internal/race: add package

Factor out duplicated race thunks from sync, syscall net
and fmt packages into a separate package and use it.

Fixes #8593

Change-Id: I156869c50946277809f6b509463752e7f7d28cdb
Reviewed-on: https://go-review.googlesource.com/14870
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

9 files changed, 65 insertions, 137 deletions

diff --git a/src/sync/cond.go b/src/sync/cond.go
index 9e6bc170f1..0aefcda908 100644
--- a/src/sync/cond.go
+++ b/src/sync/cond.go
@@ -5,6 +5,7 @@
 package sync
 
 import (
+	"internal/race"
 	"sync/atomic"
 	"unsafe"
 )
@@ -51,12 +52,12 @@ func NewCond(l Locker) *Cond {
 //
 func (c *Cond) Wait() {
 	c.checker.check()
-	if raceenabled {
-		raceDisable()
+	if race.Enabled {
+		race.Disable()
 	}
 	atomic.AddUint32(&c.waiters, 1)
-	if raceenabled {
-		raceEnable()
+	if race.Enabled {
+		race.Enable()
 	}
 	c.L.Unlock()
 	runtime_Syncsemacquire(&c.sema)
@@ -81,14 +82,14 @@ func (c *Cond) Broadcast() {
 
 func (c *Cond) signalImpl(all bool) {
 	c.checker.check()
-	if raceenabled {
-		raceDisable()
+	if race.Enabled {
+		race.Disable()
 	}
 	for {
 		old := atomic.LoadUint32(&c.waiters)
 		if old == 0 {
-			if raceenabled {
-				raceEnable()
+			if race.Enabled {
+				race.Enable()
 			}
 			return
 		}
@@ -97,8 +98,8 @@ func (c *Cond) signalImpl(all bool) {
 			new = 0
 		}
 		if atomic.CompareAndSwapUint32(&c.waiters, old, new) {
-			if raceenabled {
-				raceEnable()
+			if race.Enabled {
+				race.Enable()
 			}
 			runtime_Syncsemrelease(&c.sema, old-new)
 			return
diff --git a/src/sync/export_test.go b/src/sync/export_test.go
index 6f49b3bd8a..fa5983a2d1 100644
--- a/src/sync/export_test.go
+++ b/src/sync/export_test.go
@@ -7,5 +7,3 @@ package sync
 // Export for testing.
 var Runtime_Semacquire = runtime_Semacquire
 var Runtime_Semrelease = runtime_Semrelease
-
-const RaceEnabled = raceenabled
diff --git a/src/sync/mutex.go b/src/sync/mutex.go
index 3f280ad719..eb526144c5 100644
--- a/src/sync/mutex.go
+++ b/src/sync/mutex.go
@@ -11,6 +11,7 @@
 package sync
 
 import (
+	"internal/race"
 	"sync/atomic"
 	"unsafe"
 )
@@ -41,8 +42,8 @@ const (
 func (m *Mutex) Lock() {
 	// Fast path: grab unlocked mutex.
 	if atomic.CompareAndSwapInt32(&m.state, 0, mutexLocked) {
-		if raceenabled {
-			raceAcquire(unsafe.Pointer(m))
+		if race.Enabled {
+			race.Acquire(unsafe.Pointer(m))
 		}
 		return
 	}
@@ -85,8 +86,8 @@ func (m *Mutex) Lock() {
 		}
 	}
 
-	if raceenabled {
-		raceAcquire(unsafe.Pointer(m))
+	if race.Enabled {
+		race.Acquire(unsafe.Pointer(m))
 	}
 }
 
@@ -97,9 +98,9 @@ func (m *Mutex) Lock() {
 // It is allowed for one goroutine to lock a Mutex and then
 // arrange for another goroutine to unlock it.
 func (m *Mutex) Unlock() {
-	if raceenabled {
+	if race.Enabled {
 		_ = m.state
-		raceRelease(unsafe.Pointer(m))
+		race.Release(unsafe.Pointer(m))
 	}
 
 	// Fast path: drop lock bit.
diff --git a/src/sync/pool.go b/src/sync/pool.go
index 0cf0637024..381af0bead 100644
--- a/src/sync/pool.go
+++ b/src/sync/pool.go
@@ -5,6 +5,7 @@
 package sync
 
 import (
+	"internal/race"
 	"runtime"
 	"sync/atomic"
 	"unsafe"
@@ -59,7 +60,7 @@ type poolLocal struct {
 
 // Put adds x to the pool.
 func (p *Pool) Put(x interface{}) {
-	if raceenabled {
+	if race.Enabled {
 		// Under race detector the Pool degenerates into no-op.
 		// It's conforming, simple and does not introduce excessive
 		// happens-before edges between unrelated goroutines.
@@ -91,7 +92,7 @@ func (p *Pool) Put(x interface{}) {
 // If Get would otherwise return nil and p.New is non-nil, Get returns
 // the result of calling p.New.
 func (p *Pool) Get() interface{} {
-	if raceenabled {
+	if race.Enabled {
 		if p.New != nil {
 			return p.New()
 		}
diff --git a/src/sync/race.go b/src/sync/race.go
deleted file mode 100644
index fd0277dcc9..0000000000
--- a/src/sync/race.go
+++ /dev/null
@@ -1,42 +0,0 @@
-// Copyright 2012 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.
-
-// +build race
-
-package sync
-
-import (
-	"runtime"
-	"unsafe"
-)
-
-const raceenabled = true
-
-func raceAcquire(addr unsafe.Pointer) {
-	runtime.RaceAcquire(addr)
-}
-
-func raceRelease(addr unsafe.Pointer) {
-	runtime.RaceRelease(addr)
-}
-
-func raceReleaseMerge(addr unsafe.Pointer) {
-	runtime.RaceReleaseMerge(addr)
-}
-
-func raceDisable() {
-	runtime.RaceDisable()
-}
-
-func raceEnable() {
-	runtime.RaceEnable()
-}
-
-func raceRead(addr unsafe.Pointer) {
-	runtime.RaceRead(addr)
-}
-
-func raceWrite(addr unsafe.Pointer) {
-	runtime.RaceWrite(addr)
-}
diff --git a/src/sync/race0.go b/src/sync/race0.go
deleted file mode 100644
index 65ada1c5d3..0000000000
--- a/src/sync/race0.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// Copyright 2012 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.
-
-// +build !race
-
-package sync
-
-import (
-	"unsafe"
-)
-
-const raceenabled = false
-
-func raceAcquire(addr unsafe.Pointer) {
-}
-
-func raceRelease(addr unsafe.Pointer) {
-}
-
-func raceReleaseMerge(addr unsafe.Pointer) {
-}
-
-func raceDisable() {
-}
-
-func raceEnable() {
-}
-
-func raceRead(addr unsafe.Pointer) {
-}
-
-func raceWrite(addr unsafe.Pointer) {
-}
diff --git a/src/sync/rwmutex.go b/src/sync/rwmutex.go
index 0e8a58e5f0..d438c93c88 100644
--- a/src/sync/rwmutex.go
+++ b/src/sync/rwmutex.go
@@ -5,6 +5,7 @@
 package sync
 
 import (
+	"internal/race"
 	"sync/atomic"
 	"unsafe"
 )
@@ -27,17 +28,17 @@ const rwmutexMaxReaders = 1 << 30
 
 // RLock locks rw for reading.
 func (rw *RWMutex) RLock() {
-	if raceenabled {
+	if race.Enabled {
 		_ = rw.w.state
-		raceDisable()
+		race.Disable()
 	}
 	if atomic.AddInt32(&rw.readerCount, 1) < 0 {
 		// A writer is pending, wait for it.
 		runtime_Semacquire(&rw.readerSem)
 	}
-	if raceenabled {
-		raceEnable()
-		raceAcquire(unsafe.Pointer(&rw.readerSem))
+	if race.Enabled {
+		race.Enable()
+		race.Acquire(unsafe.Pointer(&rw.readerSem))
 	}
 }
 
@@ -46,14 +47,14 @@ func (rw *RWMutex) RLock() {
 // It is a run-time error if rw is not locked for reading
 // on entry to RUnlock.
 func (rw *RWMutex) RUnlock() {
-	if raceenabled {
+	if race.Enabled {
 		_ = rw.w.state
-		raceReleaseMerge(unsafe.Pointer(&rw.writerSem))
-		raceDisable()
+		race.ReleaseMerge(unsafe.Pointer(&rw.writerSem))
+		race.Disable()
 	}
 	if r := atomic.AddInt32(&rw.readerCount, -1); r < 0 {
 		if r+1 == 0 || r+1 == -rwmutexMaxReaders {
-			raceEnable()
+			race.Enable()
 			panic("sync: RUnlock of unlocked RWMutex")
 		}
 		// A writer is pending.
@@ -62,8 +63,8 @@ func (rw *RWMutex) RUnlock() {
 			runtime_Semrelease(&rw.writerSem)
 		}
 	}
-	if raceenabled {
-		raceEnable()
+	if race.Enabled {
+		race.Enable()
 	}
 }
 
@@ -74,9 +75,9 @@ func (rw *RWMutex) RUnlock() {
 // a blocked Lock call excludes new readers from acquiring
 // the lock.
 func (rw *RWMutex) Lock() {
-	if raceenabled {
+	if race.Enabled {
 		_ = rw.w.state
-		raceDisable()
+		race.Disable()
 	}
 	// First, resolve competition with other writers.
 	rw.w.Lock()
@@ -86,10 +87,10 @@ func (rw *RWMutex) Lock() {
 	if r != 0 && atomic.AddInt32(&rw.readerWait, r) != 0 {
 		runtime_Semacquire(&rw.writerSem)
 	}
-	if raceenabled {
-		raceEnable()
-		raceAcquire(unsafe.Pointer(&rw.readerSem))
-		raceAcquire(unsafe.Pointer(&rw.writerSem))
+	if race.Enabled {
+		race.Enable()
+		race.Acquire(unsafe.Pointer(&rw.readerSem))
+		race.Acquire(unsafe.Pointer(&rw.writerSem))
 	}
 }
 
@@ -100,17 +101,17 @@ func (rw *RWMutex) Lock() {
 // goroutine.  One goroutine may RLock (Lock) an RWMutex and then
 // arrange for another goroutine to RUnlock (Unlock) it.
 func (rw *RWMutex) Unlock() {
-	if raceenabled {
+	if race.Enabled {
 		_ = rw.w.state
-		raceRelease(unsafe.Pointer(&rw.readerSem))
-		raceRelease(unsafe.Pointer(&rw.writerSem))
-		raceDisable()
+		race.Release(unsafe.Pointer(&rw.readerSem))
+		race.Release(unsafe.Pointer(&rw.writerSem))
+		race.Disable()
 	}
 
 	// Announce to readers there is no active writer.
 	r := atomic.AddInt32(&rw.readerCount, rwmutexMaxReaders)
 	if r >= rwmutexMaxReaders {
-		raceEnable()
+		race.Enable()
 		panic("sync: Unlock of unlocked RWMutex")
 	}
 	// Unblock blocked readers, if any.
@@ -119,8 +120,8 @@ func (rw *RWMutex) Unlock() {
 	}
 	// Allow other writers to proceed.
 	rw.w.Unlock()
-	if raceenabled {
-		raceEnable()
+	if race.Enabled {
+		race.Enable()
 	}
 }
 
diff --git a/src/sync/waitgroup.go b/src/sync/waitgroup.go
index de399e64eb..c77fec306c 100644
--- a/src/sync/waitgroup.go
+++ b/src/sync/waitgroup.go
@@ -5,6 +5,7 @@
 package sync
 
 import (
+	"internal/race"
 	"sync/atomic"
 	"unsafe"
 )
@@ -46,24 +47,24 @@ func (wg *WaitGroup) state() *uint64 {
 // See the WaitGroup example.
 func (wg *WaitGroup) Add(delta int) {
 	statep := wg.state()
-	if raceenabled {
+	if race.Enabled {
 		_ = *statep // trigger nil deref early
 		if delta < 0 {
 			// Synchronize decrements with Wait.
-			raceReleaseMerge(unsafe.Pointer(wg))
+			race.ReleaseMerge(unsafe.Pointer(wg))
 		}
-		raceDisable()
-		defer raceEnable()
+		race.Disable()
+		defer race.Enable()
 	}
 	state := atomic.AddUint64(statep, uint64(delta)<<32)
 	v := int32(state >> 32)
 	w := uint32(state)
-	if raceenabled {
+	if race.Enabled {
 		if delta > 0 && v == int32(delta) {
 			// The first increment must be synchronized with Wait.
 			// Need to model this as a read, because there can be
 			// several concurrent wg.counter transitions from 0.
-			raceRead(unsafe.Pointer(&wg.sema))
+			race.Read(unsafe.Pointer(&wg.sema))
 		}
 	}
 	if v < 0 {
@@ -98,9 +99,9 @@ func (wg *WaitGroup) Done() {
 // Wait blocks until the WaitGroup counter is zero.
 func (wg *WaitGroup) Wait() {
 	statep := wg.state()
-	if raceenabled {
+	if race.Enabled {
 		_ = *statep // trigger nil deref early
-		raceDisable()
+		race.Disable()
 	}
 	for {
 		state := atomic.LoadUint64(statep)
@@ -108,28 +109,28 @@ func (wg *WaitGroup) Wait() {
 		w := uint32(state)
 		if v == 0 {
 			// Counter is 0, no need to wait.
-			if raceenabled {
-				raceEnable()
-				raceAcquire(unsafe.Pointer(wg))
+			if race.Enabled {
+				race.Enable()
+				race.Acquire(unsafe.Pointer(wg))
 			}
 			return
 		}
 		// Increment waiters count.
 		if atomic.CompareAndSwapUint64(statep, state, state+1) {
-			if raceenabled && w == 0 {
+			if race.Enabled && w == 0 {
 				// Wait must be synchronized with the first Add.
 				// Need to model this is as a write to race with the read in Add.
 				// As a consequence, can do the write only for the first waiter,
 				// otherwise concurrent Waits will race with each other.
-				raceWrite(unsafe.Pointer(&wg.sema))
+				race.Write(unsafe.Pointer(&wg.sema))
 			}
 			runtime_Semacquire(&wg.sema)
 			if *statep != 0 {
 				panic("sync: WaitGroup is reused before previous Wait has returned")
 			}
-			if raceenabled {
-				raceEnable()
-				raceAcquire(unsafe.Pointer(wg))
+			if race.Enabled {
+				race.Enable()
+				race.Acquire(unsafe.Pointer(wg))
 			}
 			return
 		}
diff --git a/src/sync/waitgroup_test.go b/src/sync/waitgroup_test.go
index 3e3e3bf824..a581660940 100644
--- a/src/sync/waitgroup_test.go
+++ b/src/sync/waitgroup_test.go
@@ -5,6 +5,7 @@
 package sync_test
 
 import (
+	"internal/race"
 	"runtime"
 	. "sync"
 	"sync/atomic"
@@ -48,7 +49,7 @@ func TestWaitGroup(t *testing.T) {
 }
 
 func knownRacy(t *testing.T) {
-	if RaceEnabled {
+	if race.Enabled {
 		t.Skip("skipping known-racy test under the race detector")
 	}
 }