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-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-#
-# Copyright 2014-2015 Canonical Limited.
-#
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
-#
-#
-# Authors:
-# Kapil Thangavelu <kapil.foss@gmail.com>
-#
-"""
-Intro
------
-
-A simple way to store state in units. This provides a key value
-storage with support for versioned, transactional operation,
-and can calculate deltas from previous values to simplify unit logic
-when processing changes.
-
-
-Hook Integration
-----------------
-
-There are several extant frameworks for hook execution, including
-
- - charmhelpers.core.hookenv.Hooks
- - charmhelpers.core.services.ServiceManager
-
-The storage classes are framework agnostic, one simple integration is
-via the HookData contextmanager. It will record the current hook
-execution environment (including relation data, config data, etc.),
-setup a transaction and allow easy access to the changes from
-previously seen values. One consequence of the integration is the
-reservation of particular keys ('rels', 'unit', 'env', 'config',
-'charm_revisions') for their respective values.
-
-Here's a fully worked integration example using hookenv.Hooks::
-
- from charmhelper.core import hookenv, unitdata
-
- hook_data = unitdata.HookData()
- db = unitdata.kv()
- hooks = hookenv.Hooks()
-
- @hooks.hook
- def config_changed():
- # Print all changes to configuration from previously seen
- # values.
- for changed, (prev, cur) in hook_data.conf.items():
- print('config changed', changed,
- 'previous value', prev,
- 'current value', cur)
-
- # Get some unit specific bookeeping
- if not db.get('pkg_key'):
- key = urllib.urlopen('https://example.com/pkg_key').read()
- db.set('pkg_key', key)
-
- # Directly access all charm config as a mapping.
- conf = db.getrange('config', True)
-
- # Directly access all relation data as a mapping
- rels = db.getrange('rels', True)
-
- if __name__ == '__main__':
- with hook_data():
- hook.execute()
-
-
-A more basic integration is via the hook_scope context manager which simply
-manages transaction scope (and records hook name, and timestamp)::
-
- >>> from unitdata import kv
- >>> db = kv()
- >>> with db.hook_scope('install'):
- ... # do work, in transactional scope.
- ... db.set('x', 1)
- >>> db.get('x')
- 1
-
-
-Usage
------
-
-Values are automatically json de/serialized to preserve basic typing
-and complex data struct capabilities (dicts, lists, ints, booleans, etc).
-
-Individual values can be manipulated via get/set::
-
- >>> kv.set('y', True)
- >>> kv.get('y')
- True
-
- # We can set complex values (dicts, lists) as a single key.
- >>> kv.set('config', {'a': 1, 'b': True'})
-
- # Also supports returning dictionaries as a record which
- # provides attribute access.
- >>> config = kv.get('config', record=True)
- >>> config.b
- True
-
-
-Groups of keys can be manipulated with update/getrange::
-
- >>> kv.update({'z': 1, 'y': 2}, prefix="gui.")
- >>> kv.getrange('gui.', strip=True)
- {'z': 1, 'y': 2}
-
-When updating values, its very helpful to understand which values
-have actually changed and how have they changed. The storage
-provides a delta method to provide for this::
-
- >>> data = {'debug': True, 'option': 2}
- >>> delta = kv.delta(data, 'config.')
- >>> delta.debug.previous
- None
- >>> delta.debug.current
- True
- >>> delta
- {'debug': (None, True), 'option': (None, 2)}
-
-Note the delta method does not persist the actual change, it needs to
-be explicitly saved via 'update' method::
-
- >>> kv.update(data, 'config.')
-
-Values modified in the context of a hook scope retain historical values
-associated to the hookname.
-
- >>> with db.hook_scope('config-changed'):
- ... db.set('x', 42)
- >>> db.gethistory('x')
- [(1, u'x', 1, u'install', u'2015-01-21T16:49:30.038372'),
- (2, u'x', 42, u'config-changed', u'2015-01-21T16:49:30.038786')]
-
-"""
-
-import collections
-import contextlib
-import datetime
-import itertools
-import json
-import os
-import pprint
-import sqlite3
-import sys
-
-__author__ = 'Kapil Thangavelu <kapil.foss@gmail.com>'
-
-
-class Storage(object):
- """Simple key value database for local unit state within charms.
-
- Modifications are not persisted unless :meth:`flush` is called.
-
- To support dicts, lists, integer, floats, and booleans values
- are automatically json encoded/decoded.
- """
- def __init__(self, path=None):
- self.db_path = path
- if path is None:
- if 'UNIT_STATE_DB' in os.environ:
- self.db_path = os.environ['UNIT_STATE_DB']
- else:
- self.db_path = os.path.join(
- os.environ.get('CHARM_DIR', ''), '.unit-state.db')
- self.conn = sqlite3.connect('%s' % self.db_path)
- self.cursor = self.conn.cursor()
- self.revision = None
- self._closed = False
- self._init()
-
- def close(self):
- if self._closed:
- return
- self.flush(False)
- self.cursor.close()
- self.conn.close()
- self._closed = True
-
- def get(self, key, default=None, record=False):
- self.cursor.execute('select data from kv where key=?', [key])
- result = self.cursor.fetchone()
- if not result:
- return default
- if record:
- return Record(json.loads(result[0]))
- return json.loads(result[0])
-
- def getrange(self, key_prefix, strip=False):
- """
- Get a range of keys starting with a common prefix as a mapping of
- keys to values.
-
- :param str key_prefix: Common prefix among all keys
- :param bool strip: Optionally strip the common prefix from the key
- names in the returned dict
- :return dict: A (possibly empty) dict of key-value mappings
- """
- self.cursor.execute("select key, data from kv where key like ?",
- ['%s%%' % key_prefix])
- result = self.cursor.fetchall()
-
- if not result:
- return {}
- if not strip:
- key_prefix = ''
- return dict([
- (k[len(key_prefix):], json.loads(v)) for k, v in result])
-
- def update(self, mapping, prefix=""):
- """
- Set the values of multiple keys at once.
-
- :param dict mapping: Mapping of keys to values
- :param str prefix: Optional prefix to apply to all keys in `mapping`
- before setting
- """
- for k, v in mapping.items():
- self.set("%s%s" % (prefix, k), v)
-
- def unset(self, key):
- """
- Remove a key from the database entirely.
- """
- self.cursor.execute('delete from kv where key=?', [key])
- if self.revision and self.cursor.rowcount:
- self.cursor.execute(
- 'insert into kv_revisions values (?, ?, ?)',
- [key, self.revision, json.dumps('DELETED')])
-
- def unsetrange(self, keys=None, prefix=""):
- """
- Remove a range of keys starting with a common prefix, from the database
- entirely.
-
- :param list keys: List of keys to remove.
- :param str prefix: Optional prefix to apply to all keys in ``keys``
- before removing.
- """
- if keys is not None:
- keys = ['%s%s' % (prefix, key) for key in keys]
- self.cursor.execute('delete from kv where key in (%s)' % ','.join(['?'] * len(keys)), keys)
- if self.revision and self.cursor.rowcount:
- self.cursor.execute(
- 'insert into kv_revisions values %s' % ','.join(['(?, ?, ?)'] * len(keys)),
- list(itertools.chain.from_iterable((key, self.revision, json.dumps('DELETED')) for key in keys)))
- else:
- self.cursor.execute('delete from kv where key like ?',
- ['%s%%' % prefix])
- if self.revision and self.cursor.rowcount:
- self.cursor.execute(
- 'insert into kv_revisions values (?, ?, ?)',
- ['%s%%' % prefix, self.revision, json.dumps('DELETED')])
-
- def set(self, key, value):
- """
- Set a value in the database.
-
- :param str key: Key to set the value for
- :param value: Any JSON-serializable value to be set
- """
- serialized = json.dumps(value)
-
- self.cursor.execute('select data from kv where key=?', [key])
- exists = self.cursor.fetchone()
-
- # Skip mutations to the same value
- if exists:
- if exists[0] == serialized:
- return value
-
- if not exists:
- self.cursor.execute(
- 'insert into kv (key, data) values (?, ?)',
- (key, serialized))
- else:
- self.cursor.execute('''
- update kv
- set data = ?
- where key = ?''', [serialized, key])
-
- # Save
- if not self.revision:
- return value
-
- self.cursor.execute(
- 'select 1 from kv_revisions where key=? and revision=?',
- [key, self.revision])
- exists = self.cursor.fetchone()
-
- if not exists:
- self.cursor.execute(
- '''insert into kv_revisions (
- revision, key, data) values (?, ?, ?)''',
- (self.revision, key, serialized))
- else:
- self.cursor.execute(
- '''
- update kv_revisions
- set data = ?
- where key = ?
- and revision = ?''',
- [serialized, key, self.revision])
-
- return value
-
- def delta(self, mapping, prefix):
- """
- return a delta containing values that have changed.
- """
- previous = self.getrange(prefix, strip=True)
- if not previous:
- pk = set()
- else:
- pk = set(previous.keys())
- ck = set(mapping.keys())
- delta = DeltaSet()
-
- # added
- for k in ck.difference(pk):
- delta[k] = Delta(None, mapping[k])
-
- # removed
- for k in pk.difference(ck):
- delta[k] = Delta(previous[k], None)
-
- # changed
- for k in pk.intersection(ck):
- c = mapping[k]
- p = previous[k]
- if c != p:
- delta[k] = Delta(p, c)
-
- return delta
-
- @contextlib.contextmanager
- def hook_scope(self, name=""):
- """Scope all future interactions to the current hook execution
- revision."""
- assert not self.revision
- self.cursor.execute(
- 'insert into hooks (hook, date) values (?, ?)',
- (name or sys.argv[0],
- datetime.datetime.utcnow().isoformat()))
- self.revision = self.cursor.lastrowid
- try:
- yield self.revision
- self.revision = None
- except:
- self.flush(False)
- self.revision = None
- raise
- else:
- self.flush()
-
- def flush(self, save=True):
- if save:
- self.conn.commit()
- elif self._closed:
- return
- else:
- self.conn.rollback()
-
- def _init(self):
- self.cursor.execute('''
- create table if not exists kv (
- key text,
- data text,
- primary key (key)
- )''')
- self.cursor.execute('''
- create table if not exists kv_revisions (
- key text,
- revision integer,
- data text,
- primary key (key, revision)
- )''')
- self.cursor.execute('''
- create table if not exists hooks (
- version integer primary key autoincrement,
- hook text,
- date text
- )''')
- self.conn.commit()
-
- def gethistory(self, key, deserialize=False):
- self.cursor.execute(
- '''
- select kv.revision, kv.key, kv.data, h.hook, h.date
- from kv_revisions kv,
- hooks h
- where kv.key=?
- and kv.revision = h.version
- ''', [key])
- if deserialize is False:
- return self.cursor.fetchall()
- return map(_parse_history, self.cursor.fetchall())
-
- def debug(self, fh=sys.stderr):
- self.cursor.execute('select * from kv')
- pprint.pprint(self.cursor.fetchall(), stream=fh)
- self.cursor.execute('select * from kv_revisions')
- pprint.pprint(self.cursor.fetchall(), stream=fh)
-
-
-def _parse_history(d):
- return (d[0], d[1], json.loads(d[2]), d[3],
- datetime.datetime.strptime(d[-1], "%Y-%m-%dT%H:%M:%S.%f"))
-
-
-class HookData(object):
- """Simple integration for existing hook exec frameworks.
-
- Records all unit information, and stores deltas for processing
- by the hook.
-
- Sample::
-
- from charmhelper.core import hookenv, unitdata
-
- changes = unitdata.HookData()
- db = unitdata.kv()
- hooks = hookenv.Hooks()
-
- @hooks.hook
- def config_changed():
- # View all changes to configuration
- for changed, (prev, cur) in changes.conf.items():
- print('config changed', changed,
- 'previous value', prev,
- 'current value', cur)
-
- # Get some unit specific bookeeping
- if not db.get('pkg_key'):
- key = urllib.urlopen('https://example.com/pkg_key').read()
- db.set('pkg_key', key)
-
- if __name__ == '__main__':
- with changes():
- hook.execute()
-
- """
- def __init__(self):
- self.kv = kv()
- self.conf = None
- self.rels = None
-
- @contextlib.contextmanager
- def __call__(self):
- from charmhelpers.core import hookenv
- hook_name = hookenv.hook_name()
-
- with self.kv.hook_scope(hook_name):
- self._record_charm_version(hookenv.charm_dir())
- delta_config, delta_relation = self._record_hook(hookenv)
- yield self.kv, delta_config, delta_relation
-
- def _record_charm_version(self, charm_dir):
- # Record revisions.. charm revisions are meaningless
- # to charm authors as they don't control the revision.
- # so logic dependnent on revision is not particularly
- # useful, however it is useful for debugging analysis.
- charm_rev = open(
- os.path.join(charm_dir, 'revision')).read().strip()
- charm_rev = charm_rev or '0'
- revs = self.kv.get('charm_revisions', [])
- if charm_rev not in revs:
- revs.append(charm_rev.strip() or '0')
- self.kv.set('charm_revisions', revs)
-
- def _record_hook(self, hookenv):
- data = hookenv.execution_environment()
- self.conf = conf_delta = self.kv.delta(data['conf'], 'config')
- self.rels = rels_delta = self.kv.delta(data['rels'], 'rels')
- self.kv.set('env', dict(data['env']))
- self.kv.set('unit', data['unit'])
- self.kv.set('relid', data.get('relid'))
- return conf_delta, rels_delta
-
-
-class Record(dict):
-
- __slots__ = ()
-
- def __getattr__(self, k):
- if k in self:
- return self[k]
- raise AttributeError(k)
-
-
-class DeltaSet(Record):
-
- __slots__ = ()
-
-
-Delta = collections.namedtuple('Delta', ['previous', 'current'])
-
-
-_KV = None
-
-
-def kv():
- global _KV
- if _KV is None:
- _KV = Storage()
- return _KV