From 9199a4c25bdd119372f5a02f2c8dec4853d5a42d Mon Sep 17 00:00:00 2001
From: ICHINOSE Shogo <shogo82148@gmail.com>
Date: Fri, 29 Dec 2023 17:26:34 +0900
Subject: [PATCH] use global rand functions

---
 .github/workflows/test.yml |  3 ++-
 rand.go                    | 21 +++++++++++++++++++++
 rand_v2.go                 | 21 +++++++++++++++++++++
 retry.go                   | 30 ------------------------------
 4 files changed, 44 insertions(+), 31 deletions(-)
 create mode 100644 rand.go
 create mode 100644 rand_v2.go

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 2fcc24a..daab423 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -10,7 +10,8 @@ jobs:
     strategy:
       matrix:
         go:
-          - "1"
+          - "stable"
+          - "1.22.0-rc.1"
           - "1.21"
           - "1.20"
           - "1.19"
diff --git a/rand.go b/rand.go
new file mode 100644
index 0000000..95f562d
--- /dev/null
+++ b/rand.go
@@ -0,0 +1,21 @@
+//go:build !go1.22
+// +build !go1.22
+
+package retry
+
+import (
+	"math/rand"
+	"time"
+)
+
+func (p *Policy) randomJitter() time.Duration {
+	jitter := int64(p.Jitter)
+	if jitter == 0 {
+		return 0
+	}
+
+	if jitter < 0 {
+		return -time.Duration(rand.Int63n(-jitter))
+	}
+	return time.Duration(rand.Int63n(jitter))
+}
diff --git a/rand_v2.go b/rand_v2.go
new file mode 100644
index 0000000..39f2ee3
--- /dev/null
+++ b/rand_v2.go
@@ -0,0 +1,21 @@
+//go:build go1.22
+// +build go1.22
+
+package retry
+
+import (
+	"math/rand/v2"
+	"time"
+)
+
+func (p *Policy) randomJitter() time.Duration {
+	jitter := p.Jitter
+	if jitter == 0 {
+		return 0
+	}
+
+	if jitter < 0 {
+		return -rand.N(-jitter)
+	}
+	return rand.N(jitter)
+}
diff --git a/retry.go b/retry.go
index 233dbe7..a40e0df 100644
--- a/retry.go
+++ b/retry.go
@@ -2,11 +2,7 @@ package retry
 
 import (
 	"context"
-	crand "crypto/rand"
-	"encoding/binary"
 	"errors"
-	"math/rand"
-	"sync"
 	"time"
 )
 
@@ -28,9 +24,6 @@ type Policy struct {
 	// Zero means no jitter.
 	// Negative value shorten the delay.
 	Jitter time.Duration
-
-	mu   sync.Mutex
-	rand *rand.Rand
 }
 
 // Retrier handles retrying.
@@ -122,29 +115,6 @@ func MarkPermanent(err error) error {
 	return &permanentError{err}
 }
 
-func (p *Policy) randomJitter() time.Duration {
-	jitter := int64(p.Jitter)
-	if jitter == 0 {
-		return 0
-	}
-
-	p.mu.Lock()
-	defer p.mu.Unlock()
-
-	if p.rand == nil {
-		// initialize rand using crypto/rand
-		var seed int64
-		if err := binary.Read(crand.Reader, binary.LittleEndian, &seed); err != nil {
-			seed = time.Now().UnixNano() // fall back to timestamp
-		}
-		p.rand = rand.New(rand.NewSource(seed))
-	}
-	if jitter < 0 {
-		return -time.Duration(p.rand.Int63n(-jitter))
-	}
-	return time.Duration(p.rand.Int63n(jitter))
-}
-
 // Continue returns whether retrying should be continued.
 func (r *Retrier) Continue() bool {
 	r.count++