Batch

Batches are processes meant to execute several functions asynchronously, collecting their return values or returning the error of the first failure (fail-fast).

Installation

Add batch to your project's dependencies in mix.exs:

def deps do
  [{:batch, "~> 0.2"}]
end

And fetch your project's dependencies:

$ mix deps.get

Usage

Let's start with an example:

batch = Batch.async([
  fn -> Blog.get_post(post_id) end,
  fn -> Blog.get_comments(post_id) end
])

{:ok, [post, comments]} = Batch.await(batch)

As shown in the example above, batches spawned with async can be awaited on by their caller process (and only their caller). They are implemented by spawning a process that sends a message to the caller once the given computation is performed. Internally, the batch process spawns a new process per function (linked and monitored by the batch process) and awaits for replies.

Successful computations are represented with the :ok atom or the {:ok, result} tuple.

batch = Batch.async([
  fn -> {:ok, 1 + 1} end,
  fn -> :ok end,
  {Enum, :fetch, [[2, 4, 6], 1]}
])

{:ok, [{:ok, 2}, :ok, {:ok, 4}]} = Batch.await(batch)

Any other value will be considered a failure. Failures and exits are reported immediately (fail-fast), shutting down all the processes.

batch = Batch.async([
  fn -> {:ok, 1 + 1} end,
  fn -> {:ok, 2 + 2} end,
  fn -> :error end
])

{:error, :error} = Batch.await(batch)

Batches can also be started as part of a supervision tree and dynamically spawned on remote nodes. We will explore all three scenarios next. Check the documentation for more information.

Documentation

Documentation is available at https://hexdocs.pm/batch

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/fertapric/batch. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

Running tests

Clone the repo and fetch its dependencies:

$ git clone https://github.com/fertapric/batch.git
$ cd batch
$ mix deps.get
$ mix test

Building docs

$ mix docs

Copyright and License

Copyright 2017 Fernando Tapia Rico

Batch source code is licensed under the MIT License.