jvmtthreading.pas

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{-----------------------------------------------------------------------------
The contents of this file are subject to the Mozilla Public License
Version 1.1 (the "License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.mozilla.org/MPL/MPL-1.1.html

Software distributed under the License is distributed on an "AS IS" basis,
WITHOUT WARRANTY OF ANY KIND, either expressed or implied. See the License for
the specific language governing rights and limitations under the License.

The Original Code is: MTThreading.pas, released on 2000-09-22.

The Initial Developer of the Original Code is Erwin Molendijk.
Portions created by Erwin Molendijk are Copyright (C) 2002 Erwin Molendijk.
All Rights Reserved.

Contributor(s): ______________________________________.

You may retrieve the latest version of this file at the Project JEDI home page,
located at http://www.delphi-jedi.org

Known Issues:
-----------------------------------------------------------------------------}
// $Id: JvMTThreading.pas,v 1.33 2005/03/09 14:57:27 marquardt Exp $

unit JvMTThreading;

{$I jvcl.inc}

interface

uses
  {$IFDEF USEJVCL}
  {$IFDEF UNITVERSIONING}
  JclUnitVersioning,
  {$ENDIF UNITVERSIONING}
  {$ENDIF USEJVCL}
  SysUtils, Classes, SyncObjs, Contnrs,
  {$IFDEF MSWINDOWS}
  Windows, Messages,
  {$ENDIF MSWINDOWS}
  {$IFDEF HAS_UNIT_LIBC}
  Libc,
  {$ENDIF HAS_UNIT_LIBC}
  {$IFDEF UNIX}
  QWindows,
  {$ENDIF UNIX}
  {$IFDEF COMPILER5}
  Forms,
  {$ENDIF COMPILER5}
  JvMTConsts, JvMTSync;

type
  TMTManager = class;
  TMTThread = class;

  TMTEvent = procedure(Thread: TMTThread) of object;

  {$IFDEF COMPILER5}
  TIntThread = class(Classes.TThread)
  public
    destructor Destroy; override;
    procedure Synchronize(Method: TThreadMethod);
    function WaitFor: Longword;
  end;
  {$ELSE}
  TIntThread = TThread;
  {$ENDIF COMPILER5}

  TMTInternalThread = class(TIntThread)
  private
    FName: string;
    FOnExecute: TNotifyEvent;
  protected
    procedure Execute; override;
    procedure RaiseName;
  public
    property Name: string read FName write FName;
    property OnExecute: TNotifyEvent read FOnExecute write FOnExecute;
  end;

  TMTThread = class(TObject)
  private
    FFinished: Boolean;
    FIntThread: TMTInternalThread;
    FManager: TMTManager;
    FName: string;
    FOnExecute: TMTEvent;
    FOnFinished: TMTEvent;
    FOnTerminating: TMTEvent;
    FReferenceCount: Integer;
    FStatusChange: TCriticalSection;
    FTerminateSignal: THandle;
    FTicket: TMTTicket;
    procedure CreateAndRun;
    function GetStatus: TMTThreadStatus;
    procedure Log(const Msg: string);
    procedure OnIntThreadExecute(Sender: TObject);
    procedure OnIntThreadTerminate(Sender: TObject);
    {$IFDEF COMPILER5}
    procedure SyncOnIntThreadTerminate;
    {$ENDIF COMPILER5}
    procedure SetName(const Value: string);
  protected
    procedure DecRef;
    procedure IncRef;
  public
    constructor Create(Manager: TMTManager; Ticket: Integer);
    destructor Destroy; override;
    procedure CheckTerminate;
    procedure Release;
    procedure Run;
    procedure Synchronize(Method: TThreadMethod);
    procedure Terminate;
    procedure Wait;
    property Name: string read FName write SetName;
    property OnExecute: TMTEvent read FOnExecute write FOnExecute;
    property OnFinished: TMTEvent read FOnFinished write FOnFinished;
    property OnTerminating: TMTEvent read FOnTerminating write FOnTerminating;
    property ReferenceCount: Integer read FReferenceCount;
    property Status: TMTThreadStatus read GetStatus;
    property TerminateSignal: THandle read FTerminateSignal;
    property ThreadManager: TMTManager read FManager;
    property Ticket: TMTTicket read FTicket;
  end;

  TMTManager = class(TObject)
  private
    FGenTicket: TCriticalSection;
    FNextTicket: TMTTicket;
    FThreads: TObjectList;
    FThreadsChange: TCriticalSection;
    function FindThread(Ticket: TMTTicket; var Thread: TMTThread): Boolean;
    function GenerateTicket: TMTTicket;
    procedure Log(const Msg: string);
    procedure TryRemoveThread(Thread: TMTThread);
    function InternalActiveThreads(RaiseID: Longword): Integer;
  protected
    procedure OnThreadFinished(Thread: TMTThread);
  public
    constructor Create;
    destructor Destroy; override;
    function AcquireNewThread: TMTThread;
    function AcquireThread(Ticket: TMTTicket; var Thread: TMTThread): Boolean;
    function ActiveThreads: Boolean;
    procedure ReleaseThread(Ticket: TMTTicket);
    procedure TerminateThreads;
    procedure WaitThreads;
  end;

function CurrentMTThread: TMTThread;

{$IFDEF USEJVCL}
{$IFDEF UNITVERSIONING}
const
  UnitVersioning: TUnitVersionInfo = (
    RCSfile: '$RCSfile: JvMTThreading.pas,v $';
    Revision: '$Revision: 1.33 $';
    Date: '$Date: 2005/03/09 14:57:27 $';
    LogPath: 'JVCL\run'
  );
{$ENDIF UNITVERSIONING}
{$ENDIF USEJVCL}

implementation

{$IFDEF USEJVCL}
uses
  JvResources;
{$ENDIF USEJVCL}

{$IFNDEF USEJVCL}
resourcestring
  RsECurThreadIsPartOfManager = 'Current MTThread is part of the MTManager';
  RsECheckTerminateCalledByWrongThread = 'CheckTerminate can only be called by the same thread';
  RsEThreadNotInitializedOrWaiting = 'Cannot run: thread is not Initializing or Waiting';
  RsECannotChangeNameOfOtherActiveThread = 'Cannot change name of other active thread';
  RsEReleaseOfUnusedTicket = 'Release of unused ticket';
{$ENDIF !USEJVCL}

threadvar
  _CurrentMTThread: TMTThread;

function CurrentMTThread: TMTThread;
begin
  Result := _CurrentMTThread;
end;


{$IFDEF COMPILER5}

type
  PSyncRequest = ^TSyncRequest;
  TSyncRequest = record
    Method: TThreadMethod;
    ExceptionObject: TObject;
    Signal: THandle;
  end;

var
  SyncRequestAvailable: Boolean;
  ThreadSyncLock: TRTLCriticalSection;
  SyncRequestList: TList = nil;
  SyncWindow: HWND;

function CheckSynchronize: Boolean;
var
  SyncRequest: PSyncRequest;
begin
  Result := False;
  // Only the main thread is allowed to synchronize thread methods.
  if GetCurrentThreadID <> MainThreadID then
    Exit;

  EnterCriticalSection(ThreadSyncLock);
  try
    if SyncRequestAvailable and (SyncRequestList <> nil) then
    begin
      // Do not block while another thread is adding a new synchronization request.
      while SyncRequestList.Count > 0 do
      begin
        SyncRequest := SyncRequestList[0];
        SyncRequestList.Delete(0);
        try
          SyncRequest.Method;
        except
          SyncRequest^.ExceptionObject := ExceptObject;
        end;
        // inform TIntThread.Synchronize
        SetEvent(SyncRequest.Signal);
        SyncRequestAvailable := False;
        Result := True;
      end;
    end;
  finally
    LeaveCriticalSection(ThreadSyncLock);
  end;
end;

procedure FinalizeSyncRequestList;
begin
  // if the list is not empty there are still waiting threads
  if SyncRequestList <> nil then
  begin
    CheckSynchronize;
    SyncRequestList.Free;
    SyncRequestList := nil;
  end;
end;

function SyncWndProc(wnd: HWND; Msg: Cardinal; wParam, lParam: Integer): Integer; stdcall;
begin
  if Msg = WM_USER + 1 then
    Result := Integer(CheckSynchronize)
  else
    Result := DefWindowProc(wnd, Msg, wParam, lParam);
end;

//=== { TIntThread } =========================================================

procedure TIntThread.Synchronize(Method: TThreadMethod);
var
  SyncRequest: TSyncRequest;
begin
  if GetCurrentThreadID = MainThreadID then
    Method
  else
  begin
    SyncRequest.Signal := CreateEvent(nil, True, False, nil);
    try
      EnterCriticalSection(ThreadSyncLock);
      try
        if SyncRequestList = nil then
          SyncRequestList := TList.Create;

        SyncRequest.ExceptionObject := nil;
        SyncRequest.Method := Method;
        // The function returns only when the item is deleted from the List.
        SyncRequestList.Add(@SyncRequest);

        SyncRequestAvailable := True;
      finally
        LeaveCriticalSection(ThreadSyncLock);
      end;
      PostMessage(SyncWindow, WM_USER + 1, 0, 0);
      // Wait for CheckSynchronize.
      WaitForSingleObject(SyncRequest.Signal, INFINITE);
    finally
      CloseHandle(SyncRequest.Signal);
    end;
    // An exception occured. Re-raise it in the calling thread's context.
    if Assigned(SyncRequest.ExceptionObject) then
      raise SyncRequest.ExceptionObject;
  end;
end;

destructor TIntThread.Destroy;
begin
  CheckSynchronize;
  inherited Destroy;
end;

function TIntThread.WaitFor: Longword;
begin
  CheckSynchronize;
  Result := inherited WaitFor;
end;

{$ENDIF COMPILER5}

//=== { TMTInternalThread } ==================================================

procedure TMTInternalThread.Execute;
begin
  RaiseName;
  if Assigned(FOnExecute) then
    FOnExecute(Self);
end;

procedure TMTInternalThread.RaiseName;
{$IFDEF COMPILER7_UP}
var
  ThreadNameInfo: TThreadNameInfo;
{$ENDIF COMPILER7_UP}
begin
  {$IFDEF COMPILER7_UP}
  ThreadNameInfo.FType := $1000;
  ThreadNameInfo.FName := PChar(FName);
  ThreadNameInfo.FThreadID := $FFFFFFFF;
  ThreadNameInfo.FFlags := 0;
  try
    RaiseException($406D1388, 0, SizeOf(ThreadNameInfo) div SizeOf(Longword),
      @ThreadNameInfo);
  except
  end;
  {$ENDIF COMPILER7_UP}
end;

//=== { TMTThread } ==========================================================

constructor TMTThread.Create(Manager: TMTManager; Ticket: Integer);
begin
  inherited Create;
  FStatusChange := TCriticalSection.Create;
  FManager := Manager;
  FTicket := Ticket;
  FName := 'MT' + IntToStr(Ticket); // do not localize
  FTerminateSignal := CreateSemaphore(nil, 0, 1, '');
end;

destructor TMTThread.Destroy;
begin
  CloseHandle(FTerminateSignal);
  FStatusChange.Free;
  inherited Destroy;
end;

procedure TMTThread.CheckTerminate;
begin
  if CurrentMTThread <> Self then
    raise EMTThreadError.CreateRes(@RsECheckTerminateCalledByWrongThread);

  if Status = tsTerminating then
    raise EMTTerminateError.Create('');
end;

procedure TMTThread.CreateAndRun;
begin
  FStatusChange.Acquire;
  try
    FIntThread := TMTInternalThread.Create(True);
    FIntThread.OnExecute := OnIntThreadExecute;
    FIntThread.OnTerminate := OnIntThreadTerminate;
    FIntThread.FreeOnTerminate := True;
    FIntThread.Name := FName;
    FIntThread.Resume;
  finally
    FStatusChange.Release;
  end;
end;

procedure TMTThread.DecRef;
begin
  InterlockedDecrement(FReferenceCount);
end;

function TMTThread.GetStatus: TMTThreadStatus;
begin
  FStatusChange.Acquire;
  try
    if FFinished then
      Result := tsFinished
    else
    if FIntThread = nil then
      Result := tsInitializing
    else
    if FIntThread.Suspended then
      Result := tsWaiting
    else
    if FIntThread.Terminated then
      Result := tsTerminating
    else
      Result := tsRunning;
  finally
    FStatusChange.Release;
  end;
end;

procedure TMTThread.IncRef;
begin
  InterlockedIncrement(FReferenceCount);
end;

procedure TMTThread.Log(const Msg: string);
begin
  // (rom) no OutputDebugString in production code
  {$IFDEF DEBUGINFO_ON}
  OutputDebugString(PChar('[' + ClassName + '] ' + Msg));
  {$ENDIF DEBUGINFO_ON}
end;

procedure TMTThread.OnIntThreadExecute(Sender: TObject);
begin
  // set the CurrentMTThread variable.
  //  this variable is global, but only to this thread.
  _CurrentMTThread := Self;