cycle-cache

# cycle-cache

A cycle-based cache for Lua.

The type maintains a cycle-count of caches, and on fetching, refreshes the
newest cache with the value if it matches. When you cycle the cache, it
rotates the caches, dropping the oldest.

## API

```lua
local CycleCache = require 'cycle-cache'
```

### `CycleCache.new(cycles?)`

Creates a new cache that will hold `cycles` cycles (defaulting to 2).

If `cycles` is less than 1, this will not cache at all.

If `cycles` is 1, then each cycle will completely empty the cache.

### `CycleCache.gc(cycles?)`

Creates a new cache that automatically cycles with each garbage collection cycle.

This does not work in Lua 5.1.

### `CycleCache:raw_get(key)`

Gets the value in the cache, or `nil` if there is none in the cache.

A found value **does not** update the cache for this method.

### `CycleCache:get(key, factory?)`

Gets the value in the cache, or `nil` if there is none in the cache. If the
value is found in an older cache cycle, it is refreshed.

If there is a factory, an absent value is automatically created and inserted
into the cache, and returned instead.

### `CycleCache:set(key, value)`

Sets the value in the cache and returns it.

If `value` is nil, clears the key from all cycles of the cache.

### `CycleCache:cycle()`

Cycle the cache, dropping all entries older than the cycle maximum.