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goid: new package 

Allows retrieving the goroutine ID for concurrency testing when the race
detector is enabled.

Updates #1472

PiperOrigin-RevId: 289155308
This commit is contained in:
Ian Gudger 2020-01-10 13:33:12 -08:00 committed by gVisor bot
parent dacd349d6f
commit 6b83111499
7 changed files with 256 additions and 0 deletions
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26
pkg/goid/BUILD Normal file
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load("//tools/go_stateify:defs.bzl", "go_library")
load("@io_bazel_rules_go//go:def.bzl", "go_test")
package(licenses = ["notice"])
go_library(
name = "goid",
srcs = [
"goid.go",
"goid_amd64.s",
"goid_race.go",
"goid_unsafe.go",
],
importpath = "gvisor.dev/gvisor/pkg/goid",
visibility = ["//visibility:public"],
)
go_test(
name = "goid_test",
size = "small",
srcs = [
"empty_test.go",
"goid_test.go",
],
embed = [":goid"],
)

22
pkg/goid/empty_test.go Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !race
package goid
import "testing"
// TestNothing exists to make the build system happy.
func TestNothing(t *testing.T) {}

24
pkg/goid/goid.go Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !race
// Package goid provides access to the ID of the current goroutine in
// race/gotsan builds.
package goid
// Get returns the ID of the current goroutine.
func Get() int64 {
panic("unimplemented for non-race builds")
}

21
pkg/goid/goid_amd64.s Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "textflag.h"
// func getg() *g
TEXT ·getg(SB),NOSPLIT,$0-8
MOVQ (TLS), R14
MOVQ R14, ret+0(FP)
RET

25
pkg/goid/goid_race.go Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Only available in race/gotsan builds.
// +build race
// Package goid provides access to the ID of the current goroutine in
// race/gotsan builds.
package goid
// Get returns the ID of the current goroutine.
func Get() int64 {
return goid()
}

74
pkg/goid/goid_test.go Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build race
package goid
import (
"runtime"
"sync"
"testing"
)
func TestInitialGoID(t *testing.T) {
const max = 10000
if id := goid(); id < 0 || id > max {
t.Errorf("got goid = %d, want 0 < goid <= %d", id, max)
}
}
// TestGoIDSquence verifies that goid returns values which could plausibly be
// goroutine IDs. If this test breaks or becomes flaky, the structs in
// goid_unsafe.go may need to be updated.
func TestGoIDSquence(t *testing.T) {
// Goroutine IDs are cached by each P.
runtime.GOMAXPROCS(1)
// Fill any holes in lower range.
for i := 0; i < 50; i++ {
var wg sync.WaitGroup
wg.Add(1)
go func() {
wg.Done()
// Leak the goroutine to prevent the ID from being
// reused.
select {}
}()
wg.Wait()
}
id := goid()
for i := 0; i < 100; i++ {
var (
newID int64
wg sync.WaitGroup
)
wg.Add(1)
go func() {
newID = goid()
wg.Done()
// Leak the goroutine to prevent the ID from being
// reused.
select {}
}()
wg.Wait()
if max := id + 100; newID <= id || newID > max {
t.Errorf("unexpected goroutine ID pattern, got goid = %d, want %d < goid <= %d (previous = %d)", newID, id, max, id)
}
id = newID
}
}

64
pkg/goid/goid_unsafe.go Normal file
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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package goid
// Structs from Go runtime. These may change in the future and require
// updating. These structs are currently the same on both AMD64 and ARM64,
// but may diverge in the future.
type stack struct {
lo uintptr
hi uintptr
}
type gobuf struct {
sp uintptr
pc uintptr
g uintptr
ctxt uintptr
ret uint64
lr uintptr
bp uintptr
}
type g struct {
stack stack
stackguard0 uintptr
stackguard1 uintptr
_panic uintptr
_defer uintptr
m uintptr
sched gobuf
syscallsp uintptr
syscallpc uintptr
stktopsp uintptr
param uintptr
atomicstatus uint32
stackLock uint32
goid int64
// More fields...
//
// We only use goid and the fields before it are only listed to
// calculate the correct offset.
}
func getg() *g
// goid returns the ID of the current goroutine.
func goid() int64 {
return getg().goid
}