線程池

unit Ut_CustomThread;

interface
uses
Classes, SysUtils, SyncObjs, Windows;
Type
//基本线程类
TBaseThread = class;
//线程错误处理类
EThreadException = class(Exception);
//线程等待错误处理类
EThreadTerminateAndWaitFor = class(EThreadException);
//线程停止模式
TThreadStopMode = (smTerminate, smSuspend);
//例外线程事件函数事件
TExceptionThreadEvent = procedure(AThread: TBaseThread; AException: Exception) of object;
//线程事件通知函数事件
TNotifyThreadEvent = procedure(AThread: TBaseThread) of object;
//同步线程事件
TSynchronizeThreadEvent = procedure(AThread: TBaseThread; AData: Pointer) of object;
//自定义线程类
TCustomThread = class(TThread)
public
//同步线程方法
procedure Synchronize(Method: TThreadMethod); overload;
//同步方法事件
procedure Synchronize(Method: TMethod); overload;
//返回值
property ReturnValue;
//结束线程
property Terminated;
End;
//基本线程类
TBaseThread = class(TCustomThread)
protected
//数据对象可以是任何一对象
FData: TObject;
// 临界区用来线程数据保护同步
FLock: TCriticalSection;
//线程停止模式
FStopMode: TThreadStopMode;
//是否停止
FStopped: Boolean;
//线程例外字符串
FTerminatingException: string;
//线程停止意外类
FTerminatingExceptionClass: TClass;
//意外事件
FOnException: TExceptionThreadEvent;
//通知线程停止事件
FOnStopped: TNotifyThreadEvent;
//
//处理例外时间
procedure DoException (AException: Exception); virtual;
//处理停止事件
procedure DoStopped; virtual;
//具体执行
procedure Execute; override;
//当前线程是否停止
function GetStopped: Boolean;
//抽象运行
procedure Run; virtual; abstract;
public
//运行后
procedure AfterRun; virtual; //3* Not abstract - otherwise it is required
//执行后
procedure AfterExecute; virtual;//5 Not abstract - otherwise it is required
//执行前
procedure BeforeExecute; virtual;//1 Not abstract - otherwise it is required
//运行前
procedure BeforeRun; virtual; //2* Not abstract - otherwise it is required
//释放
procedure Cleanup; virtual;//4*
//创建
constructor Create(ACreateSuspended: Boolean = True); virtual;
//释放
destructor Destroy; override;
//开始
procedure Start; virtual;
// 停止
procedure Stop; virtual;

// Here to make virtual
procedure Terminate; virtual;
//等待推出线程
procedure TerminateAndWaitFor; virtual;
//当前对象
property Data: TObject read FData write FData;
//停止模式
property StopMode: TThreadStopMode read FStopMode write FStopMode;
//当前是否停止
property Stopped: Boolean read GetStopped;
// in future versions (D6+) we must move to TThread.FatalException
property TerminatingException: string read FTerminatingException;
property TerminatingExceptionClass: TClass read FTerminatingExceptionClass;
// events
property OnException: TExceptionThreadEvent read FOnException write FOnException;
property OnStopped: TNotifyThreadEvent read FOnStopped write FOnStopped;
End;//TBaseThread

TBaseThreadClass = class of TBaseThread;

//线程管理类
TThreadMgr = class(TComponent)
protected
//当前线程列表
FActiveThreads: TThreadList;
//线程类
FThreadClass: TBaseThreadClass;
//线程优先级
FThreadPriority: TThreadPriority;
public
//初始化
constructor Create(AOwner: TComponent); override;
//创建一个新的线程
function CreateNewThread: TBaseThread; virtual;
//释放
destructor Destroy; override;
//获得一个线程
function GetThread: TBaseThread; virtual; abstract;
//返回一个线程
procedure ReleaseThread(AThread: TBaseThread); virtual; abstract;
//终止线程
procedure TerminateThreads; virtual;
//
property ActiveThreads: TThreadList read FActiveThreads;
property ThreadClass: TBaseThreadClass read FThreadClass write FThreadClass;
property ThreadPriority: TThreadPriority read FThreadPriority
write FThreadPriority default tpNormal;
end;

EThreadMgrError = class(Exception);
EThreadClassNotSpecified = class(EThreadMgrError);

//线程池的管理
type
TThreadMgrPool = class(TThreadMgr)
protected
//当前池的大小
FPoolSize: Integer;
//当前的池
FThreadPool: TThreadList;
// 停止一个线程
procedure ThreadStopped(AThread: TBaseThread);
public
constructor Create(AOwner: TComponent); override;
//释放线程池
destructor Destroy; override;
//获得一个线程
function GetThread: TBaseThread; override;
// //返回一个线程
procedure ReleaseThread(AThread: TBaseThread); override;
//停止所有线程
procedure TerminateThreads; override;
published
property PoolSize: Integer read FPoolSize write FPoolSize default 0;
end;

implementation

{ TCustomThread }
procedure SetThreadPriority(AThread: TThread; const APriority: TThreadPriority; const APolicy: Integer = -MaxInt);
begin
AThread.Priority := APriority;
end;
//是否是当前线程
function IsCurrentThread(AThread: TThread): boolean;
begin
result := AThread.ThreadID = GetCurrentThreadID;
end;

procedure TCustomThread.Synchronize(Method: TThreadMethod);
begin
inherited Synchronize(Method);
end;

procedure TCustomThread.Synchronize(Method: TMethod);
begin
inherited Synchronize(TThreadMethod(Method));
end;

{ TBaseThread }

procedure TBaseThread.AfterExecute;
begin

end;

procedure TBaseThread.AfterRun;
begin

end;

procedure TBaseThread.BeforeExecute;
begin

end;

procedure TBaseThread.BeforeRun;
begin

end;

procedure TBaseThread.Cleanup;
begin
FreeAndNil(FData);
end;

constructor TBaseThread.Create(ACreateSuspended: Boolean);
begin
// Before inherited - inherited creates the actual thread and if not suspeded
// will start before we initialize
FStopped := ACreateSuspended;
FLock := TCriticalSection.Create;
try
inherited Create(ACreateSuspended);
except
FreeAndNil(FLock);
raise;
end;
end;

destructor TBaseThread.Destroy;
begin
FreeOnTerminate := FALSE; //prevent destroy between Terminate & WaitFor
inherited Destroy; //Terminate&WaitFor
Cleanup;
FreeAndNil(FLock);
end;

procedure TBaseThread.DoException(AException: Exception);
begin
if Assigned(FOnException) then begin
FOnException(self, AException);
end;
end;

procedure TBaseThread.DoStopped;
begin
if Assigned(OnStopped) then begin
OnStopped(Self);
end;
end;

procedure TBaseThread.Execute;
begin
try
try
BeforeExecute;
while not Terminated do begin
if Stopped then begin
DoStopped;
// It is possible that either in the DoStopped or from another thread,
// the thread is restarted, in which case we dont want to restop it.
if Stopped then begin // DONE: if terminated?
if Terminated then begin
Break;
end;
Suspended := True; // Thread manager will revive us
if Terminated then begin
Break;
end;
end;
end;

try
BeforeRun;
try
while not Stopped do begin
Run;
end;
finally
AfterRun;
end;//tryf
finally
Cleanup;
end;

end;//while NOT Terminated
finally
AfterExecute;
end;
except
on E: Exception do begin
FTerminatingExceptionClass := E.ClassType;
FTerminatingException := E.Message;
DoException(E);
Terminate;
end;
end;//trye
end;

function TBaseThread.GetStopped: Boolean;
begin
if Assigned(FLock) then begin
FLock.Enter;
try
// Suspended may be true if checking stopped from another thread
Result := Terminated or FStopped or Suspended;
finally FLock.Leave; end;
end else begin
Result := TRUE; //user call Destroy
end;
end;

procedure TBaseThread.Start;
begin
FLock.Enter; try
if Stopped then begin
// Resume is also called for smTerminate as .Start can be used to initially start a
// thread that is created suspended
FStopped := False;
Suspended := False;
end;
finally FLock.Leave; end;
end;

procedure TBaseThread.Stop;
begin
FLock.Enter;
try
if not Stopped then begin
case FStopMode of
smTerminate: Terminate;
// DO NOT suspend here. Suspend is immediate. See Execute for implementation
smSuspend: ;
end;
FStopped := True;
end;
finally FLock.Leave; end;
end;

procedure TBaseThread.Terminate;
begin
FStopped := True;
inherited Terminate;
end;

procedure TBaseThread.TerminateAndWaitFor;
begin

if FreeOnTerminate then begin
raise EThreadTerminateAndWaitFor.Create(‘thread terminate and waitfor’);
end;
Terminate;
if Suspended then begin
Resume;
end;
WaitFor;
end;

{ TThreadMgr }

{ TThreadMgr }

constructor TThreadMgr.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FActiveThreads := TThreadList.Create;
FThreadPriority := tpNormal;
end;

function TThreadMgr.CreateNewThread: TBaseThread;
begin
if ThreadClass = nil then begin

raise EThreadClassNotSpecified.create(‘’);
end;
Result := TBaseThreadClass(ThreadClass).Create;
SetThreadPriority(Result, ThreadPriority);
end;

destructor TThreadMgr.Destroy;
begin
FreeAndNil(FActiveThreads);
inherited Destroy;
end;

procedure TThreadMgr.TerminateThreads;
begin

end;

{ TThreadMgrPool }

constructor TThreadMgrPool.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FThreadPool := TThreadList.Create;
end;

destructor TThreadMgrPool.Destroy;
var
i: integer;
LThreads: TList;
begin
PoolSize := 0;
LThreads := FThreadPool.LockList;
try
for i := 0 to LThreads.Count - 1 do
begin
TBaseThread(LThreads[i]).Free;
end;
finally FThreadPool.UnlockList; end;
FreeAndNil(FThreadPool);
inherited Destroy;
end;

function TThreadMgrPool.GetThread: TBaseThread;
var
i: integer;
LThreadPool: TList;
begin
//获得当前的池
LThreadPool := FThreadPool.LockList;
try
//是否有可用的线程
i := LThreadPool.Count - 1;
if i >= 0 then
begin
//有责返回一个线程对象
Result := TBaseThread(LThreadPool[0]);
//充当前池删掉一个线程
LThreadPool.Delete(0);
end else begin
//创建一个新的线程、
Result := CreateNewThread;
//设置停止模式
Result.StopMode := smSuspend;
end;
finally FThreadPool.UnlockList; end;
//添加到线程列表中
ActiveThreads.Add(Result);
end;

procedure TThreadMgrPool.ReleaseThread(AThread: TBaseThread);
var
LThreadPool: TList;
begin
//删除当前正在使用的线程
ActiveThreads.Remove(AThread);
LThreadPool := FThreadPool.LockList;
try
//如果线程数量大于池的数量则释放线程
// PoolSize = 0 means that we will keep all active threads in the thread pool
if ((PoolSize > 0) and (LThreadPool.Count >= PoolSize)) or AThread.Terminated then begin
if IsCurrentThread(AThread) then begin
AThread.FreeOnTerminate := True;
AThread.Terminate;
end else begin
if not AThread.Stopped then
begin
AThread.TerminateAndWaitFor;
end;
AThread.Free;
end;
end else begin
//否则就是停止线程
if not AThread.Suspended then begin
AThread.OnStopped := ThreadStopped;
AThread.Stop;
end
else begin
AThread.Free;
end;
end;
finally FThreadPool.UnlockList; end;
end;

procedure TThreadMgrPool.TerminateThreads;
begin
inherited TerminateThreads;

with FThreadPool.LockList do
try
while Count > 0 do begin
TBaseThread(Items[0]).FreeOnTerminate := true;
TBaseThread(Items[0]).Terminate;
TBaseThread(Items[0]).Start;
Delete(0);
end;
finally
FThreadPool.UnlockList;
end;
end;

procedure TThreadMgrPool.ThreadStopped(AThread: TBaseThread);
begin
FThreadPool.Add(AThread);
end;

end.

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls
,Ut_CustomThread; // uses thread pool unit

type
TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
private
    { Private declarations }
public
    { Public declarations }
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
// get a thread from thread pool

FthreadMgr.ThreadClass := Tthread1;
Fthread1 := FthreadMgr.GetThread;
FthreadMgr.ThreadClass := Tthread2;
Fthread2 := FthreadMgr.GetThread;
// stopMode

Fthread1.StopMode := smSuspend;
Fthread2.StopMode := smSuspend;
// thread execute

var
i: Integer;
begin
inherited;
for i := 1 to 500000 do
Form1.Canvas.TextOut(100, 100, IntToStr(i));
end;

procedure Tthread2.Run;
var
i: Integer;
begin
inherited;
for i := 1 to 500000 do
Form1.Canvas.TextOut(100, 200, IntToStr(i));
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
// create thread pool manager

FthreadMgr := TThreadMgrPool.Create(Self);
// max create two thread
FthreadMgr.PoolSize := 2;
end;

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