diff --git a/rcache.go b/rcache.go index 14bbbfb..64ec684 100644 --- a/rcache.go +++ b/rcache.go @@ -36,7 +36,13 @@ type cache struct { ttls map[string]time.Time watched map[string]bool + // used to stop the cache exit chan bool + + // status of the registry + // used to hold onto the cache + // in failure state + status error } var ( @@ -50,6 +56,18 @@ func backoff(attempts int) time.Duration { return time.Duration(math.Pow(10, float64(attempts))) * time.Millisecond } +func (c *cache) getStatus() error { + c.RLock() + defer c.RUnlock() + return c.status +} + +func (c *cache) setStatus(err error) { + c.Lock() + c.status = err + c.Unlock() +} + // isValid checks if the service is valid func (c *cache) isValid(services []*registry.Service, ttl time.Time) bool { // no services exist @@ -81,6 +99,11 @@ func (c *cache) quit() bool { } func (c *cache) del(service string) { + // don't blow away cache in error state + if err := c.getStatus(); err != nil { + return + } + // otherwise delete entries delete(c.cache, service) delete(c.ttls, service) } @@ -105,13 +128,26 @@ func (c *cache) get(service string) ([]*registry.Service, error) { } // get does the actual request for a service and cache it - get := func(service string) ([]*registry.Service, error) { + get := func(service string, cached []*registry.Service) ([]*registry.Service, error) { // ask the registry services, err := c.Registry.GetService(service) if err != nil { + // check the cache + if len(cached) > 0 { + // set the error status + c.setStatus(err) + // return the stale cache + return registry.Copy(cached), nil + } + // otherwise return error return nil, err } + // reset the status + if c.getStatus(); err != nil { + c.setStatus(nil) + } + // cache results c.Lock() c.set(service, registry.Copy(services)) @@ -129,7 +165,7 @@ func (c *cache) get(service string) ([]*registry.Service, error) { c.RUnlock() // get and return services - return get(service) + return get(service, services) } func (c *cache) set(service string, services []*registry.Service) { @@ -283,6 +319,7 @@ func (c *cache) run(service string) { } d := backoff(a) + c.setStatus(err) if a > 3 { log.Log("rcache: ", err, " backing off ", d) @@ -305,6 +342,7 @@ func (c *cache) run(service string) { } d := backoff(b) + c.setStatus(err) if b > 3 { log.Log("rcache: ", err, " backing off ", d) @@ -348,6 +386,13 @@ func (c *cache) watch(w registry.Watcher) error { close(stop) return err } + + // reset the error status since we succeeded + if err := c.getStatus(); err != nil { + // reset status + c.setStatus(nil) + } + c.update(res) } }