FIX: Ensure socket is closed when error is raised while opening socket

CHANGELOG

@@ -1,3 +1,8 @@
+2.2.0 - 2024-12-05
+
+- FIX: Ensure socket is closed when error is raised while opening socket
+- Feature: Add Dalli::Client memcache metrics for web_collector
+
 2.1.1 - 2024-06-19
 
 - FEATURE: improve good_job instrumentation

lib/prometheus_exporter/client.rb

@@ -59,7 +59,8 @@ def initialize(
       json_serializer: nil,
       custom_labels: nil,
       logger: Logger.new(STDERR),
-      log_level: Logger::WARN
+      log_level: Logger::WARN,
+      process_queue_once_and_stop: false
     )
       @logger = logger
       @logger.level = log_level
@@ -86,6 +87,7 @@ def initialize(
       @json_serializer = json_serializer == :oj ? PrometheusExporter::OjCompat : JSON
 
       @custom_labels = custom_labels
+      @process_queue_once_and_stop = process_queue_once_and_stop
     end
 
     def custom_labels=(custom_labels)
@@ -144,7 +146,7 @@ def process_queue
           @socket.write("\r\n")
         rescue => e
           logger.warn "Prometheus Exporter is dropping a message: #{e}"
-          @socket = nil
+          close_socket!
           raise
         end
       end
@@ -170,6 +172,11 @@ def worker_loop
     end
 
     def ensure_worker_thread!
+      if @process_queue_once_and_stop
+        worker_loop
+        return
+      end
+
       unless @worker_thread&.alive?
         @mutex.synchronize do
           return if @worker_thread&.alive?
@@ -234,8 +241,7 @@ def ensure_socket!
 
       nil
     rescue StandardError
-      @socket = nil
-      @socket_started = nil
+      close_socket!
       @socket_pid = nil
       raise
     end

lib/prometheus_exporter/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module PrometheusExporter
-  VERSION = "2.1.1"
+  VERSION = "2.2.0"
 end

test/client_test.rb

@@ -53,12 +53,32 @@ def test_standard_values
     assert_equal(expected_quantiles, summary_metric.standard_values("value", "key")[:opts])
   end
 
+  def test_close_socket_on_error
+    logs = StringIO.new
+    logger = Logger.new(logs)
+    logger.level = :error
+
+    client =
+      PrometheusExporter::Client.new(logger: logger, port: 321, process_queue_once_and_stop: true)
+    client.send("put a message in the queue")
+
+    assert_includes(
+      logs.string,
+      "Prometheus Exporter, failed to send message Connection refused - connect(2) for \"localhost\" port 321",
+    )
+  end
+
   def test_overriding_logger
     logs = StringIO.new
     logger = Logger.new(logs)
     logger.level = :warn
 
-    client = PrometheusExporter::Client.new(logger: logger, max_queue_size: 1)
+    client =
+      PrometheusExporter::Client.new(
+        logger: logger,
+        max_queue_size: 1,
+        process_queue_once_and_stop: true,
+      )
     client.send("put a message in the queue")
     client.send("put a second message in the queue to trigger the logger")