I made a new patch (skip_xid_correctly.diff) that incorporates the
points we discussed:
1. Fix the issue that consume_xids consumes nxids+1 XIDs.
2. Update lastxid when calling GetTopFullTransactionId() to support
nxids==1 case.
3. Forbid consume_xids when nxids==0.
4. Add comments explaining the return values of consume_xids and
consume_xids_until, and the rationale for incrementing consumed++ when
GetTopFullTransactionId() is called.
Also, I made another patch (support_blksz_32k.diff) that supports the
block size == 32K case.
Best,
Yushi Ogiwara
diff --git a/src/test/modules/xid_wraparound/xid_wraparound.c b/src/test/modules/xid_wraparound/xid_wraparound.c
index dce81c0c6d..63f3305ee9 100644
--- a/src/test/modules/xid_wraparound/xid_wraparound.c
+++ b/src/test/modules/xid_wraparound/xid_wraparound.c
@@ -26,6 +26,7 @@ static FullTransactionId consume_xids_common(FullTransactionId untilxid, uint64
/*
* Consume the specified number of XIDs.
+ * Returns the last XID assigned by this function.
*/
PG_FUNCTION_INFO_V1(consume_xids);
Datum
@@ -34,11 +35,8 @@ consume_xids(PG_FUNCTION_ARGS)
int64 nxids = PG_GETARG_INT64(0);
FullTransactionId lastxid;
- if (nxids < 0)
+ if (nxids <= 0)
elog(ERROR, "invalid nxids argument: %lld", (long long) nxids);
-
- if (nxids == 0)
- lastxid = ReadNextFullTransactionId();
else
lastxid = consume_xids_common(InvalidFullTransactionId, (uint64) nxids);
@@ -47,6 +45,7 @@ consume_xids(PG_FUNCTION_ARGS)
/*
* Consume XIDs, up to the given XID.
+ * Returns the last XID assigned by this function.
*/
PG_FUNCTION_INFO_V1(consume_xids_until);
Datum
@@ -88,8 +87,15 @@ consume_xids_common(FullTransactionId untilxid, uint64 nxids)
* GetNewTransactionId registers them in the subxid cache in PGPROC, until
* the cache overflows, but beyond that, we don't keep track of the
* consumed XIDs.
+ *
+ * If no top-level XID is assigned, a new one is obtained,
+ * and the consumed XID counter is incremented.
*/
- (void) GetTopTransactionId();
+ if(!FullTransactionIdIsValid(GetTopFullTransactionIdIfAny()))
+ {
+ lastxid = GetTopFullTransactionId();
+ consumed++;
+ }
for (;;)
{
diff --git a/src/test/modules/xid_wraparound/xid_wraparound.c b/src/test/modules/xid_wraparound/xid_wraparound.c
index dce81c0c6d..95832fbecc 100644
--- a/src/test/modules/xid_wraparound/xid_wraparound.c
+++ b/src/test/modules/xid_wraparound/xid_wraparound.c
@@ -64,6 +64,14 @@ consume_xids_until(PG_FUNCTION_ARGS)
PG_RETURN_FULLTRANSACTIONID(lastxid);
}
+/*
+ * These constants copied from .c files, because they're private.
+ */
+#define COMMIT_TS_XACTS_PER_PAGE (BLCKSZ / 10)
+#define SUBTRANS_XACTS_PER_PAGE (BLCKSZ / sizeof(TransactionId))
+#define CLOG_XACTS_PER_BYTE 4
+#define CLOG_XACTS_PER_PAGE (BLCKSZ * CLOG_XACTS_PER_BYTE)
+
/*
* Common functionality between the two public functions.
*/
@@ -115,7 +123,7 @@ consume_xids_common(FullTransactionId untilxid, uint64 nxids)
* If we still have plenty of XIDs to consume, try to take a shortcut
* and bump up the nextXid counter directly.
*/
- if (xids_left > 2000 &&
+ if (xids_left > COMMIT_TS_XACTS_PER_PAGE &&
consumed - last_reported_at < REPORT_INTERVAL &&
MyProc->subxidStatus.overflowed)
{
@@ -153,14 +161,6 @@ consume_xids_common(FullTransactionId untilxid, uint64 nxids)
return lastxid;
}
-/*
- * These constants copied from .c files, because they're private.
- */
-#define COMMIT_TS_XACTS_PER_PAGE (BLCKSZ / 10)
-#define SUBTRANS_XACTS_PER_PAGE (BLCKSZ / sizeof(TransactionId))
-#define CLOG_XACTS_PER_BYTE 4
-#define CLOG_XACTS_PER_PAGE (BLCKSZ * CLOG_XACTS_PER_BYTE)
-
/*
* All the interesting action in GetNewTransactionId happens when we extend
* the SLRUs, or at the uint32 wraparound. If the nextXid counter is not close
