WIP: Use NIO.2 WatchService for JRuby

.travis.yml

@@ -3,24 +3,6 @@ cache: bundler
 
 matrix:
   include:
-    - rvm: 2.3
-    - rvm: 2.4
-    - rvm: 2.5
-    - rvm: 2.6
-    - rvm: 2.5
-      os: osx
-      env:
-        # TODO: 0.8 is enough on Linux, but 2 seems needed for Travis/OSX
-        - LISTEN_TESTS_DEFAULT_LAG=2
-    - rvm: jruby
-    - rvm: truffleruby
-    - rvm: jruby-head
-    - rvm: ruby-head
-    - rvm: rbx-3
-  allow_failures:
-    - rvm: truffleruby
     - rvm: jruby
-    - rvm: ruby-head
-    - rvm: jruby-head
-    - rvm: rbx-3
-  fast_finish: true
+      env:
+        - TEST_LISTEN_ADAPTER_MODES=native

lib/listen/adapter.rb

@@ -4,10 +4,11 @@
 require 'listen/adapter/linux'
 require 'listen/adapter/polling'
 require 'listen/adapter/windows'
+require 'listen/adapter/jruby'
 
 module Listen
   module Adapter
-    OPTIMIZED_ADAPTERS = [Darwin, Linux, BSD, Windows].freeze
+    OPTIMIZED_ADAPTERS = [Jruby, Darwin, Linux, BSD, Windows].freeze
     POLLING_FALLBACK_MESSAGE = 'Listen will be polling for changes.'\
       'Learn more at https://github.com/guard/listen#listen-adapters.'.freeze
 
@@ -16,7 +17,11 @@ def select(options = {})
         _log :debug, 'Adapter: considering polling ...'
         return Polling if options[:force_polling]
         _log :debug, 'Adapter: considering optimized backend...'
-        return _usable_adapter_class if _usable_adapter_class
+        _log :debug, "Adapter: RUBY_ENGINE=#{RUBY_ENGINE}"
+        if _usable_adapter_class
+          _log :debug, "Adapter: using #{_usable_adapter_class}"
+          return _usable_adapter_class
+        end
         _log :debug, 'Adapter: falling back to polling...'
         _warn_polling_fallback(options)
         Polling

lib/listen/adapter/jruby.rb

@@ -0,0 +1,57 @@
+module Listen
+  module Adapter
+    # @see https://docs.oracle.com/javase/tutorial/essential/io/notification.html
+    class Jruby < Base
+      def self.usable?
+        RUBY_ENGINE == 'jruby'
+      end
+
+      private
+
+      def _configure(directory, &_callback)
+        require 'java'
+        java_import 'java.nio.file.FileSystems'
+        java_import 'java.nio.file.Paths'
+        java_import 'java.nio.file.StandardWatchEventKinds'
+
+        event_kinds = [
+          StandardWatchEventKinds::ENTRY_CREATE,
+          StandardWatchEventKinds::ENTRY_MODIFY,
+          StandardWatchEventKinds::ENTRY_DELETE
+        ]
+
+        @watcher ||= FileSystems.getDefault.newWatchService
+        p @watcher.class.name
+        @keys ||= {}
+        path = Paths.get(directory.to_s)
+        key = path.register(@watcher, *event_kinds)
+        @keys[key] = path
+      end
+
+      def _run
+        loop do
+          key = @watcher.take
+          dir = @keys[key]
+          unless dir.nil?
+            key.pollEvents.each do |event|
+              kind = event.kind
+              next if kind == StandardWatchEventKinds::OVERFLOW
+              name = event.context
+              child = dir.resolve(name)
+p child.to_s
+              pathname = Pathname.new(child.to_s).dirname
+              _queue_change(:dir, pathname, '.', recursive: true)
+            end
+          end
+          valid = key.reset
+          unless valid
+            @keys.delete(key)
+            break if @keys.empty?
+          end
+        end
+      end
+
+      def _process_event(dir, event); end
+    end
+  end
+end

spec/lib/listen/adapter/jruby_spec.rb

@@ -0,0 +1,11 @@
+RSpec.describe Listen::Adapter::Jruby do
+  describe 'class' do
+    subject { described_class }
+
+    if jruby?
+      it { should be_usable }
+    else
+      it { should_not be_usable }
+    end
+  end
+end

spec/lib/listen/adapter_spec.rb

@@ -5,6 +5,7 @@
     allow(Listen::Adapter::Darwin).to receive(:usable?) { false }
     allow(Listen::Adapter::Linux).to receive(:usable?) { false }
     allow(Listen::Adapter::Windows).to receive(:usable?) { false }
+    allow(Listen::Adapter::Jruby).to receive(:usable?) { false }
   end
 
   describe '.select' do
@@ -37,6 +38,12 @@
       expect(klass).to eq Listen::Adapter::Windows
     end
 
+    it 'returns JRuby adapter when usable' do
+      allow(Listen::Adapter::Jruby).to receive(:usable?) { true }
+      klass = Listen::Adapter.select
+      expect(klass).to eq Listen::Adapter::Jruby
+    end
+
     context 'no usable adapters' do
       before { allow(Kernel).to receive(:warn) }
 

spec/support/platform_helper.rb

@@ -13,3 +13,7 @@ def bsd?
 def windows?
   RbConfig::CONFIG['target_os'] =~ /mswin|mingw|cygwin/i
 end
+
+def jruby?
+  RUBY_ENGINE == 'jruby'
+end