Richard Lynch wrote:
On Mon, April 10, 2006 4:46 pm, darren kirby wrote:
quoth the Robert Cummings:
Why do you do this on every request? Why not have a cron job
retrieve an
update every 20 minutes or whatnot and stuff it into a database
table
for your page to access? Then if the cron fails to retrieve the feed
it
can just leave the table as is, and your visitors can happily view
slightly outdated feeds? Additionally this will be so much faster
that
your users might even hang around on your site :)
This is a very interesting idea, but I am not sure if it is suitable
for me at
this point. First of all, one feed in particular can change in a
matter of
seconds, and I do want it to be as up to date as possible. Secondly,
this is
just for my personal site which is very low traffic, and it is not
inconceivable that getting the feed every 20 minutes by cron would be
_more_
taxing on the network than simply grabbing it per request...
Perhaps, then, you should:
maintain a list of URLs and acceptable "age" of feed.
Attempt to snag the new content upon visit, if the content is "old"
Show the "old" content if the feed takes longer than X seconds.
You'll STILL need a timeout, which, unfortunately, means you are stuck
rolling your own solution with http://php.net/fsockopen because all
the "simple" solutions pretty much suck in terms of network timeout.
:-(
It would be REALLY NIFTY if fopen and friends which understand all
those protocols of HTTP FTP HTTPS and so on, allowed one to set a
timeout for URLs, but they don't and nobody with the skills to change
that (not me) seems even mildly interested. :-( :-( :-(
Since I've already written a class that does something like what you
want, or maybe even exactly what you want, I might as well just
provide the source, eh?
http://l-i-e.com/FeedMulti/FeedMulti.phps
No stream_select() ?
Here is an example Wez wrote years ago:
<?php
$hosts = array("host1.sample.com", "host2.sample.com", "host3.sample.com");
$timeout = 15;
$status = array();
$sockets = array();
/* Initiate connections to all the hosts simultaneously */
foreach ($hosts as $id => $host) {
$s = stream_socket_client("$host:80", $errno, $errstr, $timeout,
STREAM_CLIENT_ASYNC_CONNECT);
if ($s) {
$sockets[$id] = $s;
$status[$id] = "in progress";
} else {
$status[$id] = "failed, $errno $errstr";
}
}
/* Now, wait for the results to come back in */
while (count($sockets)) {
$read = $write = $sockets;
/* This is the magic function - explained below */
$n = stream_select($read, $write, $e = null, $timeout);
if ($n > 0) {
/* readable sockets either have data for us, or are failed
* connection attempts */
foreach ($read as $r) {
$id = array_search($r, $sockets);
$data = fread($r, 8192);
if (strlen($data) == 0) {
if ($status[$id] == "in progress") {
$status[$id] = "failed to connect";
}
fclose($r);
unset($sockets[$id]);
} else {
$status[$id] .= $data;
}
}
/* writeable sockets can accept an HTTP request */
foreach ($write as $w) {
$id = array_search($w, $sockets);
fwrite($w, "HEAD / HTTP/1.0\r\nHost: "
. $hosts[$id] . "\r\n\r\n");
$status[$id] = "waiting for response";
}
} else {
/* timed out waiting; assume that all hosts associated
* with $sockets are faulty */
foreach ($sockets as $id => $s) {
$status[$id] = "timed out " . $status[$id];
}
break;
}
}
foreach ($hosts as $id => $host) {
echo "Host: $host\n";
echo "Status: " . $status[$id] . "\n\n";
}
?>
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