Added Gantt chart

[ChrisPaulBennett]

Partially addresses #181

This is the first iteration of the Gantt chart view.
We wanted to add a few various other features (zooming, scaling of the data and pagination) but I will be going on parental leave earlier than expected. So would like to get some version out there for us to get some much needed feedback.
This also contains some small additions to the box plot.
The view itself is a full working state, just looks a bit squished when viewing a big suite.

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Applied any dependency changes to both setup.cfg (and conda-environment.yml if present).
• Tests are included (or explain why tests are not needed).
• CHANGES.md entry included if this is a change that can affect users
• Cylc-Doc pull request opened if required at cylc/cylc-doc/pull/XXXX.
• If this is a bug fix, PR should be raised against the relevant ?.?.x branch.

[ChrisPaulBennett]

That was a bit more complicated than I had envisaged. But it is now ready for review.

This branch needs changes to UI server for the query to work properly. This is currently in a pull request
cylc/cylc-uiserver#530

[MetRonnie]

Ooh, also could do with a refresh button I think

[oliver-sanders]

Nice, looking forward to this one.

Refreshing:

It could definitely do with a refresh button for now. For future work we can subscribe to the live data and have it update automatically which would be pretty cool.

Too many tasks:

We do need to protect this new view against large and or long running workflows to avoid issues. I tried running the OS35 global to see how the gantt view coped, it took a while:

But it did eventually load, although the resulting chart wasn't the most usable:

But once I used task name filtering to whittle down the number of rows, it worked rather well:

I would suggest restricting the number of tasks displayed to a configured value (maybe default ~30) and displaying a message explaining that there are too many tasks to display, please use the task filter to reduce the number. Or alternatively, doing something similar to #1510 and requiring users to manually specify the tasks they're interested in.

Too many cycles:

We have the same issue with long-running workflows where there may have been a large number of cycles. E.G. This workflow has racked up a few cycles:

Some workflows run for several months and cycle as often as 5 mins which will probably cause issues. I'm not sure how best to counter against this issue, ideas:

• Max cycle limit (i.e. show the most recent 30 cycles and display a message if there are more than 30).
• Get the UI Server to intelligently pick the time window to display and only load earlier / later cycles on request.

Simulation mode:

Cylc supports a simulation mode (e.g. cylc play --mode=simulation).
in which jobs are simulated rather than run. Simulated jobs don't add their timings to the DB which means the gantt view doesn't work with simulation mode. This is ok I think, but we might want to detect this so we can display a message explaining what's going on rather than a blank tab.

Alternatively, we could just get Cylc to stick the timings into the database? Will ask the team.

[MetRonnie]

We do need to protect this new view against large and or long running workflows to avoid issues.

How about paginating, showing the most recent tasks on the first page?

[ChrisPaulBennett]

We do need to protect this new view against large and or long running workflows to avoid issues.

How about paginating, showing the most recent tasks on the first page?

Pagination was originally going to be in this pull request. But it ended up being a fairly involved process so we thought it best to do it separately. (Actually some of the issue's in this pull request were due to the pagination efforts being removed).
As soon as this PR is in I will begin pagination.

Done?

[oliver-sanders]

LGTM, tested, task selection is good, platform filters work. Thanks!

Would be great if you could put together a screenshot or GIF for the changes section in cylc-doc, we'll announce every entry in this section one by one.

@MetRonnie, please squash merge.

[MetRonnie]

Spotted an issue with the filtering: ChrisPaulBennett#4

Done

[MetRonnie]

I'm happy with this now 👍 I did notice a couple more issues which I don't know if you want to address now or later.

Edit: address later - #1698