Merge pull request #32 from zopefoundation/support-mysql

Support retry on MySQL databases using pymysql package

CHANGES.rst

@@ -4,7 +4,7 @@ Changes
 1.1 (unreleased)
 ----------------
 
-- Nothing changed yet.
+- Add support to MySQL using pymysql.
 
 
 1.0 (2018-01-31)

mysql.cfg

@@ -0,0 +1,16 @@
+# bin/buildout -c mysql.cfg
+# mysql -u root -e "create database zope_sqlalchemy_tests"
+[buildout]
+extends = buildout.cfg
+parts +=
+    testmysql
+
+[test]
+eggs += pymysql
+
+[testmysql]
+<= test
+environment = mysqlenv
+
+[mysqlenv]
+TEST_DSN = mysql+pymysql:///zope_sqlalchemy_tests

src/zope/sqlalchemy/datamanager.py

@@ -39,6 +39,14 @@
 else:
     _retryable_errors.append((cx_Oracle.DatabaseError, lambda e: e.args[0].code == 8177))
 
+# 1213: Deadlock found when trying to get lock; try restarting transaction
+try:
+    import pymysql
+except ImportError:
+    pass
+else:
+    _retryable_errors.append((pymysql.err.OperationalError, lambda e: e.args[0] == 1213))
+
 # The status of the session is stored on the connection info
 STATUS_ACTIVE = 'active'  # session joined to transaction, writes allowed.
 STATUS_CHANGED = 'changed'  # data has been written