[SOLR-11805] SolrRequest elapsedTime is not computed correctly (premature millisecond conversion)

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 7.3
• Assignee: David Smiley
• Reporter: David Smiley
• Created: 29/Dec/17 23:54
• Updated: 08/Jun/19 15:16
• Resolved: 03/Jan/18 21:13

Description

(this is not QTime, this is what the SolrJ client request duration is captured as)
This is what SolrRequest.process looks like:

    long startTime = TimeUnit.MILLISECONDS.convert(System.nanoTime(), TimeUnit.NANOSECONDS);
    T res = createResponse(client);
    res.setResponse(client.request(this, collection));
    long endTime = TimeUnit.MILLISECONDS.convert(System.nanoTime(), TimeUnit.NANOSECONDS);
    res.setElapsedTime(endTime - startTime);
    return res;

The millisecond conversion should be delayed to the very end, otherwise it could yield a time duration of a millisecond greater than it deserves. Also, it's better to put the unit into the variable name. Also, note the convenience methods on TimeUnit like "toMillis". Here's what this should look like:

    long startNanos = System.nanoTime();
    T res = createResponse(client);
    res.setResponse(client.request(this, collection));
    long endNanos = System.nanoTime();
    res.setElapsedTime(TimeUnit.NANOSECONDS.toMillis(endNanos - startNanos));
    return res;