New API Metrics, and start of a libtsapi.so structure

[zwoop]

The new API metrics are backwards compatible with previous APIs, since the old API wraps these new APIs. New plugins / code could chose to use the Metrics.h API directly.

Work to be finished here includes

1. Decide what goes into include/api ? Do we have one new include file to #include all the include/api/*.h files?

2. What should be moved to src/api and include/api.

Lost in this merge is all the work from Chris McFarlen. Thanks!

Co-Author: Chris McFarlen chris@mcfarlen.us

[zwoop]

[approve ci autest]

[zwoop]

I did some quick tests using the remap_stats.so plugin (a global plugin), there's no noticeable difference in performance even though I'm just putting pressure on 3 single metrics (each updated on every request).

New Metrics:

100 mean bytes/fetch
1167275.00 fetches/sec, 1.16728e+08 bytes/sec
msecs/connect: 0.084 mean, 0.366 max, 0.027 min
msecs/first-response: 0.476 mean, 50.357 max, 0.024 min

Old Metrics:

100 mean bytes/fetch
1145004.00 fetches/sec, 1.14500e+08 bytes/sec
msecs/connect: 0.083 mean, 0.373 max, 0.025 min
msecs/first-response: 0.482 mean, 46.571 max, 0.023 min

The three metrics this plugin seems to create (these are all cache hits):

root@frigg /opt/ats-10 # ./bin/traffic_ctl metric match plugin
plugin.remap_stats.frigg-101.ogre.com.in_bytes 3132116893
plugin.remap_stats.frigg-101.ogre.com.out_bytes 11095556535
plugin.remap_stats.frigg-101.ogre.com.status_2xx 35223989

[zwoop]

@bneradt can you review again please ?

[bryancall]

[approve ci clang-analyzer]