Use shared memory mapping to implement a program that can only be initiated one time limit

=============================================================================////Description: Program single run Detection unit//sgao//Date: 2015-09-25//Note: The handle created by the program is automatically freed after the process ends, so there is no closing handle operation////==========================================================  ===================unit urunoncechecker;interfaceuses Sysutils,windows;type//shared memory information Tshareinfo = record AppHandle:  Thandle;  End  Pshareinfo = ^tshareinfo; Check if the program is running, create shared memory without running//parameter 1: Program ID//Parameter 2: Shared memory information (externally created, internal release)//return value: Whether the program has run function checkorcreate (aguidid:string; var A  Shareinfo:pshareinfo): Boolean; Check whether the program is running//parameter 1: Program ID//Parameter 2: Shared memory information//return value: Whether the program has run function Check (aguidid:string; out ashareinfo:pshareinfo): Boo Lean;implementation//Check whether the program is running, such as not running create shared memory//Parameter 1: Program ID//Parameter 2: Shared memory information (externally created, internally released)//return value: Whether the program has run function checkorcreate (A guidid:string;  var ashareinfo:pshareinfo): Boolean;    var Hmapfile:thandle;  Pinfo:pshareinfo;    Begin Result: = False;    If Ashareinfo = Nil then raise Exception.create (' need to pass in shared memory information ');Check if shared memory has been created hmapfile: = OpenFileMapping (file_map_all_access, False, PChar (Aguidid)); If the shared memory has not been created if Hmapfile = 0 THEN BEGIN//create memory image file--The handle is released when the program exits Hmapfile: = CreateFileMapping ($FFFFFFFF, n      Il, page_readwrite, 0, SizeOf (tshareinfo), PChar (Aguidid));      Mapped memory PInfo: = MapViewOfFile (Hmapfile, file_map_write or file_map_read, 0, 0, 0); Initializes the memory pinfo^.      Apphandle: = Ashareinfo.apphandle;      Dispose (Ashareinfo);    Ashareinfo: = PInfo;      End//shared memory already created else begin Dispose (ashareinfo);      PInfo: = MapViewOfFile (Hmapfile, file_map_write or file_map_read, 0, 0, 0);      Update shared memory information ashareinfo: = PInfo;      CloseHandle (Hmapfile);    Result: = True;  End  End Check whether the program is running//parameter 1: Program ID//Parameter 2: Shared memory information//return value: Whether the program has run function Check (aguidid:string; out ashareinfo:pshareinfo): Boo  Lean  var Hmapfile:thandle;    Begin Result: = False; Check if shared memory has been created hmapfile: = OpenFileMapping (file_map_all_access, False, PChar (AGUidid)); If shared memory has been created if Hmapfile <> 0 THEN begin ashareinfo: = MapViewOfFile (Hmapfile, file_map_write or File_map      _read, 0, 0, 0);      CloseHandle (Hmapfile);    Result: = True;  End End;end.

Test code:

Unit ufrmtest;interfaceuses Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms, Dialogs, Stdctrls , Rzedit, Urunoncechecker;const mapfile_name_guid_1 = ' {1141D1B7-F276-4F31-BB01-2E2447C256BC} '; const MAPFILE_NAME_    Guid_2 = ' {7ebaaa87-dbac-4f69-8b77-c2d58eeffa38} '; type TForm1 = Class (Tform) Btncheckorcreate:tbutton;    Btncheck:tbutton;    Btncheckorcreate2:tbutton;    Btncheck2:tbutton;    Mmo1:trzmemo;    Procedure Btncheckorcreateclick (Sender:tobject);    Procedure Btncheckclick (Sender:tobject);    Procedure Btncheckorcreate2click (Sender:tobject);  Procedure Btncheck2click (Sender:tobject); Private procedure checkorcreate (aguid:string;    aname:string); Procedure Check (aguid:string;  aname:string); Public {public declarations} End;var form1:tform1;implementation{$R *.dfm}procedure tform1.btncheck2click (Sender: TObject); Begin check (mapfile_name_guid_2, ' B '); end;procedure Tform1.btncheckclick (sender:tobject); Begin Check ( MapfilE_name_guid_1, ' A '); end;procedure Tform1.btncheckorcreate2click (sender:tobject); Begin Checkorcreate (MAPFILE_NAME_ Guid_2, ' B '); end;procedure Tform1.btncheckorcreateclick (sender:tobject); Begin Checkorcreate (Mapfile_name_guid_1, ' A '); end;//check whether the program is running procedure Tform1.check (aguid:string;  aname:string); var Bret:boolean; Pinfo:pshareinfo;begin Mmo1.  Lines.add (' Check ' program ' + AName + ' "-----------------------------');  BRet: = Urunoncechecker.check (Aguid, pInfo); If BRet then begin MMO1.  Lines.add (' program ' + AName + ' "on Run '); End ELSE begin MMO1.  Lines.add (' program ' + AName + ' "not Running"); end;end;//check or create the shared file memory of the program procedure tform1.checkorcreate (aguid:string;  aname:string); var Bret:boolean;  Pinfo:pshareinfo;  Happ:thandle; Htopwindow:hwnd;begin Mmo1.  Lines.add (' Check or create ' program ' + AName + ' "-----------------------------');  New (PInfo);  Pinfo.apphandle: = Application.handle;  BRet: = Urunoncechecker.checkorcreate (Aguid, pInfo); If BRet then begin MMO1. Lines.add (' program ' + AName + ' "in the shippingLine ');    SendMessage (Pinfo.apphandle, Wm_syscommand, Sc_restore, 0);    Htopwindow: = Getlastactivepopup (Pinfo.apphandle); if (Htopwindow <> 0) and iswindowvisible (Htopwindow) and iswindowenabled (Htopwindow) then SetForegroundWindow (HT  Opwindow); End ELSE begin MMO1.  Lines.add (' program ' + AName + ' "not running, creating shared memory '); End;end;end.

Operation Result:

Use shared memory mapping to implement a program that can only be initiated one time limit