Cache Hash

A simple key value store where pairs can expire after a set interval

Installation

Add this to your application's shard.yml:

dependencies:
  cache_hash:
    github: samueleaton/cache-hash

Usage Example

require "cache_hash"

cache_hash = CacheHash(String).new(2.seconds)

cache_hash.set "city1", "Seattle"
sleep 1 # one second elapsed

cache_hash.set "city2", "Hong Kong"
sleep 1 # two seconds elapsed

cache_hash.get "city1" #=> nil
cache_hash.get "city2" #=> "Hong Kong"

API

CacheHash(V)

Defines the type(s) for the values.

Example

CacheHash(String).new(1.minute)

.new(cache_time_span : Time::Span)

Creates a new instance of CacheHash and sets the cache interval.

.set(key : String, value : V)

Adds a key/value pair to the hash, where V is the type(s) defined at CacheHash(V), and saves the time of the action.

.get(key : String) : V | Nil

Returns the value for the the associated key. If the pair is stale (expired) or does not exists, it returns nil. If it exists but is expired, it is deleted before returning nil.

.purge

Removes all key/value pairs from the hash.

.purge_stale

Removes all stale key/value pairs from the hash.

.set_purge_interval(interval : Time::Span, stale_only : Bool = true)

Sets an interval where key/value pairs will automatically be purged.

Example:

cache_hash = CacheHash(String).new(1.minute)
cache_hash.set_purge_interval(10.minutes) # stale_only defaults to true

cache_hash = CacheHash(String).new(1.minute)
cache_hash.set_purge_interval(10.minutes, stale_only: false) # deletes all values, not just stale ones

.keys() : Array(String)

Runs purge_stale and returns an array of all the the non-stale keys.

.fresh?(key : String) : Bool

Returns true if the key/value pair exists and is not stale. If the pair is stale (expired) or does not exists, it returns false. If it exists but is expired, it is deleted before returning false.

.time(key : String) : Time

Returns the time the key/value pair was cached. If the pair is stale (expired) or does not exists, it returns nil. If it exists but is expired, it is deleted before returning nil.

.refresh(key : String) : V | Nil

Refreshes the time for the key/value pair and returns the hash value if successful, otherwise returns nil.

Contributing

1. Fork it ( https://github.com/samueleaton/cache_hash/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Sam Eaton - creator, maintainer