promdump: add "empty" category to metrics summary log line #177
Description
Presently, when printing the summary line for what metrics exports were collected, exports that dump successfully but return no results are considered successful and added to the "dumped" count. This means that for both failed and successful dumps, the summary line is often the same:
“unsuccessful”
2025/03/08 23:25:59 main: summary: 7 metrics processed (skipped: 1 dumped: 6 failed: 0)
“successful”
2025/03/10 15:28:59 main: summary: 7 metrics processed (skipped: 1 dumped: 6 failed: 0)
We should begin tracking whether a particular export returned any results and report empty exports. The resulting summary line would look something like this:
2025/03/08 23:25:59 main: summary: 7 metrics processed (skipped: 1 empty: 5 dumped: 1 failed: 0)