Delete and generate new markup cache

[fbg13]

I'm caching a big loop (~1000 pages in a pagetable field) and i want to delete it when a new page is added and after that i want to recreate it with php to avoid users waiting for 10 seconds.

I figured out the deletion part 

$path = $config->paths->assets."cache/MarkupCache/cache_name/";
if(file_exists($path)){
	CacheFile::removeAll($path, true);
}

How can i rebuild the cache with php?

[adrian]

Have you thought about using WireCache instead ?

https://processwire.com/blog/posts/processwire-core-updates-2.5.28/#wirecache-upgrades

[fbg13]

Thanks @adrian

Will update with some code after i do some more tests.

[fbg13]

I'm using this in a module

public function init() {
	$this->addHookBefore("Pages::saveReady", $this, "cacheContent");
}

protected function cacheContent($e) {
	$page = $e->arguments[0];
	if($page->template->name == "templateYouWantToCache") {
		$cache = $this->cache;
		// delete the old cache
		$cache->delete("cacheName:" . $page->id);
		$cache->get("cacheName:" . $page->id, $cache::expireNever, function() use($page){
			// code you want to cache
			$content  = $page->title . "<br>";
			$content .= $page->body; 
			return $content;
		});
	}
}

And in the template 

// since the cache already exists this will just get the cache
// but in case no cache is found it generates it
$cache->get("cacheName:".$page->id, $cache::expireNever, function() use($page){
	// code should be the same as the one that preloads the cache
	$content  = $page->title . "<br>";
	$content .= $page->body; 
	return $content;
});

 

[fbg13]

I forgot to add an expiration time.

I updated the code so that the cache never expires.

[fbg13]

The module where i generate the cache is autoloading and whenever i restart my pc and access a page that should be cached, and it is cached as i can see the entry in the caches table, the caching functions still executes.

If I refresh the page, it loads fast, 0.5 seconds compared to 13 seconds.

If I open the page in another browser the same happens, first page access doesn't load the cache, but creates it again, even though it's in the database.

Is this a bug or am i missing something?

[kongondo]

I assume you are talking about the frontend hence using the latter code in your example. According to the docs (see this example as well) on $cache->get(), it doesn't say whether a WireCache::expire* constant can be used in that combined get and save of cache, unlike in $cache->save() docs where it is explicit that those constants are allowed. Just guessing here, maybe try it like in the $cache->get() docs? i.e. passing null instead of a constant:

$cache->get("cacheName:".$page->id, null, function() use($page){
	// code should be the same as the one that preloads the cache
	$content  = $page->title . "<br>";
	$content .= $page->body; 
	return $content;
});

Edit:

You can also see the differences in the code here (get) and here (save). save() accepts constants whereas get() doesn't seem to.

Edit 2:

I am also wondering whether in the template file you needed an explicit WireCache:expireNever rather than $cache::expireNever?

Edited January 24, 2017 by kongondo

[fbg13]

I changed the code in the template to only $cache->get("cacheName"); and left the cache generation to the hook for easier debugging.

Also I changed the constant to null and opened the page in a new browser, with the same result.

Will test it a little more, but i can't restart my pc right now.

[fbg13]

With null as expiration, after a restart, it still doesn't get the cache, but when opening the page in another browser (after it was loaded in another browser) it gets it on the first load. Same with no expiration or an integer.

And I forgot to ask, but why is the code inside the hook executed?

[kongondo]

Looking at your module code again, I notice this:

// @kongondo note: here you are deleting the cache, meaning...
$cache->delete("cacheName:" . $page->id);
// @kongondo note:...that here we don't have that cache and one will be created afresh
$cache->get("cacheName:" . $page->id, $cache::expireNever, function() use($page){
	// code you want to cache
	$content  = $page->title . "<br>";
	$content .= $page->body; 
	return $content;
});

The code inside the Hook is executed because by that point, you have no cache; you have deleted it. So $cache->get() doesn't get the cache and one is created afresh.

It seems to me that a Pages::saveReady is happening when you load your pages and that is triggering the cache to be deleted and recreated? But it doesn't make sense since when you reload, your page is reloaded from the cache. Are you sure about that? Have you checked the timestamps? Maybe confirm your workflow. Are pages being created via the API when you visit some page in the frontend? 

Edited January 24, 2017 by kongondo
more info

[fbg13]

19 minutes ago, kongondo said:

Are pages being created via the API when you visit some page in the frontend? 

I'm so stupid .

I am saving the same page, I have a views field that gets incremented once per session.

[kongondo]

...mystery solved . 

Edit:

Your OP stated that you needed the Hook to run when a new page is added. Why not Hook into that instead? i.e. 'Pages::added'

Edited January 24, 2017 by kongondo
suggestion

[fbg13]

I think Pages::added might fit better.

Thanks.