PYTHON-1169 - Default maxStalenessSeconds is -1.

Author: ajdavis

pymongo/client_options.py

@@ -44,7 +44,7 @@ def _parse_read_preference(options):
 
  mode = options.get('readpreference', 0)
  tags = options.get('readpreferencetags')
- max_staleness = options.get('maxstalenessseconds')
+ max_staleness = options.get('maxstalenessseconds', -1)
  return make_read_preference(mode, tags, max_staleness)
 
 

pymongo/common.py

@@ -292,11 +292,10 @@ def validate_timeout_or_zero(option, value):
 
 
 def validate_max_staleness(option, value):
- """Validates a timeout specified in seconds returning
- a value in floating point seconds.
- """
- if value is None:
- return value
+ """Validates maxStalenessSeconds according to the Max Staleness Spec."""
+ if value == -1 or value == "-1":
+ # Default: No maximum staleness.
+ return -1
  return validate_positive_float(option, value)
 
 

pymongo/max_staleness_selectors.py

@@ -34,6 +34,7 @@
 def _validate_max_staleness(max_staleness,
  heartbeat_frequency,
  idle_write_period):
+ # We checked for max staleness -1 before this, it must be positive here.
  if max_staleness < heartbeat_frequency + idle_write_period:
  raise ConfigurationError(
  "maxStalenessSeconds must be at least heartbeatFrequencyMS +"
@@ -46,7 +47,6 @@ def _validate_max_staleness(max_staleness,
 def _with_primary(max_staleness, selection):
  """Apply max_staleness, in seconds, to a Selection with a known primary."""
  primary = selection.primary
- assert primary
 
  # Server Selection Spec: If the TopologyType is ReplicaSetWithPrimary, a
  # client MUST raise an error if maxStaleness < heartbeatFrequency +
@@ -83,7 +83,6 @@ def _no_primary(max_staleness, selection):
 
  # Secondary we've most recently checked.
  srecent = selection.secondary_with_max_last_update_time()
- assert srecent
 
  sds = []
 
@@ -111,7 +110,7 @@ def _no_primary(max_staleness, selection):
 
 def select(max_staleness, selection):
  """Apply max_staleness, in seconds, to a Selection."""
- if not max_staleness:
+ if max_staleness == -1:
  return selection
 
  if selection.primary:

pymongo/message.py

@@ -82,7 +82,7 @@ def _maybe_add_read_preference(spec, read_preference):
  if mode and (
  mode != ReadPreference.SECONDARY_PREFERRED.mode
  or tag_sets != [{}]
- or max_staleness):
+ or max_staleness != -1):
 
  if "$query" not in spec:
  spec = SON([("$query", spec)])

pymongo/mongo_client.py

@@ -255,7 +255,7 @@ def __init__(
  - `maxStalenessSeconds`: (integer or float) The maximum estimated
  length of time a replica set secondary can fall behind the primary
  in replication before it will no longer be selected for operations.
- Defaults to ``None`` (no limit).
+ Defaults to ``-1``, meaning no maximum.
 
  | **SSL configuration:**
 

pymongo/read_preferences.py

@@ -62,22 +62,22 @@ def _validate_tag_sets(tag_sets):
  return tag_sets
 
 
+# Distinct from the validator in common.py for URI option "maxStalenessSeconds".
 def _validate_max_staleness(max_staleness):
  """Validate max_staleness."""
- if max_staleness is None:
- return 0.0
-
- errmsg = "max_staleness must be an integer or float"
- try:
- max_staleness = float(max_staleness)
- except ValueError:
- raise ValueError(errmsg)
- except TypeError:
- raise TypeError(errmsg)
-
- if not 0 < max_staleness < 1e9:
- raise ValueError(
- "max_staleness must be greater than 0 and less than one billion")
+ if max_staleness != -1:
+ errmsg = "max_staleness must be an integer or float"
+ try:
+ max_staleness = float(max_staleness)
+ except ValueError:
+ raise ValueError(errmsg)
+ except TypeError:
+ raise TypeError(errmsg)
+
+ if not 0 < max_staleness < 1e9:
+ raise ValueError(
+ "max_staleness must be greater than 0"
+ " and less than one billion")
 
  return max_staleness
 
@@ -88,7 +88,7 @@ class _ServerMode(object):
 
  __slots__ = ("__mongos_mode", "__mode", "__tag_sets", "__max_staleness")
 
- def __init__(self, mode, tag_sets=None, max_staleness=None):
+ def __init__(self, mode, tag_sets=None, max_staleness=-1):
  self.__mongos_mode = _MONGOS_MODES[mode]
  self.__mode = mode
  self.__tag_sets = _validate_tag_sets(tag_sets)
@@ -107,7 +107,7 @@ def document(self):
  doc = {'mode': self.__mongos_mode}
  if self.__tag_sets not in (None, [{}]):
  doc['tags'] = self.__tag_sets
- if self.__max_staleness:
+ if self.__max_staleness != -1:
  doc['maxStalenessSeconds'] = self.__max_staleness
  return doc
 
@@ -136,9 +136,7 @@ def tag_sets(self):
  def max_staleness(self):
  """The maximum estimated length of time (in seconds) a replica set
  secondary can fall behind the primary in replication before it will
- no longer be selected for operations."""
- if not self.__max_staleness:
- return None
+ no longer be selected for operations, or -1 for no maximum."""
  return self.__max_staleness
 
  @property
@@ -152,11 +150,11 @@ def min_wire_version(self):
  `min_wire_version`, or the driver raises
  :exc:`~pymongo.errors.ConfigurationError`.
  """
- return 5 if self.__max_staleness else 0
+ return 0 if self.__max_staleness == -1 else 5
 
  def __repr__(self):
  return "%s(tag_sets=%r, max_staleness=%r)" % (
- self.name, self.__tag_sets, self.max_staleness)
+ self.name, self.__tag_sets, self.__max_staleness)
 
  def __eq__(self, other):
  if isinstance(other, _ServerMode):
@@ -182,7 +180,7 @@ def __setstate__(self, value):
  self.__mode = value['mode']
  self.__mongos_mode = _MONGOS_MODES[self.__mode]
  self.__tag_sets = _validate_tag_sets(value['tag_sets'])
- self.__max_staleness = value['max_staleness']
+ self.__max_staleness = _validate_max_staleness(value['max_staleness'])
 
 
 class Primary(_ServerMode):
@@ -227,9 +225,10 @@ class PrimaryPreferred(_ServerMode):
  - `max_staleness`: (integer or float, in seconds) The maximum estimated
  length of time a replica set secondary can fall behind the primary in
  replication before it will no longer be selected for operations.
+ Default -1, meaning no maximum.
  """
 
- def __init__(self, tag_sets=None, max_staleness=None):
+ def __init__(self, tag_sets=None, max_staleness=-1):
  super(PrimaryPreferred, self).__init__(_PRIMARY_PREFERRED,
  tag_sets,
  max_staleness)
@@ -260,9 +259,10 @@ class Secondary(_ServerMode):
  - `max_staleness`: (integer or float, in seconds) The maximum estimated
  length of time a replica set secondary can fall behind the primary in
  replication before it will no longer be selected for operations.
+ Default -1, meaning no maximum.
  """
 
- def __init__(self, tag_sets=None, max_staleness=None):
+ def __init__(self, tag_sets=None, max_staleness=-1):
  super(Secondary, self).__init__(_SECONDARY, tag_sets, max_staleness)
 
  def __call__(self, selection):
@@ -288,9 +288,10 @@ class SecondaryPreferred(_ServerMode):
  - `max_staleness`: (integer or float, in seconds) The maximum estimated
  length of time a replica set secondary can fall behind the primary in
  replication before it will no longer be selected for operations.
+ Default -1, meaning no maximum.
  """
 
- def __init__(self, tag_sets=None, max_staleness=None):
+ def __init__(self, tag_sets=None, max_staleness=-1):
  super(SecondaryPreferred, self).__init__(_SECONDARY_PREFERRED,
  tag_sets,
  max_staleness)
@@ -323,9 +324,10 @@ class Nearest(_ServerMode):
  - `max_staleness`: (integer or float, in seconds) The maximum estimated
  length of time a replica set secondary can fall behind the primary in
  replication before it will no longer be selected for operations.
+ Default -1, meaning no maximum.
  """
 
- def __init__(self, tag_sets=None, max_staleness=None):
+ def __init__(self, tag_sets=None, max_staleness=-1):
  super(Nearest, self).__init__(_NEAREST, tag_sets, max_staleness)
 
  def __call__(self, selection):
@@ -340,12 +342,12 @@ def __call__(self, selection):
  Secondary, SecondaryPreferred, Nearest)
 
 
-def make_read_preference(mode, tag_sets, max_staleness=None):
+def make_read_preference(mode, tag_sets, max_staleness=-1):
  if mode == _PRIMARY:
  if tag_sets not in (None, [{}]):
  raise ConfigurationError("Read preference primary "
  "cannot be combined with tags")
- if max_staleness:
+ if max_staleness != -1:
  raise ConfigurationError("Read preference primary cannot be "
  "combined with maxStalenessSeconds")
  return Primary()

test/test_max_staleness.py

@@ -18,6 +18,7 @@
 import os
 import time
 import sys
+import warnings
 
 sys.path[0:0] = [""]
 
@@ -162,7 +163,7 @@ def run_scenario(self):
  mode_string = pref_def.get('mode', 'primary')
  mode_string = mode_string[:1].lower() + mode_string[1:]
  mode = read_preferences.read_pref_mode_from_name(mode_string)
- max_staleness = pref_def.get('maxStalenessSeconds')
+ max_staleness = pref_def.get('maxStalenessSeconds', -1)
  tag_sets = pref_def.get('tag_sets')
 
  if scenario_def.get('error'):
@@ -224,11 +225,19 @@ def create_tests():
 
 class TestMaxStaleness(unittest.TestCase):
  def test_max_staleness(self):
+ client = MongoClient()
+ self.assertEqual(-1, client.read_preference.max_staleness)
+
+ client = MongoClient("mongodb://a/?readPreference=secondary")
+ self.assertEqual(-1, client.read_preference.max_staleness)
+
  # These tests are specified in max-staleness-tests.rst.
  with self.assertRaises(ConfigurationError):
+ # Default read pref "primary" can't be used with max staleness.
  MongoClient("mongodb://a/?maxStalenessSeconds=120")
 
  with self.assertRaises(ConfigurationError):
+ # Read pref "primary" can't be used with max staleness.
  MongoClient("mongodb://a/?readPreference=primary&"
  "maxStalenessSeconds=120")
 
@@ -240,6 +249,32 @@ def test_max_staleness(self):
  "maxStalenessSeconds=1")
  self.assertEqual(1, client.read_preference.max_staleness)
 
+ client = MongoClient("mongodb://a/?readPreference=secondary&"
+ "maxStalenessSeconds=-1")
+ self.assertEqual(-1, client.read_preference.max_staleness)
+
+ client = MongoClient(maxStalenessSeconds=-1, readPreference="nearest")
+ self.assertEqual(-1, client.read_preference.max_staleness)
+
+ with self.assertRaises(TypeError):
+ # Prohibit None.
+ MongoClient(maxStalenessSeconds=None, readPreference="nearest")
+
+ def test_max_staleness_zero(self):
+ # Zero is too small.
+ with self.assertRaises(ValueError) as ctx:
+ rs_or_single_client(maxStalenessSeconds=0,
+ readPreference="nearest")
+
+ self.assertIn("must be greater than 0", str(ctx.exception))
+
+ with warnings.catch_warnings(record=True) as ctx:
+ warnings.simplefilter("always")
+ MongoClient("mongodb://host/?maxStalenessSeconds=0"
+ "&readPreference=nearest")
+
+ self.assertIn("must be greater than 0", str(ctx[0]))
+
  @client_context.require_version_min(3, 3, 6) # SERVER-8858
  def test_last_write_date(self):
  # From max-staleness-tests.rst, "Parse lastWriteDate".

test/test_topology.py

@@ -710,12 +710,12 @@ def test_no_secondary(self):
 
  self.assertMessage(
  'No replica set members match selector'
- ' "Secondary(tag_sets=None, max_staleness=None)"',
+ ' "Secondary(tag_sets=None, max_staleness=-1)"',
  t, ReadPreference.SECONDARY)
 
  self.assertMessage(
  "No replica set members match selector"
- " \"Secondary(tag_sets=[{'dc': 'ny'}], max_staleness=None)\"",
+ " \"Secondary(tag_sets=[{'dc': 'ny'}], max_staleness=-1)\"",
  t, Secondary(tag_sets=[{'dc': 'ny'}]))
 
  def test_bad_replica_set_name(self):