58 lines
1003 B
Go
58 lines
1003 B
Go
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package pointer
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// #include <stdlib.h>
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import "C"
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import (
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"sync"
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"unsafe"
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)
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var (
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mutex sync.RWMutex
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store = map[unsafe.Pointer]interface{}{}
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)
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func Save(v interface{}) unsafe.Pointer {
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if v == nil {
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return nil
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}
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// Generate real fake C pointer.
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// This pointer will not store any data, but will bi used for indexing purposes.
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// Since Go doest allow to cast dangling pointer to unsafe.Pointer, we do rally allocate one byte.
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// Why we need indexing, because Go doest allow C code to store pointers to Go data.
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var ptr unsafe.Pointer = C.malloc(C.size_t(1))
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if ptr == nil {
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panic("can't allocate 'cgo-pointer hack index pointer': ptr == nil")
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}
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mutex.Lock()
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store[ptr] = v
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mutex.Unlock()
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return ptr
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}
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func Restore(ptr unsafe.Pointer) (v interface{}) {
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if ptr == nil {
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return nil
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}
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mutex.RLock()
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v = store[ptr]
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mutex.RUnlock()
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return
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}
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func Unref(ptr unsafe.Pointer) {
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if ptr == nil {
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return
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}
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mutex.Lock()
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delete(store, ptr)
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mutex.Unlock()
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C.free(ptr)
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}
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