MatrixSynapse/synapse/storage/_base.py

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2014-08-12 16:10:52 +02:00
# -*- coding: utf-8 -*-
# Copyright 2014 matrix.org
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
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import logging
from twisted.internet import defer
from synapse.api.errors import StoreError
import collections
logger = logging.getLogger(__name__)
class SQLBaseStore(object):
def __init__(self, hs):
self.hs = hs
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self._db_pool = hs.get_db_pool()
self._clock = hs.get_clock()
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def cursor_to_dict(self, cursor):
"""Converts a SQL cursor into an list of dicts.
Args:
cursor : The DBAPI cursor which has executed a query.
Returns:
A list of dicts where the key is the column header.
"""
col_headers = list(column[0] for column in cursor.description)
results = list(
dict(zip(col_headers, row)) for row in cursor.fetchall()
)
return results
def _execute(self, decoder, query, *args):
"""Runs a single query for a result set.
Args:
decoder - The function which can resolve the cursor results to
something meaningful.
query - The query string to execute
*args - Query args.
Returns:
The result of decoder(results)
"""
logger.debug(
"[SQL] %s Args=%s Func=%s", query, args, decoder.__name__
)
def interaction(txn):
cursor = txn.execute(query, args)
return decoder(cursor)
return self._db_pool.runInteraction(interaction)
# "Simple" SQL API methods that operate on a single table with no JOINs,
# no complex WHERE clauses, just a dict of values for columns.
def _simple_insert(self, table, values):
"""Executes an INSERT query on the named table.
Args:
table : string giving the table name
values : dict of new column names and values for them
"""
sql = "INSERT INTO %s (%s) VALUES(%s)" % (
table,
", ".join(k for k in values),
", ".join("?" for k in values)
)
def func(txn):
txn.execute(sql, values.values())
return txn.lastrowid
return self._db_pool.runInteraction(func)
def _simple_select_one(self, table, keyvalues, retcols,
allow_none=False):
"""Executes a SELECT query on the named table, which is expected to
return a single row, returning a single column from it.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with
retcols : list of strings giving the names of the columns to return
allow_none : If true, return None instead of failing if the SELECT
statement returns no rows
"""
return self._simple_selectupdate_one(
table, keyvalues, retcols=retcols, allow_none=allow_none
)
@defer.inlineCallbacks
def _simple_select_one_onecol(self, table, keyvalues, retcol,
allow_none=False):
"""Executes a SELECT query on the named table, which is expected to
return a single row, returning a single column from it."
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with
retcol : string giving the name of the column to return
"""
ret = yield self._simple_select_one(
table=table,
keyvalues=keyvalues,
retcols=[retcol],
allow_none=allow_none
)
if ret:
defer.returnValue(ret[retcol])
else:
defer.returnValue(None)
@defer.inlineCallbacks
def _simple_select_onecol(self, table, keyvalues, retcol):
"""Executes a SELECT query on the named table, which returns a list
comprising of the values of the named column from the selected rows.
Args:
table (str): table name
keyvalues (dict): column names and values to select the rows with
retcol (str): column whos value we wish to retrieve.
Returns:
Deferred: Results in a list
"""
sql = "SELECT %(retcol)s FROM %(table)s WHERE %(where)s" % {
"retcol": retcol,
"table": table,
"where": " AND ".join("%s = ?" % k for k in keyvalues.keys()),
}
def func(txn):
txn.execute(sql, keyvalues.values())
return txn.fetchall()
res = yield self._db_pool.runInteraction(func)
defer.returnValue([r[0] for r in res])
def _simple_select_list(self, table, keyvalues, retcols):
"""Executes a SELECT query on the named table, which may return zero or
more rows, returning the result as a list of dicts.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the rows with
retcols : list of strings giving the names of the columns to return
"""
sql = "SELECT %s FROM %s WHERE %s" % (
", ".join(retcols),
table,
" AND ".join("%s = ?" % (k) for k in keyvalues)
)
def func(txn):
txn.execute(sql, keyvalues.values())
return self.cursor_to_dict(txn)
return self._db_pool.runInteraction(func)
def _simple_update_one(self, table, keyvalues, updatevalues,
retcols=None):
"""Executes an UPDATE query on the named table, setting new values for
columns in a row matching the key values.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with
updatevalues : dict giving column names and values to update
retcols : optional list of column names to return
If present, retcols gives a list of column names on which to perform
a SELECT statement *before* performing the UPDATE statement. The values
of these will be returned in a dict.
These are performed within the same transaction, allowing an atomic
get-and-set. This can be used to implement compare-and-set by putting
the update column in the 'keyvalues' dict as well.
"""
return self._simple_selectupdate_one(table, keyvalues, updatevalues,
retcols=retcols)
def _simple_selectupdate_one(self, table, keyvalues, updatevalues=None,
retcols=None, allow_none=False):
""" Combined SELECT then UPDATE."""
if retcols:
select_sql = "SELECT %s FROM %s WHERE %s" % (
", ".join(retcols),
table,
" AND ".join("%s = ?" % (k) for k in keyvalues)
)
if updatevalues:
update_sql = "UPDATE %s SET %s WHERE %s" % (
table,
", ".join("%s = ?" % (k) for k in updatevalues),
" AND ".join("%s = ?" % (k) for k in keyvalues)
)
def func(txn):
ret = None
if retcols:
txn.execute(select_sql, keyvalues.values())
row = txn.fetchone()
if not row:
if allow_none:
return None
raise StoreError(404, "No row found")
if txn.rowcount > 1:
raise StoreError(500, "More than one row matched")
ret = dict(zip(retcols, row))
if updatevalues:
txn.execute(
update_sql,
updatevalues.values() + keyvalues.values()
)
if txn.rowcount == 0:
raise StoreError(404, "No row found")
if txn.rowcount > 1:
raise StoreError(500, "More than one row matched")
return ret
return self._db_pool.runInteraction(func)
def _simple_delete_one(self, table, keyvalues):
"""Executes a DELETE query on the named table, expecting to delete a
single row.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with
"""
sql = "DELETE FROM %s WHERE %s" % (
table,
" AND ".join("%s = ?" % (k) for k in keyvalues)
)
def func(txn):
txn.execute(sql, keyvalues.values())
if txn.rowcount == 0:
raise StoreError(404, "No row found")
if txn.rowcount > 1:
raise StoreError(500, "more than one row matched")
return self._db_pool.runInteraction(func)
def _simple_max_id(self, table):
"""Executes a SELECT query on the named table, expecting to return the
max value for the column "id".
Args:
table : string giving the table name
"""
sql = "SELECT MAX(id) AS id FROM %s" % table
def func(txn):
txn.execute(sql)
max_id = self.cursor_to_dict(txn)[0]["id"]
if max_id is None:
return 0
return max_id
return self._db_pool.runInteraction(func)
class Table(object):
""" A base class used to store information about a particular table.
"""
table_name = None
""" str: The name of the table """
fields = None
""" list: The field names """
EntryType = None
""" Type: A tuple type used to decode the results """
_select_where_clause = "SELECT %s FROM %s WHERE %s"
_select_clause = "SELECT %s FROM %s"
_insert_clause = "INSERT OR REPLACE INTO %s (%s) VALUES (%s)"
@classmethod
def select_statement(cls, where_clause=None):
"""
Args:
where_clause (str): The WHERE clause to use.
Returns:
str: An SQL statement to select rows from the table with the given
WHERE clause.
"""
if where_clause:
return cls._select_where_clause % (
", ".join(cls.fields),
cls.table_name,
where_clause
)
else:
return cls._select_clause % (
", ".join(cls.fields),
cls.table_name,
)
@classmethod
def insert_statement(cls):
return cls._insert_clause % (
cls.table_name,
", ".join(cls.fields),
", ".join(["?"] * len(cls.fields)),
)
@classmethod
def decode_single_result(cls, results):
""" Given an iterable of tuples, return a single instance of
`EntryType` or None if the iterable is empty
Args:
results (list): The results list to convert to `EntryType`
Returns:
EntryType: An instance of `EntryType`
"""
results = list(results)
if results:
return cls.EntryType(*results[0])
else:
return None
@classmethod
def decode_results(cls, results):
""" Given an iterable of tuples, return a list of `EntryType`
Args:
results (list): The results list to convert to `EntryType`
Returns:
list: A list of `EntryType`
"""
return [cls.EntryType(*row) for row in results]
@classmethod
def get_fields_string(cls, prefix=None):
if prefix:
to_join = ("%s.%s" % (prefix, f) for f in cls.fields)
else:
to_join = cls.fields
return ", ".join(to_join)
class JoinHelper(object):
""" Used to help do joins on tables by looking at the tables' fields and
creating a list of unique fields to use with SELECTs and a namedtuple
to dump the results into.
Attributes:
taples (list): List of `Table` classes
EntryType (type)
"""
def __init__(self, *tables):
self.tables = tables
res = []
for table in self.tables:
res += [f for f in table.fields if f not in res]
self.EntryType = collections.namedtuple("JoinHelperEntry", res)
def get_fields(self, **prefixes):
"""Get a string representing a list of fields for use in SELECT
statements with the given prefixes applied to each.
For example::
JoinHelper(PdusTable, StateTable).get_fields(
PdusTable="pdus",
StateTable="state"
)
"""
res = []
for field in self.EntryType._fields:
for table in self.tables:
if field in table.fields:
res.append("%s.%s" % (prefixes[table.__name__], field))
break
return ", ".join(res)
def decode_results(self, rows):
return [self.EntryType(*row) for row in rows]