Gnat

A nats.io client for elixir. The goals of the project are resiliency, performance, and ease of use.

Usage

{:ok, gnat} = Gnat.start_link(%{host: '127.0.0.1', port: 4222})
# Or if the server requires TLS you can start a connection with:
# {:ok, gnat} = Gnat.start_link(%{host: '127.0.0.1', port: 4222, tls: true})

{:ok, subscription} = Gnat.sub(gnat, self(), "pawnee.*")
:ok = Gnat.pub(gnat, "pawnee.news", "Leslie Knope recalled from city council (Jammed)")
receive do
  {:msg, %{body: body, topic: "pawnee.news", reply_to: nil}} ->
    IO.puts(body)
end

Benchmarks

Part of the motivation for building this library is to get better performance. To this end I've started a bench.exs script that we can use to check our performance. As of this commit the most recent numbers from running on my macbook pro are:

	ips	average	deviation	median
parse-128	81.86 K	12.22 μs	±177.12%	11.00 μs
pub - 128	146.22 K	6.84 μs	±450.03%	6.00 μs
sub-unsub-pub16	9.06 K	110.37 μs	±68.61%	102.00 μs
req-reply-4	5.67 K	176.45 μs	±19.81%	165.00 μs

These benchmarks all show single-actor performance with a locally running gnats server. Running 32 client actors on an 8-core ubuntu server sending requests to another 8-core ubuntu server running 2 gnat subscriber actors we achieved:

• 19,920 requests/sec
• 90th % latency of 2.2ms

see details in the performance issue

Development

To run the tests the typical mix test will run all tests that have not been tagged to exclude as shown in the test_helper.exs file. There are some tests that require another server to be running. These are marked with @tag :multi_server and can be included in a test run with the following command mix test --include multi_server