Update WAL buffers when restoring WAL at compute needed for LR (#325)

* Update WAL buffers when restoring WAL at compute needed for LR * Fix copying data in WAL buffers --------- Co-authored-by: Konstantin Knizhnik <[email protected]>
neondatabase · Nov 8, 2023 · 0bb356a · 0bb356a
1 parent 23b502f
commit 0bb356a
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diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -13755,3 +13755,29 @@ XLogRequestWalReceiverReply(void)
 {
 	doRequestWalReceiverReply = true;
 }
+
+void
+XLogUpdateWalBuffers(char* data, XLogRecPtr start, size_t len)
+{
+	XLogRecPtr end;
+	int idx;
+	XLogRecPtr pagebegptr;
+
+	LWLockAcquire(WALBufMappingLock, LW_EXCLUSIVE);
+
+	end = start + len;
+	idx = XLogRecPtrToBufIdx(end);
+	pagebegptr = XLogCtl->xlblocks[idx] - XLOG_BLCKSZ;
+
+	if (pagebegptr + XLOG_BLCKSZ >= end && pagebegptr < end)
+	{
+		/* Last page of the segment is present in WAL buffers */
+		char* page = &XLogCtl->pages[idx * XLOG_BLCKSZ];
+		size_t overlap = end - pagebegptr;
+		if (overlap <= len)
+			memcpy(page, data + len - overlap, overlap);
+		else
+			memcpy(page + overlap - len, data, len);
+	}
+	LWLockRelease(WALBufMappingLock);
+}
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
@@ -377,6 +377,8 @@ extern void SetWalWriterSleeping(bool sleeping);
 extern void StartupRequestWalReceiverRestart(void);
 extern void XLogRequestWalReceiverReply(void);
 
+extern void XLogUpdateWalBuffers(char* data, XLogRecPtr start, size_t len);
+
 extern void assign_max_wal_size(int newval, void *extra);
 extern void assign_checkpoint_completion_target(double newval, void *extra);