Merge pull request #6698 from heyitsanthony/session-close
concurrency: terminate session.Close if revoke takes longer than TTLrelease-3.1
commit
ae99c91903
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@ -15,6 +15,8 @@
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package concurrency
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import (
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"time"
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v3 "github.com/coreos/etcd/clientv3"
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"golang.org/x/net/context"
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)
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@ -25,6 +27,7 @@ const defaultSessionTTL = 60
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// Fault-tolerant applications may use sessions to reason about liveness.
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type Session struct {
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client *v3.Client
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opts *sessionOptions
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id v3.LeaseID
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cancel context.CancelFunc
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@ -33,25 +36,25 @@ type Session struct {
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// NewSession gets the leased session for a client.
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func NewSession(client *v3.Client, opts ...SessionOption) (*Session, error) {
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ops := &sessionOptions{ttl: defaultSessionTTL}
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ops := &sessionOptions{ttl: defaultSessionTTL, ctx: client.Ctx()}
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for _, opt := range opts {
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opt(ops)
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}
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resp, err := client.Grant(client.Ctx(), int64(ops.ttl))
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resp, err := client.Grant(ops.ctx, int64(ops.ttl))
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if err != nil {
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return nil, err
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}
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id := v3.LeaseID(resp.ID)
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ctx, cancel := context.WithCancel(client.Ctx())
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ctx, cancel := context.WithCancel(ops.ctx)
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keepAlive, err := client.KeepAlive(ctx, id)
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if err != nil || keepAlive == nil {
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return nil, err
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}
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donec := make(chan struct{})
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s := &Session{client: client, id: id, cancel: cancel, donec: donec}
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s := &Session{client: client, opts: ops, id: id, cancel: cancel, donec: donec}
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// keep the lease alive until client error or cancelled context
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go func() {
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@ -87,12 +90,16 @@ func (s *Session) Orphan() {
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// Close orphans the session and revokes the session lease.
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func (s *Session) Close() error {
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s.Orphan()
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_, err := s.client.Revoke(s.client.Ctx(), s.id)
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// if revoke takes longer than the ttl, lease is expired anyway
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ctx, cancel := context.WithTimeout(s.opts.ctx, time.Duration(s.opts.ttl)*time.Second)
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_, err := s.client.Revoke(ctx, s.id)
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cancel()
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return err
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}
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type sessionOptions struct {
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ttl int
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ctx context.Context
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}
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// SessionOption configures Session.
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@ -107,3 +114,14 @@ func WithTTL(ttl int) SessionOption {
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}
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}
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}
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// WithContext assigns a context to the session instead of defaulting to
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// using the client context. This is useful for canceling NewSession and
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// Close operations immediately without having to close the client. If the
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// context is canceled before Close() completes, the session's lease will be
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// abandoned and left to expire instead of being revoked.
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func WithContext(ctx context.Context) SessionOption {
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return func(so *sessionOptions) {
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so.ctx = ctx
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}
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}
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