Refactor memory monitoring to behave like git probing

lib/gitlab_monitor.rb

@@ -9,5 +9,6 @@ module GitLab
     autoload :DatabaseDeadTuplesCollector, "gitlab_monitor/database_dead_tuples"
     autoload :DatabaseDeadTuplesProber,    "gitlab_monitor/database_dead_tuples"
     autoload :ProcessMemory,               "gitlab_monitor/process_memory"
+    autoload :ProcessMemoryProber,         "gitlab_monitor/process_memory"
   end
 end

lib/gitlab_monitor/cli.rb

@@ -150,17 +150,9 @@ module GitLab
         end
         def run
-          memory  = ::GitLab::Monitor::ProcessMemory.new(@pid)
-          metrics = PrometheusMetrics.new
-
-          @fields.each do |field|
-            value = memory[field]
-            next unless value
-
-            metrics.add("process_memory", value, field: field, process_name: @name)
-          end
-
-          @target.write(metrics.to_s)
+          ::GitLab::Monitor::ProcessMemoryProber.new(pid: @pid, fields: @fields, name: @name)
+                                                .probe_memory
+                                                .write_to(@target)
         end
       end

lib/gitlab_monitor/process_memory.rb

@@ -34,5 +34,30 @@ module GitLab
         nil
       end
     end
+
+    # Probes a process for memory then writes metrics to a target
+    class ProcessMemoryProber
+      def initialize(options, metrics: PrometheusMetrics.new)
+        @metrics = metrics
+        @fields  = options[:fields]
+        @name    = options[:name]
+        @memory  = ProcessMemory.new(options[:pid])
+      end
+
+      def probe_memory
+        @fields.each do |field|
+          value = @memory[field]
+          next unless value
+
+          @metrics.add("#{@name.downcase}_memory_bytes", value, field: field)
+        end
+
+        self
+      end
+
+      def write_to(target)
+        target.write(@metrics.to_s)
+      end
+    end
   end
 end