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Update to avoid pseudo-random number (#5225)

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* Update to avoid pseudo-random number

This PR update the usage of rand so that non-global seed is used.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add concurrency-safe random source

See https://stackoverflow.com/questions/48958886/how-to-create-a-thread-safe-rand-source

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This commit is contained in:
Yong Tang 2022-03-16 09:24:58 -07:00 • committed by GitHub
parent c3b30cc3ef
commit aa7818e1d3
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 52 additions and 8 deletions
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10
plugin/forward/policy.go
View file

@ -1,8 +1,10 @@
package forward
import (
"math/rand"
"sync/atomic"
"time"
"github.com/coredns/coredns/plugin/pkg/rand"
)
// Policy defines a policy we use for selecting upstreams.
@ -21,13 +23,13 @@ func (r *random) List(p []*Proxy) []*Proxy {
case 1:
return p
case 2:
if rand.Int()%2 == 0 {
if rn.Int()%2 == 0 {
return []*Proxy{p[1], p[0]} // swap
}
return p
}
perms := rand.Perm(len(p))
perms := rn.Perm(len(p))
rnd := make([]*Proxy, len(p))
for i, p1 := range perms {
@ -62,3 +64,5 @@ func (r *sequential) String() string { return "sequential" }
func (r *sequential) List(p []*Proxy) []*Proxy {
return p
}
var rn = rand.New(time.Now().UnixNano())

10
plugin/grpc/policy.go
View file

@ -1,8 +1,10 @@
package grpc
import (
"math/rand"
"sync/atomic"
"time"
"github.com/coredns/coredns/plugin/pkg/rand"
)
// Policy defines a policy we use for selecting upstreams.
@ -21,13 +23,13 @@ func (r *random) List(p []*Proxy) []*Proxy {
case 1:
return p
case 2:
if rand.Int()%2 == 0 {
if rn.Int()%2 == 0 {
return []*Proxy{p[1], p[0]} // swap
}
return p
}
perms := rand.Perm(len(p))
perms := rn.Perm(len(p))
rnd := make([]*Proxy, len(p))
for i, p1 := range perms {
@ -62,3 +64,5 @@ func (r *sequential) String() string { return "sequential" }
func (r *sequential) List(p []*Proxy) []*Proxy {
return p
}
var rn = rand.New(time.Now().UnixNano())

4
plugin/loop/setup.go
View file

@ -1,7 +1,6 @@
package loop
import (
"math/rand"
"net"
"strconv"
"time"
@ -10,6 +9,7 @@ import (
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/pkg/dnsutil"
"github.com/coredns/coredns/plugin/pkg/rand"
)
func init() { plugin.Register("loop", setup) }
@ -84,4 +84,4 @@ func qname(zone string) string {
return dnsutil.Join(l1, l2, zone)
}
var r = rand.New(rand.NewSource(time.Now().UnixNano()))
var r = rand.New(time.Now().UnixNano())

36
plugin/pkg/rand/rand.go Normal file
View file

@ -0,0 +1,36 @@
// Package rand is used for concurrency safe random number generator.
package rand
import (
"math/rand"
"sync"
)
// Rand is used for concurrency safe random number generator.
type Rand struct {
m sync.Mutex
r *rand.Rand
}
// New returns a new Rand from seed.
func New(seed int64) *Rand {
return &Rand{r: rand.New(rand.NewSource(seed))}
}
// Int returns a non-negative pseudo-random int from the Source in Rand.r.
func (r *Rand) Int() int {
r.m.Lock()
v := r.r.Int()
r.m.Unlock()
return v
}
// Perm returns, as a slice of n ints, a pseudo-random permutation of the
// integers in the half-open interval [0,n) from the Source in Rand.r.
func (r *Rand) Perm(n int) []int {
r.m.Lock()
v := r.r.Perm(n)
r.m.Unlock()
return v
}