libdap::SignalHandler Class Reference

#include <SignalHandler.h>

Public Member Functions
EventHandler *	register_handler (int signum, EventHandler *eh, bool override=false)
EventHandler *	remove_handler (int signum)

Static Public Member Functions
static SignalHandler *	instance ()

Friends
class	HTTPCacheTest
class	SignalHandlerTest

Detailed Description

Singleton to handle signals. This class adapts the C-style function call interface to one suited for C++. This class records a signal's old action/handler when it installs new handler. When a signal is caught, the new handler (registered with this class) is run and then the old action/handler is performed. This ensures that when libdap++ is embedded in code which has a handler for a signal such as SIGINT which does something other than the default, that thing, whatever it may be, gets done.

This class treats signals it registers (using the EventHandler abstract class) differently than ones registered using the signal() or sigaction() system interfaces. If the register_handler() method is called and an instance of EventHandler is already bound to signum, then the old EventHandler is returned. However, if there's an existing handler that was set up with sigaction(), ..., it won't be returned. Instead it will either be run after the newly registered EventHandler or ignored, depending on register_handler()'s override parameter. This feature may be used only for POSIX.1 signals which cause process termination. They are: SIGHUP, SIGINT, SIGKILL, SIGPIPE, SIGALRM, SIGTERM, SIGUSR1, and SIGUSR2.

Note

Based on "Applying Design Patterns to Simplify Signal Handling", Douglas C. Schmidt, 1998, http://www.cs.wustl.edu/~schmidt/signal-patterns.html.

See also

EventHandler

Author

James Gallagher jgall.nosp@m.aghe.nosp@m.r@ope.nosp@m.ndap.nosp@m..org

Definition at line 66 of file SignalHandler.h.

Member Function Documentation

instance()

SignalHandler * libdap::SignalHandler::instance ( )

static

Get a pointer to the single instance of SignalHandler.

Definition at line 131 of file SignalHandler.cc.

register_handler()

EventHandler * libdap::SignalHandler::register_handler	(	int	signum,
		EventHandler *	eh,
		bool	override = false
	)

Register an event handler. By default run any previously registered action/handler such as those installed using sigaction(). For signals such as SIGALRM (the alarm signal) this may not be what you want; see the override parameter. See also the class description.

Parameters

signum	Bind the event handler to this signal number. Limited to those signals that, according to POSIX.1, cause process termination.
eh	A pointer to the EventHandler for signum.
override	If true, do not run the default handler/action. Instead run eh and then treat the signal as if the original action was SIG_IGN. Default is false.

Returns

A pointer to the old EventHandler or null.

Definition at line 151 of file SignalHandler.cc.

remove_handler()

EventHandler * libdap::SignalHandler::remove_handler

(

int

signum

)

Remove the event hander.

Parameters

signum

The signal number of the handler to remove.

Returns

The old event handler

Definition at line 220 of file SignalHandler.cc.

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

• SignalHandler.h
• SignalHandler.cc