Missing cache items [via phpfastcache] using Server Side Events

Question

I'm using Server-Sent Events, to print messages for user.

In infinite loop, every 10 seconds I check if there is any new item in cache to broadcast:

$messages_to_broadcast = $this->_cache->getItemsByTag('inbox_message');
foreach ($messages_to_broadcast as $key => $_message) {
    $_message = $_message->get();
    if($_message->recipient == $this->_user_id || $_message->recipient == 0){
        if(!is_null($html = \CRM\Engine\MessagingService::getMessageToBroadcast($_message)))
        {
           echo "event: $_message->type \n";
           echo "data:{\n";
           echo "data:\"message_html\": \"$html\" \n";
           echo "data:}\n\n";
           $this->send_keepalive = false;
           $this->_cache->deleteItem($key);
        }
    }
}

At irregular intervals, there is event, which save message to cache:

$_cache_this = self::$_cache->getItem("message_".$_message->id);
if(!$_cache_this->isHit()){
    $_cache_this->set($_message)
        ->expiresAfter(600)
        ->addTag('inbox_message');
    self::$_cache->save($_cache_this);
}

The problem is that while I check in infinite loop for new items in cache, I get empty array. When I reload page, or browser reconnect to Server Side Events stream, item appears in cache. Is there any flush method I'm missing here? I'm using files as cache method.

\phpFastCache\CacheManager::setDefaultConfig(array(
    "path" => DIR_TMP
));
global $cache;
$cache = \phpFastCache\CacheManager::getInstance('files');

Florent Poinsaut · Accepted Answer · 2019-04-30 12:38:38Z

In a loop, you have to use the detachItem method of PhpFastCache to force it to get the right value.

Here an example:

while (1) {
    $cache = $this->cacheService->getCache();
    if (null !== $cache) {
        try {
            $item = $cache->getItem('my_key');
            if ($item->isHit()) {
                echo "event: message\ndata: $item->get()\n\n";
            }
            $cache->detachItem($item);
        } catch (InvalidArgumentException | PhpfastcacheInvalidArgumentException $e) {
            $this->logger->error(
                'There has been an error when getting cache item: '
                .$e->getMessage().' - '.$e->getFile().' - '.$e->getLine()
            );
        }
    }

    ob_flush();
    flush();

    if (connection_aborted()) {
        break;
    }
    sleep(1);
}

I open a issue to ask more doc here: https://github.com/PHPSocialNetwork/phpfastcache/issues/687

Geolim4 · Accepted Answer · 2019-04-30 15:39:39Z

1

Phpfastcache is storing (the exact definition is "caching" in fact) the cache item statically in the cache backend object. So effectively you'll need to release the object using detachItem() method or clear() to empty the cache.

As described on this issue, I'll update the Wiki coming soon to clarify that behaviour for perpetual CLI scripts.

answered Apr 30, 2019 at 15:39

Geolim4

4543 silver badges14 bronze badges

1 Comment

Jędrzej Skrzypczak Over a year ago

This is probably issue solver. Although the project where I had this problem is long dead. :D

Marc D. · Accepted Answer · 2017-12-19 21:28:08Z

0

It's a while you've asked this, but usually you can only grab the items in cache by tag, haven't seen a method that let's you get all cache entries.

$entries = $cache->getItemsByTag('inbox_message')

$entries will now hold all your items.

Have a look here: https://github.com/PHPSocialNetwork/phpfastcache/blob/final/docs/examples/tagsMethods.php where you can see a complete example on usage.

edited Dec 19, 2017 at 21:28

answered Dec 19, 2017 at 20:46

Marc D.

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