postgres-github.git / summary / log / commit / refs

commit    dfb690dd52375517138ce1ee0f20a831d9585778
Author:   Alexander Korotkov <akorotkov@postgresql.org>
Date:     Sun May 03 13:21:25 2026 +0000

    Use barrier semantics when reading/writing writtenUpto
    
    The walreceiver publishes its write position lock-free via writtenUpto.
    On weakly-ordered architectures (ARM, PowerPC), both sides of this
    handshake need explicit barriers so that the lock-less reader sees a
    consistent state.
    
    Use pg_atomic_write_membarrier_u64() at both write sites and
    pg_atomic_read_membarrier_u64() in GetWalRcvWriteRecPtr().  This matches
    the barrier semantics that GetWalRcvFlushRecPtr() and other LSN-position
    functions get implicitly from their spinlock acquire/release, and
    protects from bugs caused by expectations of similar barrier guarantees
    from different LSN-position functions.
    
    Reported-by: Andres Freund <andres@anarazel.de>
    Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k%40w4bdf4z3wqoz
    Author: Xuneng Zhou <xunengzhou@gmail.com>
    Reviewed-by: Andres Freund <andres@anarazel.de>
    Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>

[parent: c34a280c85b3]