I am using Laravel 5.4, with Predis and the latest Redis (or Redis for Windows).
The keys are being saved without issue. So, I doubt it's a configuration issue.
The problem is that they are not expiring. The key is reused until it expires...similar to how a session works.
I create the key once, if it does not exist. In that same logic I then set the expiration time.
In the Controller, I have
use Illuminate\Support\Facades\Redis;
In one of the functions, Get the connection instance:
$redis = Redis::connection();
Before I create the key, I check the existence (simplified) then create and set expiration.
if(!$redis->exists($some_unique_key))
{
//set the key
$redis->set($some_unique_key, 'Some Value'));
//set the expiration
//I understand this means expire in 60s.
$redis->expire($some_unique_key,60);
}
Why could it not be expiring the key?
As I mentioned, everything else works. I see the key updating without issue if I monitor, and can query it.
For the record, I have read:
There is nothing on expiration on the Laravel documentation:
UPDATE 1
Investigating a possible cause where setting(updating) the key resets the expiry
UPDATE 2
Used @for_thestack's reasoning (in REDIS commands) to come up with the solution. See my answer with the code. Feel free to upvote @for_thestack :)
Some other process might call SET to update the key-value pair, in this case, the expiration will be removed.
// set expiration
EXPIRE key expiration_in_seconds
// update key-value pair with no expiration
SET key new_value
// now, expiration has been reset, and the key won't be expired any more
In order to keep the expiration, when you update the key-value pair, you should call SET with expiration parameters.
// get TTL, i.e. how much time left before the key will be expired
TTL key
// update with expiration parameter
SET key new_value EX ttl
You can wrap the two commands into a lua script to make it atomic. And you also need to take care of the case that key doesn't exist when you call TTL. See the document for details.