multithreading - Delphi Singleton 双重检查锁定

Question

我想实现一个单例关键部分，以保护多个类中的某些代码(不要再问了.​​.....)。我见过Delphi Singleton Pattern和 Aquire Singleton class Instance Multithread但这些使用全局函数来返回单例，我不希望这样。所以，我实现了我自己的版本:

unit SynchronizationHandler;

interface

uses
  SyncObjs;

type
  TSynchronizationHandler = class
  strict private
    FCriticalSection: TCriticalSection;
  private
    class var FSingletonCriticalSection: TCriticalSection;
    class var FInstance: TSynchronizationHandler;
  public
    constructor Create;
    destructor Destroy; override;

    procedure Lock;
    procedure Release;
    class function Instance: TSynchronizationHandler;
  end;

implementation

{ TSynchronizationHandler }

constructor TSynchronizationHandler.Create;
begin
  FCriticalSection := TCriticalSection.Create;
end;

destructor TSynchronizationHandler.Destroy;
begin
  FCriticalSection.Destroy;
end;

{Doublec check locking for this singletone}
class function TSynchronizationHandler.Instance: TSynchronizationHandler;
begin
  if not Assigned(FInstance) then
   begin
    FSingletonCriticalSection.Acquire;
    try
      if not Assigned(FInstance) then
        FInstance := TSynchronizationHandler.Create;
    finally
      FSingletonCriticalSection.Release;
    end;
  end;

  Result := FInstance;
end;

procedure TSynchronizationHandler.Lock;
begin
  FCriticalSection.Acquire;
end;

procedure TSynchronizationHandler.Release;
begin
  FCriticalSection.Release;
end;

initialization
  TSynchronizationHandler.FSingletonCriticalSection := TCriticalSection.Create;

finalization
  if Assigned(TSynchronizationHandler.FInstance) then
    TSynchronizationHandler.Instance.Free;

  TSynchronizationHandler.FSingletonCriticalSection.Free;

end.

它可以工作，但我不喜欢初始化\终结部分。有没有其他方法可以在不使用全局变量、函数的情况下完成此任务？

Answer 1

如果您想将所有必要的代码封装在类的命名空间内，那么您可以将 initialization 和 finalization 部分替换为 class constructor和一个class destructor ， 分别。这些将从单元初始化和最终化过程中隐式调用。