Subject: [PATCH v2] Repurpose PROC_COPYABLE_FLAGS as PROC_XMIN_FLAGS

From: Alvaro Herrera <[email-masked]>
Date: Sat, 14 May 2022 16:51:23 +0200

This is a slight, convenient semantics change from what commit
0f0cfb494004 introduced that lets us simplify the coding in the one
place where it is used.
---
 src/backend/storage/ipc/procarray.c | 17 +++++++----------
 src/include/storage/proc.h          |  7 +++----
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index ca22336e35..cd58c5faf0 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2685,17 +2685,14 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc)
 		TransactionIdIsNormal(xid) &&
 		TransactionIdPrecedesOrEquals(xid, xmin))
 	{
-		/* Install xmin */
+		/*
+		 * Install xmin and propagate the statusFlags that affect how the
+		 * value is interpreted by vacuum.
+		 */
 		MyProc->xmin = TransactionXmin = xmin;
-
-		/* walsender cheats by passing proc == MyProc, don't check its flags */
-		if (proc != MyProc)
-		{
-			/* Flags being copied must be valid copy-able flags. */
-			Assert((proc->statusFlags & (~PROC_COPYABLE_FLAGS)) == 0);
-			MyProc->statusFlags = proc->statusFlags;
-			ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
-		}
+		MyProc->statusFlags = (MyProc->statusFlags & ~PROC_XMIN_FLAGS) |
+			(proc->statusFlags & PROC_XMIN_FLAGS);
+		ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 
 		result = true;
 	}
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 15be21c00a..2579e619eb 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -69,11 +69,10 @@ struct XidCache
 	(PROC_IN_VACUUM | PROC_IN_SAFE_IC | PROC_VACUUM_FOR_WRAPAROUND)
 
 /*
- * Flags that are valid to copy from another proc, the parallel leader
- * process in practice.  Currently, flags that are set during parallel
- * vacuum and parallel index creation are allowed.
+ * Xmin-related flags. Make sure any flags that affect how the process' Xmin
+ * value is interpreted by VACUUM are included here.
  */
-#define		PROC_COPYABLE_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
+#define		PROC_XMIN_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
 
 /*
  * We allow a small number of "weak" relation locks (AccessShareLock,
-- 
2.30.2

--zgl76stv2tlmzxb2--