First stab at ConfigManager class

IPython/html/services/config/manager.py

@@ -0,0 +1,87 b''
+"""Manager to read and modify frontend config data in JSON files.
+"""
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+import errno
+import io
+import json
+import os
+
+from IPython.config import LoggingConfigurable
+from IPython.utils.py3compat import PY3
+from IPython.utils.traitlets import Unicode
+
+
+def recursive_update(target, new):
+    """Recursively update one dictionary using another.
+
+    None values will delete their keys.
+    """
+    for k, v in new.items():
+        if isinstance(v, dict):
+            if k not in target:
+                target[k] = {}
+            recursive_update(target[k], v)
+            if not target[k]:
+                # Prune empty subdicts
+                del target[k]
+
+        elif v is None:
+            target.pop(k, None)
+
+        else:
+            target[k] = v
+
+
+class ConfigManager(LoggingConfigurable):
+    profile_dir = Unicode()
+
+    @property
+    def config_dir(self):
+        return os.path.join(self.profile_dir, 'nbconfig')
+
+    def ensure_config_dir_exists(self):
+        try:
+            os.mkdir(self.config_dir, 0o755)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+    def file_name(self, section_name):
+        return os.path.join(self.config_dir, section_name+'.json')
+
+    def get(self, section_name):
+        """Retrieve the config data for the specified section.
+
+        Returns the data as a dictionary, or an empty dictionary if the file
+        doesn't exist.
+        """
+        filename = self.file_name(section_name)
+        if os.path.isfile(filename):
+            with io.open(filename, encoding='utf-8') as f:
+                return json.load(f)
+        else:
+            return {}
+
+    def set(self, section_name, data):
+        """Store the given config data.
+        """
+        filename = self.file_name(section_name)
+        self.ensure_config_dir_exists()
+
+        if PY3:
+            f = io.open(filename, 'w', encoding='utf-8')
+        else:
+            f = open(filename, 'wb')
+        with f:
+            json.dump(data, f)
+
+    def update(self, section_name, new_data):
+        """Modify the config section by recursively updating it with new_data.
+
+        Returns the modified config data as a dictionary.
+        """
+        data = self.get(section_name)
+        recursive_update(data, new_data)
+        self.set(section_name, data)
+        return data

IPython/html/base/handlers.py

@@ -175,6 +175,10 b' class IPythonHandler(AuthenticatedHandler):'
     def kernel_spec_manager(self):
         return self.settings['kernel_spec_manager']
 
+    @property
+    def config_manager(self):
+        return self.settings['config_manager']
+
     #---------------------------------------------------------------
     # CORS
     #---------------------------------------------------------------

IPython/html/notebookapp.py

@@ -125,19 +125,21 b' def load_handlers(name):'
 class NotebookWebApplication(web.Application):
 
     def __init__(self, ipython_app, kernel_manager, contents_manager,
-                 cluster_manager, session_manager, kernel_spec_manager, log,
+                 cluster_manager, session_manager, kernel_spec_manager,
+                 config_manager, log,
                  base_url, default_url, settings_overrides, jinja_env_options):
 
         settings = self.init_settings(
             ipython_app, kernel_manager, contents_manager, cluster_manager,
-            session_manager, kernel_spec_manager, log, base_url, default_url,
-            settings_overrides, jinja_env_options)
+            session_manager, kernel_spec_manager, config_manager, log, base_url,
+            default_url, settings_overrides, jinja_env_options)
         handlers = self.init_handlers(settings)
 
         super(NotebookWebApplication, self).__init__(handlers, **settings)
 
     def init_settings(self, ipython_app, kernel_manager, contents_manager,
                       cluster_manager, session_manager, kernel_spec_manager,
+                      config_manager,
                       log, base_url, default_url, settings_overrides,
                       jinja_env_options=None):
 
@@ -172,6 +174,7 b' class NotebookWebApplication(web.Application):'
             cluster_manager=cluster_manager,
             session_manager=session_manager,
             kernel_spec_manager=kernel_spec_manager,
+            config_manager=config_manager,
 
             # IPython stuff
             nbextensions_path = ipython_app.nbextensions_path,
@@ -607,6 +610,11 b' class NotebookApp(BaseIPythonApplication):'
         help='The cluster manager class to use.'
     )
 
+    config_manager_class = DottedObjectName('IPython.html.services.config.manager.ConfigManager',
+        config = True,
+        help='The config manager class to use'
+    )
+
     kernel_spec_manager = Instance(KernelSpecManager)
 
     def _kernel_spec_manager_default(self):
@@ -722,6 +730,10 b' class NotebookApp(BaseIPythonApplication):'
         self.cluster_manager = kls(parent=self, log=self.log)
         self.cluster_manager.update_profiles()
 
+        kls = import_item(self.config_manager_class)
+        self.config_manager = kls(parent=self, log=self.log,
+                                  profile_dir=self.profile_dir.location)
+
     def init_logging(self):
         # This prevents double log messages because tornado use a root logger that
         # self.log is a child of. The logging module dipatches log messages to a log
@@ -747,6 +759,7 b' class NotebookApp(BaseIPythonApplication):'
         self.web_app = NotebookWebApplication(
             self, self.kernel_manager, self.contents_manager,
             self.cluster_manager, self.session_manager, self.kernel_spec_manager,
+            self.config_manager,
             self.log, self.base_url, self.default_url, self.tornado_settings,
             self.jinja_environment_options
         )

IPython/html/services/config/handlers.py

@@ -11,85 +11,27 b' from tornado import web'
 from IPython.utils.py3compat import PY3
 from ...base.handlers import IPythonHandler, json_errors
 
-def recursive_update(target, new):
-    """Recursively update one dictionary using another.
-    
-    None values will delete their keys.
-    """
-    for k, v in new.items():
-        if isinstance(v, dict):
-            if k not in target:
-                target[k] = {}
-            recursive_update(target[k], v)
-            if not target[k]:
-                # Prune empty subdicts
-                del target[k]
-
-        elif v is None:
-            target.pop(k, None)
-
-        else:
-            target[k] = v
-
 class ConfigHandler(IPythonHandler):
     SUPPORTED_METHODS = ('GET', 'PUT', 'PATCH')
 
-    @property
-    def config_dir(self):
-        return os.path.join(self.profile_dir, 'nbconfig')
-
-    def ensure_config_dir_exists(self):
-        try:
-            os.mkdir(self.config_dir, 0o755)
-        except OSError as e:
-            if e.errno != errno.EEXIST:
-                raise
-
-    def file_name(self, section_name):
-        return os.path.join(self.config_dir, section_name+'.json')
-
     @web.authenticated
     @json_errors
     def get(self, section_name):
         self.set_header("Content-Type", 'application/json')
-        filename = self.file_name(section_name)
-        if os.path.isfile(filename):
-            with io.open(filename, encoding='utf-8') as f:
-                self.finish(f.read())
-        else:
-            self.finish("{}")
+        self.finish(json.dumps(self.config_manager.get(section_name)))
 
     @web.authenticated
     @json_errors
     def put(self, section_name):
-        self.get_json_body()  # Will raise 400 if content is not valid JSON
-        filename = self.file_name(section_name)
-        self.ensure_config_dir_exists()
-        with open(filename, 'wb') as f:
-            f.write(self.request.body)
+        data = self.get_json_body()  # Will raise 400 if content is not valid JSON
+        self.config_manager.set(section_name, data)
         self.set_status(204)
 
     @web.authenticated
     @json_errors
     def patch(self, section_name):
-        filename = self.file_name(section_name)
-        if os.path.isfile(filename):
-            with io.open(filename, encoding='utf-8') as f:
-                section = json.load(f)
-        else:
-            section = {}
-
-        update = self.get_json_body()
-        recursive_update(section, update)
-
-        self.ensure_config_dir_exists()
-        if PY3:
-            f = io.open(filename, 'w', encoding='utf-8')
-        else:
-            f = open(filename, 'wb')
-        with f:
-            json.dump(section, f)
-
+        new_data = self.get_json_body()
+        section = self.config_manager.update(section_name, new_data)
         self.finish(json.dumps(section))