Update span limits to comply with specification (open-telemetry#2637)

* PoC for span limit refactor

* Rename config.go to span_limits.go

* Add unit tests for truncateAttr

* Add unit tests for non-string attrs

* Add span limit benchmark tests

* Fix lint

* Isolate span limit tests

* Clean span limits test

* Test limits on exported spans

* Remove duplicate test code

* Fix lint

* Add WithRawSpanLimits option

* Add test for raw and orig span limits opts

* Add changes to changelog

* Add tests for span resource disabled

* Test unlimited instead of default limit

* Update docs

* Add fix to changelog

* Fix option docs

* Do no mutate attribute

* Fix truncateAttr comment

* Remake NewSpanLimits to be newEnvSpanLimits

Update and unify documentation accordingly.

* Update truncateAttr string slice update comment

* Update CHANGELOG.md

Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

CHANGELOG.md

@@ -14,15 +14,26 @@ This update is a breaking change of the unstable Metrics API. Code instrumented
 
 ### Added
 
+- Log the Exporters configuration in the TracerProviders message. (#2578)
 - Added support to configure the span limits with environment variables.
-  The following environment variables are used. (#2606)
+  The following environment variables are used. (#2606, #2637)
+  - `OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT`
   - `OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT`
   - `OTEL_SPAN_EVENT_COUNT_LIMIT`
+  - `OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT`
   - `OTEL_SPAN_LINK_COUNT_LIMIT`
+  - `OTEL_LINK_ATTRIBUTE_COUNT_LIMIT`
 
   If the provided environment variables are invalid (negative), the default values would be used.
 - Rename the `gc` runtime name to `go` (#2560)
-- Log the Exporters configuration in the TracerProviders message. (#2578)
+- Add span attribute value length limit.
+  The new `AttributeValueLengthLimit` field is added to the `"go.opentelemetry.io/otel/sdk/trace".SpanLimits` type to configure this limit for a `TracerProvider`.
+  The default limit for this resource is "unlimited". (#2637)
+- Add the `WithRawSpanLimits` option to `go.opentelemetry.io/otel/sdk/trace`.
+  This option replaces the `WithSpanLimits` option.
+  Zero or negative values will not be changed to the default value like `WithSpanLimits` does.
+  Setting a limit to zero will effectively disable the related resource it limits and setting to a negative value will mean that resource is unlimited.
+  Consequentially, limits should be constructed using `NewSpanLimits` and updated accordingly. (#2637)
 
 ### Changed
 
@@ -37,6 +48,14 @@ This update is a breaking change of the unstable Metrics API. Code instrumented
 
 - Remove the OTLP trace exporter limit of SpanEvents when exporting. (#2616)
 - Use port `4318` instead of `4317` for default for the `otlpmetrichttp` and `otlptracehttp` client. (#2614, #2625)
+- Unlimited span limits are now supported (negative values). (#2636, #2637)
+
+### Deprecated
+
+- Deprecated `"go.opentelemetry.io/otel/sdk/trace".WithSpanLimits`.
+  Use `WithRawSpanLimits` instead.
+  That option allows setting unlimited and zero limits, this option does not.
+  This option will be kept until the next major version incremented release. (#2637)
 
 ## [1.4.1] - 2022-02-16
 

sdk/internal/env/env.go

@@ -41,20 +41,29 @@ const (
 	// i.e. 512
 	BatchSpanProcessorMaxExportBatchSizeKey = "OTEL_BSP_MAX_EXPORT_BATCH_SIZE"
 
-	// SpanAttributesCountKey
+	// SpanAttributeValueLengthKey
+	// Maximum allowed attribute value size.
+	SpanAttributeValueLengthKey = "OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT"
+
+	// SpanAttributeCountKey
 	// Maximum allowed span attribute count
-	// Default: 128
-	SpanAttributesCountKey = "OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT"
+	SpanAttributeCountKey = "OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT"
 
 	// SpanEventCountKey
 	// Maximum allowed span event count
-	// Default: 128
 	SpanEventCountKey = "OTEL_SPAN_EVENT_COUNT_LIMIT"
 
+	// SpanEventAttributeCountKey
+	// Maximum allowed attribute per span event count.
+	SpanEventAttributeCountKey = "OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT"
+
 	// SpanLinkCountKey
 	// Maximum allowed span link count
-	// Default: 128
 	SpanLinkCountKey = "OTEL_SPAN_LINK_COUNT_LIMIT"
+
+	// SpanLinkAttributeCountKey
+	// Maximum allowed attribute per span link count
+	SpanLinkAttributeCountKey = "OTEL_LINK_ATTRIBUTE_COUNT_LIMIT"
 )
 
 // IntEnvOr returns the int value of the environment variable with name key if
@@ -101,3 +110,45 @@ func BatchSpanProcessorMaxQueueSize(defaultValue int) int {
 func BatchSpanProcessorMaxExportBatchSize(defaultValue int) int {
 	return IntEnvOr(BatchSpanProcessorMaxExportBatchSizeKey, defaultValue)
 }
+
+// SpanAttributeValueLength returns the environment variable value for the
+// OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT key if it exists, otherwise
+// defaultValue is returned.
+func SpanAttributeValueLength(defaultValue int) int {
+	return IntEnvOr(SpanAttributeValueLengthKey, defaultValue)
+}
+
+// SpanAttributeCount returns the environment variable value for the
+// OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT key if it exists, otherwise defaultValue is
+// returned.
+func SpanAttributeCount(defaultValue int) int {
+	return IntEnvOr(SpanAttributeCountKey, defaultValue)
+}
+
+// SpanEventCount returns the environment variable value for the
+// OTEL_SPAN_EVENT_COUNT_LIMIT key if it exists, otherwise defaultValue is
+// returned.
+func SpanEventCount(defaultValue int) int {
+	return IntEnvOr(SpanEventCountKey, defaultValue)
+}
+
+// SpanEventAttributeCount returns the environment variable value for the
+// OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT key if it exists, otherwise defaultValue
+// is returned.
+func SpanEventAttributeCount(defaultValue int) int {
+	return IntEnvOr(SpanEventAttributeCountKey, defaultValue)
+}
+
+// SpanLinkCount returns the environment variable value for the
+// OTEL_SPAN_LINK_COUNT_LIMIT key if it exists, otherwise defaultValue is
+// returned.
+func SpanLinkCount(defaultValue int) int {
+	return IntEnvOr(SpanLinkCountKey, defaultValue)
+}
+
+// SpanLinkAttributeCount returns the environment variable value for the
+// OTEL_LINK_ATTRIBUTE_COUNT_LIMIT key if it exists, otherwise defaultValue is
+// returned.
+func SpanLinkAttributeCount(defaultValue int) int {
+	return IntEnvOr(SpanLinkAttributeCountKey, defaultValue)
+}

sdk/trace/benchmark_test.go

@@ -25,10 +25,106 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
+func benchmarkSpanLimits(b *testing.B, limits sdktrace.SpanLimits) {
+	tp := sdktrace.NewTracerProvider(sdktrace.WithSpanLimits(limits))
+	tracer := tp.Tracer(b.Name())
+	ctx := context.Background()
+
+	const count = 8
+
+	attrs := []attribute.KeyValue{
+		attribute.Bool("bool", true),
+		attribute.BoolSlice("boolSlice", []bool{true, false}),
+		attribute.Int("int", 42),
+		attribute.IntSlice("intSlice", []int{42, -1}),
+		attribute.Int64("int64", 42),
+		attribute.Int64Slice("int64Slice", []int64{42, -1}),
+		attribute.Float64("float64", 42),
+		attribute.Float64Slice("float64Slice", []float64{42, -1}),
+		attribute.String("string", "value"),
+		attribute.StringSlice("stringSlice", []string{"value", "value-1"}),
+	}
+
+	links := make([]trace.Link, count)
+	for i := range links {
+		links[i] = trace.Link{
+			SpanContext: trace.NewSpanContext(trace.SpanContextConfig{
+				TraceID: [16]byte{0x01},
+				SpanID:  [8]byte{0x01},
+			}),
+			Attributes: attrs,
+		}
+	}
+
+	events := make([]struct {
+		name string
+		attr []attribute.KeyValue
+	}, count)
+	for i := range events {
+		events[i] = struct {
+			name string
+			attr []attribute.KeyValue
+		}{
+			name: fmt.Sprintf("event-%d", i),
+			attr: attrs,
+		}
+	}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_, span := tracer.Start(ctx, "span-name", trace.WithLinks(links...))
+		span.SetAttributes(attrs...)
+		for _, e := range events {
+			span.AddEvent(e.name, trace.WithAttributes(e.attr...))
+		}
+		span.End()
+	}
+}
+
+func BenchmarkSpanLimits(b *testing.B) {
+	b.Run("AttributeValueLengthLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.AttributeValueLengthLimit = 2
+		benchmarkSpanLimits(b, limits)
+	})
+
+	b.Run("AttributeCountLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.AttributeCountLimit = 1
+		benchmarkSpanLimits(b, limits)
+	})
+
+	b.Run("EventCountLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.EventCountLimit = 1
+		benchmarkSpanLimits(b, limits)
+	})
+
+	b.Run("LinkCountLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.LinkCountLimit = 1
+		benchmarkSpanLimits(b, limits)
+	})
+
+	b.Run("AttributePerEventCountLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.AttributePerEventCountLimit = 1
+		benchmarkSpanLimits(b, limits)
+	})
+
+	b.Run("AttributePerLinkCountLimit", func(b *testing.B) {
+		limits := sdktrace.NewSpanLimits()
+		limits.AttributePerLinkCountLimit = 1
+		benchmarkSpanLimits(b, limits)
+	})
+}
+
 func BenchmarkSpanSetAttributesOverCapacity(b *testing.B) {
-	tp := sdktrace.NewTracerProvider(
-		sdktrace.WithSpanLimits(sdktrace.SpanLimits{AttributeCountLimit: 1}),
-	)
+	limits := sdktrace.NewSpanLimits()
+	limits.AttributeCountLimit = 1
+	tp := sdktrace.NewTracerProvider(sdktrace.WithSpanLimits(limits))
 	tracer := tp.Tracer("BenchmarkSpanSetAttributesOverCapacity")
 	ctx := context.Background()
 	attrs := make([]attribute.KeyValue, 128)

sdk/trace/evictedqueue.go

@@ -29,7 +29,12 @@ func newEvictedQueue(capacity int) evictedQueue {
 // add adds value to the evictedQueue eq. If eq is at capacity, the oldest
 // queued value will be discarded and the drop count incremented.
 func (eq *evictedQueue) add(value interface{}) {
-	if len(eq.queue) == eq.capacity {
+	if eq.capacity == 0 {
+		eq.droppedCount++
+		return
+	}
+
+	if eq.capacity > 0 && len(eq.queue) == eq.capacity {
 		// Drop first-in while avoiding allocating more capacity to eq.queue.
 		copy(eq.queue[:eq.capacity-1], eq.queue[1:])
 		eq.queue = eq.queue[:eq.capacity-1]