do_upgrade_config_with_bytes drops step 9 (wait-for-checkpoint,
restart_requested=1, cbuf_put stop signal) -- materialization now
happens entirely via task 5's apply_committed_entry WAL_CONFIG_MARKER
case on every member's own apply, no restart required. Confirmed
do_upgrade_config_with_bytes was the sole production setter of
restart_requested; cluster.c's read of it is now permanently
false-for-this-trigger, which is the intended behavior.
Adds xce_upgrade_marker_committed_hook (#ifdef XCE_TESTING, mirrors
xce_snapshot_chunk_hook's nullable-function-pointer shape), firing
right after config_commit_change succeeds -- a deterministic seam for
later leadership-change fault injection (task 8.7) at exactly the
marker-commit-to-every-member-installed window. NULL by default, true
no-op in production.
Task 7 of 19.
Requirements: 1.2, 1.3, 1.4, 2.2, 5.4, 6.3
Rongsong Shen
41af05402d