const (
// XFromCache is the header added to responses that are returned from the cache
XFromCache = "X-From-Cache"
)
var ErrNoDateHeader = errors.New("no Date header")
ErrNoDateHeader indicates that the HTTP headers contained no Date header.
func CachedResponse(c Cache, req *http.Request) (resp *http.Response, err error)
CachedResponse returns the cached http.Response for req if present, and nil otherwise.
func Date(respHeaders http.Header) (date time.Time, err error)
Date parses and returns the value of the Date header.
type Cache interface {
// Get returns the []byte representation of a cached response and a bool
// set to true if the value isn't empty
Get(key string) (responseBytes []byte, ok bool)
// Set stores the []byte representation of a response against a key
Set(key string, responseBytes []byte)
// Delete removes the value associated with the key
Delete(key string)
}
A Cache interface is used by the Transport to store and retrieve responses.
type MemoryCache struct {
// contains filtered or unexported fields
}
MemoryCache is an implemtation of Cache that stores responses in an in-memory map.
func NewMemoryCache() *MemoryCache
NewMemoryCache returns a new Cache that will store items in an in-memory map
func (c *MemoryCache) Delete(key string)
Delete removes key from the cache
func (c *MemoryCache) Get(key string) (resp []byte, ok bool)
Get returns the []byte representation of the response and true if present, false if not
func (c *MemoryCache) Set(key string, resp []byte)
Set saves response resp to the cache with key
type Transport struct {
// The RoundTripper interface actually used to make requests
// If nil, http.DefaultTransport is used
Transport http.RoundTripper
Cache Cache
// If true, responses returned from the cache will be given an extra header, X-From-Cache
MarkCachedResponses bool
// contains filtered or unexported fields
}
Transport is an implementation of http.RoundTripper that will return values from a cache where possible (avoiding a network request) and will additionally add validators (etag/if-modified-since) to repeated requests allowing servers to return 304 / Not Modified
func NewMemoryCacheTransport() *Transport
NewMemoryCacheTransport returns a new Transport using the in-memory cache implementation
func NewTransport(c Cache) *Transport
NewTransport returns a new Transport with the provided Cache implementation and MarkCachedResponses set to true
func (t *Transport) CancelRequest(req *http.Request)
CancelRequest calls CancelRequest on the underlaying transport if implemented or throw a warning otherwise.
func (t *Transport) Client() *http.Client
Client returns an *http.Client that caches responses.
func (t *Transport) RoundTrip(req *http.Request) (resp *http.Response, err error)
RoundTrip takes a Request and returns a Response
If there is a fresh Response already in cache, then it will be returned without connecting to the server.
If there is a stale Response, then any validators it contains will be set on the new request to give the server a chance to respond with NotModified. If this happens, then the cached Response will be returned.
| Name | Synopsis |
|---|---|
| .. | |
| diskcache | Package diskcache provides an implementation of httpcache.Cache that uses the diskv package to supplement an in-memory map with persistent storage |
| leveldbcache | Package leveldbcache provides an implementation of httpcache.Cache that uses github.com/syndtr/goleveldb/leveldb |
| memcache | Package memcache provides an implementation of httpcache.Cache that uses App Engine's memcache package to store cached responses. |
| redis | Package redis provides a redis interface for http caching. |