Add ability to manage a pool of dynamic clients

pkg/client/typed/dynamic/client_pool.go

@@ -0,0 +1,85 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+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 dynamic
+
+import (
+	"sync"
+
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/client/restclient"
+)
+
+// ClientPool manages a pool of dynamic clients.
+type ClientPool interface {
+	// ClientForGroupVersion returns a client configured for the specified groupVersion.
+	ClientForGroupVersion(groupVersion unversioned.GroupVersion) (*Client, error)
+}
+
+// APIPathResolverFunc knows how to convert a groupVersion to its API path.
+type APIPathResolverFunc func(groupVersion unversioned.GroupVersion) string
+
+// LegacyAPIPathResolverFunc can resolve paths properly with the legacy API.
+func LegacyAPIPathResolverFunc(groupVersion unversioned.GroupVersion) string {
+	if len(groupVersion.Group) == 0 {
+		return "/api"
+	}
+	return "/apis"
+}
+
+// clientPoolImpl implements Factory
+type clientPoolImpl struct {
+	lock                sync.RWMutex
+	config              *restclient.Config
+	clients             map[unversioned.GroupVersion]*Client
+	apiPathResolverFunc APIPathResolverFunc
+}
+
+// NewClientPool returns a ClientPool from the specified config
+func NewClientPool(config *restclient.Config, apiPathResolverFunc APIPathResolverFunc) ClientPool {
+	return &clientPoolImpl{
+		config:              config,
+		clients:             map[unversioned.GroupVersion]*Client{},
+		apiPathResolverFunc: apiPathResolverFunc,
+	}
+}
+
+// ClientForGroupVersion returns a client for the specified groupVersion, creates one if none exists
+func (c *clientPoolImpl) ClientForGroupVersion(groupVersion unversioned.GroupVersion) (*Client, error) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// do we have a client already configured?
+	if existingClient, found := c.clients[groupVersion]; found {
+		return existingClient, nil
+	}
+
+	// avoid changing the original config
+	confCopy := *c.config
+	conf := &confCopy
+
+	// we need to set the api path based on group version, if no group, default to legacy path
+	conf.APIPath = c.apiPathResolverFunc(groupVersion)
+
+	// we need to make a client
+	conf.GroupVersion = &groupVersion
+	dynamicClient, err := NewClient(conf)
+	if err != nil {
+		return nil, err
+	}
+	c.clients[groupVersion] = dynamicClient
+	return dynamicClient, nil
+}