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: snglinst.tex 32309 2005-02-22 15:09:56Z ABX $ 8%% Copyright: (c) 2001 Vadim Zeitlin 9%% License: wxWindows license 10%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 11 12\section{\class{wxSingleInstanceChecker}}\label{wxsingleinstancechecker} 13 14wxSingleInstanceChecker class allows to check that only a single instance of a 15program is running. To do it, you should create an object of this class. As 16long as this object is alive, calls to 17\helpref{IsAnotherRunning()}{wxsingleinstancecheckerisanotherrunning} from 18other processes will return {\tt true}. 19 20As the object should have the life span as big as possible, it makes sense to 21create it either as a global or in \helpref{wxApp::OnInit}{wxapponinit}. For 22example: 23 24\begin{verbatim} 25bool 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 41int MyApp::OnExit() 42{ 43 delete m_checker; 44 45 return 0; 46} 47\end{verbatim} 48 49Note using \helpref{wxGetUserId()}{wxgetuserid} to construct the name: this 50allows different user to run the application concurrently which is usually the 51intended goal. If you don't use the user name in the wxSingleInstanceChecker 52name, only one user would be able to run the application at a time. 53 54This class is implemented for Win32 and Unix platforms (supporting {\tt fcntl()} 55system call, but almost all of modern Unix systems do) only. 56 57\wxheading{Derived from} 58 59No base class 60 61\wxheading{Include files} 62 63<wx/snglinst.h> 64 65\latexignore{\rtfignore{\wxheading{Members}}} 66 67\membersection{wxSingleInstanceChecker::wxSingleInstanceChecker}\label{wxsingleinstancecheckerctor} 68 69\func{}{wxSingleInstanceChecker}{\void} 70 71Default ctor, use \helpref{Create()}{wxsingleinstancecheckercreate} after it. 72 73\membersection{wxSingleInstanceChecker::wxSingleInstanceChecker}\label{wxsingleinstancecheckerwxsingleinstancechecker} 74 75\func{}{wxSingleInstanceChecker}{\param{const wxString\& }{name}, \param{const wxString\& }{path = wxEmptyString}} 76 77Like \helpref{Create()}{wxsingleinstancecheckercreate} but without 78error checking. 79 80\membersection{wxSingleInstanceChecker::Create}\label{wxsingleinstancecheckercreate} 81 82\func{bool}{Create}{\param{const wxString\& }{name}, \param{const wxString\& }{path = wxEmptyString}} 83 84Initialize the object if it had been created using the default constructor. 85Note that you can't call Create() more than once, so calling it if the 86\helpref{non default ctor}{wxsingleinstancecheckerwxsingleinstancechecker} 87had been used is an error. 88 89\wxheading{Parameters} 90 91\docparam{name}{must be given and be as unique as possible. It is used as the 92mutex name under Win32 and the lock file name under Unix. 93\helpref{GetAppName()}{wxappgetappname} and \helpref{wxGetUserId()}{wxgetuserid} 94are commonly used to construct this parameter.} 95 96\docparam{path}{is optional and is ignored under Win32 and used as the directory to 97create the lock file in under Unix (default is 98\helpref{wxGetHomeDir()}{wxgethomedir})} 99 100\wxheading{Return value} 101 102Returns {\tt false} if initialization failed, it doesn't mean that another 103instance is running - use 104\helpref{IsAnotherRunning()}{wxsingleinstancecheckerisanotherrunning} to check 105for it. 106 107\wxheading{Note} 108 109One of possible reasons while Create may fail on Unix is that the lock file 110used for checking already exists but was not created by the user. 111Therefore applications shouldn't treat failure of this function as fatal 112condition, because doing so would open them to the possibility of a Denial of 113Service attack. Instead, they should alert the user about the problem and 114offer to continue execution without checking if another instance is running. 115 116\membersection{wxSingleInstanceChecker::IsAnotherRunning}\label{wxsingleinstancecheckerisanotherrunning} 117 118\constfunc{bool}{IsAnotherRunning}{\void} 119 120Returns {\tt true} if another copy of this program is already running, {\tt 121false} otherwise. 122 123\membersection{wxSingleInstanceChecker::\destruct{wxSingleInstanceChecker}}\label{wxsingleinstancecheckerdtor} 124 125\func{}{\destruct{wxSingleInstanceChecker}}{\void} 126 127Destructor frees the associated resources. 128 129Note that it is not virtual, this class is not meant to be used polymorphically 130 131