storj/storage/common.go
Egon Elbre 83df0ee1b0
Implement ListV2 with storage rework (#303)
1. Added KeyValueStore.Iterate for implementing the different List, ListV2 etc. implementations. This allows for more efficient use of memory depending on the situation.
2. Implemented an inmemory teststore for running tests. This should allow to replace MockKeyValueStore in most places.
3. Rewrote tests
4. Pulled out logger from bolt implementation so it can be used for all other storage implementations.
5. Fixed multiple things in bolt and redis implementations.
2018-09-05 19:10:35 +03:00

159 lines
4.2 KiB
Go

// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.
package storage
import (
"bytes"
"errors"
"github.com/zeebo/errs"
)
// Delimiter separates nested paths in storage
const Delimiter = '/'
//ErrKeyNotFound used When something doesn't exist
var ErrKeyNotFound = errs.Class("key not found")
// ErrEmptyKey is returned when an empty key is used in Put
var ErrEmptyKey = errors.New("empty key")
// Key is the type for the keys in a `KeyValueStore`
type Key []byte
// Value is the type for the values in a `ValueValueStore`
type Value []byte
// Keys is the type for a slice of keys in a `KeyValueStore`
type Keys []Key
// Values is the type for a slice of Values in a `KeyValueStore`
type Values []Value
// Limit indicates how many keys to return when calling List
type Limit int
// Items keeps all ListItem
type Items []ListItem
// ListItem returns Key, Value, IsPrefix
type ListItem struct {
Key Key
Value Value
IsPrefix bool
}
// KeyValueStore is an interface describing key/value stores like redis and boltdb
type KeyValueStore interface {
// Put adds a value to store
Put(Key, Value) error
// Get gets a value to store
Get(Key) (Value, error)
// GetAll gets all values from the store
GetAll(Keys) (Values, error)
// Delete deletes key and the value
Delete(Key) error
// List lists all keys starting from start and upto limit items
List(start Key, limit Limit) (Keys, error)
// ReverseList lists all keys in revers order
ReverseList(Key, Limit) (Keys, error)
// Iterate iterates over items based on opts
Iterate(opts IterateOptions, fn func(Iterator) error) error
// Close closes the store
Close() error
}
// IterateOptions contains options for iterator
type IterateOptions struct {
// Prefix ensure
Prefix Key
// First will be the first item iterator returns or the next item (previous when reverse)
First Key
// Recurse, do not collapse items based on Delimiter
Recurse bool
// Reverse iterates in reverse order
Reverse bool
}
// Iterator iterates over a sequence of ListItems
type Iterator interface {
// Next prepares the next list item
// returns false when you reach final item
Next(item *ListItem) bool
}
// IsZero returns true if the value struct is it's zero value
func (value Value) IsZero() bool {
return len(value) == 0
}
// IsZero returns true if the key struct is it's zero value
func (key Key) IsZero() bool {
return len(key) == 0
}
// MarshalBinary implements the encoding.BinaryMarshaler interface for the Value type
func (value Value) MarshalBinary() ([]byte, error) {
return value, nil
}
// MarshalBinary implements the encoding.BinaryMarshaler interface for the Key type
func (key Key) MarshalBinary() ([]byte, error) {
return key, nil
}
// ByteSlices converts a `Keys` struct to a slice of byte-slices (i.e. `[][]byte`)
func (keys Keys) ByteSlices() [][]byte {
result := make([][]byte, len(keys))
for key, val := range keys {
result[key] = []byte(val)
}
return result
}
// String implements the Stringer interface
func (key Key) String() string { return string(key) }
// Strings returns everything as strings
func (keys Keys) Strings() []string {
strs := make([]string, 0, len(keys))
for _, key := range keys {
strs = append(strs, string(key))
}
return strs
}
// GetKeys gets all the Keys in []ListItem and converts them to Keys
func (items Items) GetKeys() Keys {
if len(items) == 0 {
return nil
}
var keys Keys
for _, item := range items {
keys = append(keys, item.Key)
}
return keys
}
// Len is the number of elements in the collection.
func (items Items) Len() int { return len(items) }
// Less reports whether the element with
// index i should sort before the element with index j.
func (items Items) Less(i, k int) bool { return items[i].Less(items[k]) }
// Swap swaps the elements with indexes i and j.
func (items Items) Swap(i, k int) { items[i], items[k] = items[k], items[i] }
// Less returns whether item should be sorted before b
func (item ListItem) Less(b ListItem) bool { return item.Key.Less(b.Key) }
// Less returns whether key should be sorted before b
func (key Key) Less(b Key) bool { return bytes.Compare([]byte(key), []byte(b)) < 0 }
// Equal returns whether key and b are equal
func (key Key) Equal(b Key) bool { return bytes.Equal([]byte(key), []byte(b)) }