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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* DNS Library for handling lookups and updates.
*
* PHP Version 5
*
* Copyright (c) 2010, Mike Pultz <mike@mikepultz.com>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of Mike Pultz nor the names of his contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRIC
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @category Networking
* @package Net_DNS2
* @author Mike Pultz <mike@mikepultz.com>
* @copyright 2010 Mike Pultz <mike@mikepultz.com>
* @license http://www.opensource.org/licenses/bsd-license.php BSD License
* @version SVN: $Id: Shm.php 137 2011-12-05 02:51:34Z mike.pultz $
* @link http://pear.php.net/package/Net_DNS2
* @since File available since Release 1.1.0
*
*/
/**
* Shared Memory-based caching for the Net_DNS2_Cache class
*
* @category Networking
* @package Net_DNS2
* @author Mike Pultz <mike@mikepultz.com>
* @license http://www.opensource.org/licenses/bsd-license.php BSD License
* @link http://pear.php.net/package/Net_DNS2
* @see Net_DNS2_Packet
*
*/
class Net_DNS2_Cache_Shm extends Net_DNS2_Cache
{
/*
* resource id of the shared memory cache
*/
private $_cache_id = false;
/*
* the IPC key
*/
private $_cache_file_tok = -1;
/**
* open a cache object
*
* @param string $cache_file path to a file to use for cache storage
* @param integer $size the size of the shared memory segment to create
*
* @throws Net_DNS2_Exception
* @access public
* @return void
*
*/
public function open($cache_file, $size, $serializer)
{
$this->cache_size = $size;
$this->cache_file = $cache_file;
$this->cache_serializer = $serializer;
//
// make sure the file exists first
//
if (!file_exists($cache_file)) {
if (file_put_contents($cache_file, '') === false) {
throw new Net_DNS2_Exception(
'failed to create empty SHM file: ' . $cache_file,
Net_DNS2_Lookups::E_CACHE_SHM_FILE
);
}
}
//
// convert the filename to a IPC key
//
$this->_cache_file_tok = ftok($cache_file, 't');
if ($this->_cache_file_tok == -1) {
throw new Net_DNS2_Exception(
'failed on ftok() file: ' . $this->_cache_file_tok,
Net_DNS2_Lookups::E_CACHE_SHM_FILE
);
}
//
// try to open an existing cache; if it doesn't exist, then there's no
// cache, and nothing to do.
//
$this->_cache_id = @shmop_open($this->_cache_file_tok, 'w', 0, 0);
if ($this->_cache_id !== false) {
//
// this returns the size allocated, and not the size used, but it's
// still a good check to make sure there's space allocated.
//
$allocated = shmop_size($this->_cache_id);
if ($allocated > 0) {
//
// read the data from the shared memory segment
//
$data = trim(shmop_read($this->_cache_id, 0, $allocated));
if ( ($data !== false) && (strlen($data) > 0) ) {
//
// unserialize and store the data
//
if ($this->cache_serializer == 'json') {
$this->cache_data = json_decode($data, true);
} else {
$this->cache_data = unserialize($data);
}
//
// call clean to clean up old entries
//
$this->clean();
}
}
}
}
/**
* Destructor
*
* @access public
*
*/
public function __destruct()
{
$fp = fopen($this->cache_file, 'r');
if ($fp !== false) {
//
// lock the file
//
flock($fp, LOCK_EX);
//
// check to see if we have an open shm segment
//
if ($this->_cache_id === false) {
//
// try opening it again, incase it was created by another
// process in the mean time
//
$this->_cache_id = @shmop_open(
$this->_cache_file_tok, 'w', 0, 0
);
if ($this->_cache_id === false) {
//
// otherwise, create it.
//
$this->_cache_id = @shmop_open(
$this->_cache_file_tok, 'c', 0, $this->cache_size
);
}
}
//
// get the size allocated to the segment
//
$allocated = shmop_size($this->_cache_id);
//
// read the contents
//
$data = trim(shmop_read($this->_cache_id, 0, $allocated));
//
// if there was some data
//
if ( ($data !== false) && (strlen($data) > 0) ) {
//
// unserialize and store the data
//
$c = $this->cache_data;
if ($this->cache_serializer == 'json') {
$this->cache_data = array_merge($c, json_decode($data, true));
} else {
$this->cache_data = array_merge($c, unserialize($data));
}
}
//
// delete the segment
//
shmop_delete($this->_cache_id);
//
// clean the data
//
$this->clean();
//
// clean up and write the data
//
$data = $this->resize();
if (!is_null($data)) {
//
// re-create segment
//
$this->_cache_id = @shmop_open(
$this->_cache_file_tok, 'c', 0644, $this->cache_size
);
if ($this->_cache_id === false) {
return;
}
$o = shmop_write($this->_cache_id, $data, 0);
}
//
// close the segment
//
shmop_close($this->_cache_id);
//
// unlock
//
flock($fp, LOCK_UN);
//
// close the file
//
fclose($fp);
}
}
};
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* c-hanging-comment-ender-p: nil
* End:
*/
?>
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