Merge pull request #4953 from ImJasonH/cpuinfo

mxpv · web-flow · commit 9c3f1713918f · 2021-01-19T13:16:30.000-08:00
Derive cpuinfo as needed, instead of at init-time
diff --git a/platforms/cpuinfo.go b/platforms/cpuinfo.go
@@ -21,21 +21,26 @@ import (
 	"os"
 	"runtime"
 	"strings"
+	"sync"
 
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
 	"github.com/pkg/errors"
 )
 
 // Present the ARM instruction set architecture, eg: v7, v8
-var cpuVariant string
+// Don't use this value directly; call cpuVariant() instead.
+var cpuVariantValue string
 
-func init() {
-	if isArmArch(runtime.GOARCH) {
-		cpuVariant = getCPUVariant()
-	} else {
-		cpuVariant = ""
-	}
+var cpuVariantOnce sync.Once
+
+func cpuVariant() string {
+	cpuVariantOnce.Do(func() {
+		if isArmArch(runtime.GOARCH) {
+			cpuVariantValue = getCPUVariant()
+		}
+	})
+	return cpuVariantValue
 }
 
 // For Linux, the kernel has already detected the ABI, ISA and Features.
diff --git a/platforms/defaults.go b/platforms/defaults.go
@@ -33,6 +33,6 @@ func DefaultSpec() specs.Platform {
 		OS:           runtime.GOOS,
 		Architecture: runtime.GOARCH,
 		// The Variant field will be empty if arch != ARM.
-		Variant: cpuVariant,
+		Variant: cpuVariant(),
 	}
 }
diff --git a/platforms/defaults_test.go b/platforms/defaults_test.go
@@ -28,7 +28,7 @@ func TestDefault(t *testing.T) {
 	expected := specs.Platform{
 		OS:           runtime.GOOS,
 		Architecture: runtime.GOARCH,
-		Variant:      cpuVariant,
+		Variant:      cpuVariant(),
 	}
 	p := DefaultSpec()
 	if !reflect.DeepEqual(p, expected) {
diff --git a/platforms/platforms.go b/platforms/platforms.go
@@ -189,8 +189,8 @@ func Parse(specifier string) (specs.Platform, error) {
 		if isKnownOS(p.OS) {
 			// picks a default architecture
 			p.Architecture = runtime.GOARCH
-			if p.Architecture == "arm" && cpuVariant != "v7" {
-				p.Variant = cpuVariant
+			if p.Architecture == "arm" && cpuVariant() != "v7" {
+				p.Variant = cpuVariant()
 			}
 
 			return p, nil
diff --git a/platforms/platforms_test.go b/platforms/platforms_test.go
@@ -31,8 +31,8 @@ func TestParseSelector(t *testing.T) {
 		defaultVariant = ""
 	)
 
-	if defaultArch == "arm" && cpuVariant != "v7" {
-		defaultVariant = cpuVariant
+	if defaultArch == "arm" && cpuVariant() != "v7" {
+		defaultVariant = cpuVariant()
 	}
 
 	for _, testcase := range []struct {

Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,6 @@ func DefaultSpec() specs.Platform {`
`33`	`33`	`OS: runtime.GOOS,`
`34`	`34`	`Architecture: runtime.GOARCH,`
`35`	`35`	`// The Variant field will be empty if arch != ARM.`
`36`		`- Variant: cpuVariant,`
	`36`	`+ Variant: cpuVariant(),`
`37`	`37`	`}`
`38`	`38`	`}`
Original file line number	Diff line number	Diff line change
`@@ -28,7 +28,7 @@ func TestDefault(t *testing.T) {`
`28`	`28`	`expected := specs.Platform{`
`29`	`29`	`OS: runtime.GOOS,`
`30`	`30`	`Architecture: runtime.GOARCH,`
`31`		`- Variant: cpuVariant,`
	`31`	`+ Variant: cpuVariant(),`
`32`	`32`	`}`
`33`	`33`	`p := DefaultSpec()`
`34`	`34`	`if !reflect.DeepEqual(p, expected) {`
Original file line number	Diff line number	Diff line change
`@@ -31,8 +31,8 @@ func TestParseSelector(t *testing.T) {`
`31`	`31`	`defaultVariant = ""`
`32`	`32`	`)`
`33`	`33`
`34`		`- if defaultArch == "arm" && cpuVariant != "v7" {`
`35`		`- defaultVariant = cpuVariant`
	`34`	`+ if defaultArch == "arm" && cpuVariant() != "v7" {`
	`35`	`+ defaultVariant = cpuVariant()`
`36`	`36`	`}`
`37`	`37`
`38`	`38`	`for _, testcase := range []struct {`