Bug fix for when geven monkey patches are applied.

Author: jonathanslenders

Diff for: examples/gevent-get-input.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+"""
+For testing: test to make sure that everything still works when gevent monkey
+patches are applied.
+"""
+from __future__ import unicode_literals
+from gevent.monkey import patch_all
+from prompt_toolkit.shortcuts import prompt, create_eventloop
+
+
+if __name__ == '__main__':
+    # Apply patches.
+    patch_all()
+
+    # There were some issues in the past when the event loop had an input hook.
+    def dummy_inputhook(*a):
+        pass
+    eventloop = create_eventloop(inputhook=dummy_inputhook)
+
+    # Ask for input.
+    answer = prompt('Give me some input: ', eventloop=eventloop)
+    print('You said: %s' % answer)

Diff for: prompt_toolkit/eventloop/inputhook.py

@@ -24,6 +24,7 @@
 """
 from __future__ import unicode_literals
 import os
+import select
 import threading
 
 __all__ = (
@@ -73,6 +74,14 @@ def thread():
 
         # Flush the read end of the pipe.
         try:
+            # Before calling 'os.read', call select.select. This fixes a bug
+            # with Gevent where the following read call blocked the select call
+            # from the eventloop that we call through 'input_is_ready_func' in
+            # the above thread.
+            # This appears to be only required when gevent.monkey.patch_all()
+            # has been executed. Otherwise it doesn't do much.
+            select.select([self._r], [], [])
+
             os.read(self._r, 1024)
         except OSError:
             # This happens when the window resizes and a SIGWINCH was received.