Modify 'reload' config to be more consistent with existing API

--reload = Runs the reloader with inotify if available and falls back on
           FS polling.
--reload=inotify = Forces the reloader to run with inotify
--reload=poll = Forces the reloader to use FS polling

gunicorn/config.py

@@ -489,6 +489,19 @@ def validate_hostport(val):
     else:
         raise TypeError("Value must consist of: hostname:port")
 
+
+def validate_reloader(val):
+    if val is None:
+        val = 'default'
+
+    choices = ['poll', 'inotify', 'default']
+
+    if val not in choices:
+        raise ConfigError(
+            'Invalid reloader type. Must be one of: %s' % choices
+        )
+
+
 def get_default_config_file():
     config_path = os.path.join(os.path.abspath(os.getcwd()),
             'gunicorn.conf.py')
@@ -806,9 +819,11 @@ class Reload(Setting):
     name = "reload"
     section = 'Debugging'
     cli = ['--reload']
-    validator = validate_bool
-    action = 'store_true'
-    default = False
+    validator = validate_reloader
+    nargs = '?'
+    const = 'default'
+    default = None
+
     desc = '''\
         Restart workers when code changes.
 
@@ -818,24 +833,14 @@ class Reload(Setting):
         The reloader is incompatible with application preloading. When using a
         paste configuration be sure that the server block does not import any
         application code or the reload will not work as designed.
+
+        When using this option, you can optionally specify whether you would
+        like to use file system polling or the kernel's inotify API to watch
+        for changes. Generally, inotify should be preferred if available
+        because it consumes less system resources. If no preference is given,
+        inotify will attempted with a fallback to FS polling.'
         '''
 
-class ReloadInotify(Setting):
-    name = 'inotify'
-    section = 'Debugging'
-    cli = ['--use-inotify']
-    validator = validate_bool
-    action = "store_true"
-    default = False
-
-    desc = '''\
-        When using the 'reload' option, use the kernel's inotify APIs to watch 
-        files instead of polling the filesystem. On many systems this could result
-        in a performance improvement when using 'reload'.
-
-        This setting must be used in conjunction with 'reload' and requires the
-        'inotify' package be installed from PyPI.
-        '''
 
 class Spew(Setting):
     name = "spew"

gunicorn/reloader.py

@@ -60,18 +60,20 @@ try:
 except ImportError:
     has_inotify = False
 
+
 class InotifyReloader():
     def __init__(self, callback=None):
-        raise ImportError('You must have the inotify module installed to use the INotify reloader')
+        raise ImportError('You must have the inotify module installed to use '
+                          'the inotify reloader')
 
 if has_inotify:
 
     class InotifyReloader(threading.Thread):
-        event_mask = (inotify.constants.IN_CREATE | inotify.constants.IN_DELETE 
-                      | inotify.constants.IN_DELETE_SELF | inotify.constants.IN_MODIFY 
-                      | inotify.constants.IN_MOVE_SELF | inotify.constants.IN_MOVED_FROM 
+        event_mask = (inotify.constants.IN_CREATE | inotify.constants.IN_DELETE
+                      | inotify.constants.IN_DELETE_SELF | inotify.constants.IN_MODIFY
+                      | inotify.constants.IN_MOVE_SELF | inotify.constants.IN_MOVED_FROM
                       | inotify.constants.IN_MOVED_TO)
-        
+
         def __init__(self, extra_files=None, callback=None):
             super(InotifyReloader, self).__init__()
             self.setDaemon(True)
@@ -102,14 +104,14 @@ if has_inotify:
 
             for dirname in self._dirs:
                 self._watcher.add_watch(dirname, mask=self.event_mask)
-            
+
             for event in self._watcher.event_gen():
                 if event is None:
                     continue
-                
-                types = event[1]
+
                 filename = event[3]
 
                 self._callback(filename)
 
 
+preferred_reloader = InotifyReloader if has_inotify else Reloader

gunicorn/workers/base.py

@@ -14,7 +14,7 @@ import traceback
 
 from gunicorn import util
 from gunicorn.workers.workertmp import WorkerTmp
-from gunicorn.reloader import Reloader, InotifyReloader, has_inotify
+from gunicorn.reloader import preferred_reloader, Reloader, InotifyReloader
 from gunicorn.http.errors import (
     InvalidHeader, InvalidHeaderName, InvalidRequestLine, InvalidRequestMethod,
     InvalidHTTPVersion, LimitRequestLine, LimitRequestHeaders,
@@ -122,8 +122,14 @@ class Worker(object):
                 self.cfg.worker_int(self)
                 time.sleep(0.1)
                 sys.exit(0)
-            
-            reloader_cls = Reloader if not self.cfg.inotify else InotifyReloader
+
+            if self.cfg.reload == 'poll':
+                reloader_cls = Reloader
+            elif self.cfg.reload == 'inotify':
+                reloader_cls = InotifyReloader
+            else:
+                reloader_cls = preferred_reloader
+
             self.reloader = reloader_cls(callback=changed)
             self.reloader.start()