Nikolay Izhikov created IGNITE-29189:
----------------------------------------
Summary: Read cpMapSnapshot.bin written by builds with the
generated EarliestCheckpointMapSnapshot serializer
Key: IGNITE-29189
URL: https://issues.apache.org/jira/browse/IGNITE-29189
Project: Ignite
Issue Type: Improvement
Reporter: Nikolay Izhikov
h3. Context
IGNITE-29185 made {{EarliestCheckpointMapSnapshot}} write and read
{{cpMapSnapshot.bin}} in the layout used by 2.17 / 2.18 (UUIDs written with
{{writeObject}}).
Builds that contain IGNITE-27775 but not IGNITE-29185 (no release, but
intermediate master builds) wrote the file with the generated
{{EarliestCheckpointMapSnapshotSerializer}}, where UUID map keys and
{{checkpointIds}} elements are written with {{U.writeUuid}} (null flag + two
longs). Such a file can't be read by the current code, so a node upgraded from
one of these builds logs "Failed to unmarshal earliest checkpoint map snapshot"
and rebuilds the earliest checkpoint map.
h3. Proposal
Support both layouts on read: {{readExternal}} reads the payload bytes once,
tries the legacy layout first and, if that fails, re-reads the same bytes with
a copy of the generated code. The legacy parse of a generated-layout payload
fails deterministically ({{StreamCorruptedException}}: the first byte of a
{{U.writeUuid}} UUID is 0x00/0x01, never a valid type code), so the fallback is
safe. Writing stays in the legacy layout.
Covered by {{EarliestCheckpointMapSnapshotSerializationTest}} (round trip,
legacy layout with 2.17 and 2.18 headers, generated layout, empty snapshot) and
{{CheckpointMapSnapshotCompatibilityTest}}.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
