[DUG] Best way to make this thread safe

[Trevor Jones]

In what way is this thread safe?

-----Original Message-----
From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Maurice Butler
Sent: Thursday, 17 May 2007 10:48 p.m.
To: 'NZ Borland Developers Group - Delphi List'
Subject: RE: [DUG] Best way to make this thread safe

May be of use - the trick is at the bottom - Initialization & Finalization

Maurice


unit ErrorLog;

interface
function Logfile(comment:string):boolean;
implementation
uses sysutils,
     ascii,
     syncobjs {required for critical section},
     Forms    {required for access to application title};
var
  ExclusiveUse : tCriticalSection;
  TempLog :TextFile;
  sFileName : string;

Procedure OpenLog;
Begin
      sFileName :=  Application.ExeName + '.' +
formatdatetime('yyyymmdd',now)+ '.log';
      AssignFile(TempLog, sFileName);
      //open file if it exists else create
      if FileExists(sFileName) then    //adding to existing file
        Append(TempLog)
      else //no file exist so create
        begin
          rewrite(Templog);
          Writeln(TempLog, 'Created for ',Application.ExeName, ' on ',
datetostr(date),' at ',timetostr(time));
          writeln(TempLog,
'===========================================================================
===');
        end;

End;

Function Logfile(comment:string):boolean;
begin
    ExclusiveUse.Enter;
    try
      result := FALSE;
      OpenLog;
      try
      	//if string contains second line move the start clear of the date
        if Pos(Ascii_LF, comment) <> 0 then
          insert(StringOfChar(' ', 20), Comment, Pos(Ascii_LF, comment)+1);

        writeln(TempLog, datetostr(date),' ',timetostr(time),', ', comment);
        result := TRUE;
      finally  //so no loose ends are left
        closeFile(TempLog);
      end;
    finally
      ExclusiveUse.Leave;
    end;
end;


initialization
begin
 ExclusiveUse := TCriticalSection.Create;
end;
Finalization
begin
 ExclusiveUse.Free;
end;
end.


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