Current section

Files

Jump to
tesla lib tesla middleware fuse.ex
Raw

lib/tesla/middleware/fuse.ex

if Code.ensure_loaded?(:fuse) do
defmodule Tesla.Middleware.Fuse do
@behaviour Tesla.Middleware
@moduledoc """
Circuit Breaker middleware using [fuse](https://github.com/jlouis/fuse)
Remember to add `{:fuse, "~> 2.4"}` to dependencies (and `:fuse` to applications in `mix.exs`)
Also, you need to recompile tesla after adding `:fuse` dependency:
```
mix deps.clean tesla
mix deps.compile tesla
```
### Example usage
```
defmodule MyClient do
use Tesla
plug Tesla.Middleware.Fuse, opts: {{:standard, 2, 10_000}, {:reset, 60_000}}
end
```
### Options
- `:name` - fuse name (defaults to module name)
- `:opts` - fuse options (see fuse docs for reference)
"""
# options borrowed from http://blog.rokkincat.com/circuit-breakers-in-elixir/
# most probably not valid for your use case
@defaults {{:standard, 2, 10_000}, {:reset, 60_000}}
def call(env, next, opts) do
opts = opts || []
name = Keyword.get(opts, :name, env.__module__)
case :fuse.ask(name, :sync) do
:ok ->
run(env, next, name)
:blown ->
{:error, :unavailable}
{:error, :not_found} ->
:fuse.install(name, Keyword.get(opts, :opts, @defaults))
run(env, next, name)
end
end
defp run(env, next, name) do
try do
Tesla.run(env, next)
rescue
_error ->
:fuse.melt(name)
{:error, :unavailable}
end
end
end
end