diff options
author | Jamie Liu <jamieliu@google.com> | 2018-10-03 13:50:58 -0700 |
---|---|---|
committer | Shentubot <shentubot@google.com> | 2018-10-03 13:52:15 -0700 |
commit | 8e729e0e1fd22147d2a609f9bae13aa4d96f02fd (patch) | |
tree | 2b5e4a04552584791f1a9e3afc14b282c7b2ea4f /pkg | |
parent | 7a6412cb0b4e52bf175a77b5f43d4a74547e9798 (diff) |
Add //pkg/sync:generic_atomicptr.
PiperOrigin-RevId: 215620949
Change-Id: I519da4b44386d950443e5784fb8c48ff9a36c5d3
Diffstat (limited to 'pkg')
-rw-r--r-- | pkg/sync/BUILD | 8 | ||||
-rw-r--r-- | pkg/sync/atomicptr_unsafe.go | 46 | ||||
-rw-r--r-- | pkg/sync/atomicptrtest/BUILD | 28 | ||||
-rw-r--r-- | pkg/sync/atomicptrtest/atomicptr_test.go | 40 |
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) + } +} |