Show existing data when opening the site locally

[Kobzol]

When you run the site locally, and open the compare.html page (which is shown by default), you will be greated with a very annoying error message (which essentially tells you that the backend has panicked, or something like that). It would be great if the default view for compare.html examined the database, and tried to show some reasonable data by default, e.g. the latest entry found in the DB and -30 days before that (same as what it does on the production web).

If there is only a single commit, it should be compared with itself (this can be useful to see absolute numbers of the benchmark metrics), to again avoid showing the error message.

[s7tya]

I'm fully supporting this. I always remember the magical period "from 2024-02-20 to 2024-02-25" while working on the compare page locally.

[s7tya]

Currently, it attempts to get commits from the past 30 days using chrono::Utc::now().date_naive() - chrono::Duration::days(30). However, the latest commit available via fetch-latest is from 2024-03-14. It cannot find any commits after 2024-05-10, which is 30 days ago from today.

rustc-perf/collector/src/lib.rs

Lines 49 to 52 in 8d37b08

	Bound::None => {
	let last_month = chrono::Utc::now().date_naive() - chrono::Duration::days(30);
	commit.is_master() && last_month <= commit.date.0.naive_utc().date()
	}

I am wondering how to solve this problem. The first idea that came to mind is to add conditions to include commits within 30 days from the latest commit here:

rustc-perf/site/src/selector.rs

Line 48 in 8d37b08

.find(|commit| bound.left_match(commit))