Finch adapter

[teamon]

A tiny adapter for https://github.com/keathley/finch - a HTTP client with built-in pooling.
Instead of building own mint+pooling adapter we could nicely integrate with Finch.

Something like this:

defmodule Tesla.Adapter.Finch do
  @behaviour Tesla.Adapter

  def call(env, opts) do
    opts = Tesla.Adapter.opts(env, opts)    
    case Finch.request(name, env.method, env.url, env.headers, env.body, opts) do
      {:ok, ...} ->  # convert finch's response to %Tesla.Env{}
      {:error, ...} -> # ensure proper error handling
    end
  end
end

[chulkilee]

Note

Pools will be started for each configured {scheme, host, port} when Finch is started. For any unconfigured {scheme, host, port}, the pool will be started the first time it is requested. Note pools are not automatically terminated if they are unused, so Finch is best suited when you are requesting a known list of static hosts.

So I believe we need a way to trigger pruning unused pools (or a way to do it) from the library.

[c-manakov]

Hey. I'm trying my hand at implementing this adapter and I'm not sure what to do with multipart and streaming. Finch's API doesn't seem to support it even though Mint does.

[keathley]

@Monyk015 There is an open issue on finch to support a streaming API: https://github.com/keathley/finch/issues/58

[keathley]

@Monyk015 streaming support has been added to finch: https://github.com/keathley/finch/pull/59