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package api
import (
"errors"
"fmt"
"time"
)
const (
// SessionBehaviorRelease is the default behavior and causes
// all associated locks to be released on session invalidation.
SessionBehaviorRelease = "release"
// SessionBehaviorDelete is new in Consul 0.5 and changes the
// behavior to delete all associated locks on session invalidation.
// It can be used in a way similar to Ephemeral Nodes in ZooKeeper.
SessionBehaviorDelete = "delete"
)
var ErrSessionExpired = errors.New("session expired")
// SessionEntry represents a session in consul
type SessionEntry struct {
CreateIndex uint64
ID string
Name string
Node string
Checks []string
LockDelay time.Duration
Behavior string
TTL string
}
// Session can be used to query the Session endpoints
type Session struct {
c *Client
}
// Session returns a handle to the session endpoints
func (c *Client) Session() *Session {
return &Session{c}
}
// CreateNoChecks is like Create but is used specifically to create
// a session with no associated health checks.
func (s *Session) CreateNoChecks(se *SessionEntry, q *WriteOptions) (string, *WriteMeta, error) {
body := make(map[string]interface{})
body["Checks"] = []string{}
if se != nil {
if se.Name != "" {
body["Name"] = se.Name
}
if se.Node != "" {
body["Node"] = se.Node
}
if se.LockDelay != 0 {
body["LockDelay"] = durToMsec(se.LockDelay)
}
if se.Behavior != "" {
body["Behavior"] = se.Behavior
}
if se.TTL != "" {
body["TTL"] = se.TTL
}
}
return s.create(body, q)
}
// Create makes a new session. Providing a session entry can
// customize the session. It can also be nil to use defaults.
func (s *Session) Create(se *SessionEntry, q *WriteOptions) (string, *WriteMeta, error) {
var obj interface{}
if se != nil {
body := make(map[string]interface{})
obj = body
if se.Name != "" {
body["Name"] = se.Name
}
if se.Node != "" {
body["Node"] = se.Node
}
if se.LockDelay != 0 {
body["LockDelay"] = durToMsec(se.LockDelay)
}
if len(se.Checks) > 0 {
body["Checks"] = se.Checks
}
if se.Behavior != "" {
body["Behavior"] = se.Behavior
}
if se.TTL != "" {
body["TTL"] = se.TTL
}
}
return s.create(obj, q)
}
func (s *Session) create(obj interface{}, q *WriteOptions) (string, *WriteMeta, error) {
var out struct{ ID string }
wm, err := s.c.write("/v1/session/create", obj, &out, q)
if err != nil {
return "", nil, err
}
return out.ID, wm, nil
}
// Destroy invalidates a given session
func (s *Session) Destroy(id string, q *WriteOptions) (*WriteMeta, error) {
wm, err := s.c.write("/v1/session/destroy/"+id, nil, nil, q)
if err != nil {
return nil, err
}
return wm, nil
}
// Renew renews the TTL on a given session
func (s *Session) Renew(id string, q *WriteOptions) (*SessionEntry, *WriteMeta, error) {
r := s.c.newRequest("PUT", "/v1/session/renew/"+id)
r.setWriteOptions(q)
rtt, resp, err := s.c.doRequest(r)
if err != nil {
return nil, nil, err
}
defer resp.Body.Close()
wm := &WriteMeta{RequestTime: rtt}
if resp.StatusCode == 404 {
return nil, wm, nil
} else if resp.StatusCode != 200 {
return nil, nil, fmt.Errorf("Unexpected response code: %d", resp.StatusCode)
}
var entries []*SessionEntry
if err := decodeBody(resp, &entries); err != nil {
return nil, nil, fmt.Errorf("Failed to read response: %v", err)
}
if len(entries) > 0 {
return entries[0], wm, nil
}
return nil, wm, nil
}
// RenewPeriodic is used to periodically invoke Session.Renew on a
// session until a doneCh is closed. This is meant to be used in a long running
// goroutine to ensure a session stays valid.
func (s *Session) RenewPeriodic(initialTTL string, id string, q *WriteOptions, doneCh chan struct{}) error {
ttl, err := time.ParseDuration(initialTTL)
if err != nil {
return err
}
waitDur := ttl / 2
lastRenewTime := time.Now()
var lastErr error
for {
if time.Since(lastRenewTime) > ttl {
return lastErr
}
select {
case <-time.After(waitDur):
entry, _, err := s.Renew(id, q)
if err != nil {
waitDur = time.Second
lastErr = err
continue
}
if entry == nil {
return ErrSessionExpired
}
// Handle the server updating the TTL
ttl, _ = time.ParseDuration(entry.TTL)
waitDur = ttl / 2
lastRenewTime = time.Now()
case <-doneCh:
// Attempt a session destroy
s.Destroy(id, q)
return nil
}
}
}
// Info looks up a single session
func (s *Session) Info(id string, q *QueryOptions) (*SessionEntry, *QueryMeta, error) {
var entries []*SessionEntry
qm, err := s.c.query("/v1/session/info/"+id, &entries, q)
if err != nil {
return nil, nil, err
}
if len(entries) > 0 {
return entries[0], qm, nil
}
return nil, qm, nil
}
// List gets sessions for a node
func (s *Session) Node(node string, q *QueryOptions) ([]*SessionEntry, *QueryMeta, error) {
var entries []*SessionEntry
qm, err := s.c.query("/v1/session/node/"+node, &entries, q)
if err != nil {
return nil, nil, err
}
return entries, qm, nil
}
// List gets all active sessions
func (s *Session) List(q *QueryOptions) ([]*SessionEntry, *QueryMeta, error) {
var entries []*SessionEntry
qm, err := s.c.query("/v1/session/list", &entries, q)
if err != nil {
return nil, nil, err
}
return entries, qm, nil
}
|