dotcloud/docker

package kvstore

import (
    "errors"
    "time"
)

// Backend represents a KV Store Backend
type Backend string

// BOLTDB backend
const BOLTDB Backend = "boltdb"

var (
    // ErrBackendNotSupported is thrown when the backend k/v store is not supported by libkv
    ErrBackendNotSupported = errors.New("Backend storage not supported yet, please choose one of")
    // ErrKeyModified is thrown during an atomic operation if the index does not match the one in the store
    ErrKeyModified = errors.New("Unable to complete atomic operation, key modified")
    // ErrKeyNotFound is thrown when the key is not found in the store during a Get operation
    ErrKeyNotFound = errors.New("Key not found in store")
    // ErrPreviousNotSpecified is thrown when the previous value is not specified for an atomic operation
    ErrPreviousNotSpecified = errors.New("Previous K/V pair should be provided for the Atomic operation")
    // ErrKeyExists is thrown when the previous value exists in the case of an AtomicPut
    ErrKeyExists = errors.New("Previous K/V pair exists, cannot complete Atomic operation")
)

// Config contains the options for a storage client
type Config struct {
    ConnectionTimeout time.Duration
    Bucket            string
}

// Store represents the backend K/V storage
// Each store should support every call listed
// here. Or it couldn't be implemented as a K/V
// backend for libkv
type Store interface {
    // Put a value at the specified key
    Put(key string, value []byte) error

    // Exists verifies if a Key exists in the store.
    Exists(key string) (bool, error)

    // List the content of a given prefix
    List(directory string) ([]*KVPair, error)

    // AtomicPut performs an atomic CAS operation on a single value.
    // Pass previous = nil to create a new key.
    AtomicPut(key string, value []byte, previous *KVPair) (*KVPair, error)

    // AtomicDelete performs an atomic delete of a single value.
    AtomicDelete(key string, previous *KVPair) error

    // Delete deletes a value at "key". Unlike AtomicDelete it doesn't check
    // whether the deleted key is at a specific version before deleting.
    Delete(key string) error

    // Close the store connection
    Close()
}

// KVPair represents {Key, Value, Lastindex} tuple
type KVPair struct {
    Key       string
    Value     []byte
    LastIndex uint64
}