ldstoretypes

Documentation

Overview

Package ldstoretypes contains types that are only needed when implementing custom components. Specifically, these types describe how data is passed to and from a DataStore.

Index

• type Collection
• type DataKind
• type ItemDescriptor
  • func (s ItemDescriptor) NotFound() ItemDescriptor
• type KeyedItemDescriptor
• type KeyedSerializedItemDescriptor
• type SerializedCollection
• type SerializedItemDescriptor
  • func (s SerializedItemDescriptor) NotFound() SerializedItemDescriptor

Types

type Collection

type Collection struct {
	Kind  DataKind
	Items []KeyedItemDescriptor
}

Collection is a list of data store items for a DataKind.

type DataKind

type DataKind interface {
	GetName() string
	Serialize(item ItemDescriptor) []byte
	Deserialize(data []byte) (ItemDescriptor, error)
}

DataKind represents a separately namespaced collection of storable data items.

The SDK passes instances of this type to the data store to specify whether it is referring to a feature flag, a user segment, etc. The data store implementation should not look for a specific data kind (such as feature flags), but should treat all data kinds generically.

The SDK's standard implementations of this type are available in the subsystems/ldstoreimpl package.

type ItemDescriptor

type ItemDescriptor struct {
	// Version is the version number of this data, provided by the SDK.
	Version int
	// Item is the data item, or nil if this is a placeholder for a deleted item.
	Item interface{}
}

ItemDescriptor is a versioned item (or placeholder) storable in a DataStore.

This is used for data stores that directly store objects as-is, as the default in-memory store does. Items are typed as interface{}; the store should not know or care what the actual object is.

For any given key within a DataKind, there can be either an existing item with a version, or a "tombstone" placeholder representing a deleted item (also with a version). Deleted item placeholders are used so that if an item is first updated with version N and then deleted with version N+1, but the SDK receives those changes out of order, version N will not overwrite the deletion.

Persistent data stores use SerializedItemDescriptor instead.

func (ItemDescriptor) NotFound

func (s ItemDescriptor) NotFound() ItemDescriptor

NotFound is a convenience method to return a value indicating no such item exists.

type KeyedItemDescriptor

type KeyedItemDescriptor struct {
	// Key is the unique key of this item within its DataKind.
	Key string
	// Item is the versioned item.
	Item ItemDescriptor
}

KeyedItemDescriptor is a key-value pair containing a ItemDescriptor.

type KeyedSerializedItemDescriptor

type KeyedSerializedItemDescriptor struct {
	// Key is the unique key of this item within its DataKind.
	Key string
	// Item is the versioned serialized item.
	Item SerializedItemDescriptor
}

KeyedSerializedItemDescriptor is a key-value pair containing a SerializedItemDescriptor.

type SerializedCollection

type SerializedCollection struct {
	Kind  DataKind
	Items []KeyedSerializedItemDescriptor
}

SerializedCollection is a list of serialized data store items for a DataKind.

type SerializedItemDescriptor

type SerializedItemDescriptor struct {
	// Version is the version number of this data, provided by the SDK.
	Version int
	// Deleted is true if this is a placeholder (tombstone) for a deleted item. If so,
	// SerializedItem will still contain a byte string representing the deleted item, but
	// the persistent store implementation has the option of not storing it if it can represent the
	// placeholder in a more efficient way.
	Deleted bool
	// SerializedItem is the data item's serialized representation. For a deleted item placeholder,
	// instead of passing nil, the SDK will provide a special value that can be stored if necessary
	// (see Deleted).
	SerializedItem []byte
}

SerializedItemDescriptor is a versioned item (or placeholder) storable in a PersistentDataStore.

This is equivalent to ItemDescriptor, but is used for persistent data stores. The SDK will convert each data item to and from its serialized string form; the persistent data store deals only with the serialized form.

func (SerializedItemDescriptor) NotFound

func (s SerializedItemDescriptor) NotFound() SerializedItemDescriptor

NotFound is a convenience method to return a value indicating no such item exists.