curl/ares/ares_process.3

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.\" Copyright 1998 by the Massachusetts Institute of Technology.
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.TH ARES_PROCESS 3 "25 July 1998"
.SH NAME
ares_process \- Process events for name resolution
.SH SYNOPSIS
.nf
.B #include <ares.h>
.PP
.B void ares_process(ares_channel \fIchannel\fP, fd_set *\fIread_fds\fP,
.B	fd_set *\fIwrite_fds\fP)
.fi
.PP
.B void ares_process_fd(ares_channel \fIchannel\fP,
.B      ares_socket_t \fIread_fd\fP,
.B	ares_socket_t \fIwrite_fd\fP)
.fi
.SH DESCRIPTION
The \fBares_process(3)\fP function handles input/output events and timeouts
associated with queries pending on the name service channel identified by
.IR channel .
The file descriptor sets pointed to by \fIread_fds\fP and \fIwrite_fds\fP
should have file descriptors set in them according to whether the file
descriptors specified by \fIares_fds(3)\fP are ready for reading and writing.
(The easiest way to determine this information is to invoke
.B select
with a timeout no greater than the timeout given by \fIares_timeout(3)\fP ).
.PP
The
.B ares_process
function will invoke callbacks for pending queries if they complete
successfully or fail.

\fBares_process_fd(3)\fP 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.
.SS EXAMPLE
The following code fragment waits for all pending queries on a channel
to complete:
.PP
.RS
.nf
int nfds, count;
fd_set readers, writers;
struct timeval tv, *tvp;

while (1)
  {
    FD_ZERO(&readers);
    FD_ZERO(&writers);
    nfds = ares_fds(channel, &readers, &writers);
    if (nfds == 0)
      break;
    tvp = ares_timeout(channel, NULL, &tv);
    count = select(nfds, &readers, &writers, NULL, tvp);
    ares_process(channel, &readers, &writers);
  }
.fi
.RE
.SH SEE ALSO
.BR ares_fds (3),
.BR ares_timeout (3)
.SH AUTHOR
Greg Hudson, MIT Information Systems
.br
Copyright 1998 by the Massachusetts Institute of Technology.