storage

Documentation

Overview

Package storage contains the interfaces for storing and retrieving data about the state of the mesh and maintaining consensus.

Index

• Variables
• func IsKeyNotFoundError(err error) bool
• func IsReservedPrefix(key []byte) bool
• func NewKeyNotFoundError(key []byte) error
• type Consensus
• type ConsensusStorage
• type DualStorage
• type MeshStorage
• type Prefix
  • func (p Prefix) Contains(key []byte) bool
  • func (p Prefix) For(key []byte) Prefix
  • func (p Prefix) ForString(key string) Prefix
  • func (p Prefix) String() string
  • func (p Prefix) TrimFrom(key []byte) []byte
• type PrefixIterator
• type Provider
• type SubscribeFunc

Variables

var (
	// ErrNotStorageNode is returned when a storage operation is attempted on a non-storage node.
	ErrNotStorageNode = fmt.Errorf("not a storage node")
	// ErrStarted is returned when the storage provider is already started.
	ErrStarted = fmt.Errorf("storage provider already started")
	// ErrClosed is returned when the storage provider is closed.
	ErrClosed = fmt.Errorf("storage provider is closed")
	// ErrNotImplemented is returned when a method is not implemented.
	ErrNotImplemented = fmt.Errorf("not implemented")
	// ErrNoLeader is returned when there is no leader.
	ErrNoLeader = fmt.Errorf("no leader")
	// ErrNotLeader is returned when the node is not the leader.
	ErrNotLeader = fmt.Errorf("not leader")
	// ErrNotVoter is returned when the node is not a voter.
	ErrNotVoter = fmt.Errorf("not voter")
	// ErrAlreadyBootstrapped is returned when the storage provider is already bootstrapped.
	ErrAlreadyBootstrapped = fmt.Errorf("already bootstrapped")
	// ErrKeyNotFound is the error returned when a key is not found.
	ErrKeyNotFound = errors.New("key not found")
	// ErrInvalidKey is the error returned when a key is invalid.
	ErrInvalidKey = errors.New("invalid key")
	// ErrInvalidPrefix is the error returned when a prefix is invalid.
	ErrInvalidPrefix = errors.New("invalid prefix")
)

Common errors for storage providers to use.

var ReservedPrefixes = []Prefix{
	RegistryPrefix,
	ConsensusPrefix,
}

ReservedPrefixes is a list of all reserved prefixes.

Functions

func IsKeyNotFoundError

func IsKeyNotFoundError(err error) bool

IsKeyNotFoundError returns true if the given error is a ErrKeyNotFound error.

func IsReservedPrefix

func IsReservedPrefix(key []byte) bool

IsReservedPrefix returns true if the given key is reserved.

func NewKeyNotFoundError

func NewKeyNotFoundError(key []byte) error

NewKeyNotFoundError returns a new ErrKeyNotFound error.

Types

type Consensus

type Consensus interface {
	// IsLeader returns true if the node is the leader of the storage group.
	IsLeader() bool
	// IsMember returns true if the node is a member of the storage group.
	IsMember() bool
	// GetPeers returns the peers of the storage group.
	GetPeers(context.Context) ([]*v1.StoragePeer, error)
	// GetLeader returns the leader of the storage group.
	GetLeader(context.Context) (*v1.StoragePeer, error)
	// AddVoter adds a voter to the consensus group.
	AddVoter(context.Context, *v1.StoragePeer) error
	// AddObserver adds an observer to the consensus group.
	AddObserver(context.Context, *v1.StoragePeer) error
	// DemoteVoter demotes a voter to an observer.
	DemoteVoter(context.Context, *v1.StoragePeer) error
	// RemovePeer removes a peer from the consensus group. If wait
	// is true, the function will wait for the peer to be removed.
	RemovePeer(ctx context.Context, peer *v1.StoragePeer, wait bool) error
}

Consensus is the interface for configuring storage consensus.

type ConsensusStorage

type ConsensusStorage interface {
	io.Closer
	raft.LogStore
	raft.StableStore

	// Snapshot returns a snapshot of the storage.
	Snapshot(ctx context.Context) (io.Reader, error)
	// Restore restores a snapshot of the storage.
	Restore(ctx context.Context, r io.Reader) error
}

ConsensusStorage is the interface for storing and retrieving data about the state of consensus. This is currently only used by the built-in raftstorage implementation.

type DualStorage

type DualStorage interface {
	MeshStorage
	ConsensusStorage
}

DualStorage represents a storage interface that can serve as both a mesh and consensus storage.

type MeshStorage

type MeshStorage interface {
	io.Closer

	// GetValue returns the value of a key.
	GetValue(ctx context.Context, key []byte) ([]byte, error)
	// PutValue sets the value of a key. TTL is optional and can be set to 0.
	PutValue(ctx context.Context, key, value []byte, ttl time.Duration) error
	// Delete removes a key.
	Delete(ctx context.Context, key []byte) error
	// ListKeys returns all keys with a given prefix.
	ListKeys(ctx context.Context, prefix []byte) ([][]byte, error)
	// IterPrefix iterates over all keys with a given prefix. It is important
	// that the iterator not attempt any write operations as this will cause
	// a deadlock. The iteration will stop if the iterator returns an error.
	IterPrefix(ctx context.Context, prefix []byte, fn PrefixIterator) error
	// Subscribe will call the given function whenever a key with the given prefix is changed.
	// The returned function can be called to unsubscribe.
	Subscribe(ctx context.Context, prefix []byte, fn SubscribeFunc) (context.CancelFunc, error)
}

MeshStorage is the interface for storing and retrieving data about the state of the mesh.

type Prefix

type Prefix []byte

Prefix is a prefix in the storage.

var (
	// RegistryPrefix is the prefix for all data stored in the mesh registry.
	RegistryPrefix Prefix = []byte("/registry")

	// ConsensusPrefix is the prefix for all data stored related to consensus.
	ConsensusPrefix Prefix = []byte("/raft")
)

func (Prefix) Contains

func (p Prefix) Contains(key []byte) bool

Contains returns true if the given key is contained in the prefix.

func (Prefix) For

func (p Prefix) For(key []byte) Prefix

For is a helper method for creating a key for the prefix.

func (Prefix) ForString

func (p Prefix) ForString(key string) Prefix

ForString is a helper method for creating a key for the prefix.

func (Prefix) String

func (p Prefix) String() string

String returns the string representation of the prefix.

func (Prefix) TrimFrom

func (p Prefix) TrimFrom(key []byte) []byte

TrimFrom returns the key without the prefix.

type PrefixIterator

type PrefixIterator func(key, value []byte) error

PrefixIterator is the function signature for iterating over all keys with a given prefix.

type Provider

type Provider interface {
	// Close should close the underlying storage as well as any other resources
	// that the provider may have allocated.
	io.Closer

	// MeshStorage returns the underlying MeshStorage instance. The provider does not
	// need to guarantee consistency on read operations.
	MeshStorage() MeshStorage
	// Consensus returns the underlying Consensus instance.
	Consensus() Consensus

	// Start should start the provider and any resources that it may need.
	Start(context.Context) error
	// Bootstrap should bootstrap the provider for first-time usage.
	Bootstrap(context.Context) error
	// Status returns the status of the storage provider.
	Status() *v1.StorageStatus
	// ListenPort should return the TCP port that the storage provider is listening on.
	ListenPort() uint16
}

Provider is a provider of MeshStorage.

type SubscribeFunc

type SubscribeFunc func(key, value []byte)

SubscribeFunc is the function signature for subscribing to changes to a key.