Restruct (#34)

* modify

* remove

* modify

* modify

* remove no use

* add online/offline notification

* modify

* format log

* add reference

lib/sessions/sessions.go

@@ -0,0 +1,92 @@
+package sessions
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+)
+
+var (
+	ErrSessionsProviderNotFound = errors.New("Session: Session provider not found")
+	ErrKeyNotAvailable          = errors.New("Session: not item found for key.")
+
+	providers = make(map[string]SessionsProvider)
+)
+
+type SessionsProvider interface {
+	New(id string) (*Session, error)
+	Get(id string) (*Session, error)
+	Del(id string)
+	Save(id string) error
+	Count() int
+	Close() error
+}
+
+// Register makes a session provider available by the provided name.
+// If a Register is called twice with the same name or if the driver is nil,
+// it panics.
+func Register(name string, provider SessionsProvider) {
+	if provider == nil {
+		panic("session: Register provide is nil")
+	}
+
+	if _, dup := providers[name]; dup {
+		panic("session: Register called twice for provider " + name)
+	}
+
+	providers[name] = provider
+}
+
+func Unregister(name string) {
+	delete(providers, name)
+}
+
+type Manager struct {
+	p SessionsProvider
+}
+
+func NewManager(providerName string) (*Manager, error) {
+	p, ok := providers[providerName]
+	if !ok {
+		return nil, fmt.Errorf("session: unknown provider %q", providerName)
+	}
+
+	return &Manager{p: p}, nil
+}
+
+func (this *Manager) New(id string) (*Session, error) {
+	if id == "" {
+		id = this.sessionId()
+	}
+	return this.p.New(id)
+}
+
+func (this *Manager) Get(id string) (*Session, error) {
+	return this.p.Get(id)
+}
+
+func (this *Manager) Del(id string) {
+	this.p.Del(id)
+}
+
+func (this *Manager) Save(id string) error {
+	return this.p.Save(id)
+}
+
+func (this *Manager) Count() int {
+	return this.p.Count()
+}
+
+func (this *Manager) Close() error {
+	return this.p.Close()
+}
+
+func (manager *Manager) sessionId() string {
+	b := make([]byte, 15)
+	if _, err := io.ReadFull(rand.Reader, b); err != nil {
+		return ""
+	}
+	return base64.URLEncoding.EncodeToString(b)
+}