ActiveGo 1.8Package concurrency
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var (
ErrElectionNotLeader = errors.New("election: not leader")
ErrElectionNoLeader = errors.New("election: no leader")
)
func NewLocker ¶
func NewLocker(s *Session, pfx string) sync.Locker
NewLocker creates a sync.Locker backed by an etcd mutex.
func NewSTM ¶
func NewSTM(c *v3.Client, apply func(STM) error, so ...stmOption) (*v3.TxnResponse, error)
NewSTM initiates a new STM instance, using snapshot isolation by default.
func NewSTMReadCommitted ¶
func NewSTMReadCommitted(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error)
NewSTMReadCommitted is deprecated.
func NewSTMRepeatable ¶
func NewSTMRepeatable(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error)
NewSTMRepeatable is deprecated.
func NewSTMSerializable ¶
func NewSTMSerializable(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error)
NewSTMSerializable is deprecated.
func WithAbortContext ¶
func WithAbortContext(ctx context.Context) stmOption
WithAbortContext specifies the context for permanently aborting the transaction.
func WithIsolation ¶
func WithIsolation(lvl Isolation) stmOption
WithIsolation specifies the transaction isolation level.
func WithPrefetch ¶
func WithPrefetch(keys ...string) stmOption
WithPrefetch is a hint to prefetch a list of keys before trying to apply. If an STM transaction will unconditionally fetch a set of keys, prefetching those keys will save the round-trip cost from requesting each key one by one with Get().
type Election ¶
type Election struct {
// contains filtered or unexported fields
}
func NewElection ¶
func NewElection(s *Session, pfx string) *Election
NewElection returns a new election on a given key prefix.
func ResumeElection ¶
func ResumeElection(s *Session, pfx string, leaderKey string, leaderRev int64) *Election
ResumeElection initializes an election with a known leader.
func (*Election) Campaign ¶
func (e *Election) Campaign(ctx context.Context, val string) error
Campaign puts a value as eligible for the election. It blocks until it is elected, an error occurs, or the context is cancelled.
func (*Election) Header ¶
func (m *Election) Header() *pb.ResponseHeader
Header is the response header from the last successful election proposal.
func (*Election) Key ¶
func (e *Election) Key() string
Key returns the leader key if elected, empty string otherwise.
func (*Election) Leader ¶
func (e *Election) Leader(ctx context.Context) (*v3.GetResponse, error)
Leader returns the leader value for the current election.
func (*Election) Observe ¶
func (e *Election) Observe(ctx context.Context) <-chan v3.GetResponse
Observe returns a channel that reliably observes ordered leader proposals as GetResponse values on every current elected leader key. It will not necessarily fetch all historical leader updates, but will always post the most recent leader value.
The channel closes when the context is canceled or the underlying watcher is otherwise disrupted.
func (*Election) Proclaim ¶
func (e *Election) Proclaim(ctx context.Context, val string) error
Proclaim lets the leader announce a new value without another election.
func (*Election) Resign ¶
func (e *Election) Resign(ctx context.Context) (err error)
Resign lets a leader start a new election.
func (*Election) Rev ¶
func (e *Election) Rev() int64
Rev returns the leader key's creation revision, if elected.
type Isolation ¶
Isolation is an enumeration of transactional isolation levels which describes how transactions should interfere and conflict.
type Isolation int
const (
// SerializableSnapshot provides serializable isolation and also checks
// for write conflicts.
SerializableSnapshot Isolation = iota
// Serializable reads within the same transactiona attempt return data
// from the at the revision of the first read.
Serializable
// RepeatableReads reads within the same transaction attempt always
// return the same data.
RepeatableReads
// ReadCommitted reads keys from any committed revision.
ReadCommitted
)
type Mutex ¶
Mutex implements the sync Locker interface with etcd
type Mutex struct {
// contains filtered or unexported fields
}
func NewMutex ¶
func NewMutex(s *Session, pfx string) *Mutex
func (*Mutex) Header ¶
func (m *Mutex) Header() *pb.ResponseHeader
Header is the response header received from etcd on acquiring the lock.
func (*Mutex) IsOwner ¶
func (m *Mutex) IsOwner() v3.Cmp
func (*Mutex) Key ¶
func (m *Mutex) Key() string
func (*Mutex) Lock ¶
func (m *Mutex) Lock(ctx context.Context) error
Lock locks the mutex with a cancelable context. If the context is canceled while trying to acquire the lock, the mutex tries to clean its stale lock entry.
func (*Mutex) Unlock ¶
func (m *Mutex) Unlock(ctx context.Context) error
type STM ¶
STM is an interface for software transactional memory.
type STM interface {
// Get returns the value for a key and inserts the key in the txn's read set.
// If Get fails, it aborts the transaction with an error, never returning.
Get(key ...string) string
// Put adds a value for a key to the write set.
Put(key, val string, opts ...v3.OpOption)
// Rev returns the revision of a key in the read set.
Rev(key string) int64
// Del deletes a key.
Del(key string)
// contains filtered or unexported methods
}
type Session ¶
Session represents a lease kept alive for the lifetime of a client. Fault-tolerant applications may use sessions to reason about liveness.
type Session struct {
// contains filtered or unexported fields
}
func NewSession ¶
func NewSession(client *v3.Client, opts ...SessionOption) (*Session, error)
NewSession gets the leased session for a client.
func (*Session) Client ¶
func (s *Session) Client() *v3.Client
Client is the etcd client that is attached to the session.
func (*Session) Close ¶
func (s *Session) Close() error
Close orphans the session and revokes the session lease.
func (*Session) Done ¶
func (s *Session) Done() <-chan struct{}
Done returns a channel that closes when the lease is orphaned, expires, or is otherwise no longer being refreshed.
func (*Session) Lease ¶
func (s *Session) Lease() v3.LeaseID
Lease is the lease ID for keys bound to the session.
func (*Session) Orphan ¶
func (s *Session) Orphan()
Orphan ends the refresh for the session lease. This is useful in case the state of the client connection is indeterminate (revoke would fail) or when transferring lease ownership.
type SessionOption ¶
SessionOption configures Session.
type SessionOption func(*sessionOptions)
func WithContext ¶
func WithContext(ctx context.Context) SessionOption
WithContext assigns a context to the session instead of defaulting to using the client context. This is useful for canceling NewSession and Close operations immediately without having to close the client. If the context is canceled before Close() completes, the session's lease will be abandoned and left to expire instead of being revoked.
func WithLease ¶
func WithLease(leaseID v3.LeaseID) SessionOption
WithLease specifies the existing leaseID to be used for the session. This is useful in process restart scenario, for example, to reclaim leadership from an election prior to restart.
func WithTTL ¶
func WithTTL(ttl int) SessionOption
WithTTL configures the session's TTL in seconds. If TTL is <= 0, the default 60 seconds TTL will be used.