mirrors/arti.git/crates/tor-netdir/src/lib.rs, branch arti-v0.2.0

Move fallback.rs into guardmgr.

2022-03-30T14:34:48Z

This is the logical place for it, I think: the GuardMgr's job is to pick the first hop for a circuit depending on remembered status for possible first hops. Making this change will let us streamline the code that interacts with these objects.

Make daemon tasks self-contained; introduce NetDirProvider

2022-03-30T13:26:43Z

The various background daemon tasks that `arti-client` used to spawn are now handled inside their respective crates instead, with functions provided to spawn them that return `TaskHandle`s. This required introducing a new trait, `NetDirProvider`, which steals some functionality from the `DirProvider` trait to enable `tor-circmgr` to depend on it (`tor-circmgr` is a dependency of `tor-dirmgr`, so it can't depend on `DirProvider` directly). While we're at it, we also make some of the tasks wait for events from the `NetDirProvider` instead of sleeping, slightly increasing efficiency.

netdir: Use an even smaller rep for list of microdescs

2022-03-16T15:52:47Z

Every time we want a microdescriptor, we know the index of that microdesc's corresponding routerstatus within the consensus. Therefore, we can use that index to store `Arc`s in a dense array, and not have to use a HashSet here at all.

tor-dirmgr: Remove redundant hashtable.

2022-03-16T15:33:19Z

We were using a hashtable to keep track of missing microdescriptor digests. But this information is redundant with the NetDir state, and there's now no longer any performance benefit to keeping a separate copy. Part of #386.

NetDir: Use less space in hash tables

2022-03-16T15:12:15Z

We previously kept missing-MD entries and present-MD entries all in the same HashSet, which resulted in using more slack space than we need. Now we use separate tables, so we can drop missing-MD entries as we move forward. Also, when constructing a NetDir, set its hash tables to their final capacities. This also lets us simplify some of our missing-md-listing code a lot.

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.

Change deny(clippy::all) to warn(clippy::all).

2022-02-14T14:24:06Z

Closes #338.

extend lints to include 'clippy::all'

2021-12-28T20:15:40Z

Make override_net_params take effect sooner.

2021-12-08T00:26:01Z

This is still not as soon as I'd like: a real change here will require refactoring DirMgr::notify().

Tests for new family-related functions.

2021-12-06T16:26:30Z