README
¶
Simple cache for Golang
Package gocache provides a simple cache for web services
- It uses in-memory storage by default (in a
map[string]*Item) & temporary disk storage for items larger than a certain treshold - It is concurrency-friendly (using sync.RWMutex)
- Key-Value
- It encodes data as JSON under the hood
- It tries to be as developer-friendly as possible
Features
Storage
- Set lifespan on data
- In memory cache
- Caching large data to temporary files
- Something similar to SQL transactions (rollback / commit)
Web
- Handle HTTP request/response caching (by using some of the request data to generate unique ID and storing prepared HTTP response)
Logging
- Request log
- Error log
Querying
- Filters for read requests
Documentation
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Overview ¶
Package gocache provides a simple cache
Index ¶
- Constants
- Variables
- func CacheHTTP(in http.Handler, identifier RequestIdentifier, cacheConfig CacheConfig) (http.Handler, error)
- type Cache
- type CacheConfig
- type CachedResponse
- type DefaultRequestIdentifier
- type EraseOneRequest
- type Item
- type ReadOneRequest
- type RequestIdentifier
- type WriteOneRequest
Constants ¶
Keys to identify request types
Variables ¶
var ErrEmptyItem = errors.New("item is empty, there's no data or file associated with it")
ErrEmptyItem occurs for attemps to decode items that don't have any data
var ErrMaxItemsReached = errors.New("the maximum number of items has been reached")
ErrMaxItemsReached occurs when the request fails because the maximum number of items in the map has been reached It is defined in the maxitems CacheConfig field
var ErrUnknownID = errors.New("ID was not found")
ErrUnknownID occurs when no resource was found for a given ID
Functions ¶
func CacheHTTP ¶
func CacheHTTP(in http.Handler, identifier RequestIdentifier, cacheConfig CacheConfig) (http.Handler, error)
CacheHTTP can be used to filter requests so that if they have a cached response already they are answered directly
Types ¶
type Cache ¶
type Cache struct {
// contains filtered or unexported fields
}
Cache provides in-memory data storage Use the NewCache func to create a new cache
func NewCache ¶
func NewCache(config CacheConfig) (*Cache, error)
NewCache instantiates a cache it calls make(map[string]*item to avoid assigning to nil map for the cache.items field) it also creates a local directory to store temporary files
func (*Cache) EraseOne ¶
func (c *Cache) EraseOne(eoreq EraseOneRequest) error
EraseOne deletes an item if the request is valid
func (*Cache) ReadOne ¶
func (c *Cache) ReadOne(roreq ReadOneRequest) (*Item, error)
ReadOne reads an item if the request is valid
func (*Cache) Start ¶
func (c *Cache) Start()
Start prepares the cache for being used it starts the cleanup loop that will take care of removing expired items
func (*Cache) WriteOne ¶
func (c *Cache) WriteOne(woreq WriteOneRequest) error
WriteOne creates or update an item if the request is valid when the item exceeds the size limit, it is stored to a temporary file
type CacheConfig ¶
CacheConfig holds the cache configuration id sets the cache id (used for error tracing and local file paths related to the cache) (default: time.Now()) interval sets the cleanup interval for the cleanup routine (default: one second) maxitems sets the maximum number of items (default: one hundred thousand) sizelimit sets the number of bytes for an item to be considered too big for in-memory (default: 500 kilobyte) an item with a size that exceeds the sizelimit will be stored a to a file
type CachedResponse ¶
CachedResponse holds data necessary for responding to identified http requests
type DefaultRequestIdentifier ¶
type DefaultRequestIdentifier struct {
// contains filtered or unexported fields
}
DefaultRequestIdentifier implements the RequestIdentifier interface
func NewRequestIdentifier ¶
func NewRequestIdentifier(itemTTL time.Duration, identifyFunc func(*http.Request) string) *DefaultRequestIdentifier
NewRequestIdentifier instanciates a new DefaultRequestIdentifier
func (*DefaultRequestIdentifier) Identify ¶
func (dri *DefaultRequestIdentifier) Identify(r *http.Request) string
Identify returns an ID based on the identity func defined
func (*DefaultRequestIdentifier) ItemTTL ¶
func (dri *DefaultRequestIdentifier) ItemTTL() time.Duration
ItemTTL defines for how long the response will be stored in the cache
type EraseOneRequest ¶
type EraseOneRequest struct {
ItemID string
// contains filtered or unexported fields
}
EraseOneRequest represents a request from the client to delete an item in the cache
type Item ¶
type Item struct {
// contains filtered or unexported fields
}
Item represents a single entity in the list (for ex: a user in a list of users) make sure every item has a unique ID
func (*Item) DecodeInto ¶
DecodeInto decodes the item in the provided variable (must be a pointer)
type ReadOneRequest ¶
type ReadOneRequest struct {
ItemID string
// contains filtered or unexported fields
}
ReadOneRequest represents a request from the client to read an item in the cache
type RequestIdentifier ¶
RequestIdentifier generates an ID from a http request and provides the item ttl in the cache
type WriteOneRequest ¶
type WriteOneRequest struct {
ItemID string
Value interface{}
Expiry time.Time
// contains filtered or unexported fields
}
WriteOneRequest represents a request from the client to add or update an item in the cache Write operations don't check if the item already exists: so if you want to make sure an item can't be overwritten, check if the item exists before
Source Files
Directories