From 1a2654b32b546d25e39a0c02410049559a3d4573 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Tue, 5 Mar 2024 12:09:18 +0100 Subject: Rework redundant code in subtrans.c When this code was written the duplicity didn't matter, but with all the SLRU-bank stuff we just added, it has become excessive. Turn it into a simpler loop with no code duplication. Also add a test so that this code becomes covered. Discussion: https://postgr.es/m/202403041517.3a35jw53os65@alvherre.pgsql --- src/backend/access/transam/subtrans.c | 29 +++++++---------------------- 1 file changed, 7 insertions(+), 22 deletions(-) (limited to 'src/backend/access/transam/subtrans.c') diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c index dc9566fb51b..50bb1d8cfc5 100644 --- a/src/backend/access/transam/subtrans.c +++ b/src/backend/access/transam/subtrans.c @@ -311,7 +311,7 @@ StartupSUBTRANS(TransactionId oldestActiveXID) FullTransactionId nextXid; int64 startPage; int64 endPage; - LWLock *prevlock; + LWLock *prevlock = NULL; LWLock *lock; /* @@ -324,42 +324,27 @@ StartupSUBTRANS(TransactionId oldestActiveXID) nextXid = TransamVariables->nextXid; endPage = TransactionIdToPage(XidFromFullTransactionId(nextXid)); - prevlock = SimpleLruGetBankLock(SubTransCtl, startPage); - LWLockAcquire(prevlock, LW_EXCLUSIVE); - while (startPage != endPage) + for (;;) { lock = SimpleLruGetBankLock(SubTransCtl, startPage); - - /* - * Check if we need to acquire the lock on the new bank then release - * the lock on the old bank and acquire on the new bank. - */ if (prevlock != lock) { - LWLockRelease(prevlock); + if (prevlock) + LWLockRelease(prevlock); LWLockAcquire(lock, LW_EXCLUSIVE); prevlock = lock; } (void) ZeroSUBTRANSPage(startPage); + if (startPage == endPage) + break; + startPage++; /* must account for wraparound */ if (startPage > TransactionIdToPage(MaxTransactionId)) startPage = 0; } - lock = SimpleLruGetBankLock(SubTransCtl, startPage); - - /* - * Check if we need to acquire the lock on the new bank then release the - * lock on the old bank and acquire on the new bank. - */ - if (prevlock != lock) - { - LWLockRelease(prevlock); - LWLockAcquire(lock, LW_EXCLUSIVE); - } - (void) ZeroSUBTRANSPage(startPage); LWLockRelease(lock); } -- cgit v1.2.3