The sane_defaults() call is now the same as you get from a default
builder: by convention, we just call that method Default::default().
The with_directories() constructor makes more sense as a constructor
for the TorClientConfigBuilder than for TorClientConfig.
The new CircMgr::build_circuits_preemptively function actually causes
preemptive circuits to be built; it gets called from arti-client, like
the other daemon tasks the CircMgr has.
I'm still not 100% sure this is the right move: should we encourage
app developers to always pick their own directories? Or should we
make it easy for them to use, well, `sane_defaults`?
This patch takes the second approach.
This patch makes sure that for every* config type we have, the defaults
you get from a Builder match those you get from Serde, and that both
match the value that you get from arti_defaults.toml. Later down the
line I'll be adding some tests to keep these in sync.
* StorageConfig still has no defaults of its own, since we aren't so
sure we want other applications to use Arti's directories by default.
Since these shell-variables are hardwired to use org.torproject.Arti as
the program name, it isn't appropriate to call them "app-specific".
If we someday reinstate APP_FOO, it should be based on a user-provided
application name.
In order to handle explicitly specified path buffers directly, we now
let CfgPath be either a string (that gets expanded) or a PathBuf
(that doesn't).
This simplifies TorClientConfig::with_directories()
Now every section that the two configuration objects share has the
same type and name. This should help us in documenting our configuration
in a way that doesn't confuse people.
There is still lots of API work to go.
To do this at all neatly, I had to split out `tor-config` from
`arti-config` again, and putting the lower level stuff (paths,
builder errors) into tor-config. I also changed our use of
derive_builder to always use a common error type, to avoid
error type proliferation.
Most of the structs in `arti-client` have example code now, to give a
clearer idea of how they're used.
Annoyingly, a lot of the types exposed in `arti-client` are actually
re-exports, which makes documentation a bit harder: example code that
references other parts of `arti-client` can't actually be run as a
doctest, since the crate it's in is a dependency of `arti-client`.
We might be able to fix this in future by doing the documentation in
`arti-client` itself, but rustdoc seems to have some weird behaviours
there that need to be investigated first (for example, it seems to merge
the re-export and original documentation, and also put the re-export
documentation on the `impl` block for some reason).
For now, though, this commit just writes the docs from the point of view
of an `arti-client` consumer, removing notes specific to the crate in
which they're defined. It's not ideal, but at least the end user
experience is decent.