mirrors/arti.git/crates/tor-config/src/lib.rs, branch arti-v0.3.0

list_builder: Use Educe to derive Default

2022-05-04T16:18:05Z

This allows us to use this with an item builder type which doesn't impl Default. (Obviously this only makes sense for items which aren't actually builders.)

Change builder list API

2022-05-04T12:50:10Z

The new API is (roughly) as discussed in https://gitlab.torproject.org/tpo/core/arti/-/issues/451 This is quite a large commit and it is not convenient to split it up. It contains the following changes: * Redo the list builder and accessor macros implemnetation, including docs and tests. * Change uses of define_list_config_builder. In each case: - Move the docs about the default value to the containing field. - Remove the other docs (which were just recapitulations, and are now not needed since the ListBuilder is no longer public). - Rewmove or replace `pub` in the define_list_builder_helper call, so that the builder is no longer public. - Change the main macro call site to use define_list_builder_helper. - Add a call to define_list_builder_accessors. * Make the module `list_builder` pub so that we have somewhere to put the overview documentation. * Consequential changes: - Change `outer.inner().replace(X)` to `outer.set_inner(X)` - Consequential changes to imports (`use` statements).

Add dependency on paste crate

2022-05-04T12:48:30Z

The list accessor macro is going to want this.

list_builder: Use $crate namespaced imports

2022-04-25T17:23:02Z

I don't think we need to bother with things in the prelude, but doing it for serde and ConfigBuildError seems nice. Noticed while writing a test case.

Rename macro_first_nonempty (from macro_coalesce_args)

2022-04-25T17:15:25Z

As per https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/471#note_2798026

config list-builder: Allow overriding the per-item build method

2022-04-25T16:04:23Z

This will be useful especially for simple lists where the entry doesn't need a separate builder type.

Introduce define_list_config_builder macro

2022-04-25T11:41:00Z

This replaces two almost-identical sets of structs and impls. More are on the way, as per https://gitlab.torproject.org/tpo/core/arti/-/issues/447

Merge branch 'clippy-allow-arc-clone' into 'main'

2022-03-01T20:38:05Z

Disable clippy::clone_on_ref_ptr See merge request tpo/core/arti!352

Add warnings about configuration stability.

2022-02-28T19:25:24Z

Disable clippy::clone_on_ref_ptr

2022-02-24T18:15:44Z

This lint is IMO inherently ill-conceived. I have looked for the reasons why this might be thought to be a good idea and there were basically two (and they are sort of contradictory): I. "Calling ‘.clone()` on an Rc, Arc, or Weak can obscure the fact that only the pointer is being cloned, not the underlying data." This is the wording from https://rust-lang.github.io/rust-clippy/v0.0.212/#clone_on_ref_ptr It is a bit terse; we are left to infer why it is a bad idea to obscure this fact. It seems to me that if it is bad to obscure some fact, that must be because the fact is a hazard. But why would it be a hazard to not copy the underlying data ? In other languages, faliing to copy the underlying data is a serious correctness hazard. There is a whose class of bugs where things were not copied, and then mutated and/or reused in multiple places in ways that were not what the programmer intended. In my experience, this is a very common bug when writing Python and Javascript. I'm told it's common in golang too. But in Rust this bug is much much harder to write. The data inside an Arc is immutable. To have this bug you'd have use interior mutability - ie mess around with Mutex or RefCell. That provides a good barrier to these kind of accidents. II. "The reason for writing Rc::clone and Arc::clone [is] to make it clear that only the pointer is being cloned, as opposed to the underlying data. The former is always fast, while the latter can be very expensive depending on what is being cloned." This is the reasoning found here https://github.com/rust-lang/rust-clippy/issues/2048 This is saying that *not* using Arc::clone is hazardous. Specifically, that a deep clone is a performance hazard. But for this argument, the lint is precisely backwards. It's linting the "good" case and asking for it to be written in a more explicit way; while the supposedly bad case can be written conveniently. Also, many objects (in our codebase, and in all the libraries we use) that are Clone are in fact simply handles. They contain Arc(s) (or similar) and are cheap to clone. Indeed, that is the usual case. It does not make sense to distinguish in the syntax we use to clone such a handle, whether the handle is a transparent Arc, or an opaque struct containing one or more other handles. Forcing Arc::clone to be written as such makes for code churn when a type is changed from Arc to Something: Clone, or vice versa.