"""A base class session manager.""" # Copyright (c) IPython Development Team. # Distributed under the terms of the Modified BSD License. import uuid import sqlite3 from tornado import web from IPython.config.configurable import LoggingConfigurable from IPython.utils.py3compat import unicode_type from IPython.utils.traitlets import Instance class SessionManager(LoggingConfigurable): kernel_manager = Instance('IPython.html.services.kernels.kernelmanager.MappingKernelManager') contents_manager = Instance('IPython.html.services.contents.manager.ContentsManager', args=()) # Session database initialized below _cursor = None _connection = None _columns = {'session_id', 'path', 'kernel_id'} @property def cursor(self): """Start a cursor and create a database called 'session'""" if self._cursor is None: self._cursor = self.connection.cursor() self._cursor.execute("""CREATE TABLE session (session_id, path, kernel_id)""") return self._cursor @property def connection(self): """Start a database connection""" if self._connection is None: self._connection = sqlite3.connect(':memory:') self._connection.row_factory = sqlite3.Row return self._connection def __del__(self): """Close connection once SessionManager closes""" self.cursor.close() def session_exists(self, path): """Check to see if the session for a given notebook exists""" self.cursor.execute("SELECT * FROM session WHERE path=?", (path,)) reply = self.cursor.fetchone() if reply is None: return False else: return True def new_session_id(self): "Create a uuid for a new session" return unicode_type(uuid.uuid4()) def create_session(self, path=None, kernel_name=None): """Creates a session and returns its model""" session_id = self.new_session_id() # allow nbm to specify kernels cwd kernel_path = self.contents_manager.get_kernel_path(path=path) kernel_id = self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name) return self.save_session(session_id, path=path, kernel_id=kernel_id) def save_session(self, session_id, path=None, kernel_id=None): """Saves the items for the session with the given session_id Given a session_id (and any other of the arguments), this method creates a row in the sqlite session database that holds the information for a session. Parameters ---------- session_id : str uuid for the session; this method must be given a session_id path : str the path for the given notebook kernel_id : str a uuid for the kernel associated with this session Returns ------- model : dict a dictionary of the session model """ self.cursor.execute("INSERT INTO session VALUES (?,?,?)", (session_id, path, kernel_id) ) return self.get_session(session_id=session_id) def get_session(self, **kwargs): """Returns the model for a particular session. Takes a keyword argument and searches for the value in the session database, then returns the rest of the session's info. Parameters ---------- **kwargs : keyword argument must be given one of the keywords and values from the session database (i.e. session_id, path, kernel_id) Returns ------- model : dict returns a dictionary that includes all the information from the session described by the kwarg. """ if not kwargs: raise TypeError("must specify a column to query") conditions = [] for column in kwargs.keys(): if column not in self._columns: raise TypeError("No such column: %r", column) conditions.append("%s=?" % column) query = "SELECT * FROM session WHERE %s" % (' AND '.join(conditions)) self.cursor.execute(query, list(kwargs.values())) try: row = self.cursor.fetchone() except KeyError: # The kernel is missing, so the session just got deleted. row = None if row is None: q = [] for key, value in kwargs.items(): q.append("%s=%r" % (key, value)) raise web.HTTPError(404, u'Session not found: %s' % (', '.join(q))) return self.row_to_model(row) def update_session(self, session_id, **kwargs): """Updates the values in the session database. Changes the values of the session with the given session_id with the values from the keyword arguments. Parameters ---------- session_id : str a uuid that identifies a session in the sqlite3 database **kwargs : str the key must correspond to a column title in session database, and the value replaces the current value in the session with session_id. """ self.get_session(session_id=session_id) if not kwargs: # no changes return sets = [] for column in kwargs.keys(): if column not in self._columns: raise TypeError("No such column: %r" % column) sets.append("%s=?" % column) query = "UPDATE session SET %s WHERE session_id=?" % (', '.join(sets)) self.cursor.execute(query, list(kwargs.values()) + [session_id]) def row_to_model(self, row): """Takes sqlite database session row and turns it into a dictionary""" if row['kernel_id'] not in self.kernel_manager: # The kernel was killed or died without deleting the session. # We can't use delete_session here because that tries to find # and shut down the kernel. self.cursor.execute("DELETE FROM session WHERE session_id=?", (row['session_id'],)) raise KeyError model = { 'id': row['session_id'], 'notebook': { 'path': row['path'] }, 'kernel': self.kernel_manager.kernel_model(row['kernel_id']) } return model def list_sessions(self): """Returns a list of dictionaries containing all the information from the session database""" c = self.cursor.execute("SELECT * FROM session") result = [] # We need to use fetchall() here, because row_to_model can delete rows, # which messes up the cursor if we're iterating over rows. for row in c.fetchall(): try: result.append(self.row_to_model(row)) except KeyError: pass return result def delete_session(self, session_id): """Deletes the row in the session database with given session_id""" # Check that session exists before deleting session = self.get_session(session_id=session_id) self.kernel_manager.shutdown_kernel(session['kernel']['id']) self.cursor.execute("DELETE FROM session WHERE session_id=?", (session_id,))