoded))
+		t.Run("Marshal", runJSONMarshalTest(decoded, encoded))
+	}
+}
+
+func runJSONMarshalTest[T any](decoded T, encoded []byte) func(*testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+
+		got, err := json.Marshal(decoded)
+		require.NoError(t, err)
+
+		var want bytes.Buffer
+		require.NoError(t, json.Compact(&want, encoded))
+		assert.Equal(t, want.String(), string(got))
+	}
+}
+
+func runJSONUnmarshalTest[T any](decoded T, encoded []byte) func(*testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+
+		var got T
+		require.NoError(t, json.Unmarshal(encoded, &got))
+		assert.Equal(t, decoded, got)
+	}
+}

trace/internal/telemetry/doc.go

@@ -0,0 +1,8 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+/*
+Package telemetry provides a lightweight representations of OpenTelemetry
+telemetry that is compatible with the OTLP JSON protobuf encoding.
+*/
+package telemetry // import "go.opentelemetry.io/otel/trace/internal/telemetry"