1 files changed, 63 insertions, 0 deletions
diff --git a/lib/gitlab/metrics/samplers/action_cable_sampler.rb b/lib/gitlab/metrics/samplers/action_cable_sampler.rb
new file mode 100644
index 00000000000..9f4979fa673
--- /dev/null
+++ b/lib/gitlab/metrics/samplers/action_cable_sampler.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Metrics
+    module Samplers
+      class ActionCableSampler < BaseSampler
+        SAMPLING_INTERVAL_SECONDS = 5
+
+        def initialize(interval = SAMPLING_INTERVAL_SECONDS, action_cable: ::ActionCable.server)
+          super(interval)
+          @action_cable = action_cable
+        end
+
+        def metrics
+          @metrics ||= {
+            active_connections: ::Gitlab::Metrics.gauge(
+              :action_cable_active_connections, 'Number of ActionCable WS clients currently connected'
+            ),
+            pool_min_size: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_min_size, 'Minimum number of worker threads in ActionCable thread pool'
+            ),
+            pool_max_size: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_max_size, 'Maximum number of worker threads in ActionCable thread pool'
+            ),
+            pool_current_size: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_current_size, 'Current number of worker threads in ActionCable thread pool'
+            ),
+            pool_largest_size: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_largest_size, 'Largest number of worker threads observed so far in ActionCable thread pool'
+            ),
+            pool_completed_tasks: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_tasks_total, 'Total number of tasks executed in ActionCable thread pool'
+            ),
+            pool_pending_tasks: ::Gitlab::Metrics.gauge(
+              :action_cable_pool_pending_tasks, 'Number of tasks waiting to be executed in ActionCable thread pool'
+            )
+          }
+        end
+
+        def sample
+          pool = @action_cable.worker_pool.executor
+          labels = {
+            server_mode: server_mode
+          }
+
+          metrics[:active_connections].set(labels, @action_cable.connections.size)
+          metrics[:pool_min_size].set(labels, pool.min_length)
+          metrics[:pool_max_size].set(labels, pool.max_length)
+          metrics[:pool_current_size].set(labels, pool.length)
+          metrics[:pool_largest_size].set(labels, pool.largest_length)
+          metrics[:pool_completed_tasks].set(labels, pool.completed_task_count)
+          metrics[:pool_pending_tasks].set(labels, pool.queue_length)
+        end
+
+        private
+
+        def server_mode
+          Gitlab::ActionCable::Config.in_app? ? 'in-app' : 'standalone'
+        end
+      end
+    end
+  end
+end