Here is the example in our gorocksdb:
// Get returns the data associated with the key from the database.
func (db *DB) Get(opts *ReadOptions, key []byte) (*Slice, error) {
var (
cErr *C.char
cValLen C.size_t
cKey = byteToChar(key)
)
cValue := C.rocksdb_get(db.c, opts.c, cKey,
C.size_t(len(key)), &cValLen, &cErr)
runtime.KeepAlive(key) //<==this is the customization we
added.
if cErr != nil {
defer C.rocksdb_free(unsafe.Pointer(cErr))
return nil, errors.New(C.GoString(cErr))
}
return NewSlice(cValue, cValLen), nil
}
// byteToChar returns *C.char from byte slice.
func byteToChar(b []byte) *C.char {
var c *C.char
if len(b) > 0 {
c = (*C.char)(unsafe.Pointer(&b[0]))
}
return c
}
My question is: if the keepalive(key) is necessary above. Will the "key" be
GC-ed when calling into C.rocksdb_get(). Does the compiler know there’s a
reference to “key” (using unsafe.pointer) and not collect “key” when
running GC?
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