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<?php
/*
** $Id$
**
** Relog Internet Tools 3 Library ("ITOOLS3")
**
** it_urlcache.class - Interface to URL content cache in DB
**
** This class relies on a DB table with the following scheme:
** url CHAR(255) NOT NULL,
** updateinterval INT NOT NULL,
** lastupdate INT NOT NULL,
** nextupdate INT NOT NULL,
** contentmd5 CHAR(32) NOT NULL,
** content TEXT NOT NULL,
** PRIMARY KEY (url),
** KEY (nextupdate)
*/
/* PRIVATE */
define("_IT_URLCACHE_DEFAULT_INTERVAL", 300);
define("_IT_URLCACHE_MAX_CONNECTIONS", 30);
class it_urlcache extends it_db_record
{
/* PRIVATE */
var $default_interval = _IT_URLCACHE_DEFAULT_INTERVAL;
var $max_connections = _IT_URLCACHE_MAX_CONNECTIONS;
function set_default_interval($default_interval)
{
$this->default_interval = $default_interval;
}
function set_max_connections($max_connections)
{
$this->max_connections = $max_connections;
}
/*
* Register an URL to be fetched by background process.
* Note: get() will return an empty string until the url is fetched for the
* first time
*/
function register($url)
{
if (!$this->read($url))
{
$tags = array("url" => $url, "updateinterval" => $this->default_interval);
$this->create($tags);
}
}
/*
* Removes the url from the cache. It won't be fetched again until register()
* is called again.
*/
function unregister($url)
{
if ($this->read($url))
$this->delete();
}
/*
* Get content of url. Returns empty string if it was never successfully
* fetched.
*/
function get_content($url)
{
$this->read($url);
return $this->data['content'];
}
/*
* Try to refetch all URLs in the database.
* Note: This is intented for background process use only as it may take
* a while to finish...
*/
function update_cache()
{
$now = time();
$pages = array();
$result = $this->table->safe_sql_select("WHERE nextupdate < $now", "url");
while (list($url) = $this->table->db->fetch_array($result))
$pages[] = $url;
$this->table->db->free($result);
$this->_fetch_urls($pages, $now);
}
/* PRIVATE */
function _update_cache($url, $content, $now)
{
$contentmd5 = md5($content);
if ($this->read($url))
{
$interval = $this->data['updateinterval'];
$age = $now - $this->data['lastupdate'];
if ($this->data['contentmd5'] == $contentmd5)
{
if ($age > ($interval * 2))
$interval = $interval * 1.5;
$tags = array("updateinterval" => $interval, "nextupdate" => $now + $interval);
}
else
{
if ($age < ($interval / 2))
$interval = $interval / 1.5;
if ($interval < $this->default_interval)
$interval = $this->default_interval;
$tags = array("updateinterval" => $interval, "lastupdate" => $now, "nextupdate" => $now + $interval, "contentmd5" => $contentmd5, "content" => $content);
}
$this->update($tags);
}
else
{
$tags = array("url" => $url, "updateinterval" => $this->default_interval, "lastupdate" => $now, "nextupdate" => $now + $this->default_interval, "contentmd5" => $contentmd5, "content" => $content);
$this->create($tags);
}
}
/*
* PRIVATE
* Fetch URL in array $urls and store update cache database accordingly
*/
function _fetch_urls($pages, $now)
{
$pos = 0;
$fds = array();
$urls = array();
$content = array();
$count = 0;
for ($pos = 0; ($pos < count($pages)) && ($pos < $this->max_connections); $pos++)
{
debug("Opening $pages[$pos]", 10);
if ($fd = fopen($pages[$pos], "r"))
{
socket_set_blocking($fd, false);
$fds[] = $fd;
$urls[] = $pages[$pos];
$content[] = "";
$count++;
debug("Opened $pages[$pos]", 10);
}
}
while ($count > 0)
{
$read = 0;
for ($i = 0; $i < count($fds); $i++)
{
if ($fds[$i])
{
if (!feof($fds[$i]))
{
$data = fread($fds[$i], 4096);
$content[$i] .= $data;
$read += strlen($data);
debug("Read " . strlen($data) . " from $urls[$i]", 10);
}
if (feof($fds[$i]))
{
fclose($fds[$i]);
$fds[$i] = 0;
$count--;
$this->_update_cache($urls[$i], $content[$i], $now);
debug("Finished $urls[$i]: " . strlen($content[$i]) . " bytes", 10);
/* Schedule next url for retrieval */
if ($pos < count($pages))
{
if ($fd = fopen($pages[$pos], "r"))
{
socket_set_blocking($fd, false);
$fds[$i] = $fd;
$urls[$i] = $pages[$pos];
$content[$i] = "";
$count++;
debug("Opened $pages[$pos]", 10);
}
$pos++;
}
}
}
}
/* We are in non-blocking mode, be nice */
if (($count > 0) && ($read == 0))
{
sleep(1);
debug("Sleeping...", 10);
}
}
}
} /* End class it_urlcache */
|