Plugin development enhancement

lib/fluent/plugin/base.rb

@@ -26,9 +26,12 @@ class Base
 
       State = Struct.new(:configure, :start, :after_start, :stop, :before_shutdown, :shutdown, :after_shutdown, :close, :terminate)
 
+      attr_accessor :under_plugin_development
+
       def initialize
         super
         @_state = State.new(false, false, false, false, false, false, false, false, false)
+        @under_plugin_development = false
       end
 
       def has_router?

lib/fluent/plugin/buffer.rb

@@ -160,6 +160,13 @@ def metadata_list
         end
       end
 
+      # it's too dangerous, and use it so carefully to remove metadata for tests
+      def metadata_list_clear!
+        synchronize do
+          @metadata_list.clear
+        end
+      end
+
       def new_metadata(timekey: nil, tag: nil, variables: nil)
         Metadata.new(timekey, tag, variables)
       end

lib/fluent/plugin/output.rb

@@ -740,6 +740,13 @@ def metadata(tag, time, record)
         end
       end
 
+      def metadata_for_test(tag, time, record)
+        raise "BUG: #metadata_for_test is available only when no actual metadata exists" unless @buffer.metadata_list.empty?
+        m = metadata(tag, time, record)
+        @buffer.metadata_list_clear!
+        m
+      end
+
       def execute_chunking(tag, es, enqueue: false)
         if @simple_chunking
           handle_stream_simple(tag, es, enqueue: enqueue)
@@ -976,6 +983,10 @@ def try_flush
           log.debug "taking back chunk for errors.", plugin_id: plugin_id, chunk: dump_unique_id_hex(chunk.unique_id)
           @buffer.takeback_chunk(chunk.unique_id)
 
+          if @under_plugin_development
+            raise
+          end
+
           @retry_mutex.synchronize do
             if @retry
               @counters_monitor.synchronize{ @num_errors += 1 }
@@ -1120,6 +1131,7 @@ def enqueue_thread_run
                 @buffer.enqueue_all{ |metadata, chunk| metadata.timekey < current_timekey && metadata.timekey + timekey_unit + timekey_wait <= now_int }
               end
             rescue => e
+              raise if @under_plugin_development
               log.error "unexpected error while checking flushed chunks. ignored.", plugin_id: plugin_id, error_class: e.class, error: e
               log.error_backtrace
             end

lib/fluent/test/driver/base.rb

@@ -40,6 +40,7 @@ def initialize(klass, opts: {}, &block)
           else
             @instance = klass
           end
+          @instance.under_plugin_development = true
 
           @logs = []
 

lib/fluent/test/driver/output.rb

@@ -18,6 +18,7 @@
 require 'fluent/test/driver/event_feeder'
 
 require 'fluent/plugin/output'
+require 'timeout'
 
 module Fluent
   module Test
@@ -43,6 +44,7 @@ def run_actual(**kwargs, &block)
           super(**kwargs, &block)
           if @flush_buffer_at_cleanup
             @instance.force_flush
+            Timeout.timeout(10){ sleep 0.1 until [email protected] || @instance.buffer.queue.size == 0 }
           end
         end
 
@@ -52,6 +54,7 @@ def formatted
 
         def flush
           @instance.force_flush
+          Timeout.timeout(10){ sleep 0.1 until [email protected] || @instance.buffer.queue.size == 0 }
         end
 
         def instance_hook_after_started