cachecontrol
implements RFC 7234 Hypertext Transfer Protocol (HTTP/1.1): Caching. It does this by parsing the Cache-Control
and other headers, providing information about requests and responses -- but cachecontrol
does not implement an actual cache backend, just the control plane to make decisions about if a particular response is cachable.
cachecontrol.CachableResponse
returns an array of reasons why a response should not be cached and when it expires. In the case that len(reasons) == 0
, the response is cachable according to the RFC. However, some people want non-compliant caches for various business use cases, so each reason is specifically named, so if your cache wants to cache POST
requests, it can easily do that, but still be RFC compliant in other situations.
package main
import (
"github.com/pquerna/cachecontrol"
"fmt"
"io/ioutil"
"net/http"
)
func main() {
req, _ := http.NewRequest("GET", "https://www.example.com/", nil)
res, _ := http.DefaultClient.Do(req)
_, _ = ioutil.ReadAll(res.Body)
reasons, expires, _ := cachecontrol.CachableResponse(req, res, cachecontrol.Options{})
fmt.Println("Reasons to not cache: ", reasons)
fmt.Println("Expiration: ", expires.String())
}
cachecontrol
is divided into two packages: cachecontrol
with a high level API, and a lower level cacheobject
package. Use Object in a high performance use case where you have previously parsed headers containing dates or would like to avoid memory allocations.
package main
import (
"github.com/pquerna/cachecontrol/cacheobject"
"fmt"
"io/ioutil"
"net/http"
)
func main() {
req, _ := http.NewRequest("GET", "https://www.example.com/", nil)
res, _ := http.DefaultClient.Do(req)
_, _ = ioutil.ReadAll(res.Body)
reqDir, _ := cacheobject.ParseRequestCacheControl(req.Header.Get("Cache-Control"))
resDir, _ := cacheobject.ParseResponseCacheControl(res.Header.Get("Cache-Control"))
expiresHeader, _ := http.ParseTime(res.Header.Get("Expires"))
dateHeader, _ := http.ParseTime(res.Header.Get("Date"))
lastModifiedHeader, _ := http.ParseTime(res.Header.Get("Last-Modified"))
obj := cacheobject.Object{
RespDirectives: resDir,
RespHeaders: res.Header,
RespStatusCode: res.StatusCode,
RespExpiresHeader: expiresHeader,
RespDateHeader: dateHeader,
RespLastModifiedHeader: lastModifiedHeader,
ReqDirectives: reqDir,
ReqHeaders: req.Header,
ReqMethod: req.Method,
NowUTC: time.Now().UTC(),
}
rv := cacheobject.ObjectResults{}
cacheobject.CachableObject(&obj, &rv)
cacheobject.ExpirationObject(&obj, &rv)
fmt.Println("Errors: ", rv.OutErr)
fmt.Println("Reasons to not cache: ", rv.OutReasons)
fmt.Println("Warning headers to add: ", rv.OutWarnings)
fmt.Println("Expiration: ", rv.OutExpirationTime.String())
}
Please open issues in Github for ideas, bugs, and general thoughts. Pull requests are of course preferred :)
cachecontrol
has recieved significant contributions from:
cachecontrol
is licensed under the Apache License, Version 2.0