diff options
Diffstat (limited to 'pkg/sync')
| -rw-r--r-- | pkg/sync/BUILD | 50 | ||||
| -rw-r--r-- | pkg/sync/LICENSE | 27 | ||||
| -rw-r--r-- | pkg/sync/atomicptr_unsafe.go | 46 | ||||
| -rw-r--r-- | pkg/sync/atomicptrtest/BUILD | 29 | ||||
| -rw-r--r-- | pkg/sync/atomicptrtest/atomicptr_test.go | 40 | ||||
| -rw-r--r-- | pkg/sync/downgradable_rwmutex_test.go | 149 | ||||
| -rw-r--r-- | pkg/sync/downgradable_rwmutex_unsafe.go | 143 | ||||
| -rw-r--r-- | pkg/sync/memmove_unsafe.go | 32 | ||||
| -rw-r--r-- | pkg/sync/norace_unsafe.go | 44 | ||||
| -rw-r--r-- | pkg/sync/race_unsafe.go | 50 | ||||
| -rw-r--r-- | pkg/sync/seqatomic_unsafe.go | 81 | ||||
| -rw-r--r-- | pkg/sync/seqatomictest/BUILD | 35 | ||||
| -rw-r--r-- | pkg/sync/seqatomictest/seqatomic_test.go | 132 | ||||
| -rw-r--r-- | pkg/sync/seqcount.go | 158 | ||||
| -rw-r--r-- | pkg/sync/seqcount_test.go | 162 | ||||
| -rw-r--r-- | pkg/sync/sync.go | 16 |
16 files changed, 0 insertions, 1194 deletions
diff --git a/pkg/sync/BUILD b/pkg/sync/BUILD deleted file mode 100644 index 1624e681c..000000000 --- a/pkg/sync/BUILD +++ /dev/null @@ -1,50 +0,0 @@ -load("//tools/go_stateify:defs.bzl", "go_library", "go_test") - -package( - default_visibility = ["//:sandbox"], - licenses = ["notice"], -) - -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 = [ - "Value", - ], - deps = [ - ":sync", - ], -) - -go_library( - name = "sync", - srcs = [ - "downgradable_rwmutex_unsafe.go", - "memmove_unsafe.go", - "norace_unsafe.go", - "race_unsafe.go", - "seqcount.go", - "sync.go", - ], - importpath = "gvisor.googlesource.com/gvisor/pkg/sync", -) - -go_test( - name = "sync_test", - size = "small", - srcs = [ - "downgradable_rwmutex_test.go", - "seqcount_test.go", - ], - embed = [":sync"], -) diff --git a/pkg/sync/LICENSE b/pkg/sync/LICENSE deleted file mode 100644 index 6a66aea5e..000000000 --- a/pkg/sync/LICENSE +++ /dev/null @@ -1,27 +0,0 @@ -Copyright (c) 2009 The Go Authors. All rights reserved. - -Redistribution and use in source and binary forms, with or without -modification, are permitted provided that the following conditions are -met: - - * Redistributions of source code must retain the above copyright -notice, this list of conditions and the following disclaimer. - * Redistributions in binary form must reproduce the above -copyright notice, this list of conditions and the following disclaimer -in the documentation and/or other materials provided with the -distribution. - * Neither the name of Google Inc. nor the names of its -contributors may be used to endorse or promote products derived from -this software without specific prior written permission. - -THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/pkg/sync/atomicptr_unsafe.go b/pkg/sync/atomicptr_unsafe.go deleted file mode 100644 index d943b7ff4..000000000 --- a/pkg/sync/atomicptr_unsafe.go +++ /dev/null @@ -1,46 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 deleted file mode 100644 index 198fbb895..000000000 --- a/pkg/sync/atomicptrtest/BUILD +++ /dev/null @@ -1,29 +0,0 @@ -load("//tools/go_stateify:defs.bzl", "go_library", "go_test") - -package(licenses = ["notice"]) - -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 deleted file mode 100644 index 3262785ce..000000000 --- a/pkg/sync/atomicptrtest/atomicptr_test.go +++ /dev/null @@ -1,40 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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) - } -} diff --git a/pkg/sync/downgradable_rwmutex_test.go b/pkg/sync/downgradable_rwmutex_test.go deleted file mode 100644 index 99c1c8be0..000000000 --- a/pkg/sync/downgradable_rwmutex_test.go +++ /dev/null @@ -1,149 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// GOMAXPROCS=10 go test - -// Copy/pasted from the standard library's sync/rwmutex_test.go, except for the -// addition of downgradingWriter and the renaming of num_iterations to -// numIterations to shut up Golint. - -package sync - -import ( - "fmt" - "runtime" - "sync/atomic" - "testing" -) - -func parallelReader(m *DowngradableRWMutex, clocked, cunlock, cdone chan bool) { - m.RLock() - clocked <- true - <-cunlock - m.RUnlock() - cdone <- true -} - -func doTestParallelReaders(numReaders, gomaxprocs int) { - runtime.GOMAXPROCS(gomaxprocs) - var m DowngradableRWMutex - clocked := make(chan bool) - cunlock := make(chan bool) - cdone := make(chan bool) - for i := 0; i < numReaders; i++ { - go parallelReader(&m, clocked, cunlock, cdone) - } - // Wait for all parallel RLock()s to succeed. - for i := 0; i < numReaders; i++ { - <-clocked - } - for i := 0; i < numReaders; i++ { - cunlock <- true - } - // Wait for the goroutines to finish. - for i := 0; i < numReaders; i++ { - <-cdone - } -} - -func TestParallelReaders(t *testing.T) { - defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1)) - doTestParallelReaders(1, 4) - doTestParallelReaders(3, 4) - doTestParallelReaders(4, 2) -} - -func reader(rwm *DowngradableRWMutex, numIterations int, activity *int32, cdone chan bool) { - for i := 0; i < numIterations; i++ { - rwm.RLock() - n := atomic.AddInt32(activity, 1) - if n < 1 || n >= 10000 { - panic(fmt.Sprintf("wlock(%d)\n", n)) - } - for i := 0; i < 100; i++ { - } - atomic.AddInt32(activity, -1) - rwm.RUnlock() - } - cdone <- true -} - -func writer(rwm *DowngradableRWMutex, numIterations int, activity *int32, cdone chan bool) { - for i := 0; i < numIterations; i++ { - rwm.Lock() - n := atomic.AddInt32(activity, 10000) - if n != 10000 { - panic(fmt.Sprintf("wlock(%d)\n", n)) - } - for i := 0; i < 100; i++ { - } - atomic.AddInt32(activity, -10000) - rwm.Unlock() - } - cdone <- true -} - -func downgradingWriter(rwm *DowngradableRWMutex, numIterations int, activity *int32, cdone chan bool) { - for i := 0; i < numIterations; i++ { - rwm.Lock() - n := atomic.AddInt32(activity, 10000) - if n != 10000 { - panic(fmt.Sprintf("wlock(%d)\n", n)) - } - for i := 0; i < 100; i++ { - } - atomic.AddInt32(activity, -10000) - rwm.DowngradeLock() - n = atomic.AddInt32(activity, 1) - if n < 1 || n >= 10000 { - panic(fmt.Sprintf("wlock(%d)\n", n)) - } - for i := 0; i < 100; i++ { - } - n = atomic.AddInt32(activity, -1) - rwm.RUnlock() - } - cdone <- true -} - -func HammerDowngradableRWMutex(gomaxprocs, numReaders, numIterations int) { - runtime.GOMAXPROCS(gomaxprocs) - // Number of active readers + 10000 * number of active writers. - var activity int32 - var rwm DowngradableRWMutex - cdone := make(chan bool) - go writer(&rwm, numIterations, &activity, cdone) - go downgradingWriter(&rwm, numIterations, &activity, cdone) - var i int - for i = 0; i < numReaders/2; i++ { - go reader(&rwm, numIterations, &activity, cdone) - } - go writer(&rwm, numIterations, &activity, cdone) - go downgradingWriter(&rwm, numIterations, &activity, cdone) - for ; i < numReaders; i++ { - go reader(&rwm, numIterations, &activity, cdone) - } - // Wait for the 4 writers and all readers to finish. - for i := 0; i < 4+numReaders; i++ { - <-cdone - } -} - -func TestDowngradableRWMutex(t *testing.T) { - defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1)) - n := 1000 - if testing.Short() { - n = 5 - } - HammerDowngradableRWMutex(1, 1, n) - HammerDowngradableRWMutex(1, 3, n) - HammerDowngradableRWMutex(1, 10, n) - HammerDowngradableRWMutex(4, 1, n) - HammerDowngradableRWMutex(4, 3, n) - HammerDowngradableRWMutex(4, 10, n) - HammerDowngradableRWMutex(10, 1, n) - HammerDowngradableRWMutex(10, 3, n) - HammerDowngradableRWMutex(10, 10, n) - HammerDowngradableRWMutex(10, 5, n) -} diff --git a/pkg/sync/downgradable_rwmutex_unsafe.go b/pkg/sync/downgradable_rwmutex_unsafe.go deleted file mode 100644 index 9a96056fc..000000000 --- a/pkg/sync/downgradable_rwmutex_unsafe.go +++ /dev/null @@ -1,143 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// This is mostly copied from the standard library's sync/rwmutex.go. -// -// Happens-before relationships indicated to the race detector: -// - Unlock -> Lock (via writerSem) -// - Unlock -> RLock (via readerSem) -// - RUnlock -> Lock (via writerSem) -// - DowngradeLock -> RLock (via readerSem) - -package sync - -import ( - "sync" - "sync/atomic" - "unsafe" -) - -// DowngradableRWMutex is identical to sync.RWMutex, but adds the DowngradeLock -// method. -type DowngradableRWMutex struct { - w sync.Mutex // held if there are pending writers - writerSem uint32 // semaphore for writers to wait for completing readers - readerSem uint32 // semaphore for readers to wait for completing writers - readerCount int32 // number of pending readers - readerWait int32 // number of departing readers -} - -const rwmutexMaxReaders = 1 << 30 - -// RLock locks rw for reading. -func (rw *DowngradableRWMutex) RLock() { - if RaceEnabled { - RaceDisable() - } - if atomic.AddInt32(&rw.readerCount, 1) < 0 { - // A writer is pending, wait for it. - runtimeSemacquire(&rw.readerSem) - } - if RaceEnabled { - RaceEnable() - RaceAcquire(unsafe.Pointer(&rw.readerSem)) - } -} - -// RUnlock undoes a single RLock call. -func (rw *DowngradableRWMutex) RUnlock() { - if RaceEnabled { - // TODO: Why does this need to be ReleaseMerge instead of - // Release? IIUC this establishes Unlock happens-before RUnlock, which - // seems unnecessary. - RaceReleaseMerge(unsafe.Pointer(&rw.writerSem)) - RaceDisable() - } - if r := atomic.AddInt32(&rw.readerCount, -1); r < 0 { - if r+1 == 0 || r+1 == -rwmutexMaxReaders { - panic("RUnlock of unlocked DowngradableRWMutex") - } - // A writer is pending. - if atomic.AddInt32(&rw.readerWait, -1) == 0 { - // The last reader unblocks the writer. - runtimeSemrelease(&rw.writerSem, false) - } - } - if RaceEnabled { - RaceEnable() - } -} - -// Lock locks rw for writing. -func (rw *DowngradableRWMutex) Lock() { - if RaceEnabled { - RaceDisable() - } - // First, resolve competition with other writers. - rw.w.Lock() - // Announce to readers there is a pending writer. - r := atomic.AddInt32(&rw.readerCount, -rwmutexMaxReaders) + rwmutexMaxReaders - // Wait for active readers. - if r != 0 && atomic.AddInt32(&rw.readerWait, r) != 0 { - runtimeSemacquire(&rw.writerSem) - } - if RaceEnabled { - RaceEnable() - RaceAcquire(unsafe.Pointer(&rw.writerSem)) - } -} - -// Unlock unlocks rw for writing. -func (rw *DowngradableRWMutex) Unlock() { - if RaceEnabled { - RaceRelease(unsafe.Pointer(&rw.writerSem)) - RaceRelease(unsafe.Pointer(&rw.readerSem)) - RaceDisable() - } - // Announce to readers there is no active writer. - r := atomic.AddInt32(&rw.readerCount, rwmutexMaxReaders) - if r >= rwmutexMaxReaders { - panic("Unlock of unlocked DowngradableRWMutex") - } - // Unblock blocked readers, if any. - for i := 0; i < int(r); i++ { - runtimeSemrelease(&rw.readerSem, false) - } - // Allow other writers to proceed. - rw.w.Unlock() - if RaceEnabled { - RaceEnable() - } -} - -// DowngradeLock atomically unlocks rw for writing and locks it for reading. -func (rw *DowngradableRWMutex) DowngradeLock() { - if RaceEnabled { - RaceRelease(unsafe.Pointer(&rw.readerSem)) - RaceDisable() - } - // Announce to readers there is no active writer and one additional reader. - r := atomic.AddInt32(&rw.readerCount, rwmutexMaxReaders+1) - if r >= rwmutexMaxReaders+1 { - panic("DowngradeLock of unlocked DowngradableRWMutex") - } - // Unblock blocked readers, if any. Note that this loop starts as 1 since r - // includes this goroutine. - for i := 1; i < int(r); i++ { - runtimeSemrelease(&rw.readerSem, false) - } - // Allow other writers to proceed to rw.w.Lock(). Note that they will still - // block on rw.writerSem since at least this reader exists, such that - // DowngradeLock() is atomic with the previous write lock. - rw.w.Unlock() - if RaceEnabled { - RaceEnable() - } -} - -//go:linkname runtimeSemacquire sync.runtime_Semacquire -func runtimeSemacquire(s *uint32) - -//go:linkname runtimeSemrelease sync.runtime_Semrelease -func runtimeSemrelease(s *uint32, handoff bool) diff --git a/pkg/sync/memmove_unsafe.go b/pkg/sync/memmove_unsafe.go deleted file mode 100644 index cd7a02dca..000000000 --- a/pkg/sync/memmove_unsafe.go +++ /dev/null @@ -1,32 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync - -import ( - "unsafe" -) - -// Memmove is exported for SeqAtomicLoad/SeqAtomicTryLoad<T>, which can't -// define it because go_generics can't update the go:linkname annotation. -// Furthermore, go:linkname silently doesn't work if the local name is exported -// (this is of course undocumented), which is why this indirection is -// necessary. -func Memmove(to, from unsafe.Pointer, n uintptr) { - memmove(to, from, n) -} - -//go:linkname memmove runtime.memmove -//go:noescape -func memmove(to, from unsafe.Pointer, n uintptr) diff --git a/pkg/sync/norace_unsafe.go b/pkg/sync/norace_unsafe.go deleted file mode 100644 index 1593b9e5d..000000000 --- a/pkg/sync/norace_unsafe.go +++ /dev/null @@ -1,44 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync - -import ( - "unsafe" -) - -// RaceEnabled is true if the Go data race detector is enabled. -const RaceEnabled = false - -// RaceDisable has the same semantics as runtime.RaceDisable. -func RaceDisable() { -} - -// RaceEnable has the same semantics as runtime.RaceEnable. -func RaceEnable() { -} - -// RaceAcquire has the same semantics as runtime.RaceAcquire. -func RaceAcquire(addr unsafe.Pointer) { -} - -// RaceRelease has the same semantics as runtime.RaceRelease. -func RaceRelease(addr unsafe.Pointer) { -} - -// RaceReleaseMerge has the same semantics as runtime.RaceReleaseMerge. -func RaceReleaseMerge(addr unsafe.Pointer) { -} diff --git a/pkg/sync/race_unsafe.go b/pkg/sync/race_unsafe.go deleted file mode 100644 index 473eaddc6..000000000 --- a/pkg/sync/race_unsafe.go +++ /dev/null @@ -1,50 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync - -import ( - "runtime" - "unsafe" -) - -// RaceEnabled is true if the Go data race detector is enabled. -const RaceEnabled = true - -// RaceDisable has the same semantics as runtime.RaceDisable. -func RaceDisable() { - runtime.RaceDisable() -} - -// RaceEnable has the same semantics as runtime.RaceEnable. -func RaceEnable() { - runtime.RaceEnable() -} - -// RaceAcquire has the same semantics as runtime.RaceAcquire. -func RaceAcquire(addr unsafe.Pointer) { - runtime.RaceAcquire(addr) -} - -// RaceRelease has the same semantics as runtime.RaceRelease. -func RaceRelease(addr unsafe.Pointer) { - runtime.RaceRelease(addr) -} - -// RaceReleaseMerge has the same semantics as runtime.RaceReleaseMerge. -func RaceReleaseMerge(addr unsafe.Pointer) { - runtime.RaceReleaseMerge(addr) -} diff --git a/pkg/sync/seqatomic_unsafe.go b/pkg/sync/seqatomic_unsafe.go deleted file mode 100644 index bea31adc5..000000000 --- a/pkg/sync/seqatomic_unsafe.go +++ /dev/null @@ -1,81 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 ( - "fmt" - "reflect" - "strings" - "unsafe" - - ssync "gvisor.googlesource.com/gvisor/pkg/sync" -) - -// Value is a required type parameter. -// -// Value must not contain any pointers, including interface objects, function -// objects, slices, maps, channels, unsafe.Pointer, and arrays or structs -// containing any of the above. An init() function will panic if this property -// does not hold. -type Value struct{} - -// SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race -// with any writer critical sections in sc. -func SeqAtomicLoad(sc *ssync.SeqCount, ptr *Value) Value { - // This function doesn't use SeqAtomicTryLoad because doing so is - // measurably, significantly (~20%) slower; Go is awful at inlining. - var val Value - for { - epoch := sc.BeginRead() - if ssync.RaceEnabled { - // runtime.RaceDisable() doesn't actually stop the race detector, - // so it can't help us here. Instead, call runtime.memmove - // directly, which is not instrumented by the race detector. - ssync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val)) - } else { - // This is ~40% faster for short reads than going through memmove. - val = *ptr - } - if sc.ReadOk(epoch) { - break - } - } - return val -} - -// SeqAtomicTryLoad returns a copy of *ptr while in a reader critical section -// in sc initiated by a call to sc.BeginRead() that returned epoch. If the read -// would race with a writer critical section, SeqAtomicTryLoad returns -// (unspecified, false). -func SeqAtomicTryLoad(sc *ssync.SeqCount, epoch ssync.SeqCountEpoch, ptr *Value) (Value, bool) { - var val Value - if ssync.RaceEnabled { - ssync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val)) - } else { - val = *ptr - } - return val, sc.ReadOk(epoch) -} - -func init() { - var val Value - typ := reflect.TypeOf(val) - name := typ.Name() - if ptrs := ssync.PointersInType(typ, name); len(ptrs) != 0 { - panic(fmt.Sprintf("SeqAtomicLoad<%s> is invalid since values %s of type %s contain pointers:\n%s", typ, name, typ, strings.Join(ptrs, "\n"))) - } -} diff --git a/pkg/sync/seqatomictest/BUILD b/pkg/sync/seqatomictest/BUILD deleted file mode 100644 index 23132650a..000000000 --- a/pkg/sync/seqatomictest/BUILD +++ /dev/null @@ -1,35 +0,0 @@ -load("//tools/go_stateify:defs.bzl", "go_library", "go_test") - -package(licenses = ["notice"]) - -load("//tools/go_generics:defs.bzl", "go_template_instance") - -go_template_instance( - name = "seqatomic_int", - out = "seqatomic_int.go", - package = "seqatomic", - suffix = "Int", - template = "//pkg/sync:generic_seqatomic", - types = { - "Value": "int", - }, -) - -go_library( - name = "seqatomic", - srcs = ["seqatomic_int.go"], - importpath = "gvisor.googlesource.com/gvisor/pkg/sync/seqatomic", - deps = [ - "//pkg/sync", - ], -) - -go_test( - name = "seqatomic_test", - size = "small", - srcs = ["seqatomic_test.go"], - embed = [":seqatomic"], - deps = [ - "//pkg/sync", - ], -) diff --git a/pkg/sync/seqatomictest/seqatomic_test.go b/pkg/sync/seqatomictest/seqatomic_test.go deleted file mode 100644 index f5e1fbfff..000000000 --- a/pkg/sync/seqatomictest/seqatomic_test.go +++ /dev/null @@ -1,132 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 seqatomic - -import ( - "sync/atomic" - "testing" - "time" - - gvsync "gvisor.googlesource.com/gvisor/pkg/sync" -) - -func TestSeqAtomicLoadUncontended(t *testing.T) { - var seq gvsync.SeqCount - const want = 1 - data := want - if got := SeqAtomicLoadInt(&seq, &data); got != want { - t.Errorf("SeqAtomicLoadInt: got %v, wanted %v", got, want) - } -} - -func TestSeqAtomicLoadAfterWrite(t *testing.T) { - var seq gvsync.SeqCount - var data int - const want = 1 - seq.BeginWrite() - data = want - seq.EndWrite() - if got := SeqAtomicLoadInt(&seq, &data); got != want { - t.Errorf("SeqAtomicLoadInt: got %v, wanted %v", got, want) - } -} - -func TestSeqAtomicLoadDuringWrite(t *testing.T) { - var seq gvsync.SeqCount - var data int - const want = 1 - seq.BeginWrite() - go func() { - time.Sleep(time.Second) - data = want - seq.EndWrite() - }() - if got := SeqAtomicLoadInt(&seq, &data); got != want { - t.Errorf("SeqAtomicLoadInt: got %v, wanted %v", got, want) - } -} - -func TestSeqAtomicTryLoadUncontended(t *testing.T) { - var seq gvsync.SeqCount - const want = 1 - data := want - epoch := seq.BeginRead() - if got, ok := SeqAtomicTryLoadInt(&seq, epoch, &data); !ok || got != want { - t.Errorf("SeqAtomicTryLoadInt: got (%v, %v), wanted (%v, true)", got, ok, want) - } -} - -func TestSeqAtomicTryLoadDuringWrite(t *testing.T) { - var seq gvsync.SeqCount - var data int - epoch := seq.BeginRead() - seq.BeginWrite() - if got, ok := SeqAtomicTryLoadInt(&seq, epoch, &data); ok { - t.Errorf("SeqAtomicTryLoadInt: got (%v, true), wanted (_, false)", got) - } - seq.EndWrite() -} - -func TestSeqAtomicTryLoadAfterWrite(t *testing.T) { - var seq gvsync.SeqCount - var data int - epoch := seq.BeginRead() - seq.BeginWrite() - seq.EndWrite() - if got, ok := SeqAtomicTryLoadInt(&seq, epoch, &data); ok { - t.Errorf("SeqAtomicTryLoadInt: got (%v, true), wanted (_, false)", got) - } -} - -func BenchmarkSeqAtomicLoadIntUncontended(b *testing.B) { - var seq gvsync.SeqCount - const want = 42 - data := want - b.RunParallel(func(pb *testing.PB) { - for pb.Next() { - if got := SeqAtomicLoadInt(&seq, &data); got != want { - b.Fatalf("SeqAtomicLoadInt: got %v, wanted %v", got, want) - } - } - }) -} - -func BenchmarkSeqAtomicTryLoadIntUncontended(b *testing.B) { - var seq gvsync.SeqCount - const want = 42 - data := want - b.RunParallel(func(pb *testing.PB) { - epoch := seq.BeginRead() - for pb.Next() { - if got, ok := SeqAtomicTryLoadInt(&seq, epoch, &data); !ok || got != want { - b.Fatalf("SeqAtomicTryLoadInt: got (%v, %v), wanted (%v, true)", got, ok, want) - } - } - }) -} - -// For comparison: -func BenchmarkAtomicValueLoadIntUncontended(b *testing.B) { - var a atomic.Value - const want = 42 - a.Store(int(want)) - b.RunParallel(func(pb *testing.PB) { - for pb.Next() { - if got := a.Load().(int); got != want { - b.Fatalf("atomic.Value.Load: got %v, wanted %v", got, want) - } - } - }) -} diff --git a/pkg/sync/seqcount.go b/pkg/sync/seqcount.go deleted file mode 100644 index 732e856a4..000000000 --- a/pkg/sync/seqcount.go +++ /dev/null @@ -1,158 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync - -import ( - "fmt" - "reflect" - "runtime" - "sync/atomic" -) - -// SeqCount is a synchronization primitive for optimistic reader/writer -// synchronization in cases where readers can work with stale data and -// therefore do not need to block writers. -// -// Compared to sync/atomic.Value: -// -// - Mutation of SeqCount-protected data does not require memory allocation, -// whereas atomic.Value generally does. This is a significant advantage when -// writes are common. -// -// - Atomic reads of SeqCount-protected data require copying. This is a -// disadvantage when atomic reads are common. -// -// - SeqCount may be more flexible: correct use of SeqCount.ReadOk allows other -// operations to be made atomic with reads of SeqCount-protected data. -// -// - SeqCount may be less flexible: as of this writing, SeqCount-protected data -// cannot include pointers. -// -// - SeqCount is more cumbersome to use; atomic reads of SeqCount-protected -// data require instantiating function templates using go_generics (see -// seqatomic.go). -type SeqCount struct { - // epoch is incremented by BeginWrite and EndWrite, such that epoch is odd - // if a writer critical section is active, and a read from data protected - // by this SeqCount is atomic iff epoch is the same even value before and - // after the read. - epoch uint32 -} - -// SeqCountEpoch tracks writer critical sections in a SeqCount. -type SeqCountEpoch struct { - val uint32 -} - -// We assume that: -// -// - All functions in sync/atomic that perform a memory read are at least a -// read fence: memory reads before calls to such functions cannot be reordered -// after the call, and memory reads after calls to such functions cannot be -// reordered before the call, even if those reads do not use sync/atomic. -// -// - All functions in sync/atomic that perform a memory write are at least a -// write fence: memory writes before calls to such functions cannot be -// reordered after the call, and memory writes after calls to such functions -// cannot be reordered before the call, even if those writes do not use -// sync/atomic. -// -// As of this writing, the Go memory model completely fails to describe -// sync/atomic, but these properties are implied by -// https://groups.google.com/forum/#!topic/golang-nuts/7EnEhM3U7B8. - -// BeginRead indicates the beginning of a reader critical section. Reader -// critical sections DO NOT BLOCK writer critical sections, so operations in a -// reader critical section MAY RACE with writer critical sections. Races are -// detected by ReadOk at the end of the reader critical section. Thus, the -// low-level structure of readers is generally: -// -// for { -// epoch := seq.BeginRead() -// // do something idempotent with seq-protected data -// if seq.ReadOk(epoch) { -// break -// } -// } -// -// However, since reader critical sections may race with writer critical -// sections, the Go race detector will (accurately) flag data races in readers -// using this pattern. Most users of SeqCount will need to use the -// SeqAtomicLoad function template in seqatomic.go. -func (s *SeqCount) BeginRead() SeqCountEpoch { - epoch := atomic.LoadUint32(&s.epoch) - for epoch&1 != 0 { - runtime.Gosched() - epoch = atomic.LoadUint32(&s.epoch) - } - return SeqCountEpoch{epoch} -} - -// ReadOk returns true if the reader critical section initiated by a previous -// call to BeginRead() that returned epoch did not race with any writer critical -// sections. -// -// ReadOk may be called any number of times during a reader critical section. -// Reader critical sections do not need to be explicitly terminated; the last -// call to ReadOk is implicitly the end of the reader critical section. -func (s *SeqCount) ReadOk(epoch SeqCountEpoch) bool { - return atomic.LoadUint32(&s.epoch) == epoch.val -} - -// BeginWrite indicates the beginning of a writer critical section. -// -// SeqCount does not support concurrent writer critical sections; clients with -// concurrent writers must synchronize them using e.g. sync.Mutex. -func (s *SeqCount) BeginWrite() { - if epoch := atomic.AddUint32(&s.epoch, 1); epoch&1 == 0 { - panic("SeqCount.BeginWrite during writer critical section") - } -} - -// EndWrite ends the effect of a preceding BeginWrite. -func (s *SeqCount) EndWrite() { - if epoch := atomic.AddUint32(&s.epoch, 1); epoch&1 != 0 { - panic("SeqCount.EndWrite outside writer critical section") - } -} - -// PointersInType returns a list of pointers reachable from values named -// valName of the given type. -// -// PointersInType is not exhaustive, but it is guaranteed that if typ contains -// at least one pointer, then PointersInTypeOf returns a non-empty list. -func PointersInType(typ reflect.Type, valName string) []string { - switch kind := typ.Kind(); kind { - case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128: - return nil - - case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice, reflect.String, reflect.UnsafePointer: - return []string{valName} - - case reflect.Array: - return PointersInType(typ.Elem(), valName+"[]") - - case reflect.Struct: - var ptrs []string - for i, n := 0, typ.NumField(); i < n; i++ { - field := typ.Field(i) - ptrs = append(ptrs, PointersInType(field.Type, fmt.Sprintf("%s.%s", valName, field.Name))...) - } - return ptrs - - default: - return []string{fmt.Sprintf("%s (of type %s with unknown kind %s)", valName, typ, kind)} - } -} diff --git a/pkg/sync/seqcount_test.go b/pkg/sync/seqcount_test.go deleted file mode 100644 index b14a8878e..000000000 --- a/pkg/sync/seqcount_test.go +++ /dev/null @@ -1,162 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync - -import ( - "reflect" - "testing" - "time" -) - -func TestSeqCountWriteUncontended(t *testing.T) { - var seq SeqCount - seq.BeginWrite() - seq.EndWrite() -} - -func TestSeqCountReadUncontended(t *testing.T) { - var seq SeqCount - epoch := seq.BeginRead() - if !seq.ReadOk(epoch) { - t.Errorf("ReadOk: got false, wanted true") - } -} - -func TestSeqCountBeginReadAfterWrite(t *testing.T) { - var seq SeqCount - var data int32 - const want = 1 - seq.BeginWrite() - data = want - seq.EndWrite() - epoch := seq.BeginRead() - if data != want { - t.Errorf("Reader: got %v, wanted %v", data, want) - } - if !seq.ReadOk(epoch) { - t.Errorf("ReadOk: got false, wanted true") - } -} - -func TestSeqCountBeginReadDuringWrite(t *testing.T) { - var seq SeqCount - var data int - const want = 1 - seq.BeginWrite() - go func() { - time.Sleep(time.Second) - data = want - seq.EndWrite() - }() - epoch := seq.BeginRead() - if data != want { - t.Errorf("Reader: got %v, wanted %v", data, want) - } - if !seq.ReadOk(epoch) { - t.Errorf("ReadOk: got false, wanted true") - } -} - -func TestSeqCountReadOkAfterWrite(t *testing.T) { - var seq SeqCount - epoch := seq.BeginRead() - seq.BeginWrite() - seq.EndWrite() - if seq.ReadOk(epoch) { - t.Errorf("ReadOk: got true, wanted false") - } -} - -func TestSeqCountReadOkDuringWrite(t *testing.T) { - var seq SeqCount - epoch := seq.BeginRead() - seq.BeginWrite() - if seq.ReadOk(epoch) { - t.Errorf("ReadOk: got true, wanted false") - } - seq.EndWrite() -} - -func BenchmarkSeqCountWriteUncontended(b *testing.B) { - var seq SeqCount - for i := 0; i < b.N; i++ { - seq.BeginWrite() - seq.EndWrite() - } -} - -func BenchmarkSeqCountReadUncontended(b *testing.B) { - var seq SeqCount - b.RunParallel(func(pb *testing.PB) { - for pb.Next() { - epoch := seq.BeginRead() - if !seq.ReadOk(epoch) { - b.Fatalf("ReadOk: got false, wanted true") - } - } - }) -} - -func TestPointersInType(t *testing.T) { - for _, test := range []struct { - name string // used for both test and value name - val interface{} - ptrs []string - }{ - { - name: "EmptyStruct", - val: struct{}{}, - }, - { - name: "Int", - val: int(0), - }, - { - name: "MixedStruct", - val: struct { - b bool - I int - ExportedPtr *struct{} - unexportedPtr *struct{} - arr [2]int - ptrArr [2]*int - nestedStruct struct { - nestedNonptr int - nestedPtr *int - } - structArr [1]struct { - nonptr int - ptr *int - } - }{}, - ptrs: []string{ - "MixedStruct.ExportedPtr", - "MixedStruct.unexportedPtr", - "MixedStruct.ptrArr[]", - "MixedStruct.nestedStruct.nestedPtr", - "MixedStruct.structArr[].ptr", - }, - }, - } { - t.Run(test.name, func(t *testing.T) { - typ := reflect.TypeOf(test.val) - ptrs := PointersInType(typ, test.name) - t.Logf("Found pointers: %v", ptrs) - if (len(ptrs) != 0 || len(test.ptrs) != 0) && !reflect.DeepEqual(ptrs, test.ptrs) { - t.Errorf("Got %v, wanted %v", ptrs, test.ptrs) - } - }) - } -} diff --git a/pkg/sync/sync.go b/pkg/sync/sync.go deleted file mode 100644 index 22c5348d7..000000000 --- a/pkg/sync/sync.go +++ /dev/null @@ -1,16 +0,0 @@ -// Copyright 2018 Google LLC -// -// 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 sync provides synchronization primitives. -package sync |