drill

b075bf61 - DRILL-4654: Add new metrics to the MetricRegistry

DRILL-4654: Add new metrics to the MetricRegistry + New metrics: - drill.queries.enqueued number of queries that have been submitted to the drillbit but have not started - drill.queries.running number of running queries for which this drillbit is the foreman - drill.queries.completed number of completed queries (or cancelled or failed) for which this drillbit was the foreman - drill.fragments.running number of query fragments that are running in the drillbit - drill.allocator.root.used amount of memory used in bytes by the internal memory allocator - drill.allocator.root.peak peak amount of memory used in bytes by the internal memory allocator - fd.usage ratio of used to total file descriptors (on *nix systems) + Rename "current" to "used" for RPC allocator current memory usage to follow convention + Borrow SystemPropertyUtil class from Netty + Configure DrillMetrics through system properties + Remove unused methods and imports closes #495