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)