Added HostErrorsCache for tracking failed hosts

v2/pkg/protocols/common/hosterrorscache/hosterrorscache.go

@@ -0,0 +1,115 @@
+package hosterrorscache
+
+import (
+	"net"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"github.com/bluele/gcache"
+)
+
+// Cache is a cache for host based errors. It allows skipping
+// certain hosts based on an error threshold.
+//
+// It uses an LRU cache internally for skipping unresponsive hosts
+// that remain so for a duration.
+type Cache struct {
+	hostMaxErrors int
+	failedTargets gcache.Cache
+}
+
+const DefaultMaxHostsCount = 10000
+
+// New returns a new host max errors cache
+func New(hostMaxErrors, maxHostsCount int) *Cache {
+	gc := gcache.New(maxHostsCount).
+		ARC().
+		Build()
+	return &Cache{failedTargets: gc, hostMaxErrors: hostMaxErrors}
+}
+
+// Close closes the host errors cache
+func (c *Cache) Close() {
+	c.failedTargets.Purge()
+}
+
+func (c *Cache) normalizeCacheValue(value string) string {
+	finalValue := value
+	if strings.HasPrefix(value, "http") {
+		if parsed, err := url.Parse(value); err == nil {
+
+			hostname := parsed.Host
+			finalPort := parsed.Port()
+			if finalPort == "" {
+				if parsed.Scheme == "https" {
+					finalPort = "443"
+				} else {
+					finalPort = "80"
+				}
+				hostname = net.JoinHostPort(parsed.Host, finalPort)
+			}
+			finalValue = hostname
+		}
+	}
+	return finalValue
+}
+
+// ErrUnresponsiveHost is returned when a host is unresponsive
+//var ErrUnresponsiveHost = errors.New("skipping as host is unresponsive")
+
+// Check returns true if a host should be skipped as it has been
+// unresponsive for a certain number of times.
+//
+// The value can be many formats -
+//   - URL: https?:// type
+//   - Host:port type
+//   - host type
+func (c *Cache) Check(value string) bool {
+	finalValue := c.normalizeCacheValue(value)
+	if !c.failedTargets.Has(finalValue) {
+		return false
+	}
+
+	numberOfErrors, err := c.failedTargets.GetIFPresent(finalValue)
+	if err != nil {
+		return false
+	}
+	numberOfErrorsValue := numberOfErrors.(int)
+
+	if numberOfErrorsValue >= c.hostMaxErrors {
+		return true
+	}
+	return false
+}
+
+// MarkFailed marks a host as failed previously
+func (c *Cache) MarkFailed(value string) {
+	finalValue := c.normalizeCacheValue(value)
+	if !c.failedTargets.Has(finalValue) {
+		_ = c.failedTargets.Set(finalValue, 1)
+		return
+	}
+
+	numberOfErrors, err := c.failedTargets.GetIFPresent(finalValue)
+	if err != nil || numberOfErrors == nil {
+		_ = c.failedTargets.Set(finalValue, 1)
+		return
+	}
+	numberOfErrorsValue := numberOfErrors.(int)
+
+	_ = c.failedTargets.Set(finalValue, numberOfErrorsValue+1)
+}
+
+var checkErrorRegexp = regexp.MustCompile(`(no address found for host|Client\.Timeout exceeded while awaiting headers|could not resolve host)`)
+
+// CheckError checks if an error represents a type that should be
+// added to the host skipping table.
+func (c *Cache) CheckError(err error) bool {
+	errString := err.Error()
+
+	if checkErrorRegexp.MatchString(errString) {
+		return true
+	}
+	return false
+}