add tests for PluginHelper, and fixes many bugs found

lib/fluent/log.rb

@@ -245,6 +245,10 @@ def flush
       @out.flush
     end
 
+    def reset
+      @out.reset if @out.respond_to?(:reset)
+    end
+
     private
 
     def dump_stacktrace(backtrace, level)

lib/fluent/plugin/base.rb

@@ -28,13 +28,73 @@ class Base
       include PluginLoggerMixin
       include PluginHelper::Mixin
 
-      def initialize; end
-      def configure(conf); end
-      def start; end
-      def stop; end
-      def shutdown; end
-      def close; end
-      def terminate; end
+      State = Struct.new(:configure, :start, :stop, :shutdown, :close, :terminate)
+
+      def initialize
+        super
+        @state = State.new(false, false, false, false, false, false)
+      end
+
+      def has_router?
+        false
+      end
+
+      def configure(conf)
+        super
+        @state.configure = true
+        self
+      end
+
+      def start
+        @log.reset
+        @state.start = true
+        self
+      end
+
+      def stop
+        @state.stop = true
+        self
+      end
+
+      def shutdown
+        @state.shutdown = true
+        self
+      end
+
+      def close
+        @state.close = true
+        self
+      end
+
+      def terminate
+        @state.terminate = true
+        @log.reset
+        self
+      end
+
+      def configured?
+        @state.configure
+      end
+
+      def started?
+        @state.start
+      end
+
+      def stopped?
+        @state.stop
+      end
+
+      def shutdown?
+        @state.shutdown
+      end
+
+      def closed?
+        @state.close
+      end
+
+      def terminated?
+        @state.terminate
+      end
     end
   end
 end

lib/fluent/plugin_helper/child_process.rb

@@ -28,24 +28,44 @@ module ChildProcess
 
       # stop     : [-]
       # shutdown : send TERM to all child processes
-      # close    : close all I/O objects for child processes
-      # terminate: send TERM again and again if processes stil exist, and KILL after timeout
+      # close    : close all I/O objects for child processes, send TERM and then KILL after timeout
+      # terminate: [-]
 
-      def child_process_execute(title, command, arguments: nil, subprocess_name: nil, read: true, write: true, encoding: 'utf-8', interval: nil, immediate: false, &block)
+      attr_reader :_child_process_processes # for tests
+
+      def child_process_execute(
+          title, command,
+          arguments: nil, subprocess_name: nil, interval: nil, immediate: false, parallel: false,
+          read: true, write: true, internal_encoding: 'utf-8', external_encoding: 'utf-8', &block
+      )
         raise ArgumentError, "BUG: title must be a symbol" unless title.is_a? Symbol
+        raise ArgumentError, "BUG: arguments required if subprocess name is replaced" if subprocess_name && !arguments
         raise ArgumentError, "BUG: both of input and output are disabled" if !read && !write
         raise ArgumentError, "BUG: block not specified which receive i/o object" unless block_given?
         raise ArgumentError, "BUG: block must have an argument for io" unless block.arity == 1
 
-        if interval
-          if immediate
-            child_process_execute_once(title, command, arguments, subprocess_name, read, write, encoding, &block)
+        running = false
+        callback = ->(io) {
+          running = true
+          begin
+            block.call(io)
+          ensure
+            running = false
           end
+        }
+
+        if immediate || !interval
+          child_process_execute_once(title, command, arguments, subprocess_name, read, write, internal_encoding, external_encoding, &callback)
+        end
+
+        if interval
           timer_execute(:child_process_execute, interval, repeat: true) do
-            child_process_execute_once(title, command, arguments, subprocess_name, read, write, encoding, &block)
+            if !parallel && running
+              log.warn "previous child process is still running. skipped.", title: title, command: command, arguments: arguments, interval: interval, parallel: parallel
+            else
+              child_process_execute_once(title, command, arguments, subprocess_name, read, write, internal_encoding, external_encoding, &callback)
+            end
           end
-        else
-          child_process_execute_once(title, command, arguments, subprocess_name, read, write, encoding, &block)
         end
       end
 
@@ -79,17 +99,20 @@ def shutdown
       def close
         super
 
+        # close_write -> kill processes -> close_read
+        # * if ext process continues to write data to it's stdout, io.close_read blocks
+        #   so killing process MUST be done before closing io for read
+
         @_child_process_processes.keys.each do |pid|
           io = @_child_process_processes[pid].io
-          io.close rescue nil
+          io.close_write rescue nil
         end
-      end
 
-      def terminate
-        alive_process_exist = true
         timeout = Time.now + @_child_process_kill_timeout
 
-        while alive_process_exist
+        while true
+          break if Time.now > timeout
+
           @_child_process_processes.keys.each do |pid|
             process = @_child_process_processes[pid]
             next unless process.alive
@@ -108,12 +131,9 @@ def terminate
           @_child_process_processes.each_pair do |pid, process|
             alive_process_found = true if process.alive
           end
+          break unless alive_process_found
 
-          if alive_process_found
-            sleep CHILD_PROCESS_LOOP_CHECK_INTERVAL
-          else
-            alive_process_exist = false
-          end
+          sleep CHILD_PROCESS_LOOP_CHECK_INTERVAL
         end
 
         @_child_process_processes.keys.each do |pid|
@@ -125,14 +145,15 @@ def terminate
           @_child_process_processes.delete(pid)
         end
 
-        super
+        @_child_process_processes.keys.each do |pid|
+          io = @_child_process_processes[pid].io
+          io.close_read rescue nil
+        end
       end
 
       ProcessInfo = Struct.new(:thread, :io, :alive)
 
-      def child_process_execute_once(title, command, arguments, subprocess_name, read, write, encoding, &block)
-        ext_enc = encoding
-        int_enc = "utf-8"
+      def child_process_execute_once(title, command, arguments, subprocess_name, read, write, internal_encoding, external_encoding, &block)
         mode = case
                when read && write then "r+"
                when read then "r"
@@ -141,22 +162,22 @@ def child_process_execute_once(title, command, arguments, subprocess_name, read,
                  raise "BUG: both read and write are false is banned before here"
                end
         cmd = command
-        if arguments # if arguments is nil, then command is executed by shell
+        if arguments || subprocess_name # if arguments is nil, then command is executed by shell
           cmd = []
           if subprocess_name
             cmd.push [command, subprocess_name]
           else
             cmd.push command
           end
-          cmd += arguments
+          cmd += (arguments || [])
         end
         log.debug "Executing command", title: title, command: command, arguments: arguments, read: read, write: write
-        io = IO.popen(cmd, mode, external_encoding: ext_enc, internal_encoding: int_enc)
+        io = IO.popen(cmd, mode, external_encoding: external_encoding, internal_encoding: internal_encoding)
         pid = io.pid
 
         m = Mutex.new
         m.lock
-        thread = thread_create do
+        thread = thread_create :child_process_callback do
           m.lock # run after plugin thread get pid, thread instance and i/o
           with_error = false
           m.unlock
@@ -173,6 +194,8 @@ def child_process_execute_once(title, command, arguments, subprocess_name, read,
           rescue => e
             log.warn "Unexpected error while processing I/O for child process", title: title, pid: pid, command: command, error_class: e.class, error: e
           end
+          io.close rescue nil
+          @_child_process_processes.delete(pid)
         end
         @_child_process_processes[pid] = ProcessInfo.new(thread, io, true)
         m.unlock

lib/fluent/plugin_helper/event_emitter.rb

@@ -42,14 +42,13 @@ def configure(conf)
         end
       end
 
-      def emits?
+      def has_router?
         true
       end
 
-      def shutdown
+      def close
         super
-
-        @router = nil # TODO: is it correct shutdown phase to disable router?
+        @router = nil
       end
     end
   end

lib/fluent/plugin_helper/event_loop.rb

@@ -20,21 +20,29 @@
 module Fluent
   module PluginHelper
     module EventLoop
+      # Currently this plugin helper is only for other helpers, not plugins.
+      # there's no way to create customized watchers to attach event loops.
       include Fluent::PluginHelper::Thread
 
       # stop     : [-]
       # shutdown : detach all event watchers on event loop
       # close    : stop event loop
       # terminate: initialize internal state
 
-      EVENT_LOOP_RUN_DEFAULT_TIMEOUT = 0.2
+      EVENT_LOOP_RUN_DEFAULT_TIMEOUT = 0.5
+
+      attr_reader :_event_loop # for tests
 
       def event_loop_attach(watcher)
         @_event_loop_mutex.synchronize do
           @_event_loop.attach(watcher)
         end
       end
 
+      def event_loop_wait_until_start
+        ::Thread.pass until event_loop_running?
+      end
+
       def event_loop_running?
         @_event_loop_running
       end
@@ -65,6 +73,9 @@ def shutdown
         @_event_loop_mutex.synchronize do
           @_event_loop.watchers.each {|w| w.detach if w.attached? }
         end
+        while @_event_loop_running
+          ::Thread.pass
+        end
 
         super
       end
@@ -85,7 +96,7 @@ def terminate
         @_event_loop = nil
         @_event_loop_running = false
         @_event_loop_mutex = nil
-        @_event_loop_run_timeout = EVENT_LOOP_RUN_DEFAULT_TIMEOUT
+        @_event_loop_run_timeout = nil
 
         super
       end