forked from asonawalla/gazette
/
cached_url.go
66 lines (55 loc) · 1.29 KB
/
cached_url.go
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package gazette
import (
"errors"
"io"
"net"
"net/http"
"net/url"
"sync"
)
// A parsing DNS caching layer on a string URL.
type CachedURL struct {
// Accessible, absolute URL of this endpoint.
Base string
// Parsed URL with cached IP-resolution applied.
cachedURL *url.URL
cachedURLMu sync.Mutex
}
func (ep *CachedURL) NewHTTPRequest(method, uri string, body io.Reader) (
*http.Request, error) {
if resolvedUrl, err := ep.ResolveURL(); err != nil {
return nil, err
} else {
return http.NewRequest(method, resolvedUrl.String()+uri, body)
}
}
func (ep *CachedURL) URL() (*url.URL, error) {
if url, err := url.Parse(ep.Base); err != nil {
return nil, err
} else if !url.IsAbs() {
return nil, errors.New("not an absolute URL: " + ep.Base)
} else {
return url, nil
}
}
func (ep *CachedURL) ResolveURL() (*url.URL, error) {
ep.cachedURLMu.Lock()
defer ep.cachedURLMu.Unlock()
if ep.cachedURL != nil {
return ep.cachedURL, nil
}
if url, err := ep.URL(); err != nil {
return nil, err
} else if r, err := net.ResolveTCPAddr("tcp", url.Host); err != nil {
return nil, err
} else {
url.Host = r.String()
ep.cachedURL = url
return url, nil
}
}
func (ep *CachedURL) InvalidateResolution() {
ep.cachedURLMu.Lock()
defer ep.cachedURLMu.Unlock()
ep.cachedURL = nil
}