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client: don't remember discovery errors permanently 

fixes camlistore.org/issue/348

Change-Id: I689319cd03dbbcc035698a2ce58d4557c28d9ac0
This commit is contained in:
Dustin Sallings 2014-01-19 00:52:21 -08:00
parent 52a68b9c30
commit 6f5b0151f2
1 changed files with 35 additions and 56 deletions
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91
pkg/client/client.go
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@ -57,13 +57,11 @@ type Client struct {
// prefix is.
server string
prefixOnce sync.Once // guards init of following 3 fields
prefixErr error
prefixv string // URL prefix before "/camli/"
isSharePrefix bool // URL is a request for a share blob
prefixOnce syncutil.Once // guards init of following 2 fields
prefixv string // URL prefix before "/camli/"
isSharePrefix bool // URL is a request for a share blob
discoOnce sync.Once
discoErr error
discoOnce syncutil.Once
searchRoot string // Handler prefix, or "" if none
downloadHelper string // or "" if none
storageGen string // storage generation, or "" if not reported
@ -224,13 +222,13 @@ type optionTrustedCert string
func (o optionTrustedCert) modifyClient(c *Client) {
cert := string(o)
if cert != "" {
c.initTrustedCertsOnce.Do(noop)
c.initTrustedCertsOnce.Do(func() {})
c.trustedCerts = []string{string(o)}
}
}
// noop is for use with sync.Onces.
func noop() {}
// noop is for use with syncutil.Onces.
func noop() error { return nil }
var shareURLRx = regexp.MustCompile(`^(.+)/(` + blob.Pattern + ")$")
@ -344,9 +342,8 @@ func (c *Client) BlobRoot() (string, error) {
// If the server isn't running an index and search handler, the error
// will be ErrNoSearchRoot.
func (c *Client) SearchRoot() (string, error) {
c.condDiscovery()
if c.discoErr != nil {
return "", c.discoErr
if err := c.condDiscovery(); err != nil {
return "", err
}
if c.searchRoot == "" {
return "", ErrNoSearchRoot
@ -364,9 +361,8 @@ func (c *Client) SearchRoot() (string, error) {
// If the server doesn't return such a value, the error will be
// ErrNoStorageGeneration.
func (c *Client) StorageGeneration() (string, error) {
c.condDiscovery()
if c.discoErr != nil {
return "", c.discoErr
if err := c.condDiscovery(); err != nil {
return "", err
}
if c.storageGen == "" {
return "", ErrNoStorageGeneration
@ -387,9 +383,8 @@ type SyncInfo struct {
// If the server isn't running any sync handler, the error
// will be ErrNoSync.
func (c *Client) SyncHandlers() ([]*SyncInfo, error) {
c.condDiscovery()
if c.discoErr != nil {
return nil, c.discoErr
if err := c.condDiscovery(); err != nil {
return nil, err
}
if c.syncHandlers == nil {
return nil, ErrNoSync
@ -552,8 +547,7 @@ func (c *Client) SearchExistingFileSchema(wholeRef blob.Ref) (blob.Ref, error) {
// the server is configured with a "download helper", and the server responds
// that all chunks of 'f' are available and match the digest of wholeRef.
func (c *Client) FileHasContents(f, wholeRef blob.Ref) bool {
c.condDiscovery()
if c.discoErr != nil {
if err := c.condDiscovery(); err != nil {
return false
}
if c.downloadHelper == "" {
@ -573,12 +567,8 @@ func (c *Client) FileHasContents(f, wholeRef blob.Ref) bool {
// the blobref hash in case of a share URL.
// Examples: http://foo.com:3179/bs or http://foo.com:3179/share
func (c *Client) prefix() (string, error) {
c.prefixOnce.Do(func() { c.initPrefix() })
if c.prefixErr != nil {
return "", c.prefixErr
}
if c.discoErr != nil {
return "", c.discoErr
if err := c.prefixOnce.Do(c.initPrefix); err != nil {
return "", err
}
return c.prefixv, nil
}
@ -609,30 +599,28 @@ func (c *Client) discoRoot() string {
// prefix to the blobserver root. If the server URL has a path
// component then it is directly used, otherwise the blobRoot
// from the discovery is used as the path.
func (c *Client) initPrefix() {
func (c *Client) initPrefix() error {
c.isSharePrefix = false
root := c.discoRoot()
u, err := url.Parse(root)
if err != nil {
c.prefixErr = err
return
return err
}
if len(u.Path) > 1 {
c.prefixv = strings.TrimRight(root, "/")
return
return nil
}
c.condDiscovery()
return c.condDiscovery()
}
func (c *Client) condDiscovery() {
c.discoOnce.Do(c.doDiscovery)
func (c *Client) condDiscovery() error {
return c.discoOnce.Do(c.doDiscovery)
}
func (c *Client) doDiscovery() {
func (c *Client) doDiscovery() error {
root, err := url.Parse(c.discoRoot())
if err != nil {
c.discoErr = err
return
return err
}
// If the path is just "" or "/", do discovery against
@ -641,32 +629,27 @@ func (c *Client) doDiscovery() {
req.Header.Set("Accept", "text/x-camli-configuration")
res, err := c.doReqGated(req)
if err != nil {
c.discoErr = err
return
return err
}
defer res.Body.Close()
if res.StatusCode != 200 {
c.discoErr = fmt.Errorf("Got status %q from blobserver URL %q during configuration discovery", res.Status, c.discoRoot())
return
return fmt.Errorf("Got status %q from blobserver URL %q during configuration discovery", res.Status, c.discoRoot())
}
// TODO(bradfitz): little weird in retrospect that we request
// text/x-camli-configuration and expect to get back
// text/javascript. Make them consistent.
if ct := res.Header.Get("Content-Type"); ct != "text/javascript" {
c.discoErr = fmt.Errorf("Blobserver returned unexpected type %q from discovery", ct)
return
return fmt.Errorf("Blobserver returned unexpected type %q from discovery", ct)
}
m := make(map[string]interface{})
if err := json.NewDecoder(res.Body).Decode(&m); err != nil {
c.discoErr = err
return
return err
}
searchRoot, ok := m["searchRoot"].(string)
if ok {
u, err := root.Parse(searchRoot)
if err != nil {
c.discoErr = fmt.Errorf("client: invalid searchRoot %q; failed to resolve", searchRoot)
return
return fmt.Errorf("client: invalid searchRoot %q; failed to resolve", searchRoot)
}
c.searchRoot = u.String()
}
@ -675,8 +658,7 @@ func (c *Client) doDiscovery() {
if ok {
u, err := root.Parse(downloadHelper)
if err != nil {
c.discoErr = fmt.Errorf("client: invalid downloadHelper %q; failed to resolve", downloadHelper)
return
return fmt.Errorf("client: invalid downloadHelper %q; failed to resolve", downloadHelper)
}
c.downloadHelper = u.String()
}
@ -685,13 +667,11 @@ func (c *Client) doDiscovery() {
blobRoot, ok := m["blobRoot"].(string)
if !ok {
c.discoErr = fmt.Errorf("No blobRoot in config discovery response")
return
return fmt.Errorf("No blobRoot in config discovery response")
}
u, err := root.Parse(blobRoot)
if err != nil {
c.discoErr = fmt.Errorf("client: error resolving blobRoot: %v", err)
return
return fmt.Errorf("client: error resolving blobRoot: %v", err)
}
c.prefixv = strings.TrimRight(u.String(), "/")
@ -702,14 +682,12 @@ func (c *Client) doDiscovery() {
from := vmap["from"].(string)
ufrom, err := root.Parse(from)
if err != nil {
c.discoErr = fmt.Errorf("client: invalid %q \"from\" sync; failed to resolve", from)
return
return fmt.Errorf("client: invalid %q \"from\" sync; failed to resolve", from)
}
to := vmap["to"].(string)
uto, err := root.Parse(to)
if err != nil {
c.discoErr = fmt.Errorf("client: invalid %q \"to\" sync; failed to resolve", to)
return
return fmt.Errorf("client: invalid %q \"to\" sync; failed to resolve", to)
}
toIndex, _ := vmap["toIndex"].(bool)
c.syncHandlers = append(c.syncHandlers, &SyncInfo{
@ -719,6 +697,7 @@ func (c *Client) doDiscovery() {
})
}
}
return nil
}
func (c *Client) newRequest(method, url string, body ...io.Reader) *http.Request {