From 3f2d0b46c3f39c815f41e1282fc3af154ae000b4 Mon Sep 17 00:00:00 2001
From: kwakubiney <kebiney@hotmail.com>
Date: Tue, 28 Nov 2023 09:38:55 +0000
Subject: [PATCH] internal: replace internal memoize with sync.OnceValues

Signed-off-by: kwakubiney <kebiney@hotmail.com>
---
 btf/btf_test.go              |  3 ++-
 cpu.go                       |  5 ++---
 internal/memoize.go          | 26 --------------------------
 internal/testutils/cgroup.go |  4 ++--
 internal/tracefs/kprobe.go   |  3 ++-
 internal/version.go          |  3 ++-
 map.go                       |  3 ++-
 7 files changed, 12 insertions(+), 35 deletions(-)
 delete mode 100644 internal/memoize.go

diff --git a/btf/btf_test.go b/btf/btf_test.go
index 843acadfe..a0bf98b00 100644
--- a/btf/btf_test.go
+++ b/btf/btf_test.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sync"
 	"testing"
 
 	"github.com/cilium/ebpf/internal"
@@ -36,7 +37,7 @@ type specAndRawBTF struct {
 	spec *Spec
 }
 
-var vmlinuxTestdata = internal.Memoize(func() (specAndRawBTF, error) {
+var vmlinuxTestdata = sync.OnceValues(func() (specAndRawBTF, error) {
 	b, err := internal.ReadAllCompressed("testdata/vmlinux.btf.gz")
 	if err != nil {
 		return specAndRawBTF{}, err
diff --git a/cpu.go b/cpu.go
index 1397d6de9..07e959efd 100644
--- a/cpu.go
+++ b/cpu.go
@@ -4,11 +4,10 @@ import (
 	"fmt"
 	"os"
 	"strings"
-
-	"github.com/cilium/ebpf/internal"
+	"sync"
 )
 
-var possibleCPU = internal.Memoize(func() (int, error) {
+var possibleCPU = sync.OnceValues(func() (int, error) {
 	return parseCPUsFromFile("/sys/devices/system/cpu/possible")
 })
 
diff --git a/internal/memoize.go b/internal/memoize.go
deleted file mode 100644
index 3de0a3fb9..000000000
--- a/internal/memoize.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package internal
-
-import (
-	"sync"
-)
-
-type memoizedFunc[T any] struct {
-	once   sync.Once
-	fn     func() (T, error)
-	result T
-	err    error
-}
-
-func (mf *memoizedFunc[T]) do() (T, error) {
-	mf.once.Do(func() {
-		mf.result, mf.err = mf.fn()
-	})
-	return mf.result, mf.err
-}
-
-// Memoize the result of a function call.
-//
-// fn is only ever called once, even if it returns an error.
-func Memoize[T any](fn func() (T, error)) func() (T, error) {
-	return (&memoizedFunc[T]{fn: fn}).do
-}
diff --git a/internal/testutils/cgroup.go b/internal/testutils/cgroup.go
index ab3183392..bf7fbc6c9 100644
--- a/internal/testutils/cgroup.go
+++ b/internal/testutils/cgroup.go
@@ -4,13 +4,13 @@ import (
 	"errors"
 	"os"
 	"strings"
+	"sync"
 	"testing"
 
-	"github.com/cilium/ebpf/internal"
 	"github.com/cilium/ebpf/internal/unix"
 )
 
-var cgroup2Path = internal.Memoize(func() (string, error) {
+var cgroup2Path = sync.OnceValues(func() (string, error) {
 	mounts, err := os.ReadFile("/proc/mounts")
 	if err != nil {
 		return "", err
diff --git a/internal/tracefs/kprobe.go b/internal/tracefs/kprobe.go
index 1b45a9a74..897740fec 100644
--- a/internal/tracefs/kprobe.go
+++ b/internal/tracefs/kprobe.go
@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+	"sync"
 	"syscall"
 
 	"github.com/cilium/ebpf/internal"
@@ -110,7 +111,7 @@ func sanitizeTracefsPath(path ...string) (string, error) {
 // Since kernel 4.1 tracefs should be mounted by default at /sys/kernel/tracing,
 // but may be also be available at /sys/kernel/debug/tracing if debugfs is mounted.
 // The available tracefs paths will depends on distribution choices.
-var getTracefsPath = internal.Memoize(func() (string, error) {
+var getTracefsPath = sync.OnceValues(func() (string, error) {
 	for _, p := range []struct {
 		path   string
 		fsType int64
diff --git a/internal/version.go b/internal/version.go
index 9b17ffb44..acd4650af 100644
--- a/internal/version.go
+++ b/internal/version.go
@@ -2,6 +2,7 @@ package internal
 
 import (
 	"fmt"
+	"sync"
 
 	"github.com/cilium/ebpf/internal/unix"
 )
@@ -79,7 +80,7 @@ func (v Version) Kernel() uint32 {
 }
 
 // KernelVersion returns the version of the currently running kernel.
-var KernelVersion = Memoize(func() (Version, error) {
+var KernelVersion = sync.OnceValues(func() (Version, error) {
 	return detectKernelVersion()
 })
 
diff --git a/map.go b/map.go
index dc2524590..7781a4897 100644
--- a/map.go
+++ b/map.go
@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"strings"
+	"sync"
 	"time"
 	"unsafe"
 
@@ -907,7 +908,7 @@ func (m *Map) nextKey(key interface{}, nextKeyOut sys.Pointer) error {
 	return nil
 }
 
-var mmapProtectedPage = internal.Memoize(func() ([]byte, error) {
+var mmapProtectedPage = sync.OnceValues(func() ([]byte, error) {
 	return unix.Mmap(-1, 0, os.Getpagesize(), unix.PROT_NONE, unix.MAP_ANON|unix.MAP_SHARED)
 })