// Purpose: interface of wxSingleInstanceChecker
// Author: wxWidgets team
// RCS-ID: $Id$
-// Licence: wxWindows license
+// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
/**
@class wxSingleInstanceChecker
wxSingleInstanceChecker class allows to check that only a single instance of a
- program is running. To do it, you should create an object of this class. As
- long as this object is alive, calls to
- wxSingleInstanceChecker::IsAnotherRunning from
- other processes will return @true.
+ program is running.
+
+ To do it, you should create an object of this class. As long as this object
+ is alive, calls to wxSingleInstanceChecker::IsAnotherRunning from other
+ processes will return @true.
As the object should have the life span as big as possible, it makes sense to
- create it either as a global or in wxApp::OnInit. For
- example:
+ create it either as a global or in wxApp::OnInit.
+ For example:
@code
bool MyApp::OnInit()
{
- const wxString name = wxString::Format("MyApp-%s", wxGetUserId().c_str());
- m_checker = new wxSingleInstanceChecker(name);
+ m_checker = new wxSingleInstanceChecker;
if ( m_checker-IsAnotherRunning() )
{
wxLogError(_("Another program instance is already running, aborting."));
- delete m_checker; // OnExit() won't be called if we return @false
- m_checker = @NULL;
+ delete m_checker; // OnExit() won't be called if we return false
+ m_checker = NULL;
- return @false;
+ return false;
}
... more initializations ...
- return @true;
+ return true;
}
int MyApp::OnExit()
}
@endcode
- Note using wxGetUserId() to construct the name: this
- allows different user to run the application concurrently which is usually the
- intended goal. If you don't use the user name in the wxSingleInstanceChecker
- name, only one user would be able to run the application at a time.
+ Note that by default wxSingleInstanceChecker::CreateDefault() is used to
+ create the checker meaning that it will be initialized differently for
+ different users and thus will allow different users to run the application
+ concurrently which is usually the required behaviour. However if only a
+ single instance of a program should be running system-wide, you need to
+ call Create() with a custom name which does @em not include wxGetUserId().
This class is implemented for Win32 and Unix platforms (supporting @c fcntl()
system call, but almost all of modern Unix systems do) only.
@library{wxbase}
- @category{misc}
+ @category{appmanagement}
*/
class wxSingleInstanceChecker
{
public:
/**
- Like Create() but without
- error checking.
+ Default constructor.
+
+ You may call Create() after using it or directly call
+ IsAnotherRunning() in which case CreateDefault() will be implicitly
+ used.
+ */
+ wxSingleInstanceChecker();
+
+ /**
+ Constructor calling Create().
+
+ This constructor does exactly the same thing as Create() but doesn't
+ allow to check for errors.
*/
wxSingleInstanceChecker(const wxString& name,
const wxString& path = wxEmptyString);
/**
Destructor frees the associated resources.
- Note that it is not virtual, this class is not meant to be used polymorphically
+
+ Note that it is not virtual, this class is not meant to be used polymorphically.
*/
~wxSingleInstanceChecker();
/**
Initialize the object if it had been created using the default constructor.
+
Note that you can't call Create() more than once, so calling it if the
- @ref wxsingleinstancechecker() "non default ctor"
- had been used is an error.
+ non default ctor had been used is an error.
@param name
- must be given and be as unique as possible. It is used as the
+ Must be given and be as unique as possible. It is used as the
mutex name under Win32 and the lock file name under Unix.
- GetAppName() and wxGetUserId()
- are commonly used to construct this parameter.
+ wxApp::GetAppName() and wxGetUserId() are commonly used to construct
+ this parameter.
@param path
- is optional and is ignored under Win32 and used as the directory to
- create the lock file in under Unix (default is
- wxGetHomeDir())
-
- @return Returns @false if initialization failed, it doesn't mean that
- another instance is running - use IsAnotherRunning()
- to check for it.
+ The path is optional and is ignored under Win32 and used as the
+ directory to create the lock file in under Unix
+ (default is wxGetHomeDir()).
+
+ @return
+ Returns @false if initialization failed, it doesn't mean that
+ another instance is running -- use IsAnotherRunning() to check for
+ it.
+
+ @note
+ One of possible reasons while Create() may fail on Unix is that the lock
+ file used for checking already exists but was not created by the user.
+ Therefore applications shouldn't treat failure of this function as fatal
+ condition, because doing so would open them to the possibility of a
+ Denial of Service attack. Instead, they should alert the user about
+ the problem and offer to continue execution without checking if
+ another instance is running.
*/
bool Create(const wxString& name,
const wxString& path = wxEmptyString);
/**
- Returns @true if another copy of this program is already running, @false
- otherwise.
+ Calls Create() with default name.
+
+ This method simply calls Create() with a string composed of
+ wxApp::GetAppName() and wxGetUserId().
+
+ Because this method uses wxApp::GetAppName(), it may only be called
+ after the global application was constructed.
+
+ @since 2.9.1
+ */
+ bool CreateDefault();
+
+ /**
+ Returns @true if another copy of this program is already running and
+ @false otherwise.
+
+ Notice that if the object was created using the default constructor
+ Create() hadn't been called before this method, it will call
+ CreateDefault() automatically.
*/
bool IsAnotherRunning() const;
};
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