Implement support for transactional variables and a test suite for it.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@13752 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/TransactionalVariable.py

+##############################################################################
+#
+# Copyright (c) 2007 Nexedi SA and Contributors. All Rights Reserved.
+#                    Yoshinori Okuji <yo@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+#
+##############################################################################
+
+r"""This module provides an interface for transactional variables.
+
+Transactional variables are data slots which can store arbitrary values
+during a transaction. Transactional variables are guaranteed to vanish
+when a transaction finishes or aborts, and specific to a single thread and
+a single transaction. They are never shared by different threads.
+
+Transactional variables are different from user-defined data in a REQUEST
+object, in the sense that one request may execute multiple transactions, but
+not vice versa. If data should persist beyond a transaction, but must not
+persist over a single request, you should use a REQUEST object instead of
+transactional variables.
+
+Also, transactional variables are different from volatile attributes,
+because transactional variables may not disappear within a transaction.
+
+The constraint is that each key must be hashable, so that it can be used
+as a key to a dictionary.
+
+Example::
+
+  from Products.ERP5Type.TransactionalVariable import getTransactionalVariable
+  tv = getTransactionalVariable()
+  try:
+    toto = tv['toto']
+  except KeyError:
+    toto = tv['toto'] = getToto()
+"""
+
+from UserDict import IterableUserDict
+from Shared.DC.ZRDB.TM import TM
+from threading import local
+
+class TransactionalVariable(TM, IterableUserDict):
+  """TransactionalVariable provides a dict-like look-n-feel.
+  This class must not be used directly outside.
+  """
+  def _begin(self, *ignored):
+    """It is required to attach this instance to somewhere in
+    ZODB so that _finish or _abort will be called at the end
+    of a transaction. A portal object is used at the moment."""
+    # Is there any other way to retrieve a portal object?
+    from Products.ERP5Type.Utils import get_request
+    portal = get_request()['PARENTS'].getPortalObject()
+    portal._v_erp5_transactional_variable = self
+
+  def _finish(self, *ignored):
+    self.clear()
+
+  def _abort(self, *ignored):
+    self.clear()
+
+  def __setitem__(self, key, value):
+    IterableUserDict.__setitem__(self, key, value)
+    self._register()
+
+transactional_variable_pool = local()
+
+def getTransactionalVariable():
+  """Return a transactional variable."""
+  try:
+    return transactional_variable_pool.instance
+  except AttributeError:
+    transactional_variable_pool.instance = TransactionalVariable()
+    return transactional_variable_pool.instance

product/ERP5Type/tests/testTransactionalVariable.py

+##############################################################################
+#
+# Copyright (c) 2007 Nexedi SARL and Contributors. All Rights Reserved.
+#                    Yoshinori Okuji <yo@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+
+import os
+import sys
+if __name__ == '__main__':
+  execfile(os.path.join(sys.path[0], 'framework.py'))
+
+# Needed in order to have a log file inside the current folder
+os.environ['EVENT_LOG_FILE'] = os.path.join(os.getcwd(), 'zLOG.log')
+os.environ['EVENT_LOG_SEVERITY'] = '-300'
+
+from Testing import ZopeTestCase
+from Products.ERP5Type.tests.ERP5TypeTestCase import ERP5TypeTestCase
+from zLOG import LOG
+from Products.CMFCore.tests.base.testcase import LogInterceptor
+from Products.ERP5Type.TransactionalVariable import getTransactionalVariable
+
+try:
+  from transaction import get as get_transaction
+except ImportError:
+  pass
+
+class TestTransactionalVariable(ERP5TypeTestCase, LogInterceptor):
+    run_all_test = 1
+    quiet = 1
+
+    # Some helper methods
+
+    def getTitle(self):
+      return "Transactional Variable"
+
+    def getBusinessTemplateList(self):
+      """
+        Return the list of business templates.
+      """
+      return ()
+
+    def afterSetUp(self):
+      self.login()
+
+    def test_01_DictInterface(self, quiet=quiet, run=run_all_test):
+      """Check if a transaction variable behaves in the same way as a dict.
+      """
+      if not run: return
+      if not quiet:
+        message = 'Test Dict Interface'
+        ZopeTestCase._print('\n '+message)
+        LOG('Testing... ', 0, message)
+
+      tv = getTransactionalVariable()
+      self.failIfEqual(tv, None)
+
+      # Test frequently used dict methods. This does not cover everything,
+      # but should be enough.
+      tv.clear()
+      self.failUnlessEqual(len(tv), 0)
+      self.failUnlessRaises(KeyError, tv.__getitem__, 'toto')
+
+      tv['toto'] = 'titi'
+      self.failUnlessEqual(len(tv), 1)
+      self.failUnlessEqual(tv['toto'], 'titi')
+
+      self.failUnlessEqual(tv.get('foo'), None)
+      tv.setdefault('foo', 'bar')
+      self.failUnlessEqual(len(tv), 2)
+      self.failUnlessEqual(tv['foo'], 'bar')
+
+      self.failUnless('foo' in tv)
+      del tv['foo']
+      self.failIf('foo' in tv)
+      self.failUnlessEqual(len(tv), 1)
+
+    def test_02_Expiration(self, quiet=quiet, run=run_all_test):
+      """Check if a transaction variable does not persist over multiple
+      transactions.
+      """
+      if not run: return
+      if not quiet:
+        message = 'Test Expiration'
+        ZopeTestCase._print('\n '+message)
+        LOG('Testing... ', 0, message)
+
+      tv = getTransactionalVariable()
+      self.failIfEqual(tv, None)
+
+      tv.clear()
+      self.failUnlessEqual(len(tv), 0)
+
+      # Commit and check.
+      tv['toto'] = 'titi'
+      self.failUnlessEqual(tv['toto'], 'titi')
+      get_transaction().commit()
+      self.failIf('toto' in tv)
+
+      # Abort and check.
+      tv['toto'] = 'titi'
+      self.failUnlessEqual(tv['toto'], 'titi')
+      get_transaction().abort()
+      self.failIf('toto' in tv)
+
+    def test_03_Durability(self, quiet=quiet, run=run_all_test):
+      """Check if a transaction variable does not disappear within the same
+      transaction.
+      """
+      if not run: return
+      if not quiet:
+        message = 'Test Durability'
+        ZopeTestCase._print('\n '+message)
+        LOG('Testing... ', 0, message)
+
+      tv = getTransactionalVariable()
+      self.failIfEqual(tv, None)
+
+      tv.clear()
+      self.failUnlessEqual(len(tv), 0)
+
+      # Set both a transaction variable and a volatile attribute,
+      # in order to detect the difference between their behaviors.
+      tv['toto'] = 'titi'
+      self.failUnlessEqual(tv['toto'], 'titi')
+      portal = self.getPortal()
+      vattr = '_v_erp5type_test_durability'
+      setattr(portal, vattr, 'dummy')
+      self.failUnlessEqual(getattr(portal, vattr), 'dummy')
+
+      # Force to minimize the connection cache so that volatile attributes
+      # and unghostified objects are discarded.
+      portal._p_jar.cacheMinimize()
+      self.failUnless('toto' in tv)
+      self.failUnlessEqual(tv['toto'], 'titi')
+      self.failUnlessEqual(getattr(portal, vattr, None), None)
+
+if __name__ == '__main__':
+  framework()
+else:
+  import unittest
+  def test_suite():
+    suite = unittest.TestSuite()
+    suite.addTest(unittest.makeSuite(TestTransactionalVariable))
+    return suite