storage: short-circuit GC queue when context expires

[tbg]

Fallout from #18199 and corresponding
testing in #15997.

When the context is expired, there is no point in shooting off another gazillion requests.

[cockroach-teamcity]

This change is 

[bdarnell]

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Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

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pkg/storage/gc_queue.go, line 859 at r1 (raw file):

	// succeeded in pushing a lot of transactions, the next time around we should have
	// less work here and manage to get to the intents, but it would be better to let
	// another goroutine push intents for transactions we've handled so that work that

s/push/resolve/

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Comments from Reviewable

[tbg]

Review status: all files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

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pkg/storage/gc_queue.go, line 859 at r1 (raw file):

Previously, bdarnell (Ben Darnell) wrote…

s/push/resolve/

Done.

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Comments from Reviewable

[nvanbenschoten]

Reviewed 1 of 2 files at r1.
Review status: 1 of 2 files reviewed at latest revision, 2 unresolved discussions, some commit checks failed.

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pkg/storage/gc_queue.go, line 415 at r2 (raw file):

			}(); err != nil {
				// Ignore above error, but if context is expired, no point in keeping going.
				if ctx.Err() != nil {

ctx.Err can return different types of errors, depending on whether the context timed out or was canceled. Why don't we return ctx.Err? Is the idea that err probably already is this ctx.Err? Same question below.

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Comments from Reviewable

[tbg]

Review status: 1 of 2 files reviewed at latest revision, 2 unresolved discussions, all commit checks successful.

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pkg/storage/gc_queue.go, line 415 at r2 (raw file):

Previously, nvanbenschoten (Nathan VanBenschoten) wrote…

ctx.Err can return different types of errors, depending on whether the context timed out or was canceled. Why don't we return ctx.Err? Is the idea that err probably already is this ctx.Err? Same question below.

Yes, and even if it isn't, I think the last error is probably more interesting than a context expired/canceled error.

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Comments from Reviewable