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/////////////////////////////////////////////////////////////////////////////
// Name: snglinst.h
// Purpose: interface of wxSingleInstanceChecker
// Author: wxWidgets team
// 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.
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:
@code
bool MyApp::OnInit()
{
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;
return false;
}
... more initializations ...
return true;
}
int MyApp::OnExit()
{
delete m_checker;
return 0;
}
@endcode
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{appmanagement}
*/
class wxSingleInstanceChecker
{
public:
/**
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.
*/
~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
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
mutex name under Win32 and the lock file name under Unix.
wxApp::GetAppName() and wxGetUserId() are commonly used to construct
this parameter.
@param path
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);
/**
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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