Do not use an extra Thread to read the input with JLine

PullRequest: truffleruby/664

Author: eregon

CHANGELOG.md

@@ -3,6 +3,7 @@
 Bug fixes:
 
 * Implement `rb_io_wait_writable` (#1586).
+* Fixed error when using arrows keys first within `irb` or `pry` (#1478, #1486).
 
 Changes:
 

spec/tags/truffle/irb/arrows_tags.txt

@@ -0,0 +1 @@
+slow:IRB supports using arrow keys first

spec/truffle/irb/arrows_spec.rb

@@ -0,0 +1,30 @@
+# Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved. This
+# code is released under a tri EPL/GPL/LGPL license. You can use it,
+# redistribute it and/or modify it under the terms of the:
+#
+# Eclipse Public License version 1.0, or
+# GNU General Public License version 2, or
+# GNU Lesser General Public License version 2.1.
+
+require_relative '../../ruby/spec_helper'
+
+describe "IRB" do
+  it "supports using arrow keys first" do
+    # --readline is needed otherwise Readline is not used when stdin is not a TTY.
+    IO.popen([*ruby_exe, "-S", "irb", "-f", "--prompt=simple", "--readline"], "r+") do |io|
+      io.gets.should == "Switch to inspect mode.\n"
+
+      io.puts "\e[A" # up arrow
+      # JLine seems to add a bell character
+      [">> \n", ">> \a\n"].should include(io.gets)
+
+      io.puts "22 + 33"
+      # The extra bell character causes a continuation line
+      [">> 22 + 33\n", "?> 22 + 33\n"].should include(io.gets)
+      io.gets.should == "=> 55\n"
+
+      io.puts "exit"
+      io.gets.should == ">> exit\n"
+    end
+  end
+end

src/main/java/org/truffleruby/stdlib/readline/ConsoleHolder.java

@@ -76,10 +76,20 @@ private ConsoleHolder(RubyContext context,
         this.in = new IoStream(context, inFd, inIo);
         this.out = new IoStream(context, outFd, outIo);
 
+        // Disable the creation of a Thread to read the input. We already handle interrupts
+        // natively. See ConsoleReader.setInput() for the logic to determine "nonBlockingEnabled".
+        final String timeout = System.getProperty(ConsoleReader.JLINE_ESC_TIMEOUT);
+        System.setProperty(ConsoleReader.JLINE_ESC_TIMEOUT, "0");
         try {
             readline = new ConsoleReader(in.getIn(), out.getOut());
         } catch (IOException e) {
             throw new UnsupportedOperationException("Couldn't initialize readline", e);
+        } finally {
+            if (timeout == null) {
+                System.clearProperty(ConsoleReader.JLINE_ESC_TIMEOUT);
+            } else {
+                System.setProperty(ConsoleReader.JLINE_ESC_TIMEOUT, timeout);
+            }
         }
 
         readline.setExpandEvents(false);