windows - 为什么我不需要在 COM 线程内创建的线程中调用 CoInitialize？

Question

为了学习多线程，我在 COM 线程 (TRemoteDataModule) 中创建了一个线程。

这是我的组件工厂:

TComponentFactory.Create(ComServer, TServerConn2, Class_ServerConn2, ciMultiInstance, tmApartment);

在线程内，我不需要调用 CoInitialize 来使用 TADOQuery.Create、.Open... .Exec

我读到 I need to initialize the COM library on a thread before you call any of the library functions except CoGetMalloc, to get a pointer to the standard allocator, and the memory allocation functions.

但在这种情况下，没有 CoInitialize 并没有给我带来任何麻烦。
这与线程模型有关吗？我在哪里可以找到这个主题的解释？

更新:

当我说 INSIDE 时，它意味着在 COM 方法上下文中:

interface
type
  TWorker = class(TThread); 

  TServerConn2 = class(TRemoteDataModule, IServerConn2)
  public 
    procedure Method(); safecall;
  end;


implementation 
  procedure TServerConn2.Method(); 
  var W: TWorker;
  begin
    W := TWorkerTread.Create(Self);
  end;

更新 2:

用于连接到数据库的TADOConnection 当前正在COM 线程上下文中创建(TThread.Create 构造函数)。尽管 TADOConnection.Open 和 TADOQuery.Create/.Open 都在 TThread.Execute 中执行。

更新 3 - Simulacrum

接口(interface):

type
  TServerConn2 = class;

  TWorker = class(TThread)
  private
    FDB: TADOConnection;
    FOwner: TServerConn2;
  protected
    procedure Execute; override;
  public
    constructor Create(Owner: TServerConn2);
    destructor Destroy; override;
  end;

  TServerConn2 = class(TRemoteDataModule, IServerConn2)
    ADOConnection1: TADOConnection;
    procedure RemoteDataModuleCreate(Sender: TObject);
  private
    { Private declarations }
  protected
    class procedure UpdateRegistry(Register: Boolean; const ClassID, ProgID: string); override;
    procedure CheckException; safecall;
  public
    User, Pswd, Str: String;
    Ok: Boolean;
  end;

实现:

class procedure TServerConn2.UpdateRegistry(Register: Boolean; const ClassID, ProgID: string);
begin
  if Register then
  begin
    inherited UpdateRegistry(Register, ClassID, ProgID);
    EnableSocketTransport(ClassID);
    EnableWebTransport(ClassID);
  end else
  begin
    DisableSocketTransport(ClassID);
    DisableWebTransport(ClassID);
    inherited UpdateRegistry(Register, ClassID, ProgID);
  end;
end;

{ TWorker }

constructor TWorker.Create(Owner: TServerConn2);
begin
  inherited Create(False);
  FreeOnTerminate := True;
  FDB := TADOConnection.Create(nil);
  FOwner := Owner;
end;

destructor TWorker.Destroy;
begin
  FDB.Free;
  FOwner.Ok := True;
  inherited;
end;

procedure TWorker.Execute;
var Qry: TADOQuery;
begin
  FDB.LoginPrompt := False;
  FDB.ConnectionString := FOwner.Str;
  FDB.Open(FOwner.User, FOwner.Pswd);

  Qry := TADOQuery.Create(nil);
  try
    Qry.Connection := FDB;
    Qry.LockType := ltReadOnly;
    Qry.SQL.Text := 'SELECT TOP 1 * FROM MyTable';
    Qry.Open;
  finally
    Qry.Free;
  end;
end;

procedure TServerConn2.CheckException;
var W: TWorker;
begin
  W := TWorker.Create(Self);
  while not Ok do Sleep(100);
end;

procedure TServerConn2.RemoteDataModuleCreate(Sender: TObject);
begin
  User := 'user';
  Pswd := 'pass';
  Str := ADOConnection1.ConnectionString;
end;

initialization
  TComponentFactory.Create(ComServer, TServerConn2,
    Class_ServerConn2, ciMultiInstance, tmApartment);
end.

更新 4

错误应该发生在这里:

function CreateADOObject(const ClassID: TGUID): IUnknown;
var
  Status: HResult;
  FPUControlWord: Word;
begin
  asm
    FNSTCW  FPUControlWord
  end;
  Status := CoCreateInstance(ClassID, nil, CLSCTX_INPROC_SERVER or
    CLSCTX_LOCAL_SERVER, IUnknown, Result);
  asm
    FNCLEX
    FLDCW FPUControlWord
  end;
  if (Status = REGDB_E_CLASSNOTREG) then
    raise Exception.CreateRes(@SADOCreateError) else
    OleCheck(Status);
end;

通过某种方式(可能是因为 TComponentFactory？)CoCreateInstance 识别出 TWorker 与 TServerConn2 处于相同的上下文中> 并且不报错？

Answer 1

以下任何一项或两项都可能适用:

1. 在未使用 COM 初始化的线程上，所有现有接口(interface)指针都会继续工作，直到您进行 COM API 调用或以其他方式要求 COM 编码，然后无法检测到未初始化的线程。也就是说，你说“没有给我带来任何麻烦”实际上可能还为时过早。

2. If any thread in the process calls Co­Initialize­[Ex] with the COINIT_MULTI­THREADED flag, then that not only initializes the current thread as a member of the multi-threaded apartment, but it also says, "Any thread which has never called Co­Initialize­[Ex] is also part of the multi-threaded apartment." - 所谓的 impicit MTA 东西