Clarifying adapter usage vs "plain Async"

[balvig]

Sorry to use GitHub issues for a question (happy to turn this into a documentation PR if applicable!), but I'm struggling to understand the difference between using this adapter with Faraday, vs using "plain" https://github.com/socketry/async with Faraday.

The in_parallel documentation shows the following example:

Async do
  response1 = Async{adapter.get("/index")}
  response2 = Async{adapter.get("/index")}
  response3 = Async{adapter.get("/index")}
  
  puts response1.wait.body # => "Hello World"
  puts response2.wait.body # => "Hello World"
  puts response3.wait.body # => "Hello World"
end

I'm having trouble understanding how this relates to the faraday adapter and what the difference is from using just https://github.com/socketry/async?

Put differently, what is the difference between these three examples?

1. Set default_adapter to async_http

Faraday.default_adapter = :async_http

response1 = adapter.get("/index")
response2 = adapter.get("/index")

puts response1.body
puts response2.body

2. Set default_adapter to async_http + use Async block

Faraday.default_adapter = :async_http

Async do
  response1 = Async{adapter.get("/index")}
  response2 = Async{adapter.get("/index")}

  puts response1.wait.body
  puts response2.wait.body
end

3. Use regular default_adapter + use Async block

Async do
  response1 = Async{adapter.get("/index")}
  response2 = Async{adapter.get("/index")}

  puts response1.wait.body
  puts response2.wait.body
end