util/log: rip out mostly defunct context logging, but make Logc family use trace

[tbg]

This was a simple change but it removes a lot of cruft and makes us log to the trace whenever the Logc family of functions is used.

Some brave soul could comb the codebase and replace all uses of the Logf via Logc when there is a context around as this would make sure that everything that makes it to log files also makes it to an associated request's trace. We could even remove the Log(|f) family completely to force the more awkward log.Infoc(context.Background(), msg, args...).
#1779 goes a few steps further, but this seems like a good short-term goal.

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This change is

[petermattis]

I see a handful of places in the code where we're calling {Replica,Store}.context( and then log.{Level}c and expecting the log message to containing the {node,store,range} ID. For example:

        log.Fatalc(r.context(context.TODO()), "processRaftCommand requires a non-zero index")

I think adding r.String() as a prefix here is the correct change. I used the following grep to find the uses of {Store,Replica}.context(:

cd storage; git grep '\.context(' | grep -v _test.go

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Review status: 0 of 11 files reviewed at latest revision, all discussions resolved, all commit checks successful.

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Comments from Reviewable

[tbg]

Good point, done (I ripped out .context() because well, it was kind of pointless at that stage, and won't be able to hold a trace).

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Review status: 0 of 16 files reviewed at latest revision, all discussions resolved, some commit checks pending.

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Comments from Reviewable

[petermattis]

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Review status: 0 of 16 files reviewed at latest revision, 1 unresolved discussion, some commit checks pending.

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server/node.go, line 258 [r2] (raw file):

// String implements fmt.Stringer.
func (n *Node) String() string {
  return fmt.Sprintf("node %d", n.Descriptor.NodeID)

s/node %d/node=%d/g for symmetry with {Store,Replica}.String().

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Comments from Reviewable

[tbg]

Review status: 0 of 16 files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

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server/node.go, line 258 [r2] (raw file):

Previously, petermattis (Peter Mattis) wrote…

s/node %d/node=%d/g for symmetry with {Store,Replica}.String().

Done.

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Comments from Reviewable

[tbg]

TFTR.

Curiously, go tool vet (via make check) locally didn't complain about the completely justified "possible formatting directive" in https://circleci.com/gh/tschottdorf/cockroach/2574). Any idea why that could be?

[petermattis]

Nope, no idea why it wouldn't fail locally as well.

[RaduBerinde]

I don't really get what the plan is here. Having a context for what node we're on etc and having that show up in the log message is something we definitely need as we implement more multi-node tests. Is there a plan to replace the stuff that was there with something else?

[tbg]

Yes, #1779.