callbacks: use uintptr instead of int as index

Since the index of the registered callbacks is basically only used as
void*/unsafe.Pointer, it makes more sense and code simpler, if
the index type is uintptr instead of a simple int.

Signed-off-by: Sven Anderson <sven@redhat.com>

internal/callbacks/callbacks.go

@@ -19,17 +19,17 @@ import (
 // to control and validate what "callbacks" get used.
 type Callbacks struct {
 	mutex sync.RWMutex
-	cmap  map[int]interface{}
+	cmap  map[uintptr]interface{}
 }
 
 // New returns a new callbacks tracker.
 func New() *Callbacks {
-	return &Callbacks{cmap: make(map[int]interface{})}
+	return &Callbacks{cmap: make(map[uintptr]interface{})}
 }
 
 // Add a callback/object to the tracker and return a new index
 // for the object.
-func (cb *Callbacks) Add(v interface{}) int {
+func (cb *Callbacks) Add(v interface{}) uintptr {
 	cb.mutex.Lock()
 	defer cb.mutex.Unlock()
 	// this approach assumes that there are typically very few callbacks
@@ -38,7 +38,7 @@ func (cb *Callbacks) Add(v interface{}) int {
 	// until we find a free key like in the cgo wiki page.
 	// If this code ever becomes a hot path there's surely plenty of room
 	// for optimization in the future :-)
-	index := len(cb.cmap) + 1
+	index := uintptr(len(cb.cmap) + 1)
 	for {
 		if _, found := cb.cmap[index]; !found {
 			break
@@ -50,14 +50,14 @@ func (cb *Callbacks) Add(v interface{}) int {
 }
 
 // Remove a callback/object given it's index.
-func (cb *Callbacks) Remove(index int) {
+func (cb *Callbacks) Remove(index uintptr) {
 	cb.mutex.Lock()
 	defer cb.mutex.Unlock()
 	delete(cb.cmap, index)
 }
 
 // Lookup returns a mapped callback/object given an index.
-func (cb *Callbacks) Lookup(index int) interface{} {
+func (cb *Callbacks) Lookup(index uintptr) interface{} {
 	cb.mutex.RLock()
 	defer cb.mutex.RUnlock()
 	return cb.cmap[index]

rbd/diff_iterate.go

@@ -126,7 +126,7 @@ func (image *Image) DiffIterate(config DiffIterateConfig) error {
 func diffIterateCallback(
 	offset C.uint64_t, length C.size_t, exists C.int, index unsafe.Pointer) C.int {
 
-	v := diffIterateCallbacks.Lookup(int(uintptr(index)))
+	v := diffIterateCallbacks.Lookup(uintptr(index))
 	config := v.(DiffIterateConfig)
 	return C.int(config.Callback(
 		uint64(offset), uint64(length), int(exists), config.Data))

rbd/watchers_mimic.go

@@ -95,7 +95,7 @@ type Watch struct {
 	image   *Image
 	wcc     watchCallbackCtx
 	handle  C.uint64_t
-	cbIndex int
+	cbIndex uintptr
 }
 
 // UpdateWatch updates the image object to watch metadata changes to the
@@ -146,7 +146,7 @@ func (w *Watch) Unwatch() error {
 
 //export imageWatchCallback
 func imageWatchCallback(index unsafe.Pointer) {
-	v := watchCallbacks.Lookup(int(uintptr(index)))
+	v := watchCallbacks.Lookup(uintptr(index))
 	wcc := v.(watchCallbackCtx)
 	wcc.callback(wcc.data)
 }