[Prototype] log: Events support literally following spec

log/event.go

@@ -0,0 +1,129 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log // import "go.opentelemetry.io/otel/log"
+
+import (
+	"slices"
+	"time"
+)
+
+// eventAttributesInlineCount is the number of attributes that are efficiently
+// stored in an array within an Event.
+const eventAttributesInlineCount = 5
+
+// Event represents an event record.
+type Event struct {
+	// Ensure forward compatibility by explicitly making this not comparable.
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+
+	timestamp         time.Time
+	observedTimestamp time.Time
+	severity          Severity
+	severityText      string
+	body              Value
+
+	// The fields below are for optimizing the implementation of Attributes and
+	// AddAttributes. This design is borrowed from the slog Record type:
+	// https://cs.opensource.google/go/go/+/refs/tags/go1.22.0:src/log/slog/record.go;l=20
+
+	// Allocation optimization: an inline array sized to hold
+	// the majority of event calls (based on examination of
+	// OpenTelemetry Semantic Conventions for Events).
+	// It holds the start of the list of attributes.
+	front [eventAttributesInlineCount]KeyValue
+
+	// The number of attributes in front.
+	nFront int
+
+	// The list of attributes except for those in front.
+	// Invariants:
+	//   - len(back) > 0 if nFront == len(front)
+	//   - Unused array elements are zero-ed. Used to detect mistakes.
+	back []KeyValue
+}
+
+// Timestamp returns the time when the event occurred.
+func (r *Event) Timestamp() time.Time {
+	return r.timestamp
+}
+
+// SetTimestamp sets the time when the event occurred.
+func (r *Event) SetTimestamp(t time.Time) {
+	r.timestamp = t
+}
+
+// ObservedTimestamp returns the time when the event was observed.
+func (r *Event) ObservedTimestamp() time.Time {
+	return r.observedTimestamp
+}
+
+// SetObservedTimestamp sets the time when the event was observed.
+func (r *Event) SetObservedTimestamp(t time.Time) {
+	r.observedTimestamp = t
+}
+
+// Severity returns the [Severity] of the event.
+func (r *Event) Severity() Severity {
+	return r.severity
+}
+
+// SetSeverity sets the [Severity] level of the event.
+func (r *Event) SetSeverity(level Severity) {
+	r.severity = level
+}
+
+// SeverityText returns severity (also known as log level) text. This is the
+// original string representation of the severity as it is known at the source.
+func (r *Event) SeverityText() string {
+	return r.severityText
+}
+
+// SetSeverityText sets severity (also known as log level) text. This is the
+// original string representation of the severity as it is known at the source.
+func (r *Event) SetSeverityText(text string) {
+	r.severityText = text
+}
+
+// Body returns the body of the event.
+func (r *Event) Body() Value {
+	return r.body
+}
+
+// SetBody sets the body of the event.
+func (r *Event) SetBody(v Value) {
+	r.body = v
+}
+
+// WalkAttributes walks all attributes the event holds by calling f for
+// each on each [KeyValue] in the [Record]. Iteration stops if f returns false.
+func (r *Event) WalkAttributes(f func(KeyValue) bool) {
+	for i := 0; i < r.nFront; i++ {
+		if !f(r.front[i]) {
+			return
+		}
+	}
+	for _, a := range r.back {
+		if !f(a) {
+			return
+		}
+	}
+}
+
+// AddAttributes adds attributes to the event.
+func (r *Event) AddAttributes(attrs ...KeyValue) {
+	var i int
+	for i = 0; i < len(attrs) && r.nFront < len(r.front); i++ {
+		a := attrs[i]
+		r.front[r.nFront] = a
+		r.nFront++
+	}
+
+	r.back = slices.Grow(r.back, len(attrs[i:]))
+	r.back = append(r.back, attrs[i:]...)
+}
+
+// AttributesLen returns the number of attributes in the event.
+func (r *Event) AttributesLen() int {
+	return r.nFront + len(r.back)
+}

log/event_bench_test.go

@@ -0,0 +1,109 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log_test
+
+import (
+	"testing"
+	"time"
+
+	"go.opentelemetry.io/otel/log"
+)
+
+func BenchmarkEvent(b *testing.B) {
+	var (
+		tStamp time.Time
+		sev    log.Severity
+		text   string
+		body   log.Value
+		attr   log.KeyValue
+		n      int
+	)
+
+	b.Run("Timestamp", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			var e log.Event
+			e.SetTimestamp(y2k)
+			tStamp = e.Timestamp()
+		}
+	})
+
+	b.Run("ObservedTimestamp", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			var e log.Event
+			e.SetObservedTimestamp(y2k)
+			tStamp = e.ObservedTimestamp()
+		}
+	})
+
+	b.Run("Severity", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			var e log.Event
+			e.SetSeverity(log.SeverityDebug)
+			sev = e.Severity()
+		}
+	})
+
+	b.Run("SeverityText", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			var e log.Event
+			e.SetSeverityText("text")
+			text = e.SeverityText()
+		}
+	})
+
+	bodyVal := log.BoolValue(true)
+	b.Run("Body", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			var e log.Event
+			e.SetBody(bodyVal)
+			body = e.Body()
+		}
+	})
+
+	attrs10 := []log.KeyValue{
+		log.Bool("b1", true),
+		log.Int("i1", 324),
+		log.Float64("f1", -230.213),
+		log.String("s1", "value1"),
+		log.Map("m1", log.Slice("slice1", log.BoolValue(true))),
+		log.Bool("b2", false),
+		log.Int("i2", 39847),
+		log.Float64("f2", 0.382964329),
+		log.String("s2", "value2"),
+		log.Map("m2", log.Slice("slice2", log.BoolValue(false))),
+	}
+	attrs5 := attrs10[:5]
+	walk := func(kv log.KeyValue) bool {
+		attr = kv
+		return true
+	}
+	b.Run("Attributes", func(b *testing.B) {
+		b.Run("5", func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				var e log.Event
+				e.AddAttributes(attrs5...)
+				n = e.AttributesLen()
+				e.WalkAttributes(walk)
+			}
+		})
+		b.Run("10", func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				var e log.Event
+				e.AddAttributes(attrs10...)
+				n = e.AttributesLen()
+				e.WalkAttributes(walk)
+			}
+		})
+	})
+
+	// Convince the linter these values are used.
+	_, _, _, _, _, _ = tStamp, sev, text, body, attr, n
+}

log/event_test.go

@@ -0,0 +1,152 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"go.opentelemetry.io/otel/log"
+)
+
+func TestEventTimestamp(t *testing.T) {
+	var e log.Event
+	e.SetTimestamp(y2k)
+	assert.Equal(t, y2k, e.Timestamp())
+}
+
+func TestEventObservedTimestamp(t *testing.T) {
+	var e log.Event
+	e.SetObservedTimestamp(y2k)
+	assert.Equal(t, y2k, e.ObservedTimestamp())
+}
+
+func TestEventSeverity(t *testing.T) {
+	var e log.Event
+	e.SetSeverity(log.SeverityInfo)
+	assert.Equal(t, log.SeverityInfo, e.Severity())
+}
+
+func TestEventSeverityText(t *testing.T) {
+	const text = "testing text"
+
+	var e log.Event
+	e.SetSeverityText(text)
+	assert.Equal(t, text, e.SeverityText())
+}
+
+func TestEventBody(t *testing.T) {
+	body := log.StringValue("testing body value")
+
+	var e log.Event
+	e.SetBody(body)
+	assert.Equal(t, body, e.Body())
+}
+
+func TestEventAttributes(t *testing.T) {
+	attrs := []log.KeyValue{
+		log.String("k1", "str"),
+		log.Float64("k2", 1.0),
+		log.Int("k3", 2),
+		log.Bool("k4", true),
+		log.Bytes("k5", []byte{1}),
+		log.Slice("k6", log.IntValue(3)),
+		log.Map("k7", log.Bool("sub1", true)),
+		log.String("k8", "str"),
+		log.Float64("k9", 1.0),
+		log.Int("k10", 2),
+		log.Bool("k11", true),
+		log.Bytes("k12", []byte{1}),
+		log.Slice("k13", log.IntValue(3)),
+		log.Map("k14", log.Bool("sub1", true)),
+		{}, // Empty.
+	}
+
+	var e log.Event
+	e.AddAttributes(attrs...)
+	require.Equal(t, len(attrs), e.AttributesLen())
+
+	t.Run("Correctness", func(t *testing.T) {
+		var i int
+		e.WalkAttributes(func(kv log.KeyValue) bool {
+			assert.Equal(t, attrs[i], kv)
+			i++
+			return true
+		})
+	})
+
+	t.Run("WalkAttributes/Filtering", func(t *testing.T) {
+		for i := 1; i <= len(attrs); i++ {
+			var j int
+			e.WalkAttributes(func(log.KeyValue) bool {
+				j++
+				return j < i
+			})
+			assert.Equal(t, i, j, "number of attributes walked incorrect")
+		}
+	})
+}
+
+func TestEventAllocationLimits(t *testing.T) {
+	const runs = 5
+
+	// Assign testing results to external scope so the compiler doesn't
+	// optimize away the testing statements.
+	var (
+		tStamp time.Time
+		sev    log.Severity
+		text   string
+		body   log.Value
+		n      int
+		attr   log.KeyValue
+	)
+
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.SetTimestamp(y2k)
+		tStamp = e.Timestamp()
+	}), "Timestamp")
+
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.SetObservedTimestamp(y2k)
+		tStamp = e.ObservedTimestamp()
+	}), "ObservedTimestamp")
+
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.SetSeverity(log.SeverityDebug)
+		sev = e.Severity()
+	}), "Severity")
+
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.SetSeverityText("severity text")
+		text = e.SeverityText()
+	}), "SeverityText")
+
+	bodyVal := log.BoolValue(true)
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.SetBody(bodyVal)
+		body = e.Body()
+	}), "Body")
+
+	attrVal := []log.KeyValue{log.Bool("k", true), log.Int("i", 1)}
+	assert.Equal(t, 0.0, testing.AllocsPerRun(runs, func() {
+		var e log.Event
+		e.AddAttributes(attrVal...)
+		n = e.AttributesLen()
+		e.WalkAttributes(func(kv log.KeyValue) bool {
+			attr = kv
+			return true
+		})
+	}), "Attributes")
+
+	// Convince the linter these values are used.
+	_, _, _, _, _, _ = tStamp, sev, text, body, n, attr
+}