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package cgo
import (
"sync"
"unsafe"
)
// #include <stdlib.h>
import "C"
// refMap is a convenient way to store opaque references that can be passed to
// C. It is useful if an API uses function pointers and you cannot pass a Go
// pointer but only a C pointer.
type refMap struct {
refs map[unsafe.Pointer]interface{}
lock sync.Mutex
}
// Put stores a value in the map. It can later be retrieved using Get. It must
// be removed using Remove to avoid memory leaks.
func (m *refMap) Put(v interface{}) unsafe.Pointer {
m.lock.Lock()
defer m.lock.Unlock()
if m.refs == nil {
m.refs = make(map[unsafe.Pointer]interface{}, 1)
}
ref := C.malloc(1)
m.refs[ref] = v
return ref
}
// Get returns a stored value previously inserted with Put. Use the same
// reference as you got from Put.
func (m *refMap) Get(ref unsafe.Pointer) interface{} {
m.lock.Lock()
defer m.lock.Unlock()
return m.refs[ref]
}
// Remove deletes a single reference from the map.
func (m *refMap) Remove(ref unsafe.Pointer) {
m.lock.Lock()
defer m.lock.Unlock()
delete(m.refs, ref)
C.free(ref)
}
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