pkg/dynamiclifecycle: Add DynamicLifecycle wrapper

Provides `WithDynamicLifecycle` which allows wrapping Cells into a DynamicFeature that would allow the Manager to manage its lifecycle.

Signed-off-by: Ovidiu Tirla <otirla@google.com>

pkg/dynamiclifecycle/wrapper.go

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Cilium
+
+package dynamiclifecycle
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+
+	"github.com/cilium/hive/cell"
+
+	"github.com/cilium/cilium/pkg/lock"
+)
+
+type featureRegistration struct {
+	Name      DynamicFeatureName
+	Deps      []DynamicFeatureName
+	Lifecycle *Lifecycle
+}
+type featureRegistrationOut struct {
+	cell.Out
+	FeatureRegistration featureRegistration `group:"dynamiclifecycle-registrations"`
+}
+
+// Lifecycle provides a wrapper over the cell.Lifecycle
+// which only allows appending hooks and performing get on them.
+type Lifecycle struct {
+	Hooks []cell.HookInterface // Lifecycle hooks
+	m     lock.Mutex
+}
+
+func (l *Lifecycle) Append(hook cell.HookInterface) {
+	l.m.Lock()
+	defer l.m.Unlock()
+	l.Hooks = append(l.Hooks, hook)
+}
+
+func (l *Lifecycle) Start(sl *slog.Logger, _ context.Context) error {
+	sl.Error("Start() should not be called, lifecycle managed by Dynamic Lifecycle. This is no-op.")
+	return fmt.Errorf("lifecycle managed by Dynamic Lifecycle")
+}
+
+func (l *Lifecycle) Stop(sl *slog.Logger, _ context.Context) error {
+	sl.Error("Stop() should not be called, lifecycle managed by Dynamic Lifecycle. This is no-op.")
+	return fmt.Errorf("lifecycle managed by Dynamic Lifecycle")
+}
+
+func (l *Lifecycle) PrintHooks() {
+	fmt.Printf("Lifecycle managed by Dynamic Lifecycle. This is no-op.")
+}
+
+// WithDynamicLifecycle provides a wrapper over the cell.Lifecycle to register DynamicFeature
+// It groups the cells by DynamicFeatureName, providing a DynamicLifecycle for each feature.
+// The hooks are immutable after the hive is initialized and are stored in a stateDB table, see table.go.
+func WithDynamicLifecycle(feature DynamicFeatureName, deps []DynamicFeatureName, cells ...cell.Cell) cell.Cell {
+	lc := &Lifecycle{}
+	return cell.Group(
+		cell.Provide(
+			func() featureRegistrationOut {
+				return featureRegistrationOut{FeatureRegistration: featureRegistration{Name: feature, Deps: deps, Lifecycle: lc}}
+			},
+		),
+		cell.Decorate(
+			func() cell.Lifecycle {
+				return lc
+			},
+			cells...,
+		),
+	)
+}