diff options
Diffstat (limited to 'vendor/github.com/goamz/goamz/aws/client.go')
-rw-r--r-- | vendor/github.com/goamz/goamz/aws/client.go | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/vendor/github.com/goamz/goamz/aws/client.go b/vendor/github.com/goamz/goamz/aws/client.go new file mode 100644 index 000000000..86d2ccec8 --- /dev/null +++ b/vendor/github.com/goamz/goamz/aws/client.go @@ -0,0 +1,124 @@ +package aws + +import ( + "math" + "net" + "net/http" + "time" +) + +type RetryableFunc func(*http.Request, *http.Response, error) bool +type WaitFunc func(try int) +type DeadlineFunc func() time.Time + +type ResilientTransport struct { + // Timeout is the maximum amount of time a dial will wait for + // a connect to complete. + // + // The default is no timeout. + // + // With or without a timeout, the operating system may impose + // its own earlier timeout. For instance, TCP timeouts are + // often around 3 minutes. + DialTimeout time.Duration + + // MaxTries, if non-zero, specifies the number of times we will retry on + // failure. Retries are only attempted for temporary network errors or known + // safe failures. + MaxTries int + Deadline DeadlineFunc + ShouldRetry RetryableFunc + Wait WaitFunc + transport *http.Transport +} + +// Convenience method for creating an http client +func NewClient(rt *ResilientTransport) *http.Client { + rt.transport = &http.Transport{ + Dial: func(netw, addr string) (net.Conn, error) { + c, err := net.DialTimeout(netw, addr, rt.DialTimeout) + if err != nil { + return nil, err + } + c.SetDeadline(rt.Deadline()) + return c, nil + }, + Proxy: http.ProxyFromEnvironment, + } + // TODO: Would be nice is ResilientTransport allowed clients to initialize + // with http.Transport attributes. + return &http.Client{ + Transport: rt, + } +} + +var retryingTransport = &ResilientTransport{ + Deadline: func() time.Time { + return time.Now().Add(5 * time.Second) + }, + DialTimeout: 10 * time.Second, + MaxTries: 3, + ShouldRetry: awsRetry, + Wait: ExpBackoff, +} + +// Exported default client +var RetryingClient = NewClient(retryingTransport) + +func (t *ResilientTransport) RoundTrip(req *http.Request) (*http.Response, error) { + return t.tries(req) +} + +// Retry a request a maximum of t.MaxTries times. +// We'll only retry if the proper criteria are met. +// If a wait function is specified, wait that amount of time +// In between requests. +func (t *ResilientTransport) tries(req *http.Request) (res *http.Response, err error) { + for try := 0; try < t.MaxTries; try += 1 { + res, err = t.transport.RoundTrip(req) + + if !t.ShouldRetry(req, res, err) { + break + } + if res != nil { + res.Body.Close() + } + if t.Wait != nil { + t.Wait(try) + } + } + + return +} + +func ExpBackoff(try int) { + time.Sleep(100 * time.Millisecond * + time.Duration(math.Exp2(float64(try)))) +} + +func LinearBackoff(try int) { + time.Sleep(time.Duration(try*100) * time.Millisecond) +} + +// Decide if we should retry a request. +// In general, the criteria for retrying a request is described here +// http://docs.aws.amazon.com/general/latest/gr/api-retries.html +func awsRetry(req *http.Request, res *http.Response, err error) bool { + retry := false + + // Retry if there's a temporary network error. + if neterr, ok := err.(net.Error); ok { + if neterr.Temporary() { + retry = true + } + } + + // Retry if we get a 5xx series error. + if res != nil { + if res.StatusCode >= 500 && res.StatusCode < 600 { + retry = true + } + } + + return retry +} |