Understanding compile time dependencies (xref)

teamon · October 19, 2017, 9:14am

I’ve been trying to understand compile-time dependencies between files/modules.
I know the basics, like when module is references inside macro it will be linked as compile-time dependency etc.
However, I can’t figure out the dependency graph for tesla

Here is the output of mix xref graph:

⌘ ~/code/tesla (master) λ elixir --version
Erlang/OTP 20 [erts-9.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

Elixir 1.6.0-dev (5b9a5ff) (compiled with OTP 20)
⌘ ~/code/tesla (master) λ mix xref graph
lib/tesla.ex
├── lib/tesla/adapter/hackney.ex (compile)
│   ├── lib/tesla/multipart.ex (compile)
│   └── lib/tesla.ex
├── lib/tesla/adapter/httpc.ex (compile)
│   ├── lib/tesla/adapter/shared.ex (compile)
│   ├── lib/tesla/multipart.ex (compile)
│   └── lib/tesla.ex
├── lib/tesla/adapter/ibrowse.ex (compile)
│   ├── lib/tesla/adapter/shared.ex (compile)
│   ├── lib/tesla/multipart.ex (compile)
│   └── lib/tesla.ex
├── lib/tesla/middleware/core.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/basic_auth.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/compression.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/logger.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/decode_rels.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/digest_auth.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/follow_redirects.ex (compile)
│   ├── lib/tesla.ex (compile)
├── lib/tesla/middleware/form_urlencoded.ex (compile)
│   ├── lib/tesla.ex (compile)
│   ├── lib/tesla/multipart.ex (compile)
├── lib/tesla/middleware/fuse.ex (compile)
│   ├── lib/tesla.ex (compile)
lib/tesla/adapter/hackney.ex
lib/tesla/adapter/httpc.ex
lib/tesla/adapter/ibrowse.ex
lib/tesla/adapter/shared.ex
lib/tesla/middleware/basic_auth.ex
lib/tesla/middleware/compression.ex
lib/tesla/middleware/core.ex
lib/tesla/middleware/decode_rels.ex
lib/tesla/middleware/digest_auth.ex
lib/tesla/middleware/follow_redirects.ex
lib/tesla/middleware/form_urlencoded.ex
lib/tesla/middleware/fuse.ex
lib/tesla/middleware/json.ex
├── lib/tesla.ex (compile)
lib/tesla/middleware/logger.ex
lib/tesla/middleware/method_override.ex
├── lib/tesla.ex (compile)
lib/tesla/middleware/retry.ex
├── lib/tesla.ex (compile)
lib/tesla/middleware/timeout.ex
├── lib/tesla.ex (compile)
lib/tesla/middleware/tuples.ex
├── lib/tesla.ex (compile)
lib/tesla/mock.ex
└── lib/tesla.ex (compile)
lib/tesla/multipart.ex

What I do not get about this, is why for example lib/tesla.ex has a dependency on lib/tesla/middleware/form_urlencoded.ex but not on lib/tesla/middleware/json.ex ?

Eiji · October 19, 2017, 10:45am

@teamon: I don’t read all sources, but you could look at compile-time &Tesla.alias/1 calls. Maybe other module use this and therefore uses only one of aliased module that you asked about.

teamon · October 19, 2017, 11:07am

Not in middlewares

⌘ ~/code/tesla (master) λ grep -R alias lib                                                                                                                                                                                               130
lib/tesla/adapter/hackney.ex:    alias Tesla.Multipart
lib/tesla/adapter/httpc.ex:  alias Tesla.Multipart
lib/tesla/adapter/ibrowse.ex:    alias Tesla.Multipart
lib/tesla.ex:    middleware = Tesla.alias(middleware)
lib/tesla.ex:    adapter = Tesla.alias(adapter)
lib/tesla.ex:  @aliases [
lib/tesla.ex:  def alias(key) when is_atom(key), do: Keyword.get(@aliases, key, key)
lib/tesla.ex:  def alias(key), do: key
lib/tesla.ex:    Application.get_env(:tesla, module, [])[:adapter] |> Tesla.alias
lib/tesla.ex:    Application.get_env(:tesla, :adapter, :httpc) |> Tesla.alias

josevalim · October 19, 2017, 11:14am

It is a bug in how we are printing the data (not in how are gathering it). I have a fix in place but first I need a test.

teamon · October 19, 2017, 11:52am

Whoo

Does this apply to dot version too?

Here too some of middleware have only one compile time dependency and some have two.

josevalim · October 19, 2017, 11:58am

Yup. Both should be fixed in master though.

teamon · October 19, 2017, 12:12pm

Indeed it is:

⌘ ~/code/tesla (master) λ elixir --version
Erlang/OTP 20 [erts-9.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

Elixir 1.6.0-dev (e95f564) (compiled with OTP 19)
⌘ ~/code/tesla (master) λ mix xref graph
lib/tesla.ex
├── lib/tesla/adapter/hackney.ex (compile)
│   ├── lib/tesla.ex
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/adapter/httpc.ex (compile)
│   ├── lib/tesla.ex
│   ├── lib/tesla/adapter/shared.ex (compile)
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/adapter/ibrowse.ex (compile)
│   ├── lib/tesla.ex
│   ├── lib/tesla/adapter/shared.ex (compile)
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/middleware/basic_auth.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/compression.ex (compile)
│   ├── lib/tesla.ex (compile)
│   └── lib/tesla/middleware/core.ex
│       └── lib/tesla.ex (compile)
├── lib/tesla/middleware/core.ex (compile)
├── lib/tesla/middleware/decode_rels.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/digest_auth.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/follow_redirects.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/form_urlencoded.ex (compile)
│   ├── lib/tesla.ex (compile)
│   ├── lib/tesla/middleware/core.ex
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/middleware/fuse.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/json.ex (compile)
│   ├── lib/tesla.ex (compile)
│   ├── lib/tesla/middleware/core.ex
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/middleware/logger.ex (compile)
│   ├── lib/tesla.ex (compile)
│   └── lib/tesla/multipart.ex (compile)
├── lib/tesla/middleware/method_override.ex (compile)
│   ├── lib/tesla.ex (compile)
│   └── lib/tesla/middleware/core.ex
├── lib/tesla/middleware/retry.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/timeout.ex (compile)
│   └── lib/tesla.ex (compile)
├── lib/tesla/middleware/tuples.ex (compile)
│   └── lib/tesla.ex (compile)
└── lib/tesla/mock.ex (compile)
    └── lib/tesla.ex (compile)
lib/tesla/adapter/hackney.ex
lib/tesla/adapter/httpc.ex
lib/tesla/adapter/ibrowse.ex
lib/tesla/adapter/shared.ex
lib/tesla/middleware/basic_auth.ex
lib/tesla/middleware/compression.ex
lib/tesla/middleware/core.ex
lib/tesla/middleware/decode_rels.ex
lib/tesla/middleware/digest_auth.ex
lib/tesla/middleware/follow_redirects.ex
lib/tesla/middleware/form_urlencoded.ex
lib/tesla/middleware/fuse.ex
lib/tesla/middleware/json.ex
lib/tesla/middleware/logger.ex
lib/tesla/middleware/method_override.ex
lib/tesla/middleware/retry.ex
lib/tesla/middleware/timeout.ex
lib/tesla/middleware/tuples.ex
lib/tesla/mock.ex
lib/tesla/multipart.ex

@josevalim You are impossible, thank you!