Added DynamicRESTMapper

On-behalf-of: @SAP [email protected]
Signed-off-by: Robert Vasek <[email protected]>

Author: gman0

pkg/reconciler/dynamicrestmapper/defaultrestmapper_mutable.go

@@ -0,0 +1,105 @@
+/*
+Copyright 2025 The KCP Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package dynamicrestmapper
+
+import (
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+// This file adds mutable methods to our fork of upstream's DefaultRESTMapper.
+
+func (m *DefaultRESTMapper) empty() bool {
+	// If one of the maps is empty, all of the maps are empty.
+	return len(m.resourceToKind) == 0
+}
+
+func (m *DefaultRESTMapper) add(typeMeta typeMeta) {
+	kind := typeMeta.groupVersionKind()
+	singular := typeMeta.groupVersionResourceSingular()
+	plural := typeMeta.groupVersionResourcePlural()
+
+	m.singularToPlural[singular] = plural
+	m.pluralToSingular[plural] = singular
+
+	m.resourceToKind[singular] = kind
+	m.resourceToKind[plural] = kind
+
+	m.kindToPluralResource[kind] = plural
+	m.kindToScope[kind] = meta.RESTScopeRoot
+}
+
+func (m *DefaultRESTMapper) remove(typeMeta typeMeta) {
+	kind := typeMeta.groupVersionKind()
+	singular := typeMeta.groupVersionResourceSingular()
+	plural := typeMeta.groupVersionResourcePlural()
+
+	delete(m.singularToPlural, singular)
+	delete(m.pluralToSingular, plural)
+
+	delete(m.resourceToKind, singular)
+	delete(m.resourceToKind, plural)
+
+	delete(m.kindToPluralResource, kind)
+	delete(m.kindToScope, kind)
+}
+
+func (m *DefaultRESTMapper) getGVKR(gvr schema.GroupVersionResource) typeMeta {
+	kind := m.resourceToKind[gvr]
+	singular := m.pluralToSingular[gvr]
+	if singular.Empty() {
+		singular = gvr
+	}
+	plural := m.singularToPlural[gvr]
+	if plural.Empty() {
+		plural = gvr
+	}
+	scope := m.kindToScope[kind]
+
+	return newTypeMeta(
+		kind.Group,
+		kind.Version,
+		kind.Kind,
+		singular.Resource,
+		plural.Resource,
+		scope,
+	)
+}
+
+func (m *DefaultRESTMapper) getGVKRs(gr schema.GroupResource) ([]typeMeta, error) {
+	gvrs, err := m.ResourcesFor(gr.WithVersion(""))
+	if err != nil {
+		return nil, err
+	}
+	gvkrs := make([]typeMeta, len(gvrs))
+	for i := range gvrs {
+		gvkrs[i] = m.getGVKR(gvrs[i])
+	}
+	return gvkrs, nil
+}
+
+// Applies the two slices to the known mappings. It is assumed there is
+// no overlap between toRemove and toAdd.
+func (m *DefaultRESTMapper) apply(toRemove []typeMeta, toAdd []typeMeta) {
+	for i := range toRemove {
+		m.remove(toRemove[i])
+	}
+
+	for i := range toAdd {
+		m.add(toAdd[i])
+	}
+}

pkg/reconciler/dynamicrestmapper/dynamicrestmapper.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2025 The KCP Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package dynamicrestmapper
+
+import (
+	"sync"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+
+	"github.com/kcp-dev/logicalcluster/v3"
+)
+
+// DynamicRESTMapper is a thread-safe RESTMapper with per-cluster GVK/GVR mappings.
+// The mapping data is fed from its associated Controller (in this package), triggered
+// on CRDs and APIBindings (and their respective APIResourceSchemas). Additionally,
+// mappings for built-in types (pkg/virtual/apiexport/schemas/builtin/builtin.go) are
+// added for each LogicalCluster by default.
+type DynamicRESTMapper struct {
+	lock      sync.RWMutex
+	byCluster map[logicalcluster.Name]*DefaultRESTMapper
+}
+
+func NewDynamicRESTMapper(defaultGroupVersions []schema.GroupVersion) *DynamicRESTMapper {
+	return &DynamicRESTMapper{
+		byCluster: make(map[logicalcluster.Name]*DefaultRESTMapper),
+	}
+}
+
+func (d *DynamicRESTMapper) deleteMappingsForCluster(clusterName logicalcluster.Name) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+	delete(d.byCluster, clusterName)
+}
+
+// ForCluster returns a RESTMapper for the specified cluster name.
+// The method never returns nil. If the cluster doesn't exist at the time
+// of calling ForCluster, or if it is deleted while holding the returned
+// RESTMapper instance, all RESTMapper's methods will empty matches and
+// NoResourceMatchError error.
+func (d *DynamicRESTMapper) ForCluster(clusterName logicalcluster.Name) *ForCluster {
+	return newForCluster(clusterName, d)
+}