// NewSession gets the leased session for a client.
func NewSession(client *v3.Client, opts ...SessionOption) (*Session, error) {
ops := &sessionOptions{ttl: defaultSessionTTL}
for _, opt := range opts {
opt(ops)
}
resp, err := client.Grant(client.Ctx(), int64(ops.ttl))
if err != nil {
return nil, err
}
id := v3.LeaseID(resp.ID)
ctx, cancel := context.WithCancel(client.Ctx())
keepAlive, err := client.KeepAlive(ctx, id)
if err != nil || keepAlive == nil {
return nil, err
}
donec := make(chan struct{})
s := &Session{client: client, id: id, cancel: cancel, donec: donec}
// keep the lease alive until client error or cancelled context
go func() {
defer close(donec)
for range keepAlive {
// eat messages until keep alive channel closes
}
}()
return s, nil
}
func NewWatchProxy(c *clientv3.Client) pb.WatchServer {
wp := &watchProxy{
cw: c.Watcher,
ctx: clientv3.WithRequireLeader(c.Ctx()),
retryLimiter: rate.NewLimiter(rate.Limit(retryPerSecond), retryPerSecond),
leaderc: make(chan struct{}),
}
wp.ranges = newWatchRanges(wp)
go func() {
// a new streams without opening any watchers won't catch
// a lost leader event, so have a special watch to monitor it
rev := int64((uint64(1) << 63) - 2)
for wp.ctx.Err() == nil {
wch := wp.cw.Watch(wp.ctx, lostLeaderKey, clientv3.WithRev(rev))
for range wch {
}
wp.mu.Lock()
close(wp.leaderc)
wp.leaderc = make(chan struct{})
wp.mu.Unlock()
wp.retryLimiter.Wait(wp.ctx)
}
wp.mu.Lock()
<-wp.ctx.Done()
wp.mu.Unlock()
wp.wg.Wait()
wp.ranges.stop()
}()
return wp
}
func NewWatchProxy(c *clientv3.Client) pb.WatchServer {
wp := &watchProxy{
cw: c.Watcher,
wgs: watchergroups{
cw: c.Watcher,
groups: make(map[watchRange]*watcherGroup),
idToGroup: make(map[receiverID]*watcherGroup),
proxyCtx: c.Ctx(),
},
ctx: c.Ctx(),
}
go func() {
<-wp.ctx.Done()
wp.wgs.stop()
}()
return wp
}
func getLeader(etcdClient *clientv3.Client, path string) (string, int64, error) {
kv := clientv3.NewKV(etcdClient)
ctx, cancel := context.WithTimeout(etcdClient.Ctx(), requestTimeout)
resp, err := kv.Get(ctx, path)
cancel()
if err != nil {
return "", 0, errors.Trace(err)
}
if len(resp.Kvs) != 1 {
return "", 0, errors.Errorf("invalid getLeader resp: %v", resp)
}
var leader pdpb.Leader
if err = leader.Unmarshal(resp.Kvs[0].Value); err != nil {
return "", 0, errors.Trace(err)
}
return leader.GetAddr(), resp.Header.Revision, nil
}
// NewSession gets the leased session for a client.
func NewSession(client *v3.Client) (*Session, error) {
clientSessions.mu.Lock()
defer clientSessions.mu.Unlock()
if s, ok := clientSessions.sessions[client]; ok {
return s, nil
}
resp, err := client.Grant(client.Ctx(), sessionTTL)
if err != nil {
return nil, err
}
id := v3.LeaseID(resp.ID)
ctx, cancel := context.WithCancel(client.Ctx())
keepAlive, err := client.KeepAlive(ctx, id)
if err != nil || keepAlive == nil {
return nil, err
}
donec := make(chan struct{})
s := &Session{client: client, id: id, cancel: cancel, donec: donec}
clientSessions.sessions[client] = s
// keep the lease alive until client error or cancelled context
go func() {
defer func() {
clientSessions.mu.Lock()
delete(clientSessions.sessions, client)
clientSessions.mu.Unlock()
close(donec)
}()
for range keepAlive {
// eat messages until keep alive channel closes
}
}()
return s, nil
}