// ExistsW works like Exists but also returns a channel that will
// receive an Event value when a node is created in case the returned
// stat is nil and the node didn't exist, or when the existing node
// is removed. It will also receive critical session events. See the
// documentation of the Event type for more details.
func (conn *Conn) ExistsW(path string) (stat *Stat, watch <-chan Event, err error) {
conn.mutex.RLock()
defer conn.mutex.RUnlock()
if conn.handle == nil {
return nil, nil, closingError("existsw", path)
}
cpath := C.CString(path)
defer C.free(unsafe.Pointer(cpath))
watchId, watchChannel := conn.createWatch(true)
var cstat Stat
rc, cerr := C.zoo_wexists(conn.handle, cpath, C.watch_handler, unsafe.Pointer(watchId), &cstat.c)
// We diverge a bit from the usual here: a ZNONODE is not an error
// for an exists call, otherwise every Exists call would have to check
// for err != nil and err.Code() != ZNONODE.
switch ErrorCode(rc) {
case ZOK:
stat = &cstat
watch = watchChannel
case ZNONODE:
watch = watchChannel
default:
conn.forgetWatch(watchId)
err = zkError(rc, cerr, "existsw", path)
}
return
}
// Exists checks if a node exists at the given path. If it does,
// stat will contain meta information on the existing node, otherwise
// it will be nil.
func (conn *Conn) Exists(path string) (stat *Stat, err error) {
conn.mutex.RLock()
defer conn.mutex.RUnlock()
if conn.handle == nil {
return nil, closingError("exists", path)
}
cpath := C.CString(path)
defer C.free(unsafe.Pointer(cpath))
var cstat Stat
rc, cerr := C.zoo_wexists(conn.handle, cpath, nil, nil, &cstat.c)
// We diverge a bit from the usual here: a ZNONODE is not an error
// for an exists call, otherwise every Exists call would have to check
// for err != nil and err.Code() != ZNONODE.
if rc == C.ZOK {
stat = &cstat
} else if rc != C.ZNONODE {
err = zkError(rc, cerr, "exists", path)
}
return
}