refactor some more

Author: wbrowne

backend/datasource/manage.go

@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/backend/instancemgmt"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/tracing"
 	"github.com/grafana/grafana-plugin-sdk-go/internal/automanagement"
 	"github.com/grafana/grafana-plugin-sdk-go/internal/buildinfo"
@@ -27,6 +28,11 @@ type ManageOpts struct {
 
 	// Stateless query conversion handler
 	QueryConversionHandler backend.QueryConversionHandler
+
+	// UseTTLInstanceManager controls whether to use the TTL-based instance manager.
+	// When true, instances will be automatically evicted from the cache after a configurable TTL.
+	// Default is false, which uses the standard instance manager.
+	UseTTLInstanceManager bool
 }
 
 // Manage starts serving the data source over gPRC with automatic instance management.
@@ -46,7 +52,17 @@ func Manage(pluginID string, instanceFactory InstanceFactoryFunc, opts ManageOpt
 	if err := backend.SetupTracer(pluginID, opts.TracingOpts); err != nil {
 		return fmt.Errorf("setup tracer: %w", err)
 	}
-	handler := automanagement.NewManager(NewInstanceManager(instanceFactory))
+
+	ip := NewInstanceProvider(instanceFactory)
+
+	var im instancemgmt.InstanceManager
+	if opts.UseTTLInstanceManager {
+		im = instancemgmt.NewTTLInstanceManager(ip)
+	} else {
+		im = instancemgmt.New(ip)
+	}
+
+	handler := automanagement.NewManager(im)
 	return backend.Manage(pluginID, backend.ServeOpts{
 		CheckHealthHandler:     handler,
 		CallResourceHandler:    handler,

backend/instancemgmt/instance_manager.go

@@ -18,6 +18,9 @@ var (
 		Name:      "active_instances",
 		Help:      "The number of active plugin instances",
 	})
+)
+
+const (
 	disposeTTL = 5 * time.Second
 )
 

backend/instancemgmt/instance_manager_test.go

@@ -7,8 +7,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
 )
 
 func TestInstanceManager(t *testing.T) {
@@ -21,7 +22,7 @@ func TestInstanceManager(t *testing.T) {
 	}
 
 	tip := &testInstanceProvider{}
-	im := NewWithOptions(tip, defaultInstanceTTL, defaultInstanceCleanup, time.Millisecond)
+	im := New(tip)
 
 	t.Run("When getting instance should create a new instance", func(t *testing.T) {
 		instance, err := im.Get(ctx, pCtx)
@@ -75,7 +76,7 @@ func TestInstanceManagerExpiration(t *testing.T) {
 	}
 
 	tip := &testInstanceProvider{}
-	im := NewWithOptions(tip, time.Millisecond, 2*time.Millisecond, 10*time.Millisecond)
+	im := newTTLInstanceManager(tip, time.Millisecond, 2*time.Millisecond)
 
 	instance, err := im.Get(ctx, pCtx)
 	require.NoError(t, err)
@@ -151,7 +152,7 @@ func TestInstanceManagerConcurrency(t *testing.T) {
 			},
 		}
 		tip := &testInstanceProvider{}
-		im := NewWithOptions(tip, defaultInstanceTTL, defaultInstanceCleanup, time.Millisecond)
+		im := newTTLInstanceManager(tip, defaultInstanceTTL, defaultInstanceCleanupInterval)
 		// Creating initial instance with old contexts
 		instanceToDispose, _ := im.Get(ctx, initialPCtx)
 

backend/instancemgmt/intance_manager_ttl.go

@@ -3,12 +3,52 @@ package instancemgmt
 import (
 	"context"
 	"fmt"
+	"time"
 
 	gocache "github.com/patrickmn/go-cache"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 )
 
+const (
+	defaultInstanceTTL             = 24 * time.Hour
+	defaultInstanceCleanupInterval = 48 * time.Hour
+)
+
+// NewTTLInstanceManager creates a new instance manager with TTL-based caching.
+// Instances will be automatically evicted from the cache after the specified TTL.
+func NewTTLInstanceManager(provider InstanceProvider) InstanceManager {
+	return newTTLInstanceManager(provider, defaultInstanceTTL, defaultInstanceCleanupInterval)
+}
+
+func newTTLInstanceManager(provider InstanceProvider, instanceTTL, instanceCleanupInterval time.Duration) InstanceManager {
+	if provider == nil {
+		panic("provider cannot be nil")
+	}
+
+	// Use go-cache for TTL-based caching
+	cache := gocache.New(instanceTTL, instanceCleanupInterval)
+
+	// Set up the OnEvicted callback to dispose instances
+	cache.OnEvicted(func(_ string, value interface{}) {
+		ci := value.(CachedInstance)
+		if disposer, valid := ci.instance.(InstanceDisposer); valid {
+			time.AfterFunc(disposeTTL, func() {
+				disposer.Dispose()
+				activeInstances.Dec()
+			})
+		} else {
+			activeInstances.Dec()
+		}
+	})
+
+	return &instanceManagerWithTTL{
+		provider: provider,
+		cache:    cache,
+		locker:   newLocker(),
+	}
+}
+
 type instanceManagerWithTTL struct {
 	locker   *locker
 	provider InstanceProvider

experimental/featuretoggles/featuretoggles.go

@@ -7,6 +7,10 @@ import (
 
 const (
 	EnabledFeatures = "GF_INSTANCE_FEATURE_TOGGLES_ENABLE"
+
+	// TTLInstanceManager is a feature toggle for enabling the TTL-based instance manager.
+	// When enabled, instances will be automatically evicted from the cache after a configurable TTL.
+	TTLInstanceManager = "ttlInstanceManager"
 )
 
 // FeatureToggles can check if feature toggles are enabled on the Grafana instance.