Add "ABI_compatibility" regions to wait_event_names.txt The current design behind the automatic generation of the C code and documentation related to wait events introduced in fa88928470b5 does not offer a way to attach new wait events without breaking ABI compatibility, as all the events are forcibly reordered for each section in the input file wait_event_names.txt. Adding new wait events to stable branches is something that has happened in the past, 0b6517a3b79a being a recent example of that with VERSION_FILE_SYNC, so we need a way to generate any C code for wait events while maintaining compatibility on stable branches already released.
This commit solves this issue by adding a new region called "ABI_compatibility" (keyword could be updated to something else if someone had a better idea) to each section of wait_event_names.txt, so as one can add new wait events to stable branches in wait_event_names.txt while keeping the code ABI-compatible. "ABI_compatibility" has no impact on the documentation generated: all the wait events of one section are still alphabetically ordered. LWLock and Lock sections generate their C code elsewhere, so they do not need an "ABI_compatibility" region. For example, let's imagine a wait_event_names.txt like that: Section: ClassName - Foo FOO_1 "Waiting in Foo 1" FOO_2 "Waiting in Foo 2" ABI_compatibility: NEW_FOO_1 "Waiting in New Foo 1" NEW_BAR_1 "Waiting in New Bar 1" This results in the following enum, where the events in the ABI region are listed last with the same ordering as in wait_event_names.txt: typedef enum { WAIT_EVENT_FOO_1, WAIT_EVENT_FOO_2, WAIT_EVENT_NEW_FOO_1, WAIT_EVENT_NEW_BAR_1 } WaitEventFoo; New wait events added in stable branches should be added at the end of each ABI_compatibility region, and ABI_compatibility should remain empty on HEAD and unreleased stable branches. This design has been suggested by Noah Misch and me. Reported-by: Noah Misch Author: Bertrand Drouvot Reviewed-by: Michael Paquier Discussion: https://postgr.es/m/20240317183114...@rfd.leadboat.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/f98dbdeb51d1175c07258cd2bd4b56f560dfc3cf Modified Files -------------- .../utils/activity/generate-wait_event_types.pl | 28 +++++++++++++++++++++- src/backend/utils/activity/wait_event_names.txt | 18 ++++++++++++++ 2 files changed, 45 insertions(+), 1 deletion(-)