Added another lock to the metrics struct to synchronize accesses to the
broker stats. There's a possible race condition if stats are updated at
the same time they are being logged.
Many of our log messages were being used to generate metrics, but are
now being aggregated and logged to a separate metrics log file and so we
don't need them in the regular logs anymore.
This addresses the goal of ticket #30830, to remove unecessary messages
and keep broker logs for debugging purposes.
Added three new metrics:
- proxyIdleCount counts the number of times a proxy polls and receives
no snowflakes
- clientDeniedCount counts the number of times a client requested a
snowflake but none were available
- clientProxyMatchCount counts the number of times a client successfully
received a snowflake
Previously the metrics log file was hardcoded and the broker wasn't
behaving properly if it was unable to open the file for logging.
Added a commandline option to specify the logfile that defaults to
Stdout.
Fixed up some documentation and log output formatting
