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)