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authorJamie Liu <jamieliu@google.com>2018-10-03 13:50:58 -0700
committerShentubot <shentubot@google.com>2018-10-03 13:52:15 -0700
commit8e729e0e1fd22147d2a609f9bae13aa4d96f02fd (patch)
tree2b5e4a04552584791f1a9e3afc14b282c7b2ea4f /pkg
parent7a6412cb0b4e52bf175a77b5f43d4a74547e9798 (diff)
Add //pkg/sync:generic_atomicptr.
PiperOrigin-RevId: 215620949 Change-Id: I519da4b44386d950443e5784fb8c48ff9a36c5d3
Diffstat (limited to 'pkg')
-rw-r--r--pkg/sync/BUILD8
-rw-r--r--pkg/sync/atomicptr_unsafe.go46
-rw-r--r--pkg/sync/atomicptrtest/BUILD28
-rw-r--r--pkg/sync/atomicptrtest/atomicptr_test.go40
4 files changed, 122 insertions, 0 deletions
diff --git a/pkg/sync/BUILD b/pkg/sync/BUILD
index 3959fea36..6ddc6e812 100644
--- a/pkg/sync/BUILD
+++ b/pkg/sync/BUILD
@@ -8,6 +8,14 @@ package(
load("//tools/go_generics:defs.bzl", "go_template")
go_template(
+ name = "generic_atomicptr",
+ srcs = ["atomicptr_unsafe.go"],
+ types = [
+ "Value",
+ ],
+)
+
+go_template(
name = "generic_seqatomic",
srcs = ["seqatomic_unsafe.go"],
types = [
diff --git a/pkg/sync/atomicptr_unsafe.go b/pkg/sync/atomicptr_unsafe.go
new file mode 100644
index 000000000..f12e9cb67
--- /dev/null
+++ b/pkg/sync/atomicptr_unsafe.go
@@ -0,0 +1,46 @@
+// Copyright 2018 Google Inc.
+//
+// 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 template doesn't exist. This file must be instantiated using the
+// go_template_instance rule in tools/go_generics/defs.bzl.
+package template
+
+import (
+ "sync/atomic"
+ "unsafe"
+)
+
+// Value is a required type parameter.
+type Value struct{}
+
+// An AtomicPtr is a pointer to a value of type Value that can be atomically
+// loaded and stored. The zero value of an AtomicPtr represents nil.
+//
+// Note that copying AtomicPtr by value performs a non-atomic read of the
+// stored pointer, which is unsafe if Store() can be called concurrently; in
+// this case, do `dst.Store(src.Load())` instead.
+type AtomicPtr struct {
+ ptr unsafe.Pointer
+}
+
+// Load returns the value set by the most recent Store. It returns nil if there
+// has been no previous call to Store.
+func (p *AtomicPtr) Load() *Value {
+ return (*Value)(atomic.LoadPointer(&p.ptr))
+}
+
+// Store sets the value returned by Load to x.
+func (p *AtomicPtr) Store(x *Value) {
+ atomic.StorePointer(&p.ptr, (unsafe.Pointer)(x))
+}
diff --git a/pkg/sync/atomicptrtest/BUILD b/pkg/sync/atomicptrtest/BUILD
new file mode 100644
index 000000000..4fa959df0
--- /dev/null
+++ b/pkg/sync/atomicptrtest/BUILD
@@ -0,0 +1,28 @@
+package(licenses = ["notice"]) # Apache 2.0
+
+load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
+load("//tools/go_generics:defs.bzl", "go_template_instance")
+
+go_template_instance(
+ name = "atomicptr_int",
+ out = "atomicptr_int.go",
+ package = "atomicptr",
+ suffix = "Int",
+ template = "//pkg/sync:generic_atomicptr",
+ types = {
+ "Value": "int",
+ },
+)
+
+go_library(
+ name = "atomicptr",
+ srcs = ["atomicptr_int.go"],
+ importpath = "gvisor.googlesource.com/gvisor/pkg/sync/atomicptr",
+)
+
+go_test(
+ name = "atomicptr_test",
+ size = "small",
+ srcs = ["atomicptr_test.go"],
+ embed = [":atomicptr"],
+)
diff --git a/pkg/sync/atomicptrtest/atomicptr_test.go b/pkg/sync/atomicptrtest/atomicptr_test.go
new file mode 100644
index 000000000..b458382b1
--- /dev/null
+++ b/pkg/sync/atomicptrtest/atomicptr_test.go
@@ -0,0 +1,40 @@
+// Copyright 2018 Google Inc.
+//
+// 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 atomicptr
+
+import (
+ "testing"
+)
+
+func newInt(val int) *int {
+ return &val
+}
+
+func TestAtomicPtr(t *testing.T) {
+ var p AtomicPtrInt
+ if got := p.Load(); got != nil {
+ t.Errorf("initial value is %p (%v), wanted nil", got, got)
+ }
+ want := newInt(42)
+ p.Store(want)
+ if got := p.Load(); got != want {
+ t.Errorf("wrong value: got %p (%v), wanted %p (%v)", got, got, want, want)
+ }
+ want = newInt(100)
+ p.Store(want)
+ if got := p.Load(); got != want {
+ t.Errorf("wrong value: got %p (%v), wanted %p (%v)", got, got, want, want)
+ }
+}