retry on fail, retry on http status codes

retry.go

@@ -0,0 +1,127 @@
+package main
+
+import (
+	"fmt"
+	"github.com/sirupsen/logrus"
+	"log"
+	"math"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"syscall"
+	"time"
+)
+
+func isPermanentError(err error) bool {
+
+	var opErr *net.OpError
+
+	urlErr, ok := err.(*url.Error)
+	if ok {
+		opErr, ok = urlErr.Err.(*net.OpError)
+		if !ok {
+			return false
+		}
+	} else {
+		netErr, ok := err.(net.Error)
+		if ok {
+			if netErr.Timeout() {
+				return false
+			}
+
+			opErr, ok = netErr.(*net.OpError)
+			if !ok {
+				return false
+			}
+		}
+	}
+
+	//This should not happen...
+	if opErr == nil {
+		logrus.Error("FIXME: isPermanentError; opErr == nil")
+		return false
+	}
+
+	if opErr.Op == "proxyconnect" {
+		logrus.Error("Error connecting to the proxy!")
+		return true
+	}
+
+	if opErr.Timeout() {
+		// Usually means that there is no route to host
+		return true
+	}
+
+	switch t := opErr.Err.(type) {
+	case *net.DNSError:
+		return true
+	case *os.SyscallError:
+
+		logrus.Printf("os.SyscallError:%+v", t)
+
+		if errno, ok := t.Err.(syscall.Errno); ok {
+			switch errno {
+			case syscall.ECONNREFUSED:
+				log.Println("connect refused")
+				return true
+			case syscall.ETIMEDOUT:
+				log.Println("timeout")
+				return false
+			}
+		}
+	}
+
+	//todo: handle the other error types
+	fmt.Println("fixme: None of the above")
+
+	return false
+}
+
+func waitTime(retries int) time.Duration {
+
+	const multiplier = 1.5
+	const wait = int64(5 * time.Second)
+
+	return time.Duration(wait * int64(math.Pow(multiplier, float64(retries))))
+}
+
+func (p *Proxy) waitRateLimit(r *http.Request) {
+
+	sHost := simplifyHost(r.Host)
+
+	limiter := p.getLimiter(sHost)
+	reservation := limiter.Reserve()
+	if !reservation.OK() {
+		logrus.WithFields(logrus.Fields{
+			"host": sHost,
+		}).Warn("Could not get reservation, make sure that burst is > 0")
+	}
+
+	delay := reservation.Delay()
+	if delay > 0 {
+		logrus.WithFields(logrus.Fields{
+			"time": delay,
+		}).Trace("Sleeping")
+		time.Sleep(delay)
+	}
+}
+
+func isHttpSuccessCode(code int) bool {
+	return code >= 200 && code < 300
+}
+
+func shouldRetryHttpCode(code int) bool {
+
+	switch {
+	case code == 403:
+	case code == 408:
+	case code == 429:
+	case code == 444:
+	case code == 499:
+	case code >= 500:
+		return true
+	}
+
+	return false
+}