fixes #8565 - only get unique, unused message/source IDs to speed up expiry
(cherry picked from commit 9fde85ad830031d38a6786d30a48519344dad446)
fixes #8565 - only get unique, unused message/source IDs to speed up expiry
(cherry picked from commit 9fde85ad830031d38a6786d30a48519344dad446)