bionic (3) Dispatcher.3I.gz

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 appropriate 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 microseconds 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)