Registry.count

You're seeing just the function count, go back to Registry module for more information.
Link to this function

count(registry)

View Source (since 1.7.0)

Specs

count(registry()) :: non_neg_integer()

Returns the number of registered keys in a registry. It runs in constant time.

Examples

In the example below we register the current process and ask for the number of keys in the registry:

iex> Registry.start_link(keys: :unique, name: Registry.UniqueCountTest)
iex> Registry.count(Registry.UniqueCountTest)
0
iex> {:ok, _} = Registry.register(Registry.UniqueCountTest, "hello", :world)
iex> {:ok, _} = Registry.register(Registry.UniqueCountTest, "world", :world)
iex> Registry.count(Registry.UniqueCountTest)
2

The same applies to duplicate registries:

iex> Registry.start_link(keys: :duplicate, name: Registry.DuplicateCountTest)
iex> Registry.count(Registry.DuplicateCountTest)
0
iex> {:ok, _} = Registry.register(Registry.DuplicateCountTest, "hello", :world)
iex> {:ok, _} = Registry.register(Registry.DuplicateCountTest, "hello", :world)
iex> Registry.count(Registry.DuplicateCountTest)
2