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SUEEventSelector Class Reference

Event selector. More...

#include <sue_sel.hpp>

Collaboration diagram for SUEEventSelector:

[legend]List of all members.

Public Methods
	SUEEventSelector ()
	Constructor.
virtual	~SUEEventSelector ()
	Destructor.
void	RegisterFdHandler (SUEFdHandler *h)
	Register file descriptor handler.
void	RemoveFdHandler (SUEFdHandler *h)
	Removes the specified handler.
void	RegisterTimeoutHandler (SUETimeoutHandler *h)
	Register a timeout handler.
void	RemoveTimeoutHandler (SUETimeoutHandler *h)
	Removes the specified handler.
void	RegisterSignalHandler (SUESignalHandler *h)
	Register a signal handler.
void	RemoveSignalHandler (SUESignalHandler *h)
	Remove a signal handler.
void	Go ()
	Main loop.
void	Break ()
	Cause main loop to break (Go() function to return).
virtual void	HandleSelectFailure (int rc)
	Handle select(2) errors.

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Detailed Description

Event selector.

This class provides an object-oriented framework for the unix select(2) system call. It uses objects of:

• SUEFdHandler class for file descriptor oriented events,
• SUETimeoutHandler class for time events,
• SUESignalHandler class for signal events. You need to create an object of this class, then decide what events you wish to handle from the very start, create the appropriate objects for these events, register them using the appropriate methods, then call Go() and enjoy. Certainly you can register more events and unregister some of the registered events at any time you want, but please note if you define no events before calling Go() then it will loop forever. Remember, you're creating an event-driven application!

Note:

This class is THE good point to start with. You *ALWAYS* need one (and in almost all cases only one) object of this class. The Go() method of this class is the main loop of your application, and the Break() method is used to break the main loop.

You can use this class as it is to create your Selector object. You might want to create a subclass when you need to use sets of handlers somewhere outside of the class (e.g., for debugging purposes), or if you want to handle select(2) failures specifically via overriding the HandleSelectFailure() method.

Examples:

chat.cpp, children.cpp, hellobot.cpp, sigs.cpp, sitter.cpp, and sleep5.cpp.

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Constructor & Destructor Documentation

SUEEventSelector::SUEEventSelector (    )

Constructor.

virtual SUEEventSelector::~SUEEventSelector (    )  [virtual]

Destructor.

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Member Function Documentation

void SUEEventSelector::Break (    )

Cause main loop to break (Go() function to return). This function sets the loop breaking flag which causes Go() function to return. The flag is cleared each time Go() is called. Go() checks for this flag after the main sequence of actions is performed, before repeating it. Examples: sigs.cpp, sitter.cpp, and sleep5.cpp.

void SUEEventSelector::Go (    )

Main loop. This function sets up the fd_set's for read, write and except notifications in accordance to the set of registered file handlers chooses the closest time event from the set of registered timeout handlers sets the signal handling functions as appropriate calls select(2) checks if any handled signals happened examines the fd_set's for FDs changed state and calls the appropriate callback methods examines the timeouts list, selects those are now in the past, removes each of them from the list of registered objects and calls its notification method checks for the loop breaking flag. If it is set, breaks the loop and returns. Otherwise, continues from the beginning. The function is intended to be the main loop of your process. Examples: chat.cpp, children.cpp, hellobot.cpp, sigs.cpp, sitter.cpp, and sleep5.cpp.

virtual void SUEEventSelector::HandleSelectFailure (  int    rc )  [inline, virtual]

Handle select(2) errors. This method is called whenever select(2) returns negative value. Parameters: rc  is the value returned by select(2) Note: override this method to handle the event yourself

void SUEEventSelector::RegisterFdHandler (  SUEFdHandler *    h )

Register file descriptor handler. Registers an FD to be watched. FD is specified with a SUEFdHandler subclass object. SUEFdHandler provides the value of the descriptor, the notification modes (r/w/e), and the callback function for notification (as a virtual method). Note: The FD handler remains registered unless it is explicitly unregistered with RemoveFdHandler method. Warning: It is assumed FD doesn't change when the handler is registered. Examples: sitter.cpp.

void SUEEventSelector::RegisterSignalHandler (  SUESignalHandler *    h )

Register a signal handler. Registers a signal specified with SUESignalHandler object Examples: sigs.cpp.

void SUEEventSelector::RegisterTimeoutHandler (  SUETimeoutHandler *    h )

Register a timeout handler. Registers a time moment at which to wake up and call the notification method. Time value (in seconds and microseconds) is specified by a SUEFdHandler subclass object which also provides a callback function for notification (as a virtual method). Note: The timeout handler remains registered unless either the moment comes and notification function is called OR it is explicitly unregistered with RemoveTimeoutHandler method. Warning: It is assumed that the value of the timeout doesn't change when it is registered. Changind it will lead to unpredictable behaviour. If you need to change thee timeout, then first unregister it, then change and register again. Examples: children.cpp, sitter.cpp, and sleep5.cpp.

void SUEEventSelector::RemoveFdHandler (  SUEFdHandler *    h )

Removes the specified handler. Removes (unregisters) an FD handler. In case the handler is not registered, silently ignores the call

void SUEEventSelector::RemoveSignalHandler (  SUESignalHandler *    h )

Remove a signal handler.

void SUEEventSelector::RemoveTimeoutHandler (  SUETimeoutHandler *    h )

Removes the specified handler. Removes (unregisters) a timeout handler. In case the handler is not registered, silently ignores the call Examples: sitter.cpp.

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The documentation for this class was generated from the following file:

• sue_sel.hpp

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