[Spike] sdk/log: Change FilterProcessor to Filterer

CHANGELOG.md

@@ -8,6 +8,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Added
+
+- Add `WithFilterer` provider option and `Filterer` interface in `go.opentelemetry.io/otel/sdk/log` that accepts a newly introduced `FilterParameters` type. (#5825)
+
 ### Changed
 
 - Enable exemplars by default in `go.opentelemetry.io/otel/sdk/metric`. Exemplars can be disabled by setting `OTEL_METRICS_EXEMPLAR_FILTER=always_off` (#5778)
@@ -19,6 +23,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - The race condition for multiple `FixedSize` exemplar reservoirs identified in #5814 is resolved. (#5819)
 - Fix log records duplication in case of heterogeneous resource attributes by correctly mapping each log record to it's resource and scope. (#5803)
 
+### Removed
+
+- Remove `go.opentelemetry.io/otel/sdk/log/internal/x` package. Filtering is now done via `Filterer` interface in `go.opentelemetry.io/otel/sdk/log`. (#5825)
+
 <!-- Released section -->
 <!-- Don't change this section unless doing release -->
 

sdk/log/example_test.go

@@ -7,7 +7,6 @@ import (
 	"context"
 	"fmt"
 	"strings"
-	"sync"
 
 	logapi "go.opentelemetry.io/otel/log"
 	"go.opentelemetry.io/otel/log/global"
@@ -51,19 +50,20 @@ func Example() {
 	// slog.SetDefault(otelslog.NewLogger("my/pkg/name", otelslog.WithLoggerProvider(provider)))
 }
 
-// Use a processor that filters out records based on the provided context.
-func ExampleProcessor_filtering() {
+// Use a filterer that filters out records based on the provided context.
+func ExampleFilterer() {
 	// Existing processor that emits telemetry.
-	var processor log.Processor = log.NewBatchProcessor(nil)
+	processor := log.NewBatchProcessor(nil)
 
-	// Wrap the processor so that it ignores processing log records
+	// Add a filterer so that the SDK ignores processing of log records
 	// when a context deriving from WithIgnoreLogs is passed
 	// to the logging methods.
-	processor = &ContextFilterProcessor{Processor: processor}
+	filterer := &ContextFilterer{}
 
 	// The created processor can then be registered with
 	// the OpenTelemetry Logs SDK using the WithProcessor option.
 	_ = log.NewLoggerProvider(
+		log.WithFilterer(filterer),
 		log.WithProcessor(processor),
 	)
 }
@@ -72,54 +72,27 @@ type key struct{}
 
 var ignoreLogsKey key
 
-// WithIgnoreLogs returns a context which is used by [ContextFilterProcessor]
+// WithIgnoreLogs returns a context which is used by [ContextFilterer]
 // to filter out log records.
 func WithIgnoreLogs(ctx context.Context) context.Context {
 	return context.WithValue(ctx, ignoreLogsKey, true)
 }
 
-// ContextFilterProcessor filters out logs when a context deriving from
-// [WithIgnoreLogs] is passed to its methods.
-type ContextFilterProcessor struct {
-	log.Processor
+// ContextFilterer filters out logs when a context deriving from
+// [WithIgnoreLogs] is passed to Logger's methods.
+type ContextFilterer struct{}
 
-	lazyFilter sync.Once
-	// Use the experimental FilterProcessor interface
-	// (go.opentelemetry.io/otel/sdk/log/internal/x).
-	filter filter
-}
-
-type filter interface {
-	Enabled(ctx context.Context, param logapi.EnabledParameters) bool
-}
-
-func (p *ContextFilterProcessor) OnEmit(ctx context.Context, record *log.Record) error {
-	if ignoreLogs(ctx) {
-		return nil
-	}
-	return p.Processor.OnEmit(ctx, record)
-}
-
-func (p *ContextFilterProcessor) Enabled(ctx context.Context, param logapi.EnabledParameters) bool {
-	p.lazyFilter.Do(func() {
-		if f, ok := p.Processor.(filter); ok {
-			p.filter = f
-		}
-	})
-	return !ignoreLogs(ctx) && (p.filter == nil || p.filter.Enabled(ctx, param))
-}
-
-func ignoreLogs(ctx context.Context) bool {
+func (p *ContextFilterer) Filter(ctx context.Context, param log.FilterParameters) bool {
 	_, ok := ctx.Value(ignoreLogsKey).(bool)
 	return ok
 }
 
 // Use a processor which redacts sensitive data from some attributes.
-func ExampleProcessor_redact() {
+func ExampleProcessor() {
 	// Existing processor that emits telemetry.
-	var processor log.Processor = log.NewBatchProcessor(nil)
+	processor := log.NewBatchProcessor(nil)
 
-	// Add a processor so that it redacts values from token attributes.
+	// Add a processor so that the SDK redacts values from token attributes.
 	redactProcessor := &RedactTokensProcessor{}
 
 	// The created processor can then be registered with

sdk/log/filterer.go

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log // import "go.opentelemetry.io/otel/sdk/log"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/log"
+)
+
+// Filterer handles filtering of log records.
+//
+// Any of the Filterer's methods may be called concurrently with itself
+// or with other methods. It is the responsibility of the Filterer to manage
+// this concurrency.
+type Filterer interface {
+	// Filter returns whether the SDK will process for the given context
+	// and param.
+	//
+	// The passed param may be a partial record (e.g a record with only the
+	// Severity set). If a Filterer needs more information than is provided, it
+	// is said to be in an indeterminate state. An implementation should
+	// return true for an indeterminate state.
+	//
+	// The returned value will be true when the SDK should process for the
+	// provided context and param, and will be false if the SDK should not
+	// process.
+	Filter(ctx context.Context, param FilterParameters) bool
+}
+
+// FilterParameters represent Filter parameters.
+type FilterParameters struct {
+	severity    log.Severity
+	severitySet bool
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+}
+
+// Severity returns the [Severity] level value, or [SeverityUndefined] if no value was set.
+// The ok result indicates whether the value was set.
+func (r *FilterParameters) Severity() (value log.Severity, ok bool) {
+	return r.severity, r.severitySet
+}
+
+// setSeverity sets the [Severity] level.
+func (r *FilterParameters) setSeverity(level log.Severity) {
+	r.severity = level
+	r.severitySet = true
+}

sdk/log/logger.go

@@ -11,7 +11,6 @@ import (
 	"go.opentelemetry.io/otel/log"
 	"go.opentelemetry.io/otel/log/embedded"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/log/internal/x"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -35,6 +34,12 @@ func newLogger(p *LoggerProvider, scope instrumentation.Scope) *logger {
 }
 
 func (l *logger) Emit(ctx context.Context, r log.Record) {
+	param := log.EnabledParameters{}
+	param.SetSeverity(r.Severity())
+	if !l.Enabled(ctx, param) {
+		return
+	}
+
 	newRecord := l.newRecord(ctx, r)
 	for _, p := range l.provider.processors {
 		if err := p.OnEmit(ctx, &newRecord); err != nil {
@@ -43,30 +48,20 @@ func (l *logger) Emit(ctx context.Context, r log.Record) {
 	}
 }
 
-// Enabled returns true if at least one Processor held by the LoggerProvider
-// that created the logger will process param for the provided context and param.
-//
-// If it is not possible to definitively determine the param will be
-// processed, true will be returned by default. A value of false will only be
-// returned if it can be positively verified that no Processor will process.
+// Enabled returns false if at least one Filterer held by the LoggerProvider
+// that created the logger will return false for the provided context and param.
 func (l *logger) Enabled(ctx context.Context, param log.EnabledParameters) bool {
-	fltrs := l.provider.filterProcessors()
-	// If there are more Processors than FilterProcessors we cannot be sure
-	// that all Processors will drop the record. Therefore, return true.
-	//
-	// If all Processors are FilterProcessors, check if any is enabled.
-	return len(l.provider.processors) > len(fltrs) || anyEnabled(ctx, param, fltrs)
-}
+	newParam := FilterParameters{}
+	if v, ok := param.Severity(); ok {
+		newParam.setSeverity(v)
+	}
 
-func anyEnabled(ctx context.Context, param log.EnabledParameters, fltrs []x.FilterProcessor) bool {
-	for _, f := range fltrs {
-		if f.Enabled(ctx, param) {
-			// At least one Processor will process the Record.
-			return true
+	for _, flt := range l.provider.filterers {
+		if !flt.Filter(ctx, newParam) {
+			return false
 		}
 	}
-	// No Processor will process the record
-	return false
+	return true
 }
 
 func (l *logger) newRecord(ctx context.Context, r log.Record) Record {