We have a headless Drupal site that is exposing an API using JSON:API. One of the resources we're exposing is a content type that has a calculated/computed field inside that generates a time-limited link. The link is only valid for 120 seconds, but it seems that JSON:API wants to cache responses containing the field data for significantly longer.
Ideally, we don't want to completely turn off caching for these nodes, since they do get requested very frequently. Instead, we just want to limit caching to about 60 seconds. So, \Drupal::service('page_cache_kill_switch')->trigger() is not an ideal solution.
I've looked into altering the cache-ability of the response on the way out via an EventSubscriber on KernelEvents::RESPONSE but that only affects the top level of processing. As in, JSON:API caches all the pieces of the response (the "normalizations") separately, for maximum cache efficiency, so even though the response isn't served from cache, the JSON:API version of each node is.
I've also tried using service injection to wrap JSON:API's normalizers so that I can adjust the cache max age. It looks like I would need to do this at the field normalization level, but the JSON:API module discourages this by throwing a LogicException with an error of JSON:API does not allow adding more normalizers!.
So, after a lot of struggling with this, the solution is surprisingly simple -- instead of manipulating caching at the response level or the JSON:API level, manipulate it at the entity level!
This worked:
/**
* Implements hook_ENTITY_TYPE_load() for nodes.
*/
function my_module_node_load(array $entities) {
foreach ($entities as $entity) {
assert($entity instanceof NodeInterface);
if ($entity->bundle() === 'my_content_type') {
// Cache "my_content_type" entities for up to 60 seconds.
$entity->addCacheableDependency(
(new CacheableMetadata())->setCacheMaxAge(60)
);
}
}
}
As a bonus, this uses core's normal caching mechanism; so, these nodes will only be cached for up to 60 secs even when being displayed on admin pages for us.
Related
I have a use-case where I need to ensure that the data is loaded to near cache, before working with it. I am using Hazelcast as Cache Manager provider. I do store data in near cache in OBJECT in-memory-format, and do cache local entries. On application start up I do warm cache by calling service cached method:
#Override
public void onApplicationEvent(final ApplicationReadyEvent applicationReadyEvent) {
applicationReadyEvent.getApplicationContext().getBean(MyService.class).myCachedMethod(); //1 warm cahce
applicationReadyEvent.getApplicationContext().getBean(MyService.class).myCachedMethod(); //2 warm near cache here
MyData myData = applicationReadyEvent.getApplicationContext().getBean(MyService.class).myCachedMethod(); // 3 warm near cache here
//4
//work with data from near cache here
myDtata.doStufff();
}
After it I do call same method several times, to load data into near cache. Issue is that some times near cache is not loaded by the time I try to work with method data. It looks like Near Cache is loaded asynchronously, and I keep receiving data not from near cache at step 4. So my question is - is there any way to make NearCache preload possible, or to ensure that at particular point NearCache is populated? Even if that mean to wait for some time for it to get populated, before using. Adding Thread.sleep() does the trick for me, but this is by no means way to go. Hazelcast version is 3.11.4
Any help appreciated.
You can preload the Near Cache using the <preloader> configuration element. See the following example config similar to one from the Reference Manual:
<near-cache name="myDataStructure">
<in-memory-format>OBJECT</in-memory-format>
<preloader enabled="true"
directory="nearcache-example"
store-initial-delay-seconds="600"
store-interval-seconds="600"/>
</near-cache>
I'm working on a simple script in a custom theme in Drupal 7 that is supposed to just rotate through different background image each time a user loads the page. This is my code in [view].tpl.php that picks which image to use.
$img_index = (!isset($_SESSION["img_index"]) || is_null($_SESSION["img_index"])) ? 1 : $_SESSION["img_index"] + 1;
if ($img_index > 2) {
$img_index = 0;
}
$_SESSION["img_index"] = $img_index;
Pretty simple stuff, and it works fine as long as Drupal starts up a session. However, if I delete my session cookie, then always shows the same image, a session is never started.
I'm assuming that since this code is in the view file that the view code is being cached for anonymous users and hence the session is never started, but I can't figure out how to otherwise do what I want.
Don't mess with session like /u/maiznieks mentioned on Reddit. It's going to affect performance.
I've had to do something similar in the past and went with an approach like /u/maiznieks mentions. It's something like this,
Return all the URLs in an array via JS on Drupal.settings.
Check if a cookie is set.
If it's not, set it and set it's value to 0.
If it's set, get the value, increase the value by one, save it to the cookie.
With that value, now you have an index.
Check if image[index] exists
If it does, show that to the user.
If it doesn't, reset index to 0 and show that. Save 0 to the cookie.
You keep caching. You keep showing the user new images on every page load.
You could set your current view to do a random sort every 5 mins. You would then only have to update the logic above to replace that image. That way you can keep something similar working for users with no JS but still keep this functionality for the rest.
You can replace cookies above with HTML5 local storage if you'd like.
#hobberwickey, I will suggest to create a custom module and implement hook_boot() in module. As per drupal bootstrap process session layer will call after cache layer everytime. hook_boot can be called in cache pages and before bootstrap process also. You can take more information here.
I call 2 locations. From an xml file I get the longtitude and the langtitude of a location. First the closest cafe, then the closest school.
$.get('https://maps.googleapis.com/maps/api/place/nearbysearch/xml?
location='+home_latitude+','+home_longtitude+'&rankby=distance&types=cafe&sensor=false&key=X',function(xml)
{
verander($(xml).find("result:first").find("geometry:first").find("location:first").find("lat").text(),$(xml).find("result:first").find("geometry:first").find("location:first").find("lng").text());
}
);
$.get('https://maps.googleapis.com/maps/api/place/nearbysearch/xml?
location='+home_latitude+','+home_longtitude+'&rankby=distance&types=school&sensor=false&key=X',function(xml)
{
verander($(xml).find("result:first").find("geometry:first").find("location:first").find("lat").text(),$(xml).find("result:first").find("geometry:first").find("location:first").find("lng").text());
}
);
But as you can see, I do the function verander(latitude,longtitude) twice.
function verander(google_lat, google_lng)
{
var bryantPark = new google.maps.LatLng(google_lat, google_lng);
var panoramaOptions =
{
position:bryantPark,
pov:
{
heading: 185,
pitch:0,
zoom:1,
},
panControl : false,
streetViewControl : false,
mapTypeControl: false,
overviewMapControl: false ,
linksControl: false,
addressControl:false,
zoomControl : false,
}
map = new google.maps.StreetViewPanorama(document.getElementById("map_canvas"), panoramaOptions);
map.setVisible(true);
}
Would it be possible to push these 2 locations in only one request(perhaps via an array)? I know it sounds silly but I really want to know if their isn't a backdoor to reduce these google maps requests.
FTR: This is what a request is for Google:
What constitutes a 'map load' in the context of the usage limits that apply to the Maps API? A single map load occurs when:
a. a map is displayed using the Maps JavaScript API (V2 or V3) when loaded by a web page or application;
b. a Street View panorama is displayed using the Maps JavaScript API (V2 or V3) by a web page or application that has not also displayed a map;
c. a SWF that loads the Maps API for Flash is loaded by a web page or application;
d. a single request is made for a map image from the Static Maps API.
e. a single request is made for a panorama image from the Street View Image API.
So I'm afraid it isn't possible, but hey, suggestions are always welcome!
Your calling places api twice and loading streetview twice. So that's four calls but I think they only count those two streetviews as once if your loading it on one page. And also your places calls will be client side so they won't count towards your limits.
But to answer your question there's no loop hole to get around the double load since you want to show the users two streetviews.
What I would do is not load anything until the client asks. Instead have a couple of call to action type buttons like <button onclick="loadStreetView('cafe')">Click here to see Nearby Cafe</button> and when clicked they will call the nearby search and load the streetview. And since it is only on client request your page loads will never increment the usage counts like when your site get's crawled by search engines.
More on those usage limits
The Google Places API has different usages then the maps. https://developers.google.com/places/policies#usage_limits
Users with an API key are allowed 1 000 requests per 24 hour period
Users who have verified their identity through the APIs console are allowed 100 000 requests per 24 hour period. A credit card is required for verification, by enabling billing in the console. We ask for your credit card purely to validate your identity. Your card will not be charged for use of the Places API.
100,000 requests a day if you verify yourself. That's pretty decent.
As for Google Maps, https://developers.google.com/maps/faq#usagelimits
You get 25,000 map loads per day and it says.
In order to accommodate sites that experience short term spikes in usage, the usage limits will only take effect for a given site once that site has exceeded the limits for more than 90 consecutive days.
So if you go over a bit not and then it seems like they won't mind.
p.s. you have an extra comma after zoom:1 and zoomControl : false and they shouldn't be there. Will cause errors in some browsers like IE. You also are missing a semicolon after var panoramaOptions = { ... } and before map = new
I'm trying to make an ajax autocomplete search box that of course uses SQL, min 3 characters, and have a SQL view of relevant fields already set up and indexed in the db. The CPU still spikes when searching, which I expected as it's running a query for every character. I want to use Zend shm cache to speed up results and reduce CPU usage. The results are stored in an array which is to be cached like this:
while($row = db2_fetch_row($stmt)) {
$fSearch[trim($row[0]).trim($row[1])] = array(/*array built here*/);
}
if (zend_shm_cache_store('fSearch', $fSearch, 10 * 60) === false) {
error_log('Failed to store search cache!');
}
Of course there's actual data inside the array instead of comments, I just shortened the code for simplicity. Rows 0&1 form the PK, and this has tested to be working properly. It's the zend_shm_cache_store that fails because the error log gets flooded with 'Failed to store search cache!'. I read that zend_shm_cache_store can store any array that can be serialized - how can I tell if my data is serialized or can be serialized? Are there any other potential causes? I did make a test page that only stored a string and that was successful, so I know caching is on.
Solved: cache size was too small for array - increased cache size and it worked fine. Sorry for the trouble.
Using the devel module I can see a lot of calls to cache_get() and cache_set(). After how long does a cached value need to be refreshed? Does the cache get invalidated every few minutes?
The module that is using cache_set sets the expiration in the call. Some things have explicit durations, others have permanent or semi-permanent lifetimes, based on the situation.
Caches get explicitly cleared when you invoke the method through the admin interface (or drush), or otherwise through the use of drupal_flush_all_caches or cache_clear_all.
Lately, I have been using a hook_cron to clear certain cache tables each night.
EDIT to answer comment:
To see which cache, I usually put this in a separate script somewhere:
require_once './includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
header("Content-Type: text/plain; encoding=utf-8");
$user = user_load(1);
print "Modules implementing hook_cron:\n" . implode("\n", module_implements('cron'));
To see expirations, examine the various cache tables in the database and look at the expire column. Modules can set expirations on each individual call to cache_set, so it can vary entry by entry.