Documentation
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Overview ¶
Package distlock provides Redis-backed distributed locking with two usage modes: fail-hard and fail-silent.
The locker wraps the bsm/redislock library and ensures locks are always released via defer, even if the handler panics. Lock release failures are logged as warnings but do not cause errors.
Basic usage (fail-hard):
locker := distlock.New(redisClient)
err := locker.WithLock(ctx, "resource:123", 30*time.Second, func() error {
// Exclusive access to resource:123 for 30 seconds
return updateResource()
})
if err != nil && errors.Is(err, distlock.ErrLockNotObtained) {
return fmt.Errorf("failed to acquire lock")
}
For background jobs that should silently skip if the lock is unavailable:
err := locker.TryWithLock(ctx, "job:cleanup", 5*time.Minute, cleanupHandler) // ErrLockNotObtained is swallowed and logged at debug level
Lock TTL is enforced by Redis; the handler should complete well before the TTL expires.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ErrLockNotObtained = redislock.ErrNotObtained
Functions ¶
This section is empty.
Types ¶
type Locker ¶
type Locker struct {
// contains filtered or unexported fields
}
func New ¶
func New(redisClient redis.UniversalClient) *Locker
func (*Locker) TryWithLock ¶
func (l *Locker) TryWithLock(ctx context.Context, key string, ttl time.Duration, handler func() error) error
Example ¶
ExampleLocker_TryWithLock shows fail-silent locking for background jobs: when the lock is unavailable the handler is skipped without an error. (Not run: requires a Redis server.)
client := redis.NewClient(&redis.Options{Addr: "localhost:6379"}) //nolint:exhaustruct
locker := distlock.New(client)
_ = locker.TryWithLock(context.Background(), "jobs:cleanup", 5*time.Minute, func() error {
// Runs only on the instance that obtained the lock.
return nil
})
func (*Locker) WithLock ¶
func (l *Locker) WithLock(ctx context.Context, key string, ttl time.Duration, handler func() error) error
Example ¶
ExampleLocker_WithLock shows fail-hard locking: the caller decides what to do when the lock is held elsewhere. (Not run: requires a Redis server.)
client := redis.NewClient(&redis.Options{Addr: "localhost:6379"}) //nolint:exhaustruct
locker := distlock.New(client)
err := locker.WithLock(context.Background(), "resource:123", 30*time.Second, func() error {
// Exclusive access to resource:123 for up to 30 seconds.
return nil
})
if errors.Is(err, distlock.ErrLockNotObtained) {
fmt.Println("another instance holds the lock")
}
Source Files