From 90507185357391a661cd856fc231b140079c8d78 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 29 Jan 2021 22:34:23 -0300 Subject: [PATCH v2 1/3] add pg_atomic_monotonic_advance_u64 --- src/include/port/atomics.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/src/include/port/atomics.h b/src/include/port/atomics.h index 856338f161..752f39d66e 100644 --- a/src/include/port/atomics.h +++ b/src/include/port/atomics.h @@ -519,6 +519,25 @@ pg_atomic_sub_fetch_u64(volatile pg_atomic_uint64 *ptr, int64 sub_) return pg_atomic_sub_fetch_u64_impl(ptr, sub_); } +static inline void +pg_atomic_monotonic_advance_u64(volatile pg_atomic_uint64 *ptr, uint64 target_) +{ +#ifndef PG_HAVE_ATOMIC_U64_SIMULATION + AssertPointerAlignment(ptr, 8); +#endif + /* FIXME is this algorithm correct if we have u64 simulation? */ + while (true) + { + uint64 currval; + + currval = pg_atomic_read_u64(ptr); + if (currval > target_) + break; /* already done by somebody else */ + if (pg_atomic_compare_exchange_u64(ptr, &currval, target_)) + break; /* successfully done */ + } +} + #undef INSIDE_ATOMICS_H #endif /* ATOMICS_H */ -- 2.20.1