//******************************************************************************
//线程池
//******************************************************************************
//作者：Cai
//日期：2011-3-10
//******************************************************************************
unit ThreadPoolClass;

interface
uses
Windows, Classes, SyncObjectClass;

type
TThreadPool = class;


TOnTerminateTask = procedure (Sender: TObject) of object;
TTaskObject = class(TObject)
private
FOwner: TThread;
FOnTerminateTask: TOnTerminateTask;
FThreadID: Cardinal;
FTaskID : Cardinal;
procedure SetOnTerminateTask(const Value: TOnTerminateTask);
protected
procedure Execute();virtual; abstract;
procedure WaitFor(iTimeOut: Cardinal);virtual;
procedure Terminate;
public
constructor Create();virtual;
destructor Destroy();override;
procedure Synchronize(AMethod: TThreadMethod);
property ThreadID:Cardinal read FThreadID;
property TaskID:Cardinal read FTaskID;
property OnTerminateTask: TOnTerminateTask read FOnTerminateTask write SetOnTerminateTask;
end;

TThreadPolicyInt = 0..6;

TOnTerminatingTask = procedure(Sender: TObject; TaskObject: TTaskObject) of object;

TThreadPool = class(TObject)
private
FCriticalSectionLocker: TCriticalSectionLocker;
FThreadList: TList;
FTaskObjectList: TList;
FThreadMaxNum: Integer;
FOnTerminatingTask: TOnTerminatingTask;
FThreadPriority: TThreadPolicyInt;
FNextTaskID: Cardinal;// 可记录已处理的任务数
procedure SetThreadMaxNum(const Value: Integer);
procedure SetOnTerminatingTask(const Value: TOnTerminatingTask);
procedure SetThreadPriority(const Value: TThreadPolicyInt);
protected
function GetIdelThreadNum(): Integer;
function WakeUpThreads(iNum:Integer): Integer;
procedure GetTaskFromList(var TaskObject: TTaskObject; bPop:Boolean=True);
procedure AddTaskToList(TaskObject: TTaskObject);
procedure DeleteTaskFromList(TaskObject: TTaskObject);
procedure ClearTaskList();
procedure ClearThreadList();
procedure ClearList();
public
constructor Create();virtual;
destructor Destroy();override;
procedure AddTask(TaskObject: TTaskObject);
procedure KillTask(TaskObject: TTaskObject);
procedure Clear();
procedure WaitFor(iTimeOut:Cardinal);virtual;
function IsThreadDone():Boolean;
property ThreadMaxNum: Integer read FThreadMaxNum write SetThreadMaxNum;
property ThreadPriority: TThreadPolicyInt read FThreadPriority write SetThreadPriority;
property OnTerminatingTask: TOnTerminatingTask read FOnTerminatingTask write SetOnTerminatingTask;
end;

implementation

type
TTaskStatus = (tsRunning, {tsSuspend, tsWillTerminate, }tsTerminating, tsTerminated, tsDestroying);

TThreadItem = class(TThread)
private
FCriticalSectionLocker: TCriticalSectionLocker;
FOwner: TThreadPool;
FTaskStatus: TTaskStatus;
// FNextTaskStatus: TTaskStatus;
FCurTaskObject: TTaskObject;
procedure SetOwner(const Value: TThreadPool);
protected
procedure Execute();override;
procedure SetTaskStatus(TaskStatus: TTaskStatus);
public
constructor Create();overload; virtual;
destructor Destroy();override;
property Owner: TThreadPool read FOwner write SetOwner;
end;

{ TThreadPool }

constructor TThreadPool.Create;
begin
FCriticalSectionLocker:= TCriticalSectionLocker.Create;
FThreadList:=TList.Create;
FTaskObjectList:=TList.Create;
FThreadMaxNum := 3;
FThreadPriority := 4;
end;

destructor TThreadPool.Destroy;
begin
ClearList();
FThreadList.Destroy;
FThreadList := nil;
FTaskObjectList.Destroy;
FTaskObjectList := nil;
FCriticalSectionLocker.Destroy;
inherited;
end;

procedure TThreadPool.KillTask(TaskObject: TTaskObject);
begin
DeleteTaskFromList(TaskObject);
end;

procedure TThreadPool.SetThreadMaxNum(const Value: Integer);
begin
FThreadMaxNum := Value;
end;

procedure TThreadPool.AddTask(TaskObject: TTaskObject);
begin
AddTaskToList(TaskObject);
end;

procedure TThreadPool.AddTaskToList(TaskObject: TTaskObject);
var
ThreadItem: TThreadItem;
begin
if not FCriticalSectionLocker.EnterLocker() then Exit;
try
if FTaskObjectList.IndexOf(TaskObject)>=0 then Exit;
FTaskObjectList.Add(TaskObject);
TaskObject.FTaskID := FNextTaskID;
Inc(FNextTaskID);
//检查线程数是否足够
//======================================
if WakeUpThreads(1)=0 then//没有线程被唤醒
if FThreadList.Count < FThreadMaxNum then
begin
ThreadItem:= TThreadItem.Create();
ThreadItem.Priority := TThreadPriority(FThreadPriority);
FThreadList.Add(ThreadItem);
ThreadItem.FOwner := Self;
WakeUpThreads(1);
end;
finally
FCriticalSectionLocker.LeaveLocker();
end;
end;

procedure TThreadPool.GetTaskFromList(var TaskObject: TTaskObject; bPop:Boolean=True);
begin
TaskObject := nil;
if not FCriticalSectionLocker.EnterLocker() then Exit;
try
if FTaskObjectList.Count=0 then Exit;
TaskObject := TTaskObject(FTaskObjectList.Items[0]);
if bPop then FTaskObjectList.Delete(0);
finally
FCriticalSectionLocker.LeaveLocker();
end;
end;

procedure TThreadPool.DeleteTaskFromList(TaskObject: TTaskObject);
var
iIndex: Integer;
begin
if not FCriticalSectionLocker.EnterLocker() then Exit;
try
if Assigned(TaskObject) then Exit;
iIndex := FTaskObjectList.IndexOf(Pointer(TaskObject));
if iIndex = -1 then Exit;
if TaskObject.FOwner=nil then Exit;
if TThreadItem(TaskObject.FOwner).FTaskStatus<>tsTerminated then
begin
TaskObject.Terminate();
TaskObject.WaitFor(DWORD(-1));
end;
FTaskObjectList.Delete(iIndex);
finally
FCriticalSectionLocker.LeaveLocker();
end;
end;

procedure TThreadPool.SetOnTerminatingTask(
const Value: TOnTerminatingTask);
begin
FOnTerminatingTask := Value;
end;

function TThreadPool.GetIdelThreadNum: Integer;
var
I: Integer;
begin
Result := 0;
if FThreadList.Count>0 then
for I:=0 to FThreadList.Count-1 do
begin
if TThread(FThreadList.Items[I]).Suspended then
Inc(Result);
end;
end;

function TThreadPool.WakeUpThreads(iNum: Integer): Integer;
var
I: Integer;
begin
Result := 0;
if FThreadList.Count>0 then
for I:=0 to FThreadList.Count-1 do
begin
if TThread(FThreadList.Items[I]).Suspended then
TThread(FThreadList.Items[I]).Resume;
end;
end;

procedure TThreadPool.ClearList;
begin
ClearTaskList();
ClearThreadList();
end;

procedure TThreadPool.ClearTaskList;
var
I: Integer;
begin
//if not FCriticalSectionLocker.EnterLocker() then Exit;
//try
if FTaskObjectList.Count>0 then
for I:=FTaskObjectList.Count-1 downto 0 do
begin
if TTaskObject(FTaskObjectList.Items[I])<>nil then
if (TTaskObject(FTaskObjectList.Items[I]).FOwner<>nil) then
begin
TTaskObject(FTaskObjectList.Items[I]).Terminate();
TTaskObject(FTaskObjectList.Items[I]).WaitFor(DWORD(-1));
if (TTaskObject(FTaskObjectList.Items[I])<>nil) and
Assigned(TTaskObject(FTaskObjectList.Items[I])) then
TTaskObject(FTaskObjectList.Items[I]).FOwner := nil;
end;
//不能释放。。因为不是TThreadPool创建的资源
//TTaskObject(FTaskObjectList.Items[I]).Destroy;
FTaskObjectList.Delete(I);
end;
//finally
//FCriticalSectionLocker.LeaveLocker();
//end;
end;

procedure TThreadPool.ClearThreadList;
var
I: Integer;
begin
if FThreadList.Count>0 then
for I:=FThreadList.Count-1 downto 0 do
begin
if Assigned(TThreadItem(FThreadList.Items[I])) then
begin
if (TThreadItem(FThreadList.Items[I]).FCurTaskObject<>nil) then
begin
if (TThreadItem(FThreadList.Items[I]).FTaskStatus<>tsTerminated) then
begin
TThreadItem(FThreadList.Items[I]).FCurTaskObject.Terminate;
TThreadItem(FThreadList.Items[I]).FCurTaskObject.WaitFor(DWORD(-1));
if (TThreadItem(FThreadList.Items[I]).FCurTaskObject <>nil) and
Assigned(TThreadItem(FThreadList.Items[I]).FCurTaskObject) then
TThreadItem(FThreadList.Items[I]).FCurTaskObject.FOwner := nil;
end;
end;
TThreadItem(FThreadList.Items[I]).Free;
end;
FThreadList.Delete(I);
end;
end;

procedure TThreadPool.WaitFor(iTimeOut: Cardinal);
var
iFirst: Cardinal;
begin
iFirst := GetTickCount();
while (iTimeOut=DWORD(-1)) or
((GetTickCount()-iFirst)>=iTimeOut) do
begin
if IsThreadDone() then Break;
Sleep(10);
end;
end;

function TThreadPool.IsThreadDone: Boolean;
var
I: Integer;
begin
Result := False;
if not FCriticalSectionLocker.EnterLocker() then Exit;
try
//任务不为空时肯定没有完成，可立即返回False
if (FTaskObjectList<>nil) and (FTaskObjectList.Count=0) then
begin
for I:=0 to FThreadList.Count-1 do
if not (TThreadItem(FThreadList.Items[I]).Suspended or
TThreadItem(FThreadList.Items[I]).Terminated) then Exit;//Suspended then Exit;
Result := True;
end;
finally
FCriticalSectionLocker.LeaveLocker();
end;
end;

procedure TThreadPool.SetThreadPriority(const Value: TThreadPolicyInt);
begin
FThreadPriority := Value;
end;

procedure TThreadPool.Clear();
begin
ClearList();
FNextTaskID := 0;
end;

{ TThreadItem }

constructor TThreadItem.Create();
begin
FCriticalSectionLocker:= TCriticalSectionLocker.Create;
Create(True);
FTaskStatus:= tsTerminated;
end;

destructor TThreadItem.Destroy;
begin
FCriticalSectionLocker.Destroy;
FTaskStatus:= tsDestroying;
inherited;
end;

procedure TThreadItem.Execute;
var
TaskObject: TTaskObject;
begin
inherited;
while not Self.Terminated do
begin
//申请任务
if FOwner=nil then Break;
FOwner.GetTaskFromList(TaskObject);
//无任务。挂起等待Pool唤醒
if TaskObject=nil then
begin
Self.Suspend;
Continue;//保证唤醒后重新申请任务
end;
//绑定任务与当前线程
TaskObject.FOwner := Self;
TaskObject.FThreadID := Self.ThreadID;
FCurTaskObject := TaskObject;
Self.SetTaskStatus(tsRunning);
//执行任务
TaskObject.Execute();
Self.SetTaskStatus(tsTerminating);
Self.SetTaskStatus(tsTerminated);
if Assigned(TaskObject.FOnTerminateTask) then TaskObject.FOnTerminateTask(TaskObject);
//解除当前绑定关系
FOwner.DeleteTaskFromList(TaskObject);
TaskObject.FOwner := nil;
FCurTaskObject := nil;
if Assigned(FOwner.FOnTerminatingTask) then FOwner.FOnTerminatingTask(FOwner, TaskObject);
end;
//不释放线程时，挂起，保留线程资源
if FTaskStatus<>tsDestroying then
Self.Suspended := True;
end;

procedure TThreadItem.SetOwner(const Value: TThreadPool);
begin
FOwner := Value;
end;

procedure TThreadItem.SetTaskStatus(TaskStatus: TTaskStatus);
begin
if not Assigned(Self) or (not Assigned(FCriticalSectionLocker)) then
begin
if Self<>nil then ;
Exit;
end;
if not FCriticalSectionLocker.EnterLocker() then Exit;
try
FTaskStatus := TaskStatus;
finally
FCriticalSectionLocker.LeaveLocker;
end;
end;

{ TTaskObject }

constructor TTaskObject.Create;
begin
//
end;

destructor TTaskObject.Destroy;
begin
Terminate();
WaitFor(DWORD(-1));
inherited;
end;

procedure TTaskObject.SetOnTerminateTask(const Value: TOnTerminateTask);
begin
FOnTerminateTask := Value;
end;

procedure TTaskObject.Synchronize(AMethod: TThreadMethod);
begin
TThread.Synchronize(Self.FOwner, AMethod);
end;

procedure TTaskObject.Terminate;
begin
if FOwner<>nil then
TThreadItem(FOwner).SetTaskStatus(tsTerminating);
//if Assigned(FOnTerminatingTask) then FOnTerminatingTask(Self);
//WaitFor();
end;

procedure TTaskObject.WaitFor(iTimeOut: Cardinal);
var
iFirst: Cardinal;
begin
iFirst := GetTickCount();
if Self=nil then Exit;
if FOwner=nil then Exit;
try
while (Self<>nil) and (FOwner<>nil) and Assigned(FOwner) and (TThreadItem(FOwner).FTaskStatus<>tsTerminated) do
begin
if (GetTickCount()-iFirst)>=iTimeOut then Break;
Sleep(5);
end;
except
end;
end;

end.