Basic resource type registry (#16622)

internal/resource/registry.go

@@ -0,0 +1,71 @@
+package resource
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/hashicorp/consul/proto-public/pbresource"
+)
+
+type Registry interface {
+	// Register the given resource type and its hooks.
+	Register(reg Registration)
+
+	// Resolve the given resource type and its hooks.
+	Resolve(typ *pbresource.Type) (reg Registration, ok bool)
+}
+
+type Registration struct {
+	// Type is the GVK of the resource type.
+	Type *pbresource.Type
+
+	// In the future, we'll add hooks, the controller etc. here.
+	// TODO: https://github.com/hashicorp/consul/pull/16622#discussion_r1134515909
+}
+
+// Hashable key for a resource type
+type TypeKey string
+
+// Resource type registry
+type TypeRegistry struct {
+	// registrations keyed by GVK
+	registrations map[string]Registration
+	lock          sync.RWMutex
+}
+
+func NewRegistry() Registry {
+	return &TypeRegistry{
+		registrations: make(map[string]Registration),
+	}
+}
+
+func (r *TypeRegistry) Register(registration Registration) {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
+	typ := registration.Type
+	if typ.Group == "" || typ.GroupVersion == "" || typ.Kind == "" {
+		panic("type field(s) cannot be empty")
+	}
+
+	key := ToGVK(registration.Type)
+	if _, ok := r.registrations[key]; ok {
+		panic(fmt.Sprintf("resource type %s already registered", key))
+	}
+
+	r.registrations[key] = registration
+}
+
+func (r *TypeRegistry) Resolve(typ *pbresource.Type) (reg Registration, ok bool) {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+
+	if registration, ok := r.registrations[ToGVK(typ)]; ok {
+		return registration, true
+	}
+	return Registration{}, false
+}
+
+func ToGVK(resourceType *pbresource.Type) string {
+	return fmt.Sprintf("%s/%s/%s", resourceType.Group, resourceType.GroupVersion, resourceType.Kind)
+}

internal/resource/registry_test.go

@@ -0,0 +1,89 @@
+package resource
+
+import (
+	"testing"
+
+	"github.com/hashicorp/consul/proto-public/pbresource"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRegister(t *testing.T) {
+	r := NewRegistry()
+
+	serviceType := &pbresource.Type{
+		Group:        "mesh",
+		GroupVersion: "v1",
+		Kind:         "service",
+	}
+
+	// register
+	serviceRegistration := Registration{Type: serviceType}
+	r.Register(serviceRegistration)
+
+	// register existing should panic
+	assertRegisterPanics(t, r.Register, serviceRegistration, "resource type mesh/v1/service already registered")
+
+	// register empty Group should panic
+	assertRegisterPanics(t, r.Register, Registration{
+		Type: &pbresource.Type{
+			Group:        "",
+			GroupVersion: "v1",
+			Kind:         "service",
+		},
+	}, "type field(s) cannot be empty")
+
+	// register empty GroupVersion should panic
+	assertRegisterPanics(t, r.Register, Registration{
+		Type: &pbresource.Type{
+			Group:        "mesh",
+			GroupVersion: "",
+			Kind:         "service",
+		},
+	}, "type field(s) cannot be empty")
+
+	// register empty Kind should panic
+	assertRegisterPanics(t, r.Register, Registration{
+		Type: &pbresource.Type{
+			Group:        "mesh",
+			GroupVersion: "v1",
+			Kind:         "",
+		},
+	}, "type field(s) cannot be empty")
+}
+
+func assertRegisterPanics(t *testing.T, registerFn func(reg Registration), registration Registration, panicString string) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("expected panic, but none occurred")
+		} else {
+			errstr, ok := r.(string)
+			if !ok {
+				t.Errorf("unexpected error type returned from panic")
+			} else if errstr != panicString {
+				t.Errorf("expected %s error message but got: %s", panicString, errstr)
+			}
+		}
+	}()
+
+	registerFn(registration)
+}
+
+func TestResolve(t *testing.T) {
+	r := NewRegistry()
+
+	serviceType := &pbresource.Type{
+		Group:        "mesh",
+		GroupVersion: "v1",
+		Kind:         "service",
+	}
+
+	// not found
+	_, ok := r.Resolve(serviceType)
+	assert.False(t, ok)
+
+	// found
+	r.Register(Registration{Type: serviceType})
+	registration, ok := r.Resolve(serviceType)
+	assert.True(t, ok)
+	assert.Equal(t, registration.Type, serviceType)
+}