ui.queryArguments: update state less aggressively

[mcsf]

To implement once #6417 is merged.

Every time ROUTE_SET is dispatched, the ui.queryArguments.current branch updates itself regardless of whether there is any change in the query data. This potentially leads to unnecessary renders in the view layer or recalculations in memoized selectors.

Test live: https://calypso.live/?branch=update/ui-query-arguments-overwrites

[lsinger]

Code is on fleek.

Are we certain that we won't ever need the timestamp when querying these events?

[mcsf]

Are we certain that we won't ever need the timestamp when querying these events?

Are you referring to the test in isEqualQuery, or to the fact that this excludes any timestamp=foo query argument? For the former: with this change, we assert that we don't care about the last time a ROUTE_SET action was dispatch, but only the last time different arguments were provided in a ROUTE_SET. For the latter: we could also rename this special value timestamp to _timestamp.

[ehg]

or to the fact that this excludes any timestamp=foo query argument?

Ooh, that passed me right by. _timestamp sounds sensible, and could save someone a headache later :)

[lsinger]

I meant the former ... but thinking about it again I realize that it will definitely update when a different route is visited. So I'm good on that front.

Good call with making an actual timestamp argument problematic -- rename to _timestamp sounds sensible!

[mcsf]

I've underscore-prefixed timestamp in b344826. It's probably easier to make this change now rather than later. I notice that it can be confusing to read _timestamp (from ui.queryArguments.*) alongside timestamp (from preferences's guided-tours-history), but it's probably a lesser evil?

[ehg]

LGTM

[mcsf]

Forgot to squash. D'oh.