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handler.go
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/
handler.go
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/*
* Copyright (C) 2016 Red Hat, Inc.
*
* 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 ofthe 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 specificlanguage governing permissions and
* limitations under the License.
*
*/
package server
import (
"context"
"encoding/json"
"fmt"
"strings"
"sync"
"sync/atomic"
"time"
etcd "github.com/coreos/etcd/client"
uuid "github.com/nu7hatch/gouuid"
"github.com/skydive-project/skydive/api/types"
"github.com/skydive-project/skydive/logging"
)
// Handler describes resources for each API
type Handler interface {
Name() string
New() types.Resource
Index() map[string]types.Resource
Get(id string) (types.Resource, bool)
Decorate(resource types.Resource)
Create(resource types.Resource, createOpts *CreateOptions) error
Delete(id string) error
AsyncWatch(f WatcherCallback) StoppableWatcher
}
// CreateOptions describes the available options when creating a resource
type CreateOptions struct {
TTL time.Duration
}
// ResourceHandler aims to creates new resource of an API
type ResourceHandler interface {
Name() string
New() types.Resource
}
// BasicAPIHandler basic implementation of an Handler, should be used as embedded struct
// for the most part of the resource
type BasicAPIHandler struct {
ResourceHandler ResourceHandler
EtcdKeyAPI etcd.KeysAPI
}
// WatcherCallback callback called by the resource watcher
type WatcherCallback func(action string, id string, resource types.Resource)
// StoppableWatcher interface
type StoppableWatcher interface {
Stop()
}
// BasicStoppableWatcher basic implementation of a resource watcher
type BasicStoppableWatcher struct {
StoppableWatcher
watcher etcd.Watcher
running atomic.Value
ctx context.Context
cancel context.CancelFunc
wg sync.WaitGroup
}
// ResourceWatcher asynchronous interface
type ResourceWatcher interface {
AsyncWatch(f WatcherCallback) StoppableWatcher
}
// Stop the resource watcher
func (s *BasicStoppableWatcher) Stop() {
s.cancel()
s.running.Store(false)
s.wg.Wait()
}
// Name returns the resource name
func (h *BasicAPIHandler) Name() string {
return h.ResourceHandler.Name()
}
// New creates a new resource
func (h *BasicAPIHandler) New() types.Resource {
return h.ResourceHandler.New()
}
// Unmarshal deserialize a resource
func (h *BasicAPIHandler) Unmarshal(b []byte) (resource types.Resource, err error) {
resource = h.ResourceHandler.New()
err = json.Unmarshal(b, resource)
return
}
// Decorate the resource
func (h *BasicAPIHandler) Decorate(resource types.Resource) {
}
func (h *BasicAPIHandler) collectNodes(flatten map[string]types.Resource, nodes etcd.Nodes) {
for _, node := range nodes {
if node.Dir {
h.collectNodes(flatten, node.Nodes)
} else {
resource, err := h.Unmarshal([]byte(node.Value))
if err != nil {
logging.GetLogger().Warningf("Failed to unmarshal capture: %s", err.Error())
continue
}
flatten[resource.ID()] = resource
}
}
}
// Index returns the list of resource available in Etcd
func (h *BasicAPIHandler) Index() map[string]types.Resource {
etcdPath := fmt.Sprintf("/%s/", h.ResourceHandler.Name())
resp, err := h.EtcdKeyAPI.Get(context.Background(), etcdPath, &etcd.GetOptions{Recursive: true})
resources := make(map[string]types.Resource)
if err == nil {
h.collectNodes(resources, resp.Node.Nodes)
}
return resources
}
// Get a specific resource
func (h *BasicAPIHandler) Get(id string) (types.Resource, bool) {
etcdPath := fmt.Sprintf("/%s/%s", h.ResourceHandler.Name(), id)
resp, err := h.EtcdKeyAPI.Get(context.Background(), etcdPath, nil)
if err != nil {
return nil, false
}
resource, err := h.Unmarshal([]byte(resp.Node.Value))
return resource, err == nil
}
// Create a new resource in Etcd
func (h *BasicAPIHandler) Create(resource types.Resource, createOpts *CreateOptions) error {
id, _ := uuid.NewV4()
resource.SetID(id.String())
data, err := json.Marshal(&resource)
if err != nil {
return err
}
var setOptions *etcd.SetOptions
if createOpts != nil {
setOptions = &etcd.SetOptions{TTL: createOpts.TTL}
}
etcdPath := fmt.Sprintf("/%s/%s", h.ResourceHandler.Name(), id)
_, err = h.EtcdKeyAPI.Set(context.Background(), etcdPath, string(data), setOptions)
return err
}
// Delete a resource
func (h *BasicAPIHandler) Delete(id string) error {
etcdPath := fmt.Sprintf("/%s/%s", h.ResourceHandler.Name(), id)
_, err := h.EtcdKeyAPI.Delete(context.Background(), etcdPath, nil)
return err
}
// Update a resource
func (h *BasicAPIHandler) Update(id string, resource types.Resource) error {
data, err := json.Marshal(&resource)
if err != nil {
return err
}
etcdPath := fmt.Sprintf("/%s/%s", h.ResourceHandler.Name(), id)
_, err = h.EtcdKeyAPI.Update(context.Background(), etcdPath, string(data))
return err
}
// AsyncWatch registers a new resource watcher
func (h *BasicAPIHandler) AsyncWatch(f WatcherCallback) StoppableWatcher {
etcdPath := fmt.Sprintf("/%s/", h.ResourceHandler.Name())
watcher := h.EtcdKeyAPI.Watcher(etcdPath, &etcd.WatcherOptions{Recursive: true})
ctx, cancel := context.WithCancel(context.Background())
sw := &BasicStoppableWatcher{
watcher: watcher,
ctx: ctx,
cancel: cancel,
}
// init phase retrieve all the previous value and use init as action for the
// callback
for id, node := range h.Index() {
f("init", id, node)
}
sw.wg.Add(1)
sw.running.Store(true)
go func() {
defer sw.wg.Done()
for sw.running.Load() == true {
resp, err := watcher.Next(sw.ctx)
if err != nil {
logging.GetLogger().Errorf("Error while watching etcd: %s", err.Error())
time.Sleep(1 * time.Second)
continue
}
if resp.Node.Dir {
continue
}
id := strings.TrimPrefix(resp.Node.Key, etcdPath)
resource := h.ResourceHandler.New()
switch resp.Action {
case "expire", "delete":
json.Unmarshal([]byte(resp.PrevNode.Value), resource)
default:
json.Unmarshal([]byte(resp.Node.Value), resource)
}
f(resp.Action, id, resource)
}
}()
return sw
}