Refactor heap_page_prune_and_freeze() parameters into a struct

heap_page_prune_and_freeze() had accumulated an unwieldy number of input
parameters and upcoming work to handle VM updates in this function will
add even more.

Introduce a new PruneFreezeParams struct to group the function’s input
parameters, improving readability and maintainability.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://postgr.es/m/yn4zp35kkdsjx6wf47zcfmxgexxt4h2og47pvnw2x5ifyrs3qc%407uw6jyyxuyf7

src/backend/access/heap/pruneheap.c

@@ -261,12 +261,18 @@ heap_page_prune_opt(Relation relation, Buffer buffer)
 			PruneFreezeResult presult;
 
 			/*
-			 * For now, pass mark_unused_now as false regardless of whether or
+			 * We don't pass the HEAP_PAGE_PRUNE_MARK_UNUSED_NOW option
-			 * not the relation has indexes, since we cannot safely determine
+			 * regardless of whether or not the relation has indexes, since we
-			 * that during on-access pruning with the current implementation.
+			 * cannot safely determine that during on-access pruning with the
+			 * current implementation.
 			 */
-			heap_page_prune_and_freeze(relation, buffer, vistest, 0,
+			PruneFreezeParams params = {.relation = relation,.buffer = buffer,
-									   NULL, &presult, PRUNE_ON_ACCESS, &dummy_off_loc, NULL, NULL);
+				.reason = PRUNE_ON_ACCESS,.options = 0,
+				.vistest = vistest,.cutoffs = NULL
+			};
+
+			heap_page_prune_and_freeze(&params, &presult, &dummy_off_loc,
+									   NULL, NULL);
 
 			/*
 			 * Report the number of tuples reclaimed to pgstats.  This is
@@ -419,60 +425,44 @@ heap_page_will_freeze(Relation relation, Buffer buffer,
  * also need to account for a reduction in the length of the line pointer
  * array following array truncation by us.
  *
- * If the HEAP_PRUNE_FREEZE option is set, we will also freeze tuples if it's
+ * params contains the input parameters used to control freezing and pruning
- * required in order to advance relfrozenxid / relminmxid, or if it's
+ * behavior. See the definition of PruneFreezeParams for more on what each
- * considered advantageous for overall system performance to do so now.  The
+ * parameter does.
- * 'cutoffs', 'presult', 'new_relfrozen_xid' and 'new_relmin_mxid' arguments
- * are required when freezing.  When HEAP_PRUNE_FREEZE option is set, we also
- * set presult->all_visible and presult->all_frozen on exit, to indicate if
- * the VM bits can be set.  They are always set to false when the
- * HEAP_PRUNE_FREEZE option is not set, because at the moment only callers
- * that also freeze need that information.
  *
- * vistest is used to distinguish whether tuples are DEAD or RECENTLY_DEAD
+ * If the HEAP_PAGE_PRUNE_FREEZE option is set in params, we will freeze
- * (see heap_prune_satisfies_vacuum).
+ * tuples if it's required in order to advance relfrozenxid / relminmxid, or
- *
+ * if it's considered advantageous for overall system performance to do so
- * options:
+ * now.  The 'params.cutoffs', 'presult', 'new_relfrozen_xid' and
- *   MARK_UNUSED_NOW indicates that dead items can be set LP_UNUSED during
+ * 'new_relmin_mxid' arguments are required when freezing.  When
- *   pruning.
+ * HEAP_PAGE_PRUNE_FREEZE option is passed, we also set presult->all_visible
- *
+ * and presult->all_frozen on exit, to indicate if the VM bits can be set.
- *   FREEZE indicates that we will also freeze tuples, and will return
+ * They are always set to false when the HEAP_PAGE_PRUNE_FREEZE option is not
- *   'all_visible', 'all_frozen' flags to the caller.
+ * passed, because at the moment only callers that also freeze need that
- *
+ * information.
- * cutoffs contains the freeze cutoffs, established by VACUUM at the beginning
- * of vacuuming the relation.  Required if HEAP_PRUNE_FREEZE option is set.
- * cutoffs->OldestXmin is also used to determine if dead tuples are
- * HEAPTUPLE_RECENTLY_DEAD or HEAPTUPLE_DEAD.
  *
  * presult contains output parameters needed by callers, such as the number of
  * tuples removed and the offsets of dead items on the page after pruning.
  * heap_page_prune_and_freeze() is responsible for initializing it.  Required
  * by all callers.
  *
- * reason indicates why the pruning is performed.  It is included in the WAL
- * record for debugging and analysis purposes, but otherwise has no effect.
- *
  * off_loc is the offset location required by the caller to use in error
  * callback.
  *
  * new_relfrozen_xid and new_relmin_mxid must provided by the caller if the
- * HEAP_PRUNE_FREEZE option is set.  On entry, they contain the oldest XID and
+ * HEAP_PAGE_PRUNE_FREEZE option is set in params.  On entry, they contain the
- * multi-XID seen on the relation so far.  They will be updated with oldest
+ * oldest XID and multi-XID seen on the relation so far.  They will be updated
- * values present on the page after pruning.  After processing the whole
+ * with oldest values present on the page after pruning.  After processing the
- * relation, VACUUM can use these values as the new relfrozenxid/relminmxid
+ * whole relation, VACUUM can use these values as the new
- * for the relation.
+ * relfrozenxid/relminmxid for the relation.
  */
 void
-heap_page_prune_and_freeze(Relation relation, Buffer buffer,
+heap_page_prune_and_freeze(PruneFreezeParams *params,
-						   GlobalVisState *vistest,
-						   int options,
-						   struct VacuumCutoffs *cutoffs,
 						   PruneFreezeResult *presult,
-						   PruneReason reason,
 						   OffsetNumber *off_loc,
 						   TransactionId *new_relfrozen_xid,
 						   MultiXactId *new_relmin_mxid)
 {
+	Buffer		buffer = params->buffer;
 	Page		page = BufferGetPage(buffer);
 	BlockNumber blockno = BufferGetBlockNumber(buffer);
 	OffsetNumber offnum,
@@ -486,10 +476,11 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 	int64		fpi_before = pgWalUsage.wal_fpi;
 
 	/* Copy parameters to prstate */
-	prstate.vistest = vistest;
+	prstate.vistest = params->vistest;
-	prstate.mark_unused_now = (options & HEAP_PAGE_PRUNE_MARK_UNUSED_NOW) != 0;
+	prstate.mark_unused_now =
-	prstate.attempt_freeze = (options & HEAP_PAGE_PRUNE_FREEZE) != 0;
+		(params->options & HEAP_PAGE_PRUNE_MARK_UNUSED_NOW) != 0;
-	prstate.cutoffs = cutoffs;
+	prstate.attempt_freeze = (params->options & HEAP_PAGE_PRUNE_FREEZE) != 0;
+	prstate.cutoffs = params->cutoffs;
 
 	/*
 	 * Our strategy is to scan the page and make lists of items to change,
@@ -583,7 +574,7 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 	prstate.visibility_cutoff_xid = InvalidTransactionId;
 
 	maxoff = PageGetMaxOffsetNumber(page);
-	tup.t_tableOid = RelationGetRelid(relation);
+	tup.t_tableOid = RelationGetRelid(params->relation);
 
 	/*
 	 * Determine HTSV for all tuples, and queue them up for processing as HOT
@@ -786,7 +777,7 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 	 * Decide if we want to go ahead with freezing according to the freeze
 	 * plans we prepared, or not.
 	 */
-	do_freeze = heap_page_will_freeze(relation, buffer,
+	do_freeze = heap_page_will_freeze(params->relation, buffer,
 									  did_tuple_hint_fpi,
 									  do_prune,
 									  do_hint_prune,
@@ -838,7 +829,7 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 		/*
 		 * Emit a WAL XLOG_HEAP2_PRUNE* record showing what we did
 		 */
-		if (RelationNeedsWAL(relation))
+		if (RelationNeedsWAL(params->relation))
 		{
 			/*
 			 * The snapshotConflictHorizon for the whole record should be the
@@ -876,11 +867,11 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
 			else
 				conflict_xid = prstate.latest_xid_removed;
 
-			log_heap_prune_and_freeze(relation, buffer,
+			log_heap_prune_and_freeze(params->relation, buffer,
 									  InvalidBuffer,	/* vmbuffer */
 									  0,	/* vmflags */
 									  conflict_xid,
-									  true, reason,
+									  true, params->reason,
 									  prstate.frozen, prstate.nfrozen,
 									  prstate.redirected, prstate.nredirected,
 									  prstate.nowdead, prstate.ndead,

src/backend/access/heap/vacuumlazy.c

@@ -1965,7 +1965,10 @@ lazy_scan_prune(LVRelState *vacrel,
 {
 	Relation	rel = vacrel->rel;
 	PruneFreezeResult presult;
-	int			prune_options = 0;
+	PruneFreezeParams params = {.relation = rel,.buffer = buf,
+		.reason = PRUNE_VACUUM_SCAN,.options = HEAP_PAGE_PRUNE_FREEZE,
+		.vistest = vacrel->vistest,.cutoffs = &vacrel->cutoffs
+	};
 
 	Assert(BufferGetBlockNumber(buf) == blkno);
 
@@ -1984,12 +1987,11 @@ lazy_scan_prune(LVRelState *vacrel,
 	 * tuples. Pruning will have determined whether or not the page is
 	 * all-visible.
 	 */
-	prune_options = HEAP_PAGE_PRUNE_FREEZE;
 	if (vacrel->nindexes == 0)
-		prune_options |= HEAP_PAGE_PRUNE_MARK_UNUSED_NOW;
+		params.options |= HEAP_PAGE_PRUNE_MARK_UNUSED_NOW;
 
-	heap_page_prune_and_freeze(rel, buf, vacrel->vistest, prune_options,
+	heap_page_prune_and_freeze(&params,
-							   &vacrel->cutoffs, &presult, PRUNE_VACUUM_SCAN,
+							   &presult,
 							   &vacrel->offnum,
 							   &vacrel->NewRelfrozenXid, &vacrel->NewRelminMxid);
 

src/include/access/heapam.h

@@ -221,6 +221,56 @@ typedef struct HeapPageFreeze
 
 } HeapPageFreeze;
 
+
+/* 'reason' codes for heap_page_prune_and_freeze() */
+typedef enum
+{
+	PRUNE_ON_ACCESS,			/* on-access pruning */
+	PRUNE_VACUUM_SCAN,			/* VACUUM 1st heap pass */
+	PRUNE_VACUUM_CLEANUP,		/* VACUUM 2nd heap pass */
+} PruneReason;
+
+/*
+ * Input parameters to heap_page_prune_and_freeze()
+ */
+typedef struct PruneFreezeParams
+{
+	Relation	relation;		/* relation containing buffer to be pruned */
+	Buffer		buffer;			/* buffer to be pruned */
+
+	/*
+	 * The reason pruning was performed.  It is used to set the WAL record
+	 * opcode which is used for debugging and analysis purposes.
+	 */
+	PruneReason reason;
+
+	/*
+	 * Contains flag bits:
+	 *
+	 * HEAP_PAGE_PRUNE_MARK_UNUSED_NOW indicates that dead items can be set
+	 * LP_UNUSED during pruning.
+	 *
+	 * HEAP_PAGE_PRUNE_FREEZE indicates that we will also freeze tuples, and
+	 * will return 'all_visible', 'all_frozen' flags to the caller.
+	 */
+	int			options;
+
+	/*
+	 * vistest is used to distinguish whether tuples are DEAD or RECENTLY_DEAD
+	 * (see heap_prune_satisfies_vacuum).
+	 */
+	GlobalVisState *vistest;
+
+	/*
+	 * Contains the cutoffs used for freezing. They are required if the
+	 * HEAP_PAGE_PRUNE_FREEZE option is set. cutoffs->OldestXmin is also used
+	 * to determine if dead tuples are HEAPTUPLE_RECENTLY_DEAD or
+	 * HEAPTUPLE_DEAD. Currently only vacuum passes in cutoffs. Vacuum
+	 * calculates them once, at the beginning of vacuuming the relation.
+	 */
+	struct VacuumCutoffs *cutoffs;
+} PruneFreezeParams;
+
 /*
  * Per-page state returned by heap_page_prune_and_freeze()
  */
@@ -264,13 +314,6 @@ typedef struct PruneFreezeResult
 	OffsetNumber deadoffsets[MaxHeapTuplesPerPage];
 } PruneFreezeResult;
 
-/* 'reason' codes for heap_page_prune_and_freeze() */
-typedef enum
-{
-	PRUNE_ON_ACCESS,			/* on-access pruning */
-	PRUNE_VACUUM_SCAN,			/* VACUUM 1st heap pass */
-	PRUNE_VACUUM_CLEANUP,		/* VACUUM 2nd heap pass */
-} PruneReason;
 
 /* ----------------
  *		function prototypes for heap access method
@@ -367,12 +410,8 @@ extern TransactionId heap_index_delete_tuples(Relation rel,
 
 /* in heap/pruneheap.c */
 extern void heap_page_prune_opt(Relation relation, Buffer buffer);
-extern void heap_page_prune_and_freeze(Relation relation, Buffer buffer,
+extern void heap_page_prune_and_freeze(PruneFreezeParams *params,
-									   GlobalVisState *vistest,
-									   int options,
-									   struct VacuumCutoffs *cutoffs,
 									   PruneFreezeResult *presult,
-									   PruneReason reason,
 									   OffsetNumber *off_loc,
 									   TransactionId *new_relfrozen_xid,
 									   MultiXactId *new_relmin_mxid);

src/tools/pgindent/typedefs.list

@@ -2348,6 +2348,7 @@ ProjectionPath
 PromptInterruptContext
 ProtocolVersion
 PrsStorage
+PruneFreezeParams
 PruneFreezeResult
 PruneReason
 PruneState