Bitmapsets as Nodes

From 61bd436b8312115cd6b6c56d8801cb15c1c341c2 Mon Sep 17 00:00:00 2001
From: amitlan <amitlangote09@gmail.com>
Date: Thu, 6 Oct 2022 17:31:37 +0900
Subject: [PATCH v1] Allow adding Bitmapsets as Nodes into plan trees

Note that this only adds some infrastructure bits and none of the
existing bitmapsets that are added to plan trees have been changed
to instead add the Node version.  So, the plan trees, or really the
bitmapsets contained in them, look the same as before as far as
Node write/read functionality is concerned.

This is needed, because it is not currently possible to write and
then read back Bitmapsets that are not direct members of write/read
capable Nodes; for example, if one needs to add a List of Bitmapsets
to a plan tree.  The most straightforward way to do that is to make
Bitmapsets be written with outNode() and read with nodeRead().
---
 src/backend/nodes/Makefile            |  3 ++-
 src/backend/nodes/copyfuncs.c         | 11 +++++++++++
 src/backend/nodes/equalfuncs.c        |  6 ++++++
 src/backend/nodes/gen_node_support.pl |  1 +
 src/backend/nodes/outfuncs.c          | 11 +++++++++++
 src/backend/nodes/readfuncs.c         |  4 ++++
 src/include/nodes/bitmapset.h         |  5 +++++
 src/include/nodes/meson.build         |  1 +
 8 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/backend/nodes/Makefile b/src/backend/nodes/Makefile
index 7450e191ee..da5307771b 100644
--- a/src/backend/nodes/Makefile
+++ b/src/backend/nodes/Makefile
@@ -57,7 +57,8 @@ node_headers = \
 	nodes/replnodes.h \
 	nodes/supportnodes.h \
 	nodes/value.h \
-	utils/rel.h
+	utils/rel.h \
+	nodes/bitmapset.h
 
 # see also catalog/Makefile for an explanation of these make rules
 
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e76fda8eba..1482019327 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -160,6 +160,17 @@ _copyExtensibleNode(const ExtensibleNode *from)
 	return newnode;
 }
 
+/* Custom copy routine for Node bitmapsets */
+static Bitmapset *
+_copyBitmapset(const Bitmapset *from)
+{
+	Bitmapset *newnode = bms_copy(from);
+
+	newnode->type = T_Bitmapset;
+
+	return newnode;
+}
+
 
 /*
  * copyObjectImpl -- implementation of copyObject(); see nodes/nodes.h
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 0373aa30fe..e8706c461a 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -210,6 +210,12 @@ _equalList(const List *a, const List *b)
 	return true;
 }
 
+/* Custom equal routine for Node bitmapsets */
+static bool
+_equalBitmapset(const Bitmapset *a, const Bitmapset *b)
+{
+	return bms_equal(a, b);
+}
 
 /*
  * equal
diff --git a/src/backend/nodes/gen_node_support.pl b/src/backend/nodes/gen_node_support.pl
index 81b8c184a9..ccb5aff874 100644
--- a/src/backend/nodes/gen_node_support.pl
+++ b/src/backend/nodes/gen_node_support.pl
@@ -71,6 +71,7 @@ my @all_input_files = qw(
   nodes/supportnodes.h
   nodes/value.h
   utils/rel.h
+  nodes/bitmapset.h
 );
 
 # Nodes from these input files are automatically treated as nodetag_only.
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 64c65f060b..b3ffd8cec2 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -328,6 +328,17 @@ outBitmapset(StringInfo str, const Bitmapset *bms)
 	appendStringInfoChar(str, ')');
 }
 
+/* Custom write routine for Node bitmapsets */
+static void
+_outBitmapset(StringInfo str, const Bitmapset *bms)
+{
+	Assert(IsA(bms, Bitmapset));
+	WRITE_NODE_TYPE("BITMAPSET");
+
+	outBitmapset(str, bms);
+}
+
+
 /*
  * Print the value of a Datum given its type.
  */
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index b4ff855f7c..a5372a6a60 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -230,6 +230,10 @@ _readBitmapset(void)
 		result = bms_add_member(result, val);
 	}
 
+	/* Matches what _copyBitmapset() does. */
+	if (result)
+		result->type = T_Bitmapset;
+
 	return result;
 }
 
diff --git a/src/include/nodes/bitmapset.h b/src/include/nodes/bitmapset.h
index 75b5ce1a8e..9046ca177f 100644
--- a/src/include/nodes/bitmapset.h
+++ b/src/include/nodes/bitmapset.h
@@ -20,6 +20,8 @@
 #ifndef BITMAPSET_H
 #define BITMAPSET_H
 
+#include "nodes/nodes.h"
+
 /*
  * Forward decl to save including pg_list.h
  */
@@ -48,6 +50,9 @@ typedef int32 signedbitmapword; /* must be the matching signed type */
 
 typedef struct Bitmapset
 {
+	pg_node_attr(custom_copy_equal, custom_read_write)
+
+	NodeTag		type;
 	int			nwords;			/* number of words in array */
 	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];	/* really [nwords] */
 } Bitmapset;
diff --git a/src/include/nodes/meson.build b/src/include/nodes/meson.build
index b7df232081..94701af8e1 100644
--- a/src/include/nodes/meson.build
+++ b/src/include/nodes/meson.build
@@ -19,6 +19,7 @@ node_support_input_i = [
   'nodes/supportnodes.h',
   'nodes/value.h',
   'utils/rel.h',
+  'nodes/bitmapset.h',
 ]
 
 node_support_input = []
-- 
2.35.3