improve error handling and mention cache size default in the docs

Author: pawel-maciejczek

server/adkrest/handler.go

@@ -15,6 +15,7 @@
 package adkrest
 
 import (
+	"fmt"
 	"net/http"
 	"time"
 
@@ -34,9 +35,12 @@ import (
 
 // NewServer creates a new ADK REST API server which implements [http.Handler] interface.
 func NewServer(cfg ServerConfig) (*Server, error) {
-	debugTelemetry := services.NewDebugTelemetry(&services.DebugTelemetryConfig{
+	debugTelemetry, err := services.NewDebugTelemetryWithConfig(&services.DebugTelemetryConfig{
 		TraceCapacity: cfg.DebugConfig.TraceCapacity,
 	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create debug telemetry service: %w", err)
+	}
 
 	router := mux.NewRouter().StrictSlash(true)
 	// TODO: Allow taking a prefix to allow customizing the path
@@ -69,7 +73,7 @@ type ServerConfig struct {
 // DebugTelemetryConfig contains parameters for the debug telemetry.
 type DebugTelemetryConfig struct {
 	// Maximum number of traces to keep in memory.
-	// If <= 0, the default capacity is used.
+	// If <= 0, the default capacity 10_000 is used.
 	TraceCapacity int
 }
 

server/adkrest/internal/services/debugtelemetry.go

@@ -17,6 +17,7 @@ package services
 import (
 	"cmp"
 	"context"
+	"fmt"
 	"slices"
 	"sync"
 	"time"
@@ -44,19 +45,23 @@ type DebugTelemetry struct {
 
 type DebugTelemetryConfig struct {
 	// Maximum number of traces to keep in memory.
-	// If 0, default capacity (10k) is used.
+	// If <= 0, default capacity (10_000) is used.
 	TraceCapacity int
 }
 
-// NewDebugTelemetry returns a new DebugTelemetry instance with default capacity (10k).
-func NewDebugTelemetry(cfg *DebugTelemetryConfig) *DebugTelemetry {
+// NewDebugTelemetryWithConfig returns a new DebugTelemetry instance with custom capacity.
+func NewDebugTelemetryWithConfig(cfg *DebugTelemetryConfig) (*DebugTelemetry, error) {
 	capacity := defaultTraceCapacity
 	if cfg != nil && cfg.TraceCapacity > 0 {
 		capacity = cfg.TraceCapacity
 	}
-	return &DebugTelemetry{
-		store: newSpanStore(capacity),
+	store, err := newSpanStore(capacity)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create span store: %w", err)
 	}
+	return &DebugTelemetry{
+		store: store,
+	}, nil
 }
 
 func (d *DebugTelemetry) SpanProcessor() sdktrace.SpanProcessor {
@@ -132,17 +137,18 @@ type spanStore struct {
 	recordsByEventID map[string][]*spanRecord
 }
 
-func newSpanStore(capacity int) *spanStore {
+func newSpanStore(capacity int) (*spanStore, error) {
 	store := &spanStore{
 		recordsBySpanID:     make(map[string]*spanRecord),
 		traceIDsBySessionID: make(map[string]map[string]struct{}),
 		recordsByEventID:    make(map[string][]*spanRecord),
 	}
-	cache, err := lru.NewWithEvict(capacity, store.evict)
-	if err == nil {
-		store.recordsByTraceID = cache
+	var err error
+	store.recordsByTraceID, err = lru.NewWithEvict(capacity, store.evict)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create LRU cache: %w", err)
 	}
-	return store
+	return store, nil
 }
 
 func (s *spanStore) getSpansByEventID(id string) []DebugSpan {

server/adkrest/internal/services/debugtelemetry_test.go

@@ -212,7 +212,7 @@ func TestDebugTelemetryGetSpansBySessionID(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			debugTelemetry, tp, lp := setup()
+			debugTelemetry, tp, lp := setup(t)
 
 			if tt.testSetup != nil {
 				tt.testSetup(ctx, tp.Tracer("test-tracer"), lp.Logger("test-logger"))
@@ -349,7 +349,7 @@ func TestDebugTelemetryGetSpansByEventID(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			debugTelemetry, tp, lp := setup()
+			debugTelemetry, tp, lp := setup(t)
 
 			if tt.testSetup != nil {
 				tt.testSetup(ctx, tp.Tracer("test-tracer"), lp.Logger("test-logger"))
@@ -380,7 +380,7 @@ func TestDebugTelemetryGetSpansByEventID(t *testing.T) {
 func TestDebugTelemetryLRU(t *testing.T) {
 	ctx := t.Context()
 
-	debugTelemetry, tp, lp := setupWithConfig(&DebugTelemetryConfig{TraceCapacity: 2})
+	debugTelemetry, tp, lp := setupWithConfig(t, &DebugTelemetryConfig{TraceCapacity: 2})
 	tracer := tp.Tracer("test-tracer")
 
 	// 1. Add Trace 1.
@@ -456,8 +456,11 @@ func TestDebugTelemetryLRU(t *testing.T) {
 	}
 }
 
-func setupWithConfig(cfg *DebugTelemetryConfig) (*DebugTelemetry, *sdktrace.TracerProvider, *sdklog.LoggerProvider) {
-	debugTelemetry := NewDebugTelemetry(cfg)
+func setupWithConfig(t *testing.T, cfg *DebugTelemetryConfig) (*DebugTelemetry, *sdktrace.TracerProvider, *sdklog.LoggerProvider) {
+	debugTelemetry, err := NewDebugTelemetryWithConfig(cfg)
+	if err != nil {
+		t.Fatalf("Failed to create debug telemetry: %v", err)
+	}
 	tp := sdktrace.NewTracerProvider(
 		sdktrace.WithSpanProcessor(debugTelemetry.SpanProcessor()),
 	)
@@ -466,12 +469,6 @@ func setupWithConfig(cfg *DebugTelemetryConfig) (*DebugTelemetry, *sdktrace.Trac
 	return debugTelemetry, tp, lp
 }
 
-func setup() (*DebugTelemetry, *sdktrace.TracerProvider, *sdklog.LoggerProvider) {
-	debugTelemetry := NewDebugTelemetry(nil)
-	tp := sdktrace.NewTracerProvider(
-		sdktrace.WithSpanProcessor(debugTelemetry.SpanProcessor()),
-	)
-	lp := sdklog.NewLoggerProvider(sdklog.WithProcessor(debugTelemetry.LogProcessor()))
-
-	return debugTelemetry, tp, lp
+func setup(t *testing.T) (*DebugTelemetry, *sdktrace.TracerProvider, *sdklog.LoggerProvider) {
+	return setupWithConfig(t, nil)
 }