caching

Documentation

Overview

Package caching implements a Storage wrapper that implements caching on reads, and is backed by another Storage instance. The caching layer is intentionally simple.

Index

• func HashKey(parts ...string) string
• type Cache
• type Item

Functions

func HashKey

func HashKey(parts ...string) string

HashKey composes a hex-encoded SHA256 string from the supplied parts. The local schema version and KeyType are included in the hash.

Types

type Cache

type Cache interface {
	// Put caches the supplied Items into the cache. If an Item already exists in
	// the cache, it will be overridden.
	//
	// If exp, the supplied expiration Duration, is >0, the cache should only
	// store the data if it can expire it after this period of time.
	//
	// This method does not return whether or not the caching storage was
	// successful.
	Put(c context.Context, exp time.Duration, items ...*Item)

	// Get retrieves a cached entry. If the entry was present, a non-nil value
	// will be returned, even if the data length is zero. If the entry was not
	// present, nil will be returned.
	//
	// This method does not distinguish between an error and missing data. Either
	// valid data is returned, or it is not.
	Get(c context.Context, items ...*Item)
}

Cache is a simple cache interface. It is capable of storage and retrieval.

type Item

type Item struct {
	// Schema is the item's schema value. If empty, the item is schemaless.
	Schema string

	// Type is the item's type identifier. If empty, the item has no type.
	Type string

	// Key is the item's individual key. It uniquely identifies the Item within
	// the scope of the Schema and Type.
	Key string

	// Data is the Item's data. For Put, the contents of this Data will be used to
	// populate the cache. For Get, this value will be non-nil and populated with
	// the retrieved data, or nil if the item was not present in the cache.
	Data []byte
}

Item is a single cache item. An item is uniquely identified by its Schema and Key sequence.