以下是TNetEncoding.GetBase64Encoding
的原始Delphi源代码。但我怀疑在AtomicCmpExchange(Pointer(FBase64Encoding), Pointer(LEncoding), nil) <> nil
TNetEncoding = class
private
class var
FBase64Encoding: TNetEncoding;
与
class function TNetEncoding.GetBase64Encoding: TNetEncoding;
var
LEncoding: TBase64Encoding;
begin
if FBase64Encoding = nil then
begin
LEncoding := TBase64Encoding.Create;
if AtomicCmpExchange(Pointer(FBase64Encoding), Pointer(LEncoding), nil) <> nil then
LEncoding.Free;
{$IFDEF AUTOREFCOUNT}
FBase64Encoding.__ObjAddRef;
{$ENDIF AUTOREFCOUNT}
end;
Result := FBase64Encoding;
end;
我认为必须写成:
class function TNetEncoding.GetBase64Encoding: TNetEncoding;
var
LEncoding: TBase64Encoding;
begin
if FBase64Encoding = nil then
begin
LEncoding := TBase64Encoding.Create;
if AtomicCmpExchange(Pointer(FBase64Encoding), Pointer(LEncoding), nil) <> nil then
LEncoding.Free
{$IFDEF AUTOREFCOUNT}
!!!ELSE!!! FBase64Encoding.__ObjAddRef;
{$ENDIF AUTOREFCOUNT}
end;
Result := FBase64Encoding;
end;
我错了吗?
答案 0 :(得分:8)
你是对的。当if语句的计算结果为true时,代码将失败。当发生这种情况时,另一个线程已经设法首先分配单例,并且已经增加了引用计数。不应再次增加引用计数。
您应该提交错误报告。