Adding task pending time in MSQ reports

[cryptoe]

• Added a new field pendingMs in MSQ task reports. This helps in figuring out the exact run time of the MSQ worker tasks.
• Fixed data races.

The payload now looks like

"workers": {
          "0": [
            {
              "workerId": "query-3dc0c45d-34d7-4b15-86c9-cdb2d3ebfc4e-worker0_0",
              "state": "SUCCESS",
              "durationMs": 15511,
              "pendingMs": 137
            }
          ]
        }

Release notes

A new field in MSQ task report which captures the milliseconds elapsed between when the worker task was first requested and when it fully started RUNNING. Actual work time can be calculated using actualWorkTimeMS = durationMs - pendingMs

[kfaraz]

pendingTimeMillis would probably be a better name and more in line with rest of the names in Druid.

[cryptoe]

Since we already have durationMs as part of line:389 of this payload, having pendingTimeMillis would be weird. If you feel strongly about it, I can change.

[adarshsanjeev]

We are using millis as convention in this class, so it's a bit unfortunate that we already have "durationMs" in the taskReport. Would the best thing be to call it pendingTimeMillis in the code and expose it in the report as getPendingTimeInMs. As a nit, I think it should be getPendingTimeInMs though.

[adarshsanjeev]

Looks good overall, minor comments

[adarshsanjeev]

nit: this looks a bit weird due to the parenthesis and new lines.

Suggested change

	if ((!canceledWorkerTasks.contains(taskId))
	if (!canceledWorkerTasks.contains(taskId) && !tracker.isComplete()) {

[cryptoe]

I personally find 2 not statements a little tricky so hence like the parenthesis. Keeping it as is for now.