Ets

:ets, the Elixir way

Ets is a set of Elixir modules that wrap Erlang Term Storage (:ets). The purposes of this package is to improve the developer experience when both learning and interacting with Erlang Term Storage.

This will be accomplished by:

• Conforming to Elixir standards:
  • Two versions of all functions:
    • Main function (e.g. get returns {:ok, return}/{:error, reason} tuples.
    • Bang function (e.g. get!) returns unwrapped value or raises on :error.
  • All options specified via keyword list.
• Wrapping unhelpful ArgumentError's with appropriate error returns.
  • Avoid adding performance overhead by using try/rescue instead of pre-validation
  • On rescue, try to determine what went wrong (e.g. missing table) and return appropriate error
  • Fall back to {:error, :unknown_error} if unable to determine reason.
• Appropriate error returns/raises when encountering $end_of_table.
• Providing Elixir friendly documentation.
• Providing Ets.Set and Ets.Bag modules with appropriate function signatures and error handling.
  • Ets.Set.get returns a single item (or nil/provided default) instead of list as sets never have multiple records for a key.

Usage

Creating Ets Tables

Ets Tables can be created using the new function of the appropriate module, either Ets.Set (for ordered and unordered sets) or Ets.Bag (for duplicate or non-duplicate bags) (Ets.Bag coming soon). See module documentation for more examples and documentation.

Create Examples

iex> {:ok, set} = Set.new(ordered: true, keypos: 3, read_concurrency: true, compressed: false)
iex> Set.info!(set)[:read_concurrency]
true

# Named :ets tables via the name keyword
iex> {:ok, set} = Set.new(name: :my_ets_table)
iex> Set.info!(set)[:name]
:my_ets_table

Adding/Updating/Retrieving records

To add records to an Ets table, use put or put_new with a tuple record or a list of tuple records. put will overwrite existing records with the same key. put_new not insert if the key already exists. When passing a list of tuple records, all records are inserted in an atomic and isolated manner, but with put_new no records are inserted if at least one existing key is found.

Record Examples

iex> Set.new(ordered: true)
iex> |> Set.put!({:a, :b})
iex> |> Set.put!({:a, :c})
iex> |> Set.put!({:c, :d})
iex> |> Set.to_list!()
[{:a, :c}, {:c, :d}]

iex> Set.new(ordered: true)
iex> |> Set.put!({:a, :b})
iex> |> Set.put({:a, :c})
iex> |> Set.to_list!()
[{:a, :b}]

Current Progress

• Ets
  • All
• Ets.Set
  • Put (insert)
  • Get (lookup)
  • Delete
  • Delete All
  • First
  • Next
  • Last
  • Previous
  • Match
  • Has Key (Member)
  • Info
  • Delete
  • To List (tab2list)
  • Wrap
• Ets.Bag

Installation

Ets can be installed by adding ets to your list of dependencies in mix.exs:

def deps do
  [
    {:ets, "~> 0.3.0"}
  ]
end

Docs can be found at https://hexdocs.pm/ets.

Contributing

Contributions welcome. Specifically looking to:

• Add remainder of functions (See Erlang Docs).
• Discover and add zero-impact recovery for any additional possible :ets ArgumentErrors.