为什么我不需要在COM线程中创建的线程中调用CoInitialize？ [英] Why I don't need call CoInitialize in a thread created inside a COM Thread?
问题描述
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Thread中，我不需要调用CoInitialize来使用 TADOQuery .Create ， .Open ... .Exec
我读到我需要在调用任何库函数（CoGetMalloc除外）之前初始化COM库，获取一个指向标准分配器的指针和内存分配函数。
但在这种情况下，没有CoInitialize没有给我带来任何麻烦。
这与线程模型相关吗？
在哪里可以找到此主题的解释？
UPDATE：
当我说INSIDE时，它意味着在COM方法上下文：
interface
type
TWorker = class（TThread）;
TServerConn2 = class（TRemoteDataModule，IServerConn2）
public
procedure Method（）;安全报
end;
实现
procedure TServerConn2.Method（）;
var W：TWorker;
begin
W：= TWorkerTread.Create（Self）;
end;
UPDATE 2：
用于连接数据库的 TADOConnection 当前正在COM线程上下文中创建（ TThread.Create构造函数）。虽然 TADOConnection.Open 和 TADOQuery.Create / .Open 都在 。执行。
UPDATE 3 - Simulacrum
接口：
type
TServerConn2 = class;
TWorker = class（TThread）
private
FDB：TADOConnection;
FOwner：TServerConn2;
protected
procedure执行;覆盖;
public
构造函数Create（Owner：TServerConn2）;
destructor Destroy;覆盖;
end;
TServerConn2 = class（TRemoteDataModule，IServerConn2）
ADOConnection1：TADOConnection;
procedure RemoteDataModuleCreate（Sender：TObject）;
private
{private declarations}
protected
类过程UpdateRegistry（Register：Boolean; const ClassID，ProgID：string）;覆盖;
procedure CheckException;安全报
public
用户，Pswd，Str：String;
Ok：Boolean;
end;实施： 类过程TServerConn2.UpdateRegistry（Register：Boolean; const ClassID，ProgID：string）;
begin
if注册then
begin
继承UpdateRegistry（Register，ClassID，ProgID）;
EnableSocketTransport（ClassID）;
EnableWebTransport（ClassID）;
end else
begin
DisableSocketTransport（ClassID）;
DisableWebTransport（ClassID）;
继承UpdateRegistry（Register，ClassID，ProgID）;
end;
end;
{TWorker}
构造函数TWorker.Create（Owner：TServerConn2）;
begin
inherited Create（False）;
FreeOnTerminate：= True;
FDB：= TADOConnection.Create（nil）;
FOwner：=所有者;
end;
destructor TWorker.Destroy;
begin
FDB.Free;
FOwner.Ok：= True;
inherited;
end;
过程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;
过程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;
初始化
TComponentFactory.Create（ComServer，TServerConn2，
Class_ServerConn2，ciMultiInstance，tmApartment）;
end。
UPDATE 4
错误应该发生在这里：
function CreateADOObject（const ClassID：TGUID）：IUnknown;
var
状态：HResult;
FPUControlWord：Word;
begin
asm
FNSTCW FPUControlWord
end;
状态：= CoCreateInstance（ClassID，nil，CLSCTX_INPROC_SERVER或
CLSCTX_LOCAL_SERVER，IUnknown，Result）;
asm
FNCLEX
FLDCW FPUControlWord
end;
if（Status = REGDB_E_CLASSNOTREG）then
raise Exception.CreateRes（@SADOCreateError）else
OleCheck（Status）;
end;
不知何故（因为 TComponentFactory ） CoCreateInstance 标识 TWorker 与 TServerConn2
解决方案以下任一或两者可能适用：
在未使用COM初始化的线程中，所有现有的接口指针都会一直工作，直到您进行COM API调用，否则需要COM编组，然后检测未初始化的线程失败。也就是说，您的没有给我带来任何麻烦实际上可能太早了。
如果进程中的任何线程调用具有COINIT_MULTITHREADED标志的CoInitialize [Ex]，那么不仅会初始化当前线程作为多线程公寓的成员，但它也说，任何从未调用CoInitialize [Ex]的线程也是多线程公寓的一部分。 - 所谓的隐含MTA的东西
In order to learn multithreading, I've created a thread inside a COM Thread (TRemoteDataModule).
This is my Component Factory:
TComponentFactory.Create(ComServer, TServerConn2, Class_ServerConn2, ciMultiInstance, tmApartment);
Inside the Thread, I didn't needed to Call CoInitialize to use TADOQuery.Create, .Open... .Exec
But in this case, the absence of CoInitialize didn't brought me any trouble.
Is this related with Thread Model?
Where can I Find the explanation for this subject?
UPDATE:
When I say INSIDE, it means inside the COM method context:
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;
UPDATE 2:
The TADOConnection used to connect to database are currently being created in the COM Thread context (TThread.Create constructor). Although, TADOConnection.Open and TADOQuery.Create/.Open are both being performed inside TThread.Execute .
UPDATE 3 - Simulacrum
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;
Implementation:
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.
UPDATE 4
The error should happen here:
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;
By somehow (because of TComponentFactory maybe?) CoCreateInstance identifies that TWorker is in the same context than TServerConn2 and don't raise errors?
解决方案 Either or both of the following might apply:
On a thread not initialized with COM all existing interface pointers keep working until you make a COM API call or otherwise require COM marshalling which then fails detecting an uninitialized thread. That is, your "didn't brought me any trouble" might actually be too early to say.
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