class ActiveSupport::Cache::FileStore

cache.increment("baz") # => 6
cache.write("baz", 5)

To set a specific value, call #write:

cache.increment("bar", 100) # => 100
cache.increment("foo") # => 1

If the key is unset, it starts from +0+:

Increment a cached integer value. Returns the updated value.

def increment(name, amount = 1, options = nil)
  modify_value(name, amount, options)
end