Add database_connection_pool stats to GoodJob::Process.current_state (

TheOdinProject#1019)

* Add connection_pool stats to `GoodJob::Process.current_stat`

This commit adds snapshot of database connection pool to a
`GoodJob::Process.current_stat` method.

* `size` - Total capacity of connection pool
* `active` - Number of connections in the pool that are in_use/active

* Rename `database_connection_pool` and add simple test

---------

Co-authored-by: Ben Sheldon [he/him] <bensheldon@gmail.com>

app/models/good_job/process.rb

@@ -63,6 +63,10 @@ def self.ns_current_state
         cron_enabled: GoodJob.configuration.enable_cron?,
         total_succeeded_executions_count: GoodJob::Scheduler.instances.sum { |scheduler| scheduler.stats.fetch(:succeeded_executions_count) },
         total_errored_executions_count: GoodJob::Scheduler.instances.sum { |scheduler| scheduler.stats.fetch(:errored_executions_count) },
+        database_connection_pool: {
+          size: connection_pool.size,
+          active: connection_pool.connections.count(&:in_use?),
+        },
       }
     end
 

spec/app/models/good_job/process_spec.rb

@@ -23,6 +23,17 @@
     end
   end
 
+  describe '.ns_current_state' do
+    it 'contains information about the process' do
+      expect(described_class.ns_current_state).to include(
+        database_connection_pool: include(
+          size: be_an(Integer),
+          active: be_an(Integer)
+        )
+      )
+    end
+  end
+
   describe '.register' do
     it 'registers the process' do
       process = nil