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