View Source ExKits.Cache.LRU (ex_kits v0.2.7)
This modules implements a simple LRU cache, using 2 ets tables for it.
For using it, you need to start it:
iex> LRU.start_link(:my_cache, 1000)Or add it to your supervisor tree, like: worker(LRU, [:my_cache, 1000])
Using
iex> LRU.start_link(:my_cache, 1000)
{:ok, #PID<0.60.0>}
iex> LRU.put(:my_cache, "id", "value")
:ok
iex> LRU.get(:my_cache, "id", touch = false)
"value"To take some action when old keys are evicted from the cache when it is full,
you can pass an :evict_fn option to LRU.start_link/3. This is
helpful for cleaning up processes that depend on values in the cache, or
logging, or instrumentation of cache evictions etc.
iex> evict = fn(key,value) -> IO.inspect("#{key}=#{value} evicted") end
iex> LRU.start_link(:my_cache, 10, evict_fn: evict)
{:ok, #PID<0.60.0>}Design
First ets table save the key values pairs, the second save order of inserted elements.
Summary
Functions
Removes the entry stored under the given key from cache.
Returns the value associated with key in cache. If cache does not contain key,
returns nil. touch defines, if the order in LRU should be actualized.
Stores the given value under key in cache. If cache already has key, the stored
value is replaced by the new one. This updates the order of LRU cache.
Selects and returns the first value in the cache that matches the given condition.
Creates an LRU of the given size as part of a supervision tree with a registered name
Updates a value in cache. If key is not present in cache then nothing is done.
touch defines, if the order in LRU should be actualized. The function assumes, that
the element exists in a cache.
Types
Functions
@spec delete(atom(), any(), non_neg_integer()) :: :ok
Removes the entry stored under the given key from cache.
@spec get(atom(), any(), boolean(), non_neg_integer()) :: any()
Returns the value associated with key in cache. If cache does not contain key,
returns nil. touch defines, if the order in LRU should be actualized.
@spec put(atom(), any(), any(), non_neg_integer()) :: :ok
Stores the given value under key in cache. If cache already has key, the stored
value is replaced by the new one. This updates the order of LRU cache.
@spec select(atom(), (any() -> boolean()), non_neg_integer()) :: any()
Selects and returns the first value in the cache that matches the given condition.
Examples
iex> LRU.select(:my_cache, fn value -> value > 10 end)
15Parameters
name- The name of the cache.match_fun- A function that takes a value and returns a boolean indicating whether it matches the condition.timeout(optional) - The timeout value in milliseconds for the operation. Defaults to 5000.
Returns
The first value in the cache that matches the given condition, or nil if no match is found.
@spec start_link(atom(), non_neg_integer(), Keyword.t()) :: Agent.on_start()
Creates an LRU of the given size as part of a supervision tree with a registered name
Options
:evict_fn- function that accepts (key, value) and takes some action when keys are evicted when the cache is full.
@spec update(atom(), any(), any(), boolean(), non_neg_integer()) :: :ok
Updates a value in cache. If key is not present in cache then nothing is done.
touch defines, if the order in LRU should be actualized. The function assumes, that
the element exists in a cache.