Add progress indicators when spawning

- Uses JupyterHub 0.9 feature, no effect for <0.9.
- Closes: #81

.travis.yml

@@ -31,6 +31,7 @@ install:
     - if [ $JHUB_VER != "master" -a $JHUB_VER != "0.9.0b2" ]; then pip install "tornado<5.0"; fi
     - pip install --pre -f travis-wheels/wheelhouse -r jupyterhub/dev-requirements.txt
     - pip install --pre -e jupyterhub
+    - pip install --pre -f travis-wheels/wheelhouse -r requirements.txt
 
 script:
     - travis_retry py.test --lf --cov batchspawner batchspawner/tests -v

batchspawner/batchspawner.py

@@ -17,11 +17,18 @@
 """
 import pwd
 import os
+import sys
 
 import xml.etree.ElementTree as ET
 
 from jinja2 import Template
 
+# For the progress method of JupyterHub 0.9, requiring Python 3.5+.
+# If not supported, don't support it which is OK.
+if sys.version_info >= (3, 5):
+    import asyncio
+    from async_generator import async_generator, yield_, yield_from_
+
 from tornado import gen
 from tornado.process import Subprocess
 from subprocess import CalledProcessError
@@ -394,6 +401,27 @@ def stop(self, now=False):
                              self.job_id, self.current_ip, self.port)
                 )
 
+    # The progress method is only supported on JupyterHub 0.9, which
+    # only supports Python 3.5+.  It requires asyncio coroutines.
+    if sys.version_info >= (3, 5):
+        @async_generator
+        async def progress(self):
+            while True:
+                if self.state_ispending():
+                    await yield_({
+                        "message": "Pending in queue...",
+                    })
+                elif self.state_isrunning():
+                    await yield_({
+                        "message": "Cluster job running... waiting to connect",
+                    })
+                    return
+                else:
+                    await yield_({
+                        "message": "Unknown status...",
+                    })
+                await gen.sleep(.1)
+
 import re
 
 class BatchSpawnerRegexStates(BatchSpawnerBase):

requirements.txt

@@ -1,2 +1,3 @@
+async_generator>=1.8; python_version >= '3.5'
 jinja2
 jupyterhub>=0.5