| 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: wxWidgets 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 | \latexignore{\rtfignore{\wxheading{Members}}} |
| 66 | |
| 67 | \membersection{wxSingleInstanceChecker::wxSingleInstanceChecker}\label{wxsingleinstancecheckerctor} |
| 68 | |
| 69 | \func{}{wxSingleInstanceChecker}{\void} |
| 70 | |
| 71 | Default 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 | |
| 77 | Like \helpref{Create()}{wxsingleinstancecheckercreate} but without |
| 78 | error checking. |
| 79 | |
| 80 | \membersection{wxSingleInstanceChecker::Create}\label{wxsingleinstancecheckercreate} |
| 81 | |
| 82 | \func{bool}{Create}{\param{const wxString\& }{name}, \param{const wxString\& }{path = wxEmptyString}} |
| 83 | |
| 84 | Initialize the object if it had been created using the default constructor. |
| 85 | Note that you can't call Create() more than once, so calling it if the |
| 86 | \helpref{non default ctor}{wxsingleinstancecheckerwxsingleinstancechecker} |
| 87 | had 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 |
| 92 | mutex name under Win32 and the lock file name under Unix. |
| 93 | \helpref{GetAppName()}{wxappgetappname} and \helpref{wxGetUserId()}{wxgetuserid} |
| 94 | are commonly used to construct this parameter.} |
| 95 | |
| 96 | \docparam{path}{is optional and is ignored under Win32 and used as the directory to |
| 97 | create the lock file in under Unix (default is |
| 98 | \helpref{wxGetHomeDir()}{wxgethomedir})} |
| 99 | |
| 100 | \wxheading{Return value} |
| 101 | |
| 102 | Returns {\tt false} if initialization failed, it doesn't mean that another |
| 103 | instance is running - use |
| 104 | \helpref{IsAnotherRunning()}{wxsingleinstancecheckerisanotherrunning} to check |
| 105 | for it. |
| 106 | |
| 107 | \wxheading{Note} |
| 108 | |
| 109 | One of possible reasons while Create may fail on Unix is that the lock file |
| 110 | used for checking already exists but was not created by the user. |
| 111 | Therefore applications shouldn't treat failure of this function as fatal |
| 112 | condition, because doing so would open them to the possibility of a Denial of |
| 113 | Service attack. Instead, they should alert the user about the problem and |
| 114 | offer to continue execution without checking if another instance is running. |
| 115 | |
| 116 | \membersection{wxSingleInstanceChecker::IsAnotherRunning}\label{wxsingleinstancecheckerisanotherrunning} |
| 117 | |
| 118 | \constfunc{bool}{IsAnotherRunning}{\void} |
| 119 | |
| 120 | Returns {\tt true} if another copy of this program is already running, {\tt |
| 121 | false} otherwise. |
| 122 | |
| 123 | \membersection{wxSingleInstanceChecker::\destruct{wxSingleInstanceChecker}}\label{wxsingleinstancecheckerdtor} |
| 124 | |
| 125 | \func{}{\destruct{wxSingleInstanceChecker}}{\void} |
| 126 | |
| 127 | Destructor frees the associated resources. |
| 128 | |
| 129 | Note that it is not virtual, this class is not meant to be used polymorphically |
| 130 | |