SignalHandler Class Reference

#include <SignalHandler.h>

Collaboration diagram for SignalHandler:

Collaboration graph
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List of all members.

Public Member Functions

EventHandlerregister_handler (int signum, EventHandler *eh, bool override=false)
EventHandlerremove_handler (int signum)
virtual ~SignalHandler ()

Static Public Member Functions

static SignalHandlerinstance ()

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 <jgallagher@opendap.org>

Definition at line 63 of file SignalHandler.h.


Constructor & Destructor Documentation

virtual SignalHandler::~SignalHandler (  )  [inline, virtual]

Definition at line 104 of file SignalHandler.h.


Member Function Documentation

SignalHandler * SignalHandler::instance (  )  [static]

Get a pointer to the single instance of SignalHandler.

Definition at line 122 of file SignalHandler.cc.

Referenced by DODSFilter::establish_timeout().

EventHandler * 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 142 of file SignalHandler.cc.

References long_to_string().

Referenced by DODSFilter::establish_timeout().

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EventHandler * 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 211 of file SignalHandler.cc.


Friends And Related Function Documentation

friend class HTTPCacheTest [friend]

Definition at line 98 of file SignalHandler.h.

friend class SignalHandlerTest [friend]

Definition at line 97 of file SignalHandler.h.


The documentation for this class was generated from the following files:
Generated on Wed Jun 27 12:58:24 2007 for libdap++ by  doxygen 1.4.7