Lazily start TelemetryEventBuffers

Author: sl0thentr0py

sentry-ruby/lib/sentry/client.rb

@@ -49,11 +49,11 @@ def initialize(configuration)
       @spotlight_transport = SpotlightTransport.new(configuration) if configuration.spotlight
 
       if configuration.enable_logs
-        @log_event_buffer = LogEventBuffer.new(configuration, self).start
+        @log_event_buffer = LogEventBuffer.new(configuration, self)
       end
 
       if configuration.enable_metrics
-        @metric_event_buffer = MetricEventBuffer.new(configuration, self).start
+        @metric_event_buffer = MetricEventBuffer.new(configuration, self)
       end
     end
 

sentry-ruby/lib/sentry/telemetry_event_buffer.rb

@@ -36,11 +36,6 @@ def initialize(configuration, client, event_class:, max_items:, max_items_before
       log_debug("[#{self.class}] Initialized buffer with max_items=#{@max_items}, flush_interval=#{FLUSH_INTERVAL}s")
     end
 
-    def start
-      ensure_thread
-      self
-    end
-
     def flush
       @mutex.synchronize do
         return if empty?
@@ -55,6 +50,8 @@ def flush
     alias_method :run, :flush
 
     def add_item(item)
+      return unless ensure_thread
+
       unless item.is_a?(@event_class)
         log_debug("[#{self.class}] expected a #{@event_class}, got #{item.class}")
         return

sentry-ruby/spec/support/shared_examples_for_telemetry_event_buffers.rb

@@ -24,6 +24,27 @@
   describe "#add_item" do
     let(:max_items) { 3 }
 
+    it "spawns new thread" do
+      expect do
+        subject.add_item(event)
+      end.to change { Thread.list.count }.by(1)
+
+      expect(subject.instance_variable_get(:@thread)).to be_a(Thread)
+    end
+
+    it "spawns only one thread" do
+      expect do
+        subject.add_item(event)
+      end.to change { Thread.list.count }.by(1)
+
+      thread = subject.instance_variable_get(:@thread)
+      expect(thread).to receive(:alive?).and_return(true)
+
+      expect do
+        subject.add_item(event)
+      end.to change { Thread.list.count }.by(0)
+    end
+
     it "does nothing when there are no pending items" do
       expect(client).not_to receive(:capture_envelope)
 
@@ -156,7 +177,6 @@
 
       it "keeps the background thread alive after an error" do
         subject.add_item(event)
-        subject.start
 
         thread = subject.instance_variable_get(:@thread)