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<?php

/**

 * Smarty Internal Plugin

 *

 * @package    Smarty

 * @subpackage Cacher

 */

/**

 * Smarty Cache Handler Base for Key/Value Storage Implementations

 * This class implements the functionality required to use simple key/value stores

 * for hierarchical cache groups. key/value stores like memcache or APC do not support

 * wildcards in keys, therefore a cache group cannot be cleared like "a|*" - which

 * is no problem to filesystem and RDBMS implementations.

 * This implementation is based on the concept of invalidation. While one specific cache

 * can be identified and cleared, any range of caches cannot be identified. For this reason

 * each level of the cache group hierarchy can have its own value in the store. These values

 * are nothing but microtimes, telling us when a particular cache group was cleared for the

 * last time. These keys are evaluated for every cache read to determine if the cache has

 * been invalidated since it was created and should hence be treated as inexistent.

 * Although deep hierarchies are possible, they are not recommended. Try to keep your

 * cache groups as shallow as possible. Anything up 3-5 parents should be ok. So

 * »a|b|c« is a good depth where »a|b|c|d|e|f|g|h|i|j|k« isn't. Try to join correlating

 * cache groups: if your cache groups look somewhat like »a|b|$page|$items|$whatever«

 * consider using »a|b|c|$page-$items-$whatever« instead.

 *

 * @package    Smarty

 * @subpackage Cacher

 * @author     Rodney Rehm

 */

abstract class Smarty_CacheResource_KeyValueStore extends Smarty_CacheResource

{

    /**

     * cache for contents

     *

     * @var array

     */

    protected $contents = array();

    /**

     * cache for timestamps

     *

     * @var array

     */

    protected $timestamps = array();

    /**

     * populate Cached Object with meta data from Resource

     *

     * @param Smarty_Template_Cached   $cached    cached object

     * @param Smarty_Internal_Template $_template template object

     *

     * @return void

     */

    public function populate(Smarty_Template_Cached $cached, Smarty_Internal_Template $_template)

    {

        $cached->filepath = $_template->source->uid . '#' . $this->sanitize($cached->source->resource) . '#' .

                            $this->sanitize($cached->cache_id) . '#' . $this->sanitize($cached->compile_id);

        $this->populateTimestamp($cached);

    }

    /**

     * populate Cached Object with timestamp and exists from Resource

     *

     * @param Smarty_Template_Cached $cached cached object

     *

     * @return void

     */

    public function populateTimestamp(Smarty_Template_Cached $cached)

    {

        if (!$this->fetch(

            $cached->filepath,

            $cached->source->name,

            $cached->cache_id,

            $cached->compile_id,

            $content,

            $timestamp,

            $cached->source->uid

        )

        ) {

            return;

        }

        $cached->content = $content;

        $cached->timestamp = (int)$timestamp;

        $cached->exists = !!$cached->timestamp;

    }

    /**

     * Read the cached template and process the header

     *

     * @param \Smarty_Internal_Template $_smarty_tpl do not change variable name, is used by compiled template

     * @param Smarty_Template_Cached    $cached      cached object

     * @param boolean                   $update      flag if called because cache update

     *

     * @return boolean                 true or false if the cached content does not exist

     */

    public function process(

        Smarty_Internal_Template $_smarty_tpl,

        Smarty_Template_Cached $cached = null,

        $update = false

    ) {

        if (!$cached) {

            $cached = $_smarty_tpl->cached;

        }

        $content = $cached->content ? $cached->content : null;

        $timestamp = $cached->timestamp ? $cached->timestamp : null;

        if ($content === null || !$timestamp) {

            if (!$this->fetch(

                $_smarty_tpl->cached->filepath,

                $_smarty_tpl->source->name,

                $_smarty_tpl->cache_id,

                $_smarty_tpl->compile_id,

                $content,

                $timestamp,

                $_smarty_tpl->source->uid

            )

            ) {

                return false;

            }

        }

        if (isset($content)) {

            eval('?>' . $content);

            return true;

        }

        return false;

    }

    /**

     * Write the rendered template output to cache

     *

     * @param Smarty_Internal_Template $_template template object

     * @param string                   $content   content to cache

     *

     * @return boolean                  success

     */

    public function writeCachedContent(Smarty_Internal_Template $_template, $content)

    {

        $this->addMetaTimestamp($content);

        return $this->write(array($_template->cached->filepath => $content), $_template->cache_lifetime);

    }

    /**

     * Read cached template from cache

     *

     * @param Smarty_Internal_Template $_template template object

     *

     * @return string|false  content

     */

    public function readCachedContent(Smarty_Internal_Template $_template)

    {

        $content = $_template->cached->content ? $_template->cached->content : null;

        $timestamp = null;

        if ($content === null) {

            if (!$this->fetch(

                $_template->cached->filepath,

                $_template->source->name,

                $_template->cache_id,

                $_template->compile_id,

                $content,

                $timestamp,

                $_template->source->uid

            )

            ) {

                return false;

            }

        }

        if (isset($content)) {

            return $content;

        }

        return false;

    }

    /**

     * Empty cache

     * {@internal the $exp_time argument is ignored altogether }}

     *

     * @param Smarty  $smarty   Smarty object

     * @param integer $exp_time expiration time [being ignored]

     *

     * @return integer number of cache files deleted [always -1]

     * @uses   purge() to clear the whole store

     * @uses   invalidate() to mark everything outdated if purge() is inapplicable

     */

    public function clearAll(Smarty $smarty, $exp_time = null)

    {

        if (!$this->purge()) {

            $this->invalidate(null);

        }

        return -1;

    }

    /**

     * Empty cache for a specific template

     * {@internal the $exp_time argument is ignored altogether}}

     *

     * @param Smarty  $smarty        Smarty object

     * @param string  $resource_name template name

     * @param string  $cache_id      cache id

     * @param string  $compile_id    compile id

     * @param integer $exp_time      expiration time [being ignored]

     *

     * @return int number of cache files deleted [always -1]

     * @throws \SmartyException

     * @uses   buildCachedFilepath() to generate the CacheID

     * @uses   invalidate() to mark CacheIDs parent chain as outdated

     * @uses   delete() to remove CacheID from cache

     */

    public function clear(Smarty $smarty, $resource_name, $cache_id, $compile_id, $exp_time)

    {

        $uid = $this->getTemplateUid($smarty, $resource_name);

        $cid = $uid . '#' . $this->sanitize($resource_name) . '#' . $this->sanitize($cache_id) . '#' .

               $this->sanitize($compile_id);

        $this->delete(array($cid));

        $this->invalidate($cid, $resource_name, $cache_id, $compile_id, $uid);

        return -1;

    }

    /**

     * Get template's unique ID

     *

     * @param Smarty $smarty        Smarty object

     * @param string $resource_name template name

     *

     * @return string filepath of cache file

     * @throws \SmartyException

     */

    protected function getTemplateUid(Smarty $smarty, $resource_name)

    {

        if (isset($resource_name)) {

            $source = Smarty_Template_Source::load(null, $smarty, $resource_name);

            if ($source->exists) {

                return $source->uid;

            }

        }

        return '';

    }

    /**

     * Sanitize CacheID components

     *

     * @param string $string CacheID component to sanitize

     *

     * @return string sanitized CacheID component

     */

    protected function sanitize($string)

    {

        $string = trim($string, '|');

        if (!$string) {

            return '';

        }

        return preg_replace('#[^\w\|]+#S', '_', $string);

    }

    /**

     * Fetch and prepare a cache object.

     *

     * @param string  $cid           CacheID to fetch

     * @param string  $resource_name template name

     * @param string  $cache_id      cache id

     * @param string  $compile_id    compile id

     * @param string  $content       cached content

     * @param integer &$timestamp    cached timestamp (epoch)

     * @param string  $resource_uid  resource's uid

     *

     * @return boolean success

     */

    protected function fetch(

        $cid,

        $resource_name = null,

        $cache_id = null,

        $compile_id = null,

        &$content = null,

        &$timestamp = null,

        $resource_uid = null

    ) {

        $t = $this->read(array($cid));

        $content = !empty($t[ $cid ]) ? $t[ $cid ] : null;

        $timestamp = null;

        if ($content && ($timestamp = $this->getMetaTimestamp($content))) {

            $invalidated =

                $this->getLatestInvalidationTimestamp($cid, $resource_name, $cache_id, $compile_id, $resource_uid);

            if ($invalidated > $timestamp) {

                $timestamp = null;

                $content = null;

            }

        }

        return !!$content;

    }

    /**

     * Add current microtime to the beginning of $cache_content

     * {@internal the header uses 8 Bytes, the first 4 Bytes are the seconds, the second 4 Bytes are the microseconds}}

     *

     * @param string &$content the content to be cached

     */

    protected function addMetaTimestamp(&$content)

    {

        $mt = explode(' ', microtime());

        $ts = pack('NN', $mt[ 1 ], (int)($mt[ 0 ] * 100000000));

        $content = $ts . $content;

    }

    /**

     * Extract the timestamp the $content was cached

     *

     * @param string &$content the cached content

     *

     * @return float  the microtime the content was cached

     */

    protected function getMetaTimestamp(&$content)

    {

        extract(unpack('N1s/N1m/a*content', $content));

        /**

         * @var  int $s

         * @var  int $m

         */

        return $s + ($m / 100000000);

    }

    /**

     * Invalidate CacheID

     *

     * @param string $cid           CacheID

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's uid

     *

     * @return void

     */

    protected function invalidate(

        $cid = null,

        $resource_name = null,

        $cache_id = null,

        $compile_id = null,

        $resource_uid = null

    ) {

        $now = microtime(true);

        $key = null;

        // invalidate everything

        if (!$resource_name && !$cache_id && !$compile_id) {

            $key = 'IVK#ALL';

        } // invalidate all caches by template

        else {

            if ($resource_name && !$cache_id && !$compile_id) {

                $key = 'IVK#TEMPLATE#' . $resource_uid . '#' . $this->sanitize($resource_name);

            } // invalidate all caches by cache group

            else {

                if (!$resource_name && $cache_id && !$compile_id) {

                    $key = 'IVK#CACHE#' . $this->sanitize($cache_id);

                } // invalidate all caches by compile id

                else {

                    if (!$resource_name && !$cache_id && $compile_id) {

                        $key = 'IVK#COMPILE#' . $this->sanitize($compile_id);

                    } // invalidate by combination

                    else {

                        $key = 'IVK#CID#' . $cid;

                    }

                }

            }

        }

        $this->write(array($key => $now));

    }

    /**

     * Determine the latest timestamp known to the invalidation chain

     *

     * @param string $cid           CacheID to determine latest invalidation timestamp of

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's filepath

     *

     * @return float  the microtime the CacheID was invalidated

     */

    protected function getLatestInvalidationTimestamp(

        $cid,

        $resource_name = null,

        $cache_id = null,

        $compile_id = null,

        $resource_uid = null

    ) {

        // abort if there is no CacheID

        if (false && !$cid) {

            return 0;

        }

        // abort if there are no InvalidationKeys to check

        if (!($_cid = $this->listInvalidationKeys($cid, $resource_name, $cache_id, $compile_id, $resource_uid))) {

            return 0;

        }

        // there are no InValidationKeys

        if (!($values = $this->read($_cid))) {

            return 0;

        }

        // make sure we're dealing with floats

        $values = array_map('floatval', $values);

        return max($values);

    }

    /**

     * Translate a CacheID into the list of applicable InvalidationKeys.

     * Splits 'some|chain|into|an|array' into array( '#clearAll#', 'some', 'some|chain', 'some|chain|into', ... )

     *

     * @param string $cid           CacheID to translate

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's filepath

     *

     * @return array  list of InvalidationKeys

     * @uses   $invalidationKeyPrefix to prepend to each InvalidationKey

     */

    protected function listInvalidationKeys(

        $cid,

        $resource_name = null,

        $cache_id = null,

        $compile_id = null,

        $resource_uid = null

    ) {

        $t = array('IVK#ALL');

        $_name = $_compile = '#';

        if ($resource_name) {

            $_name .= $resource_uid . '#' . $this->sanitize($resource_name);

            $t[] = 'IVK#TEMPLATE' . $_name;

        }

        if ($compile_id) {

            $_compile .= $this->sanitize($compile_id);

            $t[] = 'IVK#COMPILE' . $_compile;

        }

        $_name .= '#';

        $cid = trim($cache_id, '|');

        if (!$cid) {

            return $t;

        }

        $i = 0;

        while (true) {

            // determine next delimiter position

            $i = strpos($cid, '|', $i);

            // add complete CacheID if there are no more delimiters

            if ($i === false) {

                $t[] = 'IVK#CACHE#' . $cid;

                $t[] = 'IVK#CID' . $_name . $cid . $_compile;

                $t[] = 'IVK#CID' . $_name . $_compile;

                break;

            }

            $part = substr($cid, 0, $i);

            // add slice to list

            $t[] = 'IVK#CACHE#' . $part;

            $t[] = 'IVK#CID' . $_name . $part . $_compile;

            // skip past delimiter position

            $i++;

        }

        return $t;

    }

    /**

     * Check is cache is locked for this template

     *

     * @param Smarty                 $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     *

     * @return boolean               true or false if cache is locked

     */

    public function hasLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $key = 'LOCK#' . $cached->filepath;

        $data = $this->read(array($key));

        return $data && time() - $data[ $key ] < $smarty->locking_timeout;

    }

    /**

     * Lock cache for this template

     *

     * @param Smarty                 $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     *

     * @return bool|void

     */

    public function acquireLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $cached->is_locked = true;

        $key = 'LOCK#' . $cached->filepath;

        $this->write(array($key => time()), $smarty->locking_timeout);

    }

    /**

     * Unlock cache for this template

     *

     * @param Smarty                 $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     *

     * @return bool|void

     */

    public function releaseLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $cached->is_locked = false;

        $key = 'LOCK#' . $cached->filepath;

        $this->delete(array($key));

    }

    /**

     * Read values for a set of keys from cache

     *

     * @param array $keys list of keys to fetch

     *

     * @return array list of values with the given keys used as indexes

     */

    abstract protected function read(array $keys);

    /**

     * Save values for a set of keys to cache

     *

     * @param array $keys   list of values to save

     * @param int   $expire expiration time

     *

     * @return boolean true on success, false on failure

     */

    abstract protected function write(array $keys, $expire = null);

    /**

     * Remove values from cache

     *

     * @param array $keys list of keys to delete

     *

     * @return boolean true on success, false on failure

     */

    abstract protected function delete(array $keys);

    /**

     * Remove *all* values from cache

     *

     * @return boolean true on success, false on failure

     */

    protected function purge()

    {

        return false;

    }

}