cache

Documentation

Overview

Package cache is a memory store for key-value pairs for all loaded symbols available for output.

Index

• Variables
• type Cache
  • func NewCache() *Cache
  • func (ca *Cache) Add(key string, value string, sizeLimit uint16) error
  • func (ca *Cache) Check(key string) bool
  • func (ca *Cache) Get(key string) (string, error)
  • func (ca *Cache) Invalid() bool
  • func (ca *Cache) Invalidate()
  • func (ca *Cache) Keys(level uint32) []string
  • func (ca *Cache) Last() string
  • func (ca *Cache) Levels() uint32
  • func (ca *Cache) Pop() error
  • func (ca *Cache) Push() error
  • func (ca *Cache) ReservedSize(key string) (uint16, error)
  • func (ca *Cache) Reset()
  • func (ca *Cache) Update(key string, value string) error
  • func (ca *Cache) WithCacheSize(cacheSize uint32) *Cache
• type Memory

Variables

var (
	ErrDup = fmt.Errorf("duplicate key")
)

Types

type Cache

type Cache struct {
	// Total allowed cumulative size of values (not code) in cache
	CacheSize uint32
	// Currently used bytes by all values (not code) in cache
	CacheUseSize uint32
	// All loaded cache items
	Cache []map[string]string
	// Size limits for all loaded symbols.
	Sizes map[string]uint16
	// Last inserted value (regardless of scope)
	LastValue string
	// contains filtered or unexported fields
}

Cache stores loaded content, enforcing size limits and keeping track of size usage.

TODO: hide values from client, while allowing cbor serialization

func NewCache

func NewCache() *Cache

NewCache creates a new ready-to-use Cache object

func (*Cache) Add

func (ca *Cache) Add(key string, value string, sizeLimit uint16) error

Add implements the Memory interface.

func (*Cache) Check

func (ca *Cache) Check(key string) bool

Check returns true if a key already exists in the cache.

func (*Cache) Get

func (ca *Cache) Get(key string) (string, error)

Get implements the Memory interface.

func (*Cache) Invalid

func (ca *Cache) Invalid() bool

Invalid implements the Memory interface.

func (*Cache) Invalidate

func (ca *Cache) Invalidate()

Invalidate implements the Memory interface.

func (*Cache) Keys

func (ca *Cache) Keys(level uint32) []string

Keys implements the Memory interface.

func (*Cache) Last

func (ca *Cache) Last() string

Last implements the Memory interface.

TODO: needs to be invalidated when out of scope

func (*Cache) Levels

func (ca *Cache) Levels() uint32

Levels implements the Memory interface.

func (*Cache) Pop

func (ca *Cache) Pop() error

Pop implements the Memory interface.

func (*Cache) Push

func (ca *Cache) Push() error

Push implements the Memory interface.

func (*Cache) ReservedSize

func (ca *Cache) ReservedSize(key string) (uint16, error)

ReservedSize implements the Memory interface.

func (*Cache) Reset

func (ca *Cache) Reset()

Reset implements the Memory interface.

func (*Cache) Update

func (ca *Cache) Update(key string, value string) error

Update implements the Memory interface.

func (*Cache) WithCacheSize

func (ca *Cache) WithCacheSize(cacheSize uint32) *Cache

WithCacheSize is a chainable method that applies a cumulative cache size limitation for all cached items.

type Memory

type Memory interface {
	// Add adds a cache value under a cache symbol key.
	//
	// Also stores the size limitation of for key for later updates.
	//
	// Must fail if:
	// 	* key already defined
	// 	* value is longer than size limit
	// 	* adding value exceeds cumulative cache capacity
	Add(key string, val string, sizeLimit uint16) error
	// Update sets a new value for an existing key.
	//
	// Uses the size limitation from when the key was added.
	//
	// Must fail if:
	// - key not defined
	// - value is longer than size limit
	// - replacing value exceeds cumulative cache capacity
	Update(key string, val string) error
	// ReservedSize returns the maximum byte size available for the given symbol.
	ReservedSize(key string) (uint16, error)
	// Get the content currently loaded for a single key, loaded at any level.
	//
	// Must fail if key has not been loaded.
	Get(key string) (string, error)
	// Push adds a new level to the cache.
	Push() error
	// Pop frees the cache of the current level and makes the previous level the current level.
	//
	// Fails if already on top level.
	Pop() error
	// Reset flushes all state contents below the top level.
	Reset()
	// Levels returns the current number of levels.
	Levels() uint32
	// Keys returns all storage keys for the given level.
	Keys(level uint32) []string
	// Last returns the last inserted value
	//
	// The stored last inserter value must be reset to an empty string
	Last() string
	// Invalidate marks a cache as invalid.
	//
	// An invalid cache should not be persisted or propagated
	Invalidate()
	// Invalid returns true if cache is invalid.
	//
	// An invalid cache should not be persisted or propagated
	Invalid() bool
}

Memory defines the interface for store of a symbol mapped content cache.