Remove 32-bit and 64-bit handlemaps.

The code confuses the race-detector, and the work-arounds to fool the
race-detector fools humans. No conclusive benchmark data supports
the usefulness of the handle maps.

fuse/nodefs/api.go

@@ -170,9 +170,6 @@ type Options struct {
 	// uid/gid.
 	*fuse.Owner
 
-	// If set, use a more portable, but slower inode number
-	// generation scheme.  This will make inode numbers (exported
-	// back to callers) stay within int32, which is necessary for
-	// making stat() succeed in 32-bit programs.
+	// This option exists for compatibility and is ignored.
 	PortableInodes bool
 }

fuse/nodefs/fsconnector.go

@@ -56,7 +56,7 @@ func NewFileSystemConnector(root Node, opts *Options) (c *FileSystemConnector) {
 	if opts == nil {
 		opts = NewOptions()
 	}
-	c.inodeMap = newHandleMap(opts.PortableInodes)
+	c.inodeMap = newPortableHandleMap()
 	c.rootNode = newInode(true, root)
 
 	// Make sure we don't reuse generation numbers.

fuse/nodefs/handle.go

 package nodefs
 
 import (
-	"fmt"
 	"log"
 	"sync"
-	"unsafe"
 )
 
 // HandleMap translates objects in Go space to 64-bit handles that can
@@ -132,220 +130,3 @@ func (m *portableHandleMap) Has(h uint64) bool {
 	m.RUnlock()
 	return ok
 }
-
-// 32 bits version of HandleMap
-type int32HandleMap struct {
-	mutex   sync.Mutex
-	handles map[uint32]*handled
-}
-
-func (m *int32HandleMap) Register(obj *handled) (handle uint64) {
-	m.mutex.Lock()
-	h := uint32(uintptr(unsafe.Pointer(obj)))
-	if obj.count == 0 {
-		m.handles[h] = obj
-		obj.handle = uint64(h)
-	}
-	handle = uint64(h)
-	obj.count++
-	m.mutex.Unlock()
-	return uint64(handle)
-}
-
-func (m *int32HandleMap) Has(h uint64) bool {
-	m.mutex.Lock()
-	ok := m.handles[uint32(h)] != nil
-	m.mutex.Unlock()
-	return ok
-}
-
-func (m *int32HandleMap) Handle(obj *handled) uint64 {
-	if obj.count == 0 {
-		return 0
-	}
-
-	h := uint32(uintptr(unsafe.Pointer(obj)))
-	return uint64(h)
-}
-
-func (m *int32HandleMap) Count() int {
-	m.mutex.Lock()
-	c := len(m.handles)
-	m.mutex.Unlock()
-	return c
-}
-
-func (m *int32HandleMap) Forget(handle uint64, count int) (forgotten bool, obj *handled) {
-	obj = m.Decode(handle)
-
-	m.mutex.Lock()
-	obj.count -= count
-	if obj.count == 0 {
-		obj.check = 0
-		delete(m.handles, uint32(handle))
-		forgotten = true
-	} else if obj.count < 0 {
-		log.Panicf("underflow: handle %d count %d, obj %d", handle, count, obj.count)
-	}
-	obj.handle = 0
-	m.mutex.Unlock()
-	return forgotten, obj
-}
-
-func (m *int32HandleMap) Decode(handle uint64) *handled {
-	val := (*handled)(unsafe.Pointer(uintptr(handle & ((1 << 32) - 1))))
-	return val
-}
-func newInt32HandleMap() *int32HandleMap {
-	return &int32HandleMap{
-		handles: make(map[uint32]*handled),
-	}
-}
-
-// 64 bits version of HandleMap. It uses the free bits on x64_64
-// (16+3) to do an extra sanity check on the data.  (Thanks to Russ
-// Cox for this suggestion).  In addition, it stores the object in a
-// map, so the Go runtime will not garbage collect it.
-type int64HandleMap struct {
-	mutex    sync.Mutex
-	handles  map[uint64]*handled
-	nextFree uint32
-}
-
-func (m *int64HandleMap) verify() {
-	if !paranoia {
-		return
-	}
-
-	m.mutex.Lock()
-	defer m.mutex.Unlock()
-	for k, v := range m.handles {
-		if m.Decode(k) != v {
-			panic("handle map out of sync")
-		}
-	}
-}
-
-func newInt64HandleMap() *int64HandleMap {
-	return &int64HandleMap{
-		handles:  make(map[uint64]*handled),
-		nextFree: 1, // to make tests easier.
-	}
-}
-
-// NewHandleMap creates a new HandleMap.  If verify is given, we
-// use remaining bits in the handle to store sanity check bits.
-func newHandleMap(portable bool) (hm handleMap) {
-	if portable {
-		return newPortableHandleMap()
-	}
-
-	var obj *handled
-	switch unsafe.Sizeof(obj) {
-	case 8:
-		return newInt64HandleMap()
-	case 4:
-		return newInt32HandleMap()
-	default:
-		log.Fatalf("Unknown size.")
-	}
-
-	return nil
-}
-
-func (m *int64HandleMap) Count() int {
-	m.mutex.Lock()
-	c := len(m.handles)
-	m.mutex.Unlock()
-	return c
-}
-
-func (m *int64HandleMap) Register(obj *handled) (handle uint64) {
-	defer m.verify()
-
-	m.mutex.Lock()
-	if obj.count == 0 {
-		handle = uint64(uintptr(unsafe.Pointer(obj)))
-
-		rest := (handle &^ (1<<48 - 1))
-		if rest != 0 {
-			panic("more than 48 bits in address")
-		}
-		if handle&0x7 != 0 {
-			panic("unaligned ptr")
-		}
-		handle >>= 3
-
-		check := m.nextFree
-		m.nextFree++
-		m.nextFree = m.nextFree & (1<<(64-48+3) - 1)
-
-		handle |= uint64(check) << (48 - 3)
-		if obj.check != 0 {
-			panic(_ALREADY_MSG)
-		}
-		obj.check = check
-		obj.handle = handle
-		m.handles[handle] = obj
-	} else {
-		handle = m.handle(obj)
-	}
-	obj.count++
-	m.mutex.Unlock()
-
-	return handle
-}
-
-func (m *int64HandleMap) handle(obj *handled) (handle uint64) {
-	if obj.count == 0 {
-		return 0
-	}
-
-	handle = uint64(uintptr(unsafe.Pointer(obj)))
-	handle >>= 3
-	handle |= uint64(obj.check) << (48 - 3)
-	return handle
-}
-
-func (m *int64HandleMap) Handle(obj *handled) (handle uint64) {
-	m.mutex.Lock()
-	m.mutex.Unlock()
-	return m.handle(obj)
-}
-
-func (m *int64HandleMap) Forget(handle uint64, count int) (forgotten bool, obj *handled) {
-	defer m.verify()
-	obj = m.Decode(handle)
-
-	m.mutex.Lock()
-	obj.count -= count
-	if obj.count == 0 {
-		delete(m.handles, handle)
-		obj.check = 0
-		obj.handle = 0
-		forgotten = true
-	} else if obj.count < 0 {
-		log.Panicf("underflow: handle %d count %d, %d", handle, count, obj.count)
-	}
-	m.mutex.Unlock()
-	return forgotten, obj
-}
-
-func (m *int64HandleMap) Has(handle uint64) bool {
-	m.mutex.Lock()
-	ok := m.handles[handle] != nil
-	m.mutex.Unlock()
-	return ok
-}
-
-func (m *int64HandleMap) Decode(handle uint64) (val *handled) {
-	ptrBits := uintptr(handle & (1<<45 - 1))
-	check := uint32(handle >> 45)
-	val = (*handled)(unsafe.Pointer(ptrBits << 3))
-	if val.check != check {
-		msg := fmt.Sprintf("handle check mismatch; handle has 0x%x, object has 0x%x",
-			check, val.check)
-		panic(msg)
-	}
-	return val
-}

fuse/nodefs/handle_test.go

@@ -3,7 +3,6 @@ package nodefs
 import (
 	"strings"
 	"testing"
-	"unsafe"
 )
 
 func markSeen(t *testing.T, substr string) {
@@ -17,26 +16,11 @@ func markSeen(t *testing.T, substr string) {
 	}
 }
 
-func TestHandleMapUnaligned(t *testing.T) {
-	if unsafe.Sizeof(t) < 8 {
-		t.Log("skipping test for 32 bits")
-		return
-	}
-	hm := newHandleMap(false)
-
-	b := make([]byte, 100)
-	v := (*handled)(unsafe.Pointer(&b[1]))
-
-	defer markSeen(t, "unaligned")
-	hm.Register(v)
-	t.Error("Unaligned register did not panic")
-}
-
 func TestHandleMapLookupCount(t *testing.T) {
 	for _, portable := range []bool{true, false} {
 		t.Log("portable:", portable)
 		v := new(handled)
-		hm := newHandleMap(portable)
+		hm := newPortableHandleMap()
 		h1 := hm.Register(v)
 		h2 := hm.Register(v)
 
@@ -75,10 +59,8 @@ func TestHandleMapLookupCount(t *testing.T) {
 }
 
 func TestHandleMapBasic(t *testing.T) {
-	for _, portable := range []bool{true, false} {
-		t.Log("portable:", portable)
 	v := new(handled)
-		hm := newHandleMap(portable)
+	hm := newPortableHandleMap()
 	h := hm.Register(v)
 	t.Logf("Got handle 0x%x", h)
 	if !hm.Has(h) {
@@ -103,11 +85,10 @@ func TestHandleMapBasic(t *testing.T) {
 	if v.check != 0 {
 		t.Errorf("forgotten object still has a check.")
 	}
-	}
 }
 
 func TestHandleMapMultiple(t *testing.T) {
-	hm := newHandleMap(false)
+	hm := newPortableHandleMap()
 	for i := 0; i < 10; i++ {
 		v := &handled{}
 		h := hm.Register(v)
@@ -119,17 +100,3 @@ func TestHandleMapMultiple(t *testing.T) {
 		}
 	}
 }
-
-func TestHandleMapCheckFail(t *testing.T) {
-	if unsafe.Sizeof(t) < 8 {
-		t.Log("skipping test for 32 bits")
-		return
-	}
-	defer markSeen(t, "check mismatch")
-
-	v := new(handled)
-	hm := newHandleMap(false)
-	h := hm.Register(v)
-	hm.Decode(h | (uint64(1) << 63))
-	t.Error("Borked decode did not panic")
-}

fuse/nodefs/inode.go

@@ -178,7 +178,7 @@ func (n *Inode) rmChild(name string) (ch *Inode) {
 // Can only be called on untouched root inodes.
 func (n *Inode) mountFs(opts *Options) {
 	n.mountPoint = &fileSystemMount{
-		openFiles:  newHandleMap(false),
+		openFiles:  newPortableHandleMap(),
 		mountInode: n,
 		options:    opts,
 	}