README.md

zcaffeine: ZIO-friendly Caffeine wrapper

zcaffeine is a ZIO-friendly wrapper for the Caffeine cache library.

• Built for ZIO 2
• Available for Scala 2.13 and Scala 3

Setup

Add the library to your dependencies:

libraryDependencies += "com.stuart" %% "zcaffeine" % "1.0.0-M1"

Snapshots are also published on Sonatype’s snapshots repository.

Usage

The ZCaffeine object is the entrypoint for configuring your cache, by using either:

• A CaffeineSpec, either in its string representation or already loaded
• An unconfigured builder

Please note that setting that can be configured by a CaffeineSpec can also be configured from the builder, with the builder supporting more options:

• Setting removal and/or evictions listeners
• Dynamically setting the expiration of cache entries based on the key & value
• Enabling scheduling of cache maintenance (rather than running maintenance on cache operations)
• Compute a cache entry weight dynamically, based on the key & value

After configuration, the cache can be constructed through either:

• build(): builds a "manually operated" Cache which requires the use of get(key, mappingFunction)/getAll(keys, mappingFunction)/put(key,value) to load or replace values in the cache
• build(loadOne,loadAll,reloadOne): builds an "automated" LoadingCache cache which offers, along with the other methods from Cache, get(key)/getAll(keys)/refresh/refreshAll that defers to loadOne/loadAll,reloadAll to compute the cache entries

Note: loadAll and reloadOne are optional: both defer to loadOne if missing, but they can set if the behavior should differ (eg. parallel computation in loadAll)

Examples

Building a cache

// Configure a cache
val zcaffeine = ZCaffeine[Any, String, String]().map(
    _.initialCapacity(InitialCapacity(1))
      .maximumSize(MaxSize(10))
      .enableScheduling()
      .recordStats()
      .expireAfter(
        afterCreate = (key, _, _) => key.length.hour,
        afterUpdate = (key, _, _, _) => key.length.minutes,
        afterRead = (_, _, _, _) => Duration.Infinity
      )
  )
  
val getTime = ZIO.clockWith(_.instant)

// Create a Cache 
val cache = zcaffeine.flatMap(_.build())

// Create a LoadingCache
val loadingCache = zcaffeine.flatMap(
    _.build(
      loadOne = key => getTime.map(time => s"one::$key:$time"),
      loadAll = Some(keys => getTime.map(time => keys.map(key => (key, s"all::$key:$time")).toMap)),
      reloadOne = Some((key, oldValue) => getTime.map(time => s"reload::$key:$oldValue-->$time"))
    )
  )  

Using a cache

You can also find additional examples from zcaffeine’s tests.

/**********************************************/
/*               Using a Cache                */
/* Supposing cache = Cache[Any,String,String] */
/**********************************************/


// get or compute
cache.get("key")
// get all or compute all
cache.getAll("key1","key2"))(keys => ZIO.succeed(keys.map(key => (key, key + key)).toMap))
// get only if cached
cache.getIfPresent("key3")
// insert or replace
cache.put("key", ZIO.succeed("value1"))
// invalidate one
cache.invalidate("key")
// invalidate all
cache.invalidateAll
// invalidate all specified keys
cache.invalidateAll("key1","key2")


/*****************************************************/
/*               Using a LoadingCache                */
/* Supposing cache = LoadingCache[Any,String,String] */
/*****************************************************/

// get or compute using the functions set while building the cache
cache.get("key1")
// get all or compute all using the functions set while building the cache
cache.getAll(Set("key1","key2"))
// refresh using the functions set while building the cache and get
cache.refresh("key1")
// refresh all using the functions set while building the cache and get all
cache.refreshAll("key1","key2")

License

This project is published under the Apache 2.0 license.