fdwatch.h

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/* fdwatch.h - header file for fdwatch package
**
** This package abstracts the use of the select() and/or poll() system
** calls.  The basic function of these calls is to watch a set of
** file descriptors for activity.  select() originated in the BSD world,
** while poll() came from SysV land, and their interfaces are somewhat
** different.  fdwatch lets you write your code to a single interface,
** with the portability differences hidden inside the package.
**
** Furthermore, if your system implements both select() and poll(),
** then fdwatch will use whichever call is most advantageous.  It may
** actually switch back and forth at runtime, as the workload changes.
**
** Usage is fairly simple.  Call fdwatch_get_nfiles() to initialize
** the package and find out how many fine descriptors are available.
** Then each time through your main loop, call fdwatch_clear(), then
** fdwatch_add_fd() for each of the descriptors you want to watch,
** then call fdwatch() to actually perform the watch.  After it returns
** you can check which descriptors are ready via fdwatch_check_fd().
**
** If your descriptor set hasn't changed from the last time through
** the loop, you can skip calling fdwatch_clear() and fdwatch_add_fd()
** to save a little CPU time.
**
**
** Copyright