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// Package errors implements an error handling plugin.
package errors
import (
"context"
"regexp"
"sync/atomic"
"time"
"unsafe"
"github.com/coredns/coredns/plugin"
clog "github.com/coredns/coredns/plugin/pkg/log"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
var log = clog.NewWithPlugin("errors")
type pattern struct {
ptimer unsafe.Pointer
count uint32
period time.Duration
pattern *regexp.Regexp
}
func (p *pattern) timer() *time.Timer {
return (*time.Timer)(atomic.LoadPointer(&p.ptimer))
}
func (p *pattern) setTimer(t *time.Timer) {
atomic.StorePointer(&p.ptimer, unsafe.Pointer(t))
}
// errorHandler handles DNS errors (and errors from other plugin).
type errorHandler struct {
patterns []*pattern
stopFlag uint32
Next plugin.Handler
}
func newErrorHandler() *errorHandler {
return &errorHandler{}
}
func (h *errorHandler) logPattern(i int) {
cnt := atomic.SwapUint32(&h.patterns[i].count, 0)
if cnt > 0 {
log.Errorf("%d errors like '%s' occurred in last %s",
cnt, h.patterns[i].pattern.String(), h.patterns[i].period)
}
}
func (h *errorHandler) inc(i int) bool {
if atomic.LoadUint32(&h.stopFlag) > 0 {
return false
}
if atomic.AddUint32(&h.patterns[i].count, 1) == 1 {
ind := i
t := time.AfterFunc(h.patterns[ind].period, func() {
h.logPattern(ind)
})
h.patterns[ind].setTimer(t)
if atomic.LoadUint32(&h.stopFlag) > 0 && t.Stop() {
h.logPattern(ind)
}
}
return true
}
func (h *errorHandler) stop() {
atomic.StoreUint32(&h.stopFlag, 1)
for i := range h.patterns {
t := h.patterns[i].timer()
if t != nil && t.Stop() {
h.logPattern(i)
}
}
}
// ServeDNS implements the plugin.Handler interface.
func (h *errorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
rcode, err := plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
if err != nil {
strErr := err.Error()
for i := range h.patterns {
if h.patterns[i].pattern.MatchString(strErr) {
if h.inc(i) {
return rcode, err
}
break
}
}
state := request.Request{W: w, Req: r}
log.Errorf("%d %s %s: %s", rcode, state.Name(), state.Type(), strErr)
}
return rcode, err
}
// Name implements the plugin.Handler interface.
func (h *errorHandler) Name() string { return "errors" }
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