Delphi multithreaded Programming (15)-Multi-threaded synchronization Waitabletimer (Waiting Timer object) [continued]

Reprinted from: In Case of blog

This is a special study of the second parameter of the SetWaitableTimer (starting time)

It has a positive, negative, 0 value of three cases, preceded by 0 values

Learn negative values first (relative time), that is, how long it takes to start from the current count

This relative time is measured in 1/100 nanoseconds, such as assignment: 3*10000000 equivalent to 3 seconds

1 1,  MS (ms);  11,  µs (subtlety);  11,the,the  NS (nanosecond);  11, he,He,He, PS (leather seconds);

of this example

Code files

Unit unit1;interfaceuses Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms, Dialogs, Stdctrls;ty    PE TForm1 = Class (Tform) Button1:tbutton;    Procedure Button1Click (Sender:tobject);  Procedure Formdestroy (Sender:tobject);  End;var form1:tform1;implementation{$R *.dfm}var F:integer; Hwaitabletimer:thandle;function Mythreadfun (p:pointer): DWORD;  Stdcall;var I, Y:integer;  Y:= 20* F; If WaitForSingleObject (Hwaitabletimer, INFINITE) =wait_object_0 then begin for i:= 0 to $ do begin Form1.can Vas.      Lock;      Form1.Canvas.TextOut (x, Y, IntToStr (i));      Form1.Canvas.UnLock;    Sleep (1);  End  End  result:= 0;end;procedure Tform1.button1click (sender:tobject); var Threadid:dword;  Duetime:int64;begin hwaitabletimer:= CreateWaitableTimer (nil, True, nil);    Duetime:= -3*10000000;      3 seconds after execution of SetWaitableTimer (Hwaitabletimer, duetime, 0, Nil, nil, False); Repaint;  f:= 0; CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID);  CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID);  CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID); End;procedure Tform1.formdestroy (sender:tobject); begin CloseHandle (Hwaitabletimer); end;end.

Form files

Object Form1:tform1 Left  = 0  Top = 0  Caption = ' Form1 '  clientheight = $  clientwidth = 179  Color = Clbtnface  font.charset = default_charset  font.color = clwindowtext  font.height = -11  font.name = ' Tahoma '  font.style = []  oldcreateorder = False  OnDestroy = Formdestroy  pixelsperinch =  TextHeight = Object Button1:tbutton left =-----------Width =----------    Caption = ' Button1 '    taborder = 0    OnClick = Button1Click  endend

　　

When we need an absolute time, such as 2009-2-18 13:10:5, the function needs the Int64 value should be the time of the tfiletime format

See the definition of three related time types (Tfiletime, Tsystemtime, Tdatetime) first

Tfiletime aka FILETIME or _filetime_filetime = record    Dwlowdatetime:dword;    Dwhighdatetime:dword;end;//tsystemtime also known as Sytemtime or _systemtime_systemtime=record    Wyear:word;    Wmonth:word;    Wdayofweek:word;    Wday:word;    Whour:word;    Wminute:word;    Wsecond:word;    Wmilliseconds:word;end; Tdatetime= type Double;

Tfiletime is equivalent to a Int64, which is usually assigned by tsystemtime or Tdatetime and then converted to the past

In the example, I converted the past through the following process:

Strtodatetime->datetimetosystemtime->systemtimetofiletime->localfiletimetofiletime

The following program executes three threads on February 18, 2009 1:10 P.M. 5 Seconds (Form IBID., I have found the right time to test successfully)

Unit unit1;interfaceuses Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms, Dialogs, Stdctrls;ty    PE TForm1 = Class (Tform) Button1:tbutton;    Procedure Button1Click (Sender:tobject);  Procedure Formdestroy (Sender:tobject);  End;var form1:tform1;implementation{$R *.dfm}var F:integer; Hwaitabletimer:thandle;function Mythreadfun (p:pointer): DWORD;  Stdcall;var I,y:integer;begin Inc (f);  Y: = * f; If WaitForSingleObject (Hwaitabletimer, INFINITE) = Wait_object_0 THEN begin for I: = 0 to + do begin FORM1.      Canvas.lock;      Form1.Canvas.TextOut (x, Y, IntToStr (i));      Form1.Canvas.Unlock;    Sleep (1);  End  End  Result: = 0;end;procedure Tform1.button1click (sender:tobject); Const Strtime = ' 2009-2-18 13:10:5 '; var Threadid:dword;  Duetime:int64;  St:tsystemtime;  Ft,utc:tfiletime; Dt:tdatetime;begin Datetimetosystemtime (Strtodatetime (Strtime), ST);  {from tdatetime to Tsystemtime}            SystemTimeToFileTime (St, FT);         {from tsystemtime to Tfiletime}                 LocalFileTimeToFileTime (ft, UTC);  {from local time to international Standard Time UTC}                            Duetime: = Int64 (UTC);  {The function requires Int64} hwaitabletimer: = CreateWaitableTimer (nil, True, nil);  SetWaitableTimer (Hwaitabletimer, duetime, 0, Nil, nil, False); Repaint;  F: = 0;  CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID);  CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID);  CreateThread (nil, 0, @MyThreadFun, nil, 0, ThreadID); End;procedure Tform1.formdestroy (sender:tobject); begin CloseHandle (Hwaitabletimer); end;end.

　　

The next step is the callback function for the Waitabletimer object.

Delphi multithreaded Programming (15)-Multi-threaded synchronization Waitabletimer (Waiting Timer object) [continued]