Section: C Library Functions (3)
Updated: 25 July 1998
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ares_process - Process events for name resolution
void ares_process(ares_channel channel, fd_set *read_fds,
void ares_process_fd(ares_channel channel,
The ares_process(3) function handles input/output events and timeouts
associated with queries pending on the name service channel identified by
The file descriptor sets pointed to by read_fds and write_fds
should have file descriptors set in them according to whether the file
descriptors specified by ares_fds(3) are ready for reading and writing.
(The easiest way to determine this information is to invoke
with a timeout no greater than the timeout given by ares_timeout(3) ).
function will invoke callbacks for pending queries if they complete
successfully or fail.
ares_process_fd(3) works the same way but acts and operates only on the
specific file descriptors (sockets) you pass in to the function. Use
ARES_SOCKET_BAD for "no action". This function is of course provided to allow
users of c-ares to void select() in their applications and within c-ares.
The following code fragment waits for all pending queries on a channel
int nfds, count;
fd_set readers, writers;
struct timeval tv, *tvp;
nfds = ares_fds(channel, &readers, &writers);
if (nfds == 0)
tvp = ares_timeout(channel, NULL, &tv);
count = select(nfds, &readers, &writers, NULL, tvp);
ares_process(channel, &readers, &writers);
Greg Hudson, MIT Information Systems
Copyright 1998 by the Massachusetts Institute of Technology.
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