dispatcher(3i) [debian man page]

Dispatcher(3I)						    InterViews Reference Manual 					    Dispatcher(3I)

NAME

       Dispatcher - wait on multiple file descriptors until a condition occurs

SYNOPSIS

       #include <Dispatch/dispatcher.h>

DESCRIPTION

       Conceptually, the dispatcher plays the role of detecting new data on multiple input file descriptors and dispatching the data to the appro-
       priate iohandlers.  The dispatcher also notifies iohandlers of expired timers.  Notification of either an I/O condition or an expired timer
       occurs  by  calling one of the iohandler's virtual functions (see IOHandler(3I)).  Since a program needs only one instance of Dispatcher, a
       static member function is provided to create that instance if necessary and return it.

PUBLIC OPERATIONS

       enum DispatcherMask { ReadMask, WriteMask, ExceptMask }
       virtual IOHandler* handler(int fd, DispatcherMask)
       virtual void link(int fd, DispatcherMask, IOHandler*)
       virtual void unlink(int fd)
	      Return a file descriptor's iohandler, link a file descriptor to an iohandler, or unlink a file descriptor from its iohandlers.   The
	      DispatcherMask  describes  the  I/O  condition that the iohandler is interested in, such as whether the file descriptor has new data
	      available for reading.  If the I/O condition occurs, the iohandler will be expected to read data from  the  file	descriptor,  write
	      data to the file descriptor, or handle the exception depending on the I/O condition.

       virtual void startTimer(long sec, long usec, IOHandler*)
       virtual void stopTimer(IOHandler*)
	      Attach an iohandler to a timer or remove a timer before it expires.  A timer expires after the given number of seconds and microsec-
	      onds have elapsed.  If a timer expires, the dispatcher will notify the attached iohandler.  Timers will not expire until the program
	      calls either variant of Dispatcher::dispatch.

       virtual void dispatch()
       virtual boolean dispatch(long& sec, long& usec)
	      With no arguments, block indefinitely until an I/O condition occurs or a timer expires and then notify the attached iohandler.  With
	      two arguments, block no longer than the given number of seconds and microseconds.  If both  numbers  are	zero,  the  function  will
	      return  immediately  after  checking  all file descriptors and timers.  The return value will be true if an I/O condition caused the
	      function to return and false if the function returned because a timer expired or it exceeded the given poll time.  The function will
	      decrease the given poll time by the amount of time it spent blocking.

       static Dispatcher& instance()
       static void instance(Dispatcher*)
	      With  no	arguments, create an instance of Dispatcher if it doesn't already exist and return it.	With an argument, set the instance
	      of Dispatcher that will be used throughout the program.

SEE ALSO

       select(2), IOHandler(3I)

InterViews							 21 December 1990						    Dispatcher(3I)

Check Out this Related Man Page

IOHandler(3I)						    InterViews Reference Manual 					     IOHandler(3I)

NAME

       IOHandler - read input, write output, or handle an I/O exception or timeout

SYNOPSIS

       #include <Dispatch/iohandler.h>

DESCRIPTION

       An iohandler reads data from a file descriptor, writes data to a file descriptor, handles an I/O exception on a file descriptor, or handles
       a timer's expiration.  Once the user has requested the dispatcher to attach an iohandler to a file descriptor or a  timer,  the	dispatcher
       will automatically notify the iohandler when the file descriptor's I/O condition changes or the timer expires.

       For convenience, the user can use a derived generic class (see IOCallback(3I)) to make the iohandler do nothing more than call an arbitrary
       object's member function.

PUBLIC OPERATIONS

       virtual int inputReady(int fd)
       virtual int outputReady(int fd)
       virtual int exceptionRaised(int fd)
	      The dispatcher will call one of these functions to notify an iohandler that it can read data from a file descriptor, write data to a
	      file  descriptor, or handle an I/O exception on a file descriptor.  The iohandler should perform the appropriate action and tell the
	      dispatcher what to do next.  A negative return value means that the iohandler encountered an error or it doesn't	want  to  read	or
	      write  anything  more.   The  dispatcher	will unlink the iohandler from its file descriptor automatically.  A positive return value
	      means that the iohandler didn't read or write everything that it could have.  The dispatcher will call the iohandler again in  round
	      robin  fashion  WITHOUT  checking  select, which means that the iohandler will be called again as soon as the rest of the iohandlers
	      have performed their actions.  A zero return value means that the iohandler finished reading or writing everything it was  able  to.
	      The dispatcher must check the descriptor's status with the select call before it can call the iohandler again.

       virtual void timerExpired(long sec, long usec)
	      The  dispatcher will call this function to notify an iohandler that a timer has expired.	For informational purposes, the parameters
	      give the current time in seconds and microseconds since midnight January 1, 1970.  If the iohandler wants to  reset  the	timer,	it
	      must tell the dispatcher to start another timer.

SEE ALSO

       Dispatcher(3I), IOCallback(3I)

InterViews							  9 January 1991						     IOHandler(3I)

Linux and UNIX Man Pages

dispatcher(3i) [debian man page]

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