CODEWITHSUNDEEP
phpsessioncachingglobal
Dave Archer
Dave Archer

Reputation: 3060

Is there a way to clear some session data from ALL sessions?

In general, I have the following scenario:

The cache is readonly, i.e customers viewing products on the site.

But there are calls like getProductIdsByCategory($categoryId) and the productIds from these results are cached too, per user, not using the global cache that I've read about.

A problem is that if someone on the admin side adds a new product and relates it to a category, then customers will not have the new productId come up in their cached getProductIdsByCategory until a new session is started.

Is there a way to clear e.g $_SESSION['x'] from ALL sessions on the server when a new product is added? I don't want to destroy all sessions because customers will then lose their logins etc.

Or should I move these cached productId searches to the global cache?

p.s am using a custom built cache, not memcached or similar.

Thanks

Upvotes: 3

Views: 4984

Answers (7)

Gihan
Gihan

Reputation: 11

<?php session_destroy(); ?> // To delete whole session
// OR
<?php unset($_SESSION['myVar']); ?>  // To delete a session myVar

Upvotes: 0

user180897
user180897

Reputation: 11

To disable all existing sessions for a particular application, simply modify your application to change the name of the session using PHP's session_name('new_session_name'). This function needs to be called before each call to session_start().

This won't actually clear the current sessions, but it renders them no longer useful for this application.

Upvotes: 1

Tam&#225;s Szelei
Tam&#225;s Szelei

Reputation: 23921

Yes, you should move it to a global cache. Sessions are not meant to be accessed globally, I hardly think it's possible.

Upvotes: 0

chaos
chaos

Reputation: 124287

By default, the session data is just serialized files somewhere in your filesystem, and it is possible to go modify all of them to remove the information in question (respecting locking so that you don't step on any currently open sessions).

I don't really recommend it, though. What I would recommend is making a method of signalling that this cached data should be refreshed, like a database-stored timestamp that gets looked at when session_start() happens, and if the cached data is older than the timestamp, the cache is flushed.

Upvotes: 5

Jani Hartikainen
Jani Hartikainen

Reputation: 43243

Unless you store sessions in a database, clearing any specific bit of data will be tricky.

I would suggest caching in files rather than user sessions. This way you achieve the same benefits, but you get total control over what is cached and when it gets cleared.

Upvotes: 1

Bassel Safadi
Bassel Safadi

Reputation: 487

to clear a session value use:

unset($_SESSION['x']);

you may loop on sessions for that

Upvotes: -2

Aiden Bell
Aiden Bell

Reputation: 28386

Sounds to be like you could do with real shared state through a caching system like memcache.

The only other way that prints to mind is have the application check for flags for dirty cache data and delete it itself, or if your cache is in a database in a parsable serialized form write an expensive script to read them all, but that will create nasty lag with requests that have already read the data.

I would go with real shared state than checking for object copies.

Upvotes: 3

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