Does ristretto fires event when ttl expires

smartaquarius10 · January 27, 2021, 9:17pm

Team,

I’m making an app where I have to save data in db and ristretto as well. Does ristretto fires any event on ttl expiration of an object. It would be easier to manage the db in parallel.

Especially in oauth servers this is needed.

@mrjn, @ibrahim. I would be grateful if you can suggest here.

dmai · January 27, 2021, 9:24pm

You can set a func for OnEvict which gets called every time a cached key gets evicted (like when a TTL expires). GitHub - dgraph-io/ristretto: A high performance memory-bound Go cache

smartaquarius10 · January 28, 2021, 7:18pm

Oops. sorry I just missed that. Thanks a lot for help.

Sorry for being little lazy but just a quick question, consider I save string type key values in ristretto
key=“Name”
Value=“Daniel”
Cost=1

As per this definition, func(hashes [2]uint64, value interface{}, cost int64), what will be the value of these parameters:

hashes array and value

ibrahim · January 29, 2021, 10:11am

@smartaquarius10 looks like our readme is out of date. You’ll have to set the OnEvict function which accepts an *ristretto.Item

github.com

dgraph-io/ristretto/blob/b1486d8516f2a911714d62a50c32b9a0ce5d0287/cache.go#L113-L115


	// OnEvict is called for every eviction and passes the hashed key, value,
	// and cost to the function.
	OnEvict func(item *Item)

See this for an example of how to use it

github.com

dgraph-io/ristretto/blob/b1486d8516f2a911714d62a50c32b9a0ce5d0287/cache_test.go#L220-L233


	c, err := NewCache(&Config{
		NumCounters:        100,
		MaxCost:            10,
		BufferItems:        64,
		IgnoreInternalCost: true,
		Cost: func(value interface{}) int64 {
			return int64(value.(int))
		},
		OnEvict: func(item *Item) {
			m.Lock()
			defer m.Unlock()
			evicted[item.Key] = struct{}{}
		},
	})

smartaquarius10 · February 2, 2021, 7:09pm

Hey @ibrahim,

Thanks a lot for sharing. This one what I wanted so that I can remove the same value from my actual storage DB.

Thank you

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Does ristretto fires event when ttl expires

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