sorted

Documentation

Overview

Package sorted provides a KeyValue interface and constructor registry.

Index

• Constants
• Variables
• func CheckSizes(key, value string) error
• func Foreach(kv KeyValue, fn func(key, value string) error) error
• func ForeachInRange(kv KeyValue, start, end string, fn func(key, value string) error) error
• func RegisterKeyValue(typ string, fn func(jsonconfig.Obj) (KeyValue, error))
• type BatchMutation
  • func NewBatchMutation() BatchMutation
• type Iterator
• type KeyValue
  • func NewKeyValue(cfg jsonconfig.Obj) (KeyValue, error)
  • func NewKeyValueMaybeWipe(cfg jsonconfig.Obj) (KeyValue, error)
  • func NewMemoryKeyValue() KeyValue
• type Mutation
• type NeedWipeError
  • func (e NeedWipeError) Error() string
• type Wiper

Constants

const (
	MaxKeySize   = 767   // Maximum size, in bytes, for a key in any store implementing KeyValue.
	MaxValueSize = 63000 // Maximum size, in bytes, for a value in any store implementing KeyValue. MaxKeySize and MaxValueSize values originate from InnoDB and MySQL limitations.
)

const DefaultKVFileType = "leveldb"

Variables

var (
	ErrNotFound      = errors.New("sorted: key not found")
	ErrKeyTooLarge   = fmt.Errorf("sorted: key size is over %v", MaxKeySize)
	ErrValueTooLarge = fmt.Errorf("sorted: value size is over %v", MaxValueSize)
)

Functions

func CheckSizes

func CheckSizes(key, value string) error

CheckSizes returns ErrKeyTooLarge if key does not respect KeyMaxSize or ErrValueTooLarge if value does not respect ValueMaxSize

func Foreach

func Foreach(kv KeyValue, fn func(key, value string) error) error

Foreach runs fn for each key/value pair in kv. If fn returns an error, that same error is returned from Foreach and iteration stops.

func ForeachInRange

func ForeachInRange(kv KeyValue, start, end string, fn func(key, value string) error) error

ForeachInRange runs fn for each key/value pair in kv in the range of start and end, which behave the same as kv.Find. If fn returns an error, that same error is returned from Foreach and iteration stops.

func RegisterKeyValue

func RegisterKeyValue(typ string, fn func(jsonconfig.Obj) (KeyValue, error))

Types

type BatchMutation

type BatchMutation interface {
	Set(key, value string)
	Delete(key string)
}

func NewBatchMutation

func NewBatchMutation() BatchMutation

type Iterator

type Iterator interface {
	// Next moves the iterator to the next key/value pair.
	// It returns false when the iterator is exhausted.
	Next() bool

	// Key returns the key of the current key/value pair.
	// Only valid after a call to Next returns true.
	Key() string

	// KeyBytes returns the key as bytes. The returned bytes
	// should not be written and are invalid after the next call
	// to Next or Close.
	// TODO(bradfitz): rename this and change it to return a
	// mem.RO instead?
	KeyBytes() []byte

	// Value returns the value of the current key/value pair.
	// Only valid after a call to Next returns true.
	Value() string

	// ValueBytes returns the value as bytes. The returned bytes
	// should not be written and are invalid after the next call
	// to Next or Close.
	// TODO(bradfitz): rename this and change it to return a
	// mem.RO instead?
	ValueBytes() []byte

	// Close closes the iterator and returns any accumulated error. Exhausting
	// all the key/value pairs in a table is not considered to be an error.
	// It is valid to call Close multiple times. Other methods should not be
	// called after the iterator has been closed.
	Close() error
}

Iterator iterates over an index KeyValue's key/value pairs in key order.

An iterator must be closed after use, but it is not necessary to read an iterator until exhaustion.

An iterator is not necessarily goroutine-safe, but it is safe to use multiple iterators concurrently, with each in a dedicated goroutine.

type KeyValue

type KeyValue interface {
	// Get gets the value for the given key. It returns ErrNotFound if the DB
	// does not contain the key.
	Get(key string) (string, error)

	Set(key, value string) error

	// Delete deletes keys. Deleting a non-existent key does not return an error.
	Delete(key string) error

	BeginBatch() BatchMutation
	CommitBatch(b BatchMutation) error

	// Find returns an iterator positioned before the first key/value pair
	// whose key is 'greater than or equal to' the given key. There may be no
	// such pair, in which case the iterator will return false on Next.
	//
	// The optional end value specifies the exclusive upper
	// bound. If the empty string, the iterator returns keys
	// where "key >= start".
	// If non-empty, the iterator returns keys where
	// "key >= start && key < endHint".
	//
	// Any error encountered will be implicitly returned via the iterator. An
	// error-iterator will yield no key/value pairs and closing that iterator
	// will return that error.
	Find(start, end string) Iterator

	// Close is a polite way for the server to shut down the storage.
	// Implementations should never lose data after a Set, Delete,
	// or CommmitBatch, though.
	Close() error
}

KeyValue is a sorted, enumerable key-value interface supporting batch mutations.

func NewKeyValue

func NewKeyValue(cfg jsonconfig.Obj) (KeyValue, error)

NewKeyValue returns a KeyValue as defined by cfg. It returns an error of type NeedWipeError when the returned KeyValue should be fixed with Wipe.

func NewKeyValueMaybeWipe

func NewKeyValueMaybeWipe(cfg jsonconfig.Obj) (KeyValue, error)

NewKeyValueMaybeWipe calls NewKeyValue and wipes the KeyValue if, and only if, NewKeyValue has returned a NeedWipeError.

func NewMemoryKeyValue

func NewMemoryKeyValue() KeyValue

NewMemoryKeyValue returns a KeyValue implementation that's backed only by memory. It's mostly useful for tests and development.

type Mutation

type Mutation interface {
	Key() string
	Value() string
	IsDelete() bool
}

type NeedWipeError

type NeedWipeError struct {
	Msg string
}

NeedWipeError is returned by NewKeyValue when the returned KeyValue is not usable until Wipe has been called on it.

func (NeedWipeError) Error

func (e NeedWipeError) Error() string

type Wiper

type Wiper interface {
	KeyValue

	// Wipe removes all key/value pairs, and resets the storage to a blank state.
	// For a given storage, when NewKeyValue returns a NeedWipeError, Wipe
	// should be implemented so that it fixes the returned KeyValue.
	Wipe() error
}

Wiper is an optional interface that may be implemented by storage implementations.