Better express platform requirements in s_lock.h. Presently, s_lock.h insists that every platform provide TAS(), and its header comment doesn't say which of the macros a new platform actually needs to supply. The real contract is that a platform must provide either S_LOCK() or a TAS() for the default S_LOCK() to be built on.
To better express that, this commit moves the "no spinlock support" error to where the default S_LOCK() is defined, compiles s_lock() only when the default S_LOCK() is in use, and provides a default TAS_SPIN() only when there is a TAS() to base it on. The direct callers of s_lock() in the spinlock tests are adjusted to match. The header comment is reworked accordingly, dropping the note about pre-9.5 volatile requirements and the caution about TAS() spuriously failing along the way. Co-authored-by: Tom Lane <[email protected]> Discussion: https://postgr.es/m/afkUeI7UhacZ5ZFm%40nathan Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/d9b5a63f49d9d372a6609243eb0e9417a0a35e6f Modified Files -------------- src/backend/storage/lmgr/s_lock.c | 4 +++- src/include/storage/s_lock.h | 46 +++++++++++++++++++-------------------- src/test/regress/regress.c | 2 +- 3 files changed, 26 insertions(+), 26 deletions(-)
