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PYTHON-4960 More informative error message for stale primary #2115

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Merged
merged 5 commits into from
Mar 5, 2025
Merged

PYTHON-4960 More informative error message for stale primary #2115

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309b1a3
PYTHON-4960 Add tests
ShaneHarvey Jan 31, 2025
372b364
PYTHON-4960 Add more information to ServerDescriptions when marking a…
ShaneHarvey Jan 31, 2025
2057ae7
PYTHON-4960 Resync tests
ShaneHarvey Feb 4, 2025
0c2a667
Merge branch 'master' into PYTHON-4960
ShaneHarvey Mar 4, 2025
d722993
PYTHON-4960 Apply test changes to async
ShaneHarvey Mar 4, 2025
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18 changes: 14 additions & 4 deletions pymongo/topology_description.py
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@
from bson.min_key import MinKey
from bson.objectid import ObjectId
from pymongo import common
from pymongo.errors import ConfigurationError
from pymongo.errors import ConfigurationError, PyMongoError
from pymongo.read_preferences import ReadPreference, _AggWritePref, _ServerMode
from pymongo.server_description import ServerDescription
from pymongo.server_selectors import Selection
Expand Down Expand Up @@ -563,7 +563,11 @@ def _update_rs_from_primary(
if None not in new_election_tuple:
if None not in max_election_tuple and new_election_tuple < max_election_tuple:
# Stale primary, set to type Unknown.
sds[server_description.address] = server_description.to_unknown()
sds[server_description.address] = server_description.to_unknown(
PyMongoError(
f"primary marked stale due to electionId/setVersion mismatch, {new_election_tuple} is stale compared to {max_election_tuple}"
)
)
return _check_has_primary(sds), replica_set_name, max_set_version, max_election_id
max_election_id = server_description.election_id

Expand All @@ -578,7 +582,11 @@ def _update_rs_from_primary(
max_election_safe = tuple(MinKey() if i is None else i for i in max_election_tuple)
if new_election_safe < max_election_safe:
# Stale primary, set to type Unknown.
sds[server_description.address] = server_description.to_unknown()
sds[server_description.address] = server_description.to_unknown(
PyMongoError(
f"primary marked stale due to electionId/setVersion mismatch, {new_election_tuple} is stale compared to {max_election_tuple}"
)
)
return _check_has_primary(sds), replica_set_name, max_set_version, max_election_id
else:
max_election_id = server_description.election_id
Expand All @@ -591,7 +599,9 @@ def _update_rs_from_primary(
and server.address != server_description.address
):
# Reset old primary's type to Unknown.
sds[server.address] = server.to_unknown()
sds[server.address] = server.to_unknown(
PyMongoError("primary marked stale due to discovery of newer primary")
)

# There can be only one prior primary.
break
Expand Down
3 changes: 3 additions & 0 deletions test/asynchronous/test_discovery_and_monitoring.py
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,9 @@ def check_outcome(self, topology, outcome):
server_type_name(expected_server_type),
server_type_name(actual_server_description.server_type),
)
expected_error = expected_server.get("error")
if expected_error:
self.assertIn(expected_error, str(actual_server_description.error))

self.assertEqual(expected_server.get("setName"), actual_server_description.replica_set_name)

Expand Down
3 changes: 2 additions & 1 deletion test/discovery_and_monitoring/rs/new_primary.json
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,8 @@
"servers": {
"a:27017": {
"type": "Unknown",
"setName": null
"setName": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
6 changes: 4 additions & 2 deletions test/discovery_and_monitoring/rs/new_primary_new_electionid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down Expand Up @@ -123,7 +124,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to electionId/setVersion mismatch"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
6 changes: 4 additions & 2 deletions test/discovery_and_monitoring/rs/new_primary_new_setversion.json
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down Expand Up @@ -123,7 +124,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to electionId/setVersion mismatch"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
4 changes: 3 additions & 1 deletion test/discovery_and_monitoring/rs/primary_disconnect_electionid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down Expand Up @@ -124,6 +125,7 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"error": "primary marked stale due to electionId/setVersion mismatch",
"electionId": null
},
"b:27017": {
Expand Down
4 changes: 3 additions & 1 deletion test/discovery_and_monitoring/rs/primary_disconnect_setversion.json
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down Expand Up @@ -124,6 +125,7 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"error": "primary marked stale due to electionId/setVersion mismatch",
"electionId": null
},
"b:27017": {
Expand Down
3 changes: 2 additions & 1 deletion test/discovery_and_monitoring/rs/setversion_greaterthan_max_without_electionid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
3 changes: 2 additions & 1 deletion test/discovery_and_monitoring/rs/setversion_without_electionid-pre-6.0.json
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
6 changes: 4 additions & 2 deletions test/discovery_and_monitoring/rs/use_setversion_without_electionid-pre-6.0.json
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to discovery of newer primary"
},
"b:27017": {
"type": "RSPrimary",
Expand Down Expand Up @@ -117,7 +118,8 @@
"a:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to electionId/setVersion mismatch"
},
"b:27017": {
"type": "RSPrimary",
Expand Down
6 changes: 4 additions & 2 deletions test/discovery_and_monitoring/rs/use_setversion_without_electionid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,8 @@
"b:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to electionId/setVersion mismatch"
}
},
"topologyType": "ReplicaSetWithPrimary",
Expand Down Expand Up @@ -128,7 +129,8 @@
"b:27017": {
"type": "Unknown",
"setName": null,
"electionId": null
"electionId": null,
"error": "primary marked stale due to electionId/setVersion mismatch"
}
},
"topologyType": "ReplicaSetWithPrimary",
Expand Down
3 changes: 3 additions & 0 deletions test/test_discovery_and_monitoring.py
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,9 @@ def check_outcome(self, topology, outcome):
server_type_name(expected_server_type),
server_type_name(actual_server_description.server_type),
)
expected_error = expected_server.get("error")
if expected_error:
self.assertIn(expected_error, str(actual_server_description.error))

self.assertEqual(expected_server.get("setName"), actual_server_description.replica_set_name)

Expand Down
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