docs/latex/wx/snglinst.tex

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %% Name:        snglinst.tex
   3 %% Purpose:     wxSingleInstanceChecker documentation
   4 %% Author:      Vadim Zeitlin
   5 %% Modified by:
   6 %% Created:     08.06.01
   7 %% RCS-ID:      $Id$
   8 %% Copyright:   (c) 2001 Vadim Zeitlin
   9 %% License:     wxWindows license
  10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  11
  12 \section{\class{wxSingleInstanceChecker}}\label{wxsingleinstancechecker}
  13
  14 wxSingleInstanceChecker class allows to check that only a single instance of a
  15 program is running. To do it, you should create an object of this class. As
  16 long as this object is alive, calls to
  17 \helpref{IsAnotherRunning()}{wxsingleinstancecheckerisanotherrunning} from
  18 other processes will return {\tt true}.
  19
  20 As the object should have the life span as big as possible, it makes sense to
  21 create it either as a global or in \helpref{wxApp::OnInit}{wxapponinit}. For
  22 example:
  23
  24 \begin{verbatim}
  25 bool MyApp::OnInit()
  26 {
  27     const wxString name = wxString::Format("MyApp-%s", wxGetUserId().c_str());
  28     m_checker = new wxSingleInstanceChecker(name);
  29     if ( m_checker->IsAnotherRunning() )
  30     {
  31         wxLogError(_("Another program instance is already running, aborting."));
  32
  33         return false;
  34     }
  35
  36     ... more initializations ...
  37
  38     return true;
  39 }
  40
  41 int MyApp::OnExit()
  42 {
  43     delete m_checker;
  44
  45     return 0;
  46 }
  47 \end{verbatim}
  48
  49 Note using \helpref{wxGetUserId()}{wxgetuserid} to construct the name: this
  50 allows different user to run the application concurrently which is usually the
  51 intended goal. If you don't use the user name in the wxSingleInstanceChecker
  52 name, only one user would be able to run the application at a time.
  53
  54 This class is implemented for Win32 and Unix platforms (supporting {\tt fcntl()}
  55 system call, but almost all of modern Unix systems do) only.
  56
  57 \wxheading{Derived from}
  58
  59 No base class
  60
  61 \wxheading{Include files}
  62
  63 <wx/snglinst.h>
  64
  65 \wxheading{Library}
  66
  67 \helpref{wxBase}{librarieslist}
  68
  69 \latexignore{\rtfignore{\wxheading{Members}}}
  70
  71 \membersection{wxSingleInstanceChecker::wxSingleInstanceChecker}\label{wxsingleinstancecheckerctor}
  72
  73 \func{}{wxSingleInstanceChecker}{\void}
  74
  75 Default ctor, use \helpref{Create()}{wxsingleinstancecheckercreate} after it.
  76
  77 \membersection{wxSingleInstanceChecker::wxSingleInstanceChecker}\label{wxsingleinstancecheckerwxsingleinstancechecker}
  78
  79 \func{}{wxSingleInstanceChecker}{\param{const wxString\& }{name}, \param{const wxString\& }{path = wxEmptyString}}
  80
  81 Like \helpref{Create()}{wxsingleinstancecheckercreate} but without
  82 error checking.
  83
  84 \membersection{wxSingleInstanceChecker::Create}\label{wxsingleinstancecheckercreate}
  85
  86 \func{bool}{Create}{\param{const wxString\& }{name}, \param{const wxString\& }{path = wxEmptyString}}
  87
  88 Initialize the object if it had been created using the default constructor.
  89 Note that you can't call Create() more than once, so calling it if the
  90 \helpref{non default ctor}{wxsingleinstancecheckerwxsingleinstancechecker}
  91 had been used is an error.
  92
  93 \wxheading{Parameters}
  94
  95 \docparam{name}{must be given and be as unique as possible. It is used as the
  96 mutex name under Win32 and the lock file name under Unix.
  97 \helpref{GetAppName()}{wxappgetappname} and \helpref{wxGetUserId()}{wxgetuserid}
  98 are commonly used to construct this parameter.}
  99
 100 \docparam{path}{is optional and is ignored under Win32 and used as the directory to
 101 create the lock file in under Unix (default is
 102 \helpref{wxGetHomeDir()}{wxgethomedir})}
 103
 104 \wxheading{Return value}
 105
 106 Returns {\tt false} if initialization failed, it doesn't mean that another
 107 instance is running - use
 108 \helpref{IsAnotherRunning()}{wxsingleinstancecheckerisanotherrunning} to check
 109 for it.
 110
 111 \wxheading{Note}
 112
 113 One of possible reasons while Create may fail on Unix is that the lock file
 114 used for checking already exists but was not created by the user.
 115 Therefore applications shouldn't treat failure of this function as fatal
 116 condition, because doing so would open them to the possibility of a Denial of
 117 Service attack. Instead, they should alert the user about the problem and
 118 offer to continue execution without checking if another instance is running.
 119
 120 \membersection{wxSingleInstanceChecker::IsAnotherRunning}\label{wxsingleinstancecheckerisanotherrunning}
 121
 122 \constfunc{bool}{IsAnotherRunning}{\void}
 123
 124 Returns {\tt true} if another copy of this program is already running, {\tt
 125 false} otherwise.
 126
 127 \membersection{wxSingleInstanceChecker::\destruct{wxSingleInstanceChecker}}\label{wxsingleinstancecheckerdtor}
 128
 129 \func{}{\destruct{wxSingleInstanceChecker}}{\void}
 130
 131 Destructor frees the associated resources.
 132
 133 Note that it is not virtual, this class is not meant to be used polymorphically
 134