From 297e698652ac08a9f2e4412a655b6cdd0ece0d8e Mon Sep 17 00:00:00 2001
From: David Christensen <david.christensen@crunchydata.com>
Date: Fri, 19 Jan 2024 12:32:24 -0500
Subject: [PATCH v4 19/22] feature: Teach bloom about PageUsableSpace

---
 contrib/bloom/bloom.h    | 22 +++++++++++-----------
 contrib/bloom/blutils.c  |  4 ++--
 contrib/bloom/blvacuum.c |  2 +-
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index 6d645aa3a2..eadb37aca5 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -106,16 +106,13 @@ typedef struct BloomOptions
 											 * index key */
 } BloomOptions;
 
-/*
- * FreeBlockNumberArray - array of block numbers sized so that metadata fill
- * all space in metapage.
- */
-typedef BlockNumber FreeBlockNumberArray[
-	MAXALIGN_DOWN(
-		PageUsableSpaceMax - MAXALIGN(sizeof(BloomPageOpaqueData))
-		- MAXALIGN(sizeof(uint16) * 2 + sizeof(uint32) + sizeof(BloomOptions))
-		) / sizeof(BlockNumber)
-];
+#define CalcFreeBlockNumberArraySize(usablespace) \
+	(MAXALIGN_DOWN((usablespace) -										\
+				   MAXALIGN(sizeof(BloomPageOpaqueData))				\
+				   - MAXALIGN(sizeof(uint16) * 2 + sizeof(uint32) + sizeof(BloomOptions)) \
+		) / sizeof(BlockNumber) )
+
+typedef BlockNumber FreeBlockNumberArray[FLEXIBLE_ARRAY_MEMBER];
 
 /* Metadata of bloom index */
 typedef struct BloomMetaPageData
@@ -127,11 +124,14 @@ typedef struct BloomMetaPageData
 	FreeBlockNumberArray notFullPage;
 } BloomMetaPageData;
 
+#define SizeOfFreeBlockNumberArray CalcFreeBlockNumberArraySize(PageUsableSpace)
+#define SizeOfBloomMetaPageData (offsetof(BloomMetaPageData,notFullPage) + (SizeOfFreeBlockNumberArray))
+
 /* Magic number to distinguish bloom pages from others */
 #define BLOOM_MAGICK_NUMBER (0xDBAC0DED)
 
 /* Number of blocks numbers fit in BloomMetaPageData */
-#define BloomMetaBlockN		(sizeof(FreeBlockNumberArray) / sizeof(BlockNumber))
+#define BloomMetaBlockN		(SizeOfFreeBlockNumberArray / sizeof(BlockNumber))
 
 #define BloomPageGetMeta(page)	((BloomMetaPageData *) PageGetContents(page))
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6836129c90..f42efa4907 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -432,10 +432,10 @@ BloomFillMetapage(Relation index, Page metaPage)
 	 */
 	BloomInitPage(metaPage, BLOOM_META);
 	metadata = BloomPageGetMeta(metaPage);
-	memset(metadata, 0, sizeof(BloomMetaPageData));
+	memset(metadata, 0, SizeOfBloomMetaPageData);
 	metadata->magickNumber = BLOOM_MAGICK_NUMBER;
 	metadata->opts = *opts;
-	((PageHeader) metaPage)->pd_lower += sizeof(BloomMetaPageData);
+	((PageHeader) metaPage)->pd_lower += SizeOfBloomMetaPageData;
 
 	/* If this fails, probably FreeBlockNumberArray size calc is wrong: */
 	Assert(((PageHeader) metaPage)->pd_lower <= ((PageHeader) metaPage)->pd_upper);
diff --git a/contrib/bloom/blvacuum.c b/contrib/bloom/blvacuum.c
index 0998240fea..b22e1fb15b 100644
--- a/contrib/bloom/blvacuum.c
+++ b/contrib/bloom/blvacuum.c
@@ -37,7 +37,7 @@ blbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 	Relation	index = info->index;
 	BlockNumber blkno,
 				npages;
-	FreeBlockNumberArray notFullPage;
+	BlockNumber notFullPage[CalcFreeBlockNumberArraySize(PageUsableSpaceMax)];
 	int			countPage = 0;
 	BloomState	state;
 	Buffer		buffer;
-- 
2.40.1