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dynalock.go
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dynalock.go
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package dynalock
import (
"context"
"errors"
"time"
)
const (
// DefaultLockTTL default duration for locks
DefaultLockTTL = 20 * time.Second
listDefaultTimeout = 5 * time.Second
noTTLSet = -1
)
var (
// ErrKeyNotFound record not found in the table
ErrKeyNotFound = errors.New("key not found in table")
// ErrKeyExists record already exists in table
ErrKeyExists = errors.New("key already exists in table")
// ErrKeyModified record has been modified, this probably means someone beat you to the change/lock
ErrKeyModified = errors.New("key has been modified")
// ErrLockAcquireCancelled lock acquire was cancelled
ErrLockAcquireCancelled = errors.New("lock acquire was cancelled")
// ErrLockAcquireFailed lock acquire failed due with polling disabled
ErrLockAcquireFailed = errors.New("failed to acquire lock")
)
// Store represents the backend K/V storage
type Store interface {
// Put a value at the specified key
Put(key string, options ...WriteOption) error
// Get a value given its key
Get(key string, options ...ReadOption) (*KVPair, error)
// List the content of a given prefix
List(prefix string, options ...ReadOption) ([]*KVPair, error)
// Delete the value at the specified key
Delete(key string) error
// Verify if a Key exists in the store
Exists(key string, options ...ReadOption) (bool, error)
// NewLock creates a lock for a given key.
// The returned Locker is not held and must be acquired
// with `.Lock`. The Value is optional.
NewLock(key string, options ...LockOption) (Locker, error)
// Atomic CAS operation on a single value.
// Pass previous = nil to create a new key.
// Pass previous = kv to update an existing value.
AtomicPut(key string, options ...WriteOption) (bool, *KVPair, error)
// Atomic delete of a single value
AtomicDelete(key string, previous *KVPair) (bool, error)
}
// Locker provides locking mechanism on top of the store.
// Similar to `sync.Lock` except it may return errors.
type Locker interface {
// Lock attempt to lock the store record, this will BLOCK and retry at a rate of once every 3 seconds
Lock(stopChan chan struct{}) (<-chan struct{}, error)
// Lock attempt to lock the store record, this will BLOCK and retry at a rate of once every 3 seconds
LockWithContext(ctx context.Context) (<-chan struct{}, error)
// Unlock this will unlock and perfom a DELETE to remove the store record
Unlock() error
}