Version: v1.2.0 Latest Latest

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Published: May 14, 2021 License: MIT Imports: 2 Imported by: 13


State Stores

State Stores provide a common way to interact with different data store implementations, and allow users to opt-in to advanced capabilities using defined metadata.

Currently supported state stores are:

  • AWS DynamoDB
  • Aerospike
  • Azure Blob Storage
  • Azure CosmosDB
  • Azure Table Storage
  • Cassandra
  • Cloud Firestore (Datastore mode)
  • CloudState
  • Couchbase
  • Etcd
  • HashiCorp Consul
  • Hazelcast
  • Memcached
  • MongoDB
  • PostgreSQL
  • Redis
  • RethinkDB
  • SQL Server
  • Zookeeper

Implementing a new State Store

A compliant state store needs to implement one or more interfaces: Store and TransactionalStore.

The interface for Store:

type Store interface {
	Init(metadata Metadata) error
	Delete(req *DeleteRequest) error
	BulkDelete(req []DeleteRequest) error
	Get(req *GetRequest) (*GetResponse, error)
	Set(req *SetRequest) error
	BulkSet(req []SetRequest) error

The interface for TransactionalStore:

type TransactionalStore interface {
	Init(metadata Metadata) error
	Multi(reqs []TransactionalRequest) error

See the documentation site for examples.




View Source
const (
	FirstWrite = "first-write"
	LastWrite  = "last-write"
	Strong     = "strong"
	Eventual   = "eventual"


This section is empty.


func CheckRequestOptions added in v0.3.0

func CheckRequestOptions(options interface{}) error

CheckRequestOptions checks if request options use supported keywords

func DeleteWithOptions added in v0.3.0

func DeleteWithOptions(method func(req *DeleteRequest) error, req *DeleteRequest) error

DeleteWithOptions handles DeleteRequest with options

func SetWithOptions added in v0.3.0

func SetWithOptions(method func(req *SetRequest) error, req *SetRequest) error

SetWithOptions handles SetRequest with request options


type BulkGetResponse added in v1.0.0

type BulkGetResponse struct {
	Key      string            `json:"key"`
	Data     []byte            `json:"data"`
	ETag     *string           `json:"etag,omitempty"`
	Metadata map[string]string `json:"metadata"`
	Error    string            `json:"error,omitempty"`

BulkGetResponse is the response object for bulk get response.

type BulkStore added in v1.0.0

type BulkStore interface {
	BulkDelete(req []DeleteRequest) error
	BulkGet(req []GetRequest) (bool, []BulkGetResponse, error)
	BulkSet(req []SetRequest) error

BulkStore is an interface to perform bulk operations on store

type DefaultBulkStore added in v1.0.0

type DefaultBulkStore struct {
	// contains filtered or unexported fields

DefaultBulkStore is a default implementation of BulkStore

func NewDefaultBulkStore added in v1.0.0

func NewDefaultBulkStore(store Store) DefaultBulkStore

NewDefaultBulkStore build a default bulk store

func (*DefaultBulkStore) BulkDelete added in v1.0.0

func (b *DefaultBulkStore) BulkDelete(req []DeleteRequest) error

BulkDelete performs a bulk delete operation

func (*DefaultBulkStore) BulkGet added in v1.0.0

func (b *DefaultBulkStore) BulkGet(req []GetRequest) (bool, []BulkGetResponse, error)

BulkGet performs a bulks get operations

func (*DefaultBulkStore) BulkSet added in v1.0.0

func (b *DefaultBulkStore) BulkSet(req []SetRequest) error

BulkSet performs a bulks save operation

func (*DefaultBulkStore) Features added in v1.1.1

func (b *DefaultBulkStore) Features() []Feature

Features returns the features of the encapsulated store

type DeleteRequest

type DeleteRequest struct {
	Key      string            `json:"key"`
	ETag     *string           `json:"etag,omitempty"`
	Metadata map[string]string `json:"metadata"`
	Options  DeleteStateOption `json:"options,omitempty"`

DeleteRequest is the object describing a delete state request

func (DeleteRequest) GetKey added in v0.2.0

func (r DeleteRequest) GetKey() string

Key gets the Key on a DeleteRequest

func (DeleteRequest) GetMetadata added in v0.2.0

func (r DeleteRequest) GetMetadata() map[string]string

Metadata gets the Metadata on a DeleteRequest

type DeleteStateOption

type DeleteStateOption struct {
	Concurrency string `json:"concurrency,omitempty"` // "concurrency"
	Consistency string `json:"consistency"`           // "eventual, strong"

DeleteStateOption controls how a state store reacts to a delete request

type ETagError added in v1.0.0

type ETagError struct {
	// contains filtered or unexported fields

ETagError is a custom error type for etag exceptions

func NewETagError added in v1.0.0

func NewETagError(kind ETagErrorKind, err error) *ETagError

NewETagError returns an ETagError wrapping an existing context error

func (*ETagError) Error added in v1.0.0

func (e *ETagError) Error() string

func (*ETagError) Kind added in v1.0.0

func (e *ETagError) Kind() ETagErrorKind

type ETagErrorKind added in v1.0.0

type ETagErrorKind string
const (
	ETagInvalid  ETagErrorKind = "invalid"
	ETagMismatch ETagErrorKind = "mismatch"

type Feature added in v1.1.1

type Feature string

Feature names a feature that can be implemented by PubSub components.

const (
	// FeatureETag is the feature to etag metadata in state store.
	FeatureETag Feature = "ETAG"
	// FeatureTransactional is the feature that performs transactional operations.
	FeatureTransactional Feature = "TRANSACTIONAL"

func (Feature) IsPresent added in v1.1.1

func (f Feature) IsPresent(features []Feature) bool

IsPresent checks if a given feature is present in the list.

type GetRequest

type GetRequest struct {
	Key      string            `json:"key"`
	Metadata map[string]string `json:"metadata"`
	Options  GetStateOption    `json:"options,omitempty"`

GetRequest is the object describing a state fetch request

type GetResponse

type GetResponse struct {
	Data     []byte            `json:"data"`
	ETag     *string           `json:"etag,omitempty"`
	Metadata map[string]string `json:"metadata"`

GetResponse is the request object for getting state

type GetStateOption

type GetStateOption struct {
	Consistency string `json:"consistency"` // "eventual, strong"

GetStateOption controls how a state store reacts to a get request

type KeyInt added in v0.2.0

type KeyInt interface {
	GetKey() string
	GetMetadata() map[string]string

KeyInt is an interface that allows gets of the Key and Metadata inside requests

type Metadata

type Metadata struct {
	Properties map[string]string `json:"properties"`

Metadata contains a state store specific set of metadata properties

type OperationType

type OperationType string

OperationType describes a CRUD operation performed against a state store

const Delete OperationType = "delete"

Delete is a delete operation

const Upsert OperationType = "upsert"

Upsert is an update or create operation

type SetRequest

type SetRequest struct {
	Key      string            `json:"key"`
	Value    interface{}       `json:"value"`
	ETag     *string           `json:"etag,omitempty"`
	Metadata map[string]string `json:"metadata,omitempty"`
	Options  SetStateOption    `json:"options,omitempty"`

SetRequest is the object describing an upsert request

func (SetRequest) GetKey added in v0.2.0

func (r SetRequest) GetKey() string

GetKey gets the Key on a SetRequest

func (SetRequest) GetMetadata added in v0.2.0

func (r SetRequest) GetMetadata() map[string]string

GetMetadata gets the Key on a SetRequest

type SetStateOption

type SetStateOption struct {
	Concurrency string `json:"concurrency,omitempty"` // first-write, last-write
	Consistency string `json:"consistency"`           // "eventual, strong"

SetStateOption controls how a state store reacts to a set request

type Store

type Store interface {
	Init(metadata Metadata) error
	Features() []Feature
	Delete(req *DeleteRequest) error
	Get(req *GetRequest) (*GetResponse, error)
	Set(req *SetRequest) error

Store is an interface to perform operations on store

type TransactionalStateOperation added in v0.3.0

type TransactionalStateOperation struct {
	Operation OperationType `json:"operation"`
	Request   interface{}   `json:"request"`

TransactionalStateOperation describes operation type, key, and value for transactional operation.

type TransactionalStateRequest added in v0.3.0

type TransactionalStateRequest struct {
	Operations []TransactionalStateOperation `json:"operations"`
	Metadata   map[string]string             `json:"metadata,omitempty"`

TransactionalStateRequest describes a transactional operation against a state store that comprises multiple types of operations The Request field is either a DeleteRequest or SetRequest

type TransactionalStore

type TransactionalStore interface {
	Init(metadata Metadata) error
	Multi(request *TransactionalStateRequest) error

TransactionalStore is an interface for initialization and support multiple transactional requests


Path Synopsis
Package zookeeper is a generated GoMock package.
Package zookeeper is a generated GoMock package.

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