Add MySQL driver

Change-Id: Ia10be91f8985d4e2159437ad94096a690ee84dc3

setup-mysql-env.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+set -x -e
+
+. functions.sh
+
+clean_exit () {
+    local error_code="$?"
+    kill $(jobs -p)
+    rm -rf ${MYSQL_DATA}
+    return $error_code
+}
+
+wait_for_line () {
+    while read line
+    do
+        echo "$line" | grep -q "$1" && break
+    done < "$2"
+    # Read the fifo for ever otherwise process would block
+    cat "$2" >/dev/null &
+}
+
+trap "clean_exit" EXIT
+
+# On systems like Fedora here's where mysqld can be found
+export PATH=$PATH:/usr/libexec
+
+# Start MySQL process for tests
+MYSQL_DATA=`mktemp -d /tmp/tooz-mysql-XXXXX`
+mkfifo ${MYSQL_DATA}/out
+mysqld --datadir=${MYSQL_DATA} --pid-file=${MYSQL_DATA}/mysql.pid --socket=${MYSQL_DATA}/mysql.socket --skip-networking --skip-grant-tables &> ${MYSQL_DATA}/out &
+# Wait for MySQL to start listening to connections
+wait_for_line "mysqld: ready for connections." ${MYSQL_DATA}/out
+mysql -S ${MYSQL_DATA}/mysql.socket -e 'CREATE DATABASE test;'
+export TOOZ_TEST_MYSQL_URL="mysql://root@localhost/test?unix_socket=${MYSQL_DATA}/mysql.socket"
+
+# Yield execution to venv command
+$*

setup.cfg

@@ -31,6 +31,7 @@ tooz.backends =
     ipc = tooz.drivers.ipc:IPCDriver
     redis = tooz.drivers.redis:RedisDriver
     postgresql = tooz.drivers.pgsql:PostgresDriver
+    mysql = tooz.drivers.mysql:MySQLDriver
 
 [build_sphinx]
 all_files = 1

test-requirements.txt

@@ -10,3 +10,4 @@ testscenarios>=0.4
 coverage>=3.6
 sysv_ipc>=0.6.8
 psycopg2
+pymysql

tooz/drivers/mysql.py

@@ -0,0 +1,126 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright © 2014 eNovance
+#
+# Author: Julien Danjou <julien@danjou.info>
+#
+# 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.
+import pymysql
+
+import tooz
+from tooz import coordination
+from tooz.drivers import _retry
+from tooz import locking
+from tooz import utils
+
+
+class MySQLLock(locking.Lock):
+    """A MySQL based lock."""
+
+    def __init__(self, name, connection):
+        super(MySQLLock, self).__init__(name)
+        self._conn = connection
+
+    def acquire(self, blocking=True):
+        if blocking is False:
+            try:
+                cur = self._conn.cursor()
+                cur.execute("SELECT GET_LOCK(%s, 0);", self.name)
+                # Can return NULL on error
+                if cur.fetchone()[0] is 1:
+                    return True
+                return False
+            except pymysql.MySQLError as e:
+                raise coordination.ToozError(utils.exception_message(e))
+        else:
+            def _acquire():
+                try:
+                    cur = self._conn.cursor()
+                    cur.execute("SELECT GET_LOCK(%s, 0);", self.name)
+                    if cur.fetchone()[0] is 1:
+                        return True
+                except pymysql.MySQLError as e:
+                    raise coordination.ToozError(utils.exception_message(e))
+                raise _retry.Retry
+            kwargs = _retry.RETRYING_KWARGS.copy()
+            if blocking is not True:
+                kwargs['stop_max_delay'] = blocking
+            return _retry.Retrying(**kwargs).call(_acquire)
+
+    def release(self):
+        try:
+            cur = self._conn.cursor()
+            cur.execute("SELECT RELEASE_LOCK(%s);", self.name)
+            return cur.fetchone()[0]
+        except pymysql.MySQLError as e:
+            raise coordination.ToozError(utils.exception_message(e))
+
+
+class MySQLDriver(coordination.CoordinationDriver):
+
+    def __init__(self, member_id, parsed_url, options):
+        """Initialize the MySQL driver."""
+        super(MySQLDriver, self).__init__()
+        self._host = parsed_url.netloc
+        self._port = parsed_url.port
+        self._dbname = parsed_url.path[1:]
+        self._username = parsed_url.username
+        self._password = parsed_url.password
+        self._unix_socket = options.get("unix_socket", [None])[-1]
+
+    def _start(self):
+        try:
+            if self._unix_socket:
+                self._conn = pymysql.Connect(unix_socket=self._unix_socket,
+                                             port=self._port,
+                                             user=self._username,
+                                             passwd=self._password,
+                                             database=self._dbname)
+            else:
+                self._conn = pymysql.Connect(host=self._host,
+                                             port=self._port,
+                                             user=self._username,
+                                             passwd=self._password,
+                                             database=self._dbname)
+        except pymysql.err.OperationalError as e:
+            raise coordination.ToozConnectionError(utils.exception_message(e))
+
+    def _stop(self):
+        self._conn.close()
+
+    def get_lock(self, name):
+        return MySQLLock(name, self._conn)
+
+    @staticmethod
+    def watch_join_group(group_id, callback):
+        raise tooz.NotImplemented
+
+    @staticmethod
+    def unwatch_join_group(group_id, callback):
+        raise tooz.NotImplemented
+
+    @staticmethod
+    def watch_leave_group(group_id, callback):
+        raise tooz.NotImplemented
+
+    @staticmethod
+    def unwatch_leave_group(group_id, callback):
+        raise tooz.NotImplemented
+
+    @staticmethod
+    def watch_elected_as_leader(group_id, callback):
+        raise tooz.NotImplemented
+
+    @staticmethod
+    def unwatch_elected_as_leader(group_id, callback):
+        raise tooz.NotImplemented

tooz/tests/test_coordination.py

@@ -35,6 +35,8 @@ class TestAPI(testscenarios.TestWithScenarios,
         ('ipc', {'url': 'ipc://'}),
         ('redis', {'url': 'redis://localhost:6379?timeout=5'}),
         ('postgresql', {'url': os.getenv("TOOZ_TEST_PGSQL_URL")}),
+        ('mysql', {'url': os.getenv("TOOZ_TEST_MYSQL_URL"),
+                   'bad_url': 'mysql://localhost:1'}),
     ]
 
     # Only certain drivers have the tested support for timeouts that we test
@@ -78,6 +80,14 @@ class TestAPI(testscenarios.TestWithScenarios,
         self._coord.stop()
         super(TestAPI, self).tearDown()
 
+    def test_connection_error(self):
+        if not hasattr(self, "bad_url"):
+            raise testcase.TestSkipped("No bad URL provided")
+        coord = tooz.coordination.get_coordinator(self.bad_url,
+                                                  self.member_id)
+        self.assertRaises(tooz.coordination.ToozConnectionError,
+                          coord.start)
+
     def test_stop_first(self):
         c = tooz.coordination.get_coordinator(self.url,
                                               self.member_id)

tox.ini

@@ -82,6 +82,9 @@ deps = {[testenv:py34]deps}
 basepython = python3.4
 commands = {toxinidir}/setup-postgresql-env.sh python setup.py testr --slowest --testr-args="{posargs}"
 
+[testenv:py27-mysql]
+commands = {toxinidir}/setup-mysql-env.sh python setup.py testr --slowest --testr-args="{posargs}"
+
 [testenv:cover]
 commands = python setup.py testr --slowest --coverage --testr-args="{posargs}"