service

package
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Published: Oct 22, 2020 License: MIT Imports: 14 Imported by: 0

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Index

Constants

This section is empty.

Variables

View Source
var (
	// ErrNotObtained is returned when a lock cannot be obtained.
	ErrNotObtained = errors.New("redislock: not obtained")

	// ErrLockNotHeld is returned when trying to release an inactive lock.
	ErrLockNotHeld = errors.New("redislock: lock not held")
)
View Source
var MAX_HOUR int
View Source
var MAX_MINUTE int
View Source
var (
	RateLimiter = ratelimiter{}
)

Functions

This section is empty.

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client wraps a redis client.

func NewRedisLock

func NewRedisLock(client *_redis.Client) *Client

New creates a new Client instance with a custom namespace.

func (*Client) Obtain

func (c *Client) Obtain(key string, ttl time.Duration, opt *Options) (*Lock, error)

Obtain tries to obtain a new lock using a key with the given TTL. May return ErrNotObtained if not successful.

type Lock

type Lock struct {
	// contains filtered or unexported fields
}

Lock represents an obtained, distributed lock.

func Obtain

func Obtain(client *_redis.Client, key string, ttl time.Duration, opt *Options) (*Lock, error)

Obtain is a short-cut for New(...).Obtain(...).

func (*Lock) Key

func (l *Lock) Key() string

Key returns the redis key used by the lock.

func (*Lock) Metadata

func (l *Lock) Metadata() string

Metadata returns the metadata of the lock.

func (*Lock) Refresh

func (l *Lock) Refresh(ttl time.Duration, opt *Options) error

Refresh extends the lock with a new TTL. May return ErrNotObtained if refresh is unsuccessful.

func (*Lock) Release

func (l *Lock) Release() error

Release manually releases the lock. May return ErrLockNotHeld.

func (*Lock) TTL

func (l *Lock) TTL() (time.Duration, error)

TTL returns the remaining time-to-live. Returns 0 if the lock has expired.

func (*Lock) Token

func (l *Lock) Token() string

Token returns the token value set by the lock.

type Options

type Options struct {
	// RetryStrategy allows to customise the lock retry strategy.
	// Default: do not retry
	RetryStrategy RetryStrategy

	// Metadata string is appended to the lock token.
	Metadata string

	// Context provides an optional context for timeout and cancellation control.
	// If requested, Obtain will by default retry until the TTL exires. This
	// behaviour can be tweaked with a custom context deadline.
	Context context.Context
}

Options describe the options for the lock

type RedisClient

type RedisClient interface {
	SetNX(ctx context.Context, key string, value interface{}, expiration time.Duration) *redis.BoolCmd
	Eval(ctx context.Context, script string, keys []string, args ...interface{}) *redis.Cmd
	EvalSha(ctx context.Context, sha1 string, keys []string, args ...interface{}) *redis.Cmd
	ScriptExists(ctx context.Context, scripts ...string) *redis.BoolSliceCmd
	ScriptLoad(ctx context.Context, script string) *redis.StringCmd
}

RedisClient is a minimal client interface.

type RetryStrategy

type RetryStrategy interface {
	// NextBackoff returns the next backoff duration.
	NextBackoff() time.Duration
}

RetryStrategy allows to customise the lock retry strategy.

func ExponentialBackoff

func ExponentialBackoff(min, max time.Duration) RetryStrategy

ExponentialBackoff strategy is an optimization strategy with a retry time of 2**n milliseconds (n means number of times). You can set a minimum and maximum value, the recommended minimum value is not less than 16ms.

func LimitRetry

func LimitRetry(s RetryStrategy, max int) RetryStrategy

LimitRetry limits the number of retries to max attempts.

func LinearBackoff

func LinearBackoff(backoff time.Duration) RetryStrategy

LinearBackoff allows retries regularly with customized intervals

func NoRetry

func NoRetry() RetryStrategy

NoRetry acquire the lock only once.

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