mobile/bind/seq/ref.go

71 lines
1.5 KiB
Go

// Copyright 2014 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.
package seq
//#cgo LDFLAGS: -llog
//#include <android/log.h>
//#include <string.h>
//import "C"
import (
"fmt"
"sync"
)
type countedObj struct {
obj interface{}
cnt int32
}
// refs stores Go objects that have been passed to another language.
var refs struct {
sync.Mutex
next int32 // next reference number to use for Go object, always negative
refs map[interface{}]int32
objs map[int32]countedObj
}
func init() {
refs.Lock()
refs.next = -24 // Go objects get negative reference numbers. Arbitrary starting point.
refs.refs = make(map[interface{}]int32)
refs.objs = make(map[int32]countedObj)
refs.Unlock()
}
// A Ref represents a Java or Go object passed across the language
// boundary.
type Ref struct {
Num int32
}
// Get returns the underlying object.
func (r *Ref) Get() interface{} {
refs.Lock()
o, ok := refs.objs[r.Num]
refs.Unlock()
if !ok {
panic(fmt.Sprintf("unknown ref %d", r.Num))
}
return o.obj
}
// Delete decrements the reference count and removes the pinned object
// from the object map when the reference count becomes zero.
func Delete(num int32) {
refs.Lock()
defer refs.Unlock()
o, ok := refs.objs[num]
if !ok {
panic(fmt.Sprintf("seq.Delete unknown refnum: %d", num))
}
if o.cnt <= 1 {
delete(refs.objs, num)
delete(refs.refs, o.obj)
} else {
refs.objs[num] = countedObj{o.obj, o.cnt - 1}
}
}