You can't update a GHA cache once you create it, so if we use the same cache
for each job in a matrix build, then we end up populating it for the first job
that completes, so any slower jobs don't get their dependencies cached.
On the other hand, if we create 20 500MB cache items on each build, we're going
to exhaust the cache storage as soon as we do a build. So, instead, let's just
do the caching for the main branch, and hope that other branches can still
benefit from it.
* Replace custom cancellation action with `concurrency`
* Improve step names
... so don't have three steps with the same name
* Bump version of checkout action
checkout@v2 uses an old version of nodejs, which is deprecated.
Currently, the cache of the xtask binary isn't working terribly well:
* we seem to build it on each run anyway, presumably because we don't cache any of the intermediate build
artifacts. Running the binary directly rather than indirecting via "cargo" prevents this.
* There is no sharing of the cache between the "rust" and "bindings" CI, because we use different cache keys.
This PR addresses both problems, and hopefully speeds up CI a bit as a result.
`matrix-sdk-crypto-nodejs` and `matrix-sdk-crypto-js` are no longer
default members of the Cargo virtual workspace. The Github Actions
workflows for the bindings now live in a `bindings_ci.yml` files
(ideally, it should be in a subdirectory,
`.github/workflows/bindings/ci.yml` but it doesn't work).
> [`cargo-nextest`](https://nexte.st/index.html) is a next-generation
> test runner for Rust projects.
This patch installs and uses `nextest` to run our own tests.
Comparing `cargo test` and `cargo nextest` with hyperfine provides the
following results:
```sh
$ hyperfine 'cargo test --workspace' 'cargo nextest run --workspace && cargo test --doc'
Benchmark 1: cargo test --workspace
Time (mean ± σ): 51.785 s ± 2.066 s [User: 183.471 s, System: 10.563 s]
Range (min … max): 49.151 s … 56.641 s 10 runs
Benchmark 2: cargo nextest run --workspace && cargo test --doc
Time (mean ± σ): 44.556 s ± 0.894 s [User: 192.213 s, System: 11.441 s]
Range (min … max): 43.170 s … 45.762 s 10 runs
```
Benchmark 2 is 1.16 times faster than Benchmark 1.
