[CF 5652] v6 - pg_dsm_registry_allocations system view

This branch was automatically generated by a robot using patches from an
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https://commitfest.postgresql.org/patch/5652

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Patch(es): https://www.postgresql.org/message-id/aG17iFEpcN4ENJfz@nathan
Author(s): Florents Tselai

Author: Commitfest Bot

doc/src/sgml/system-views.sgml

@@ -81,6 +81,11 @@
       <entry>open cursors</entry>
      </row>
 
+     <row>
+      <entry><link linkend="view-pg-dsm-registry-allocations"><structname>pg_dsm_registry_allocations</structname></link></entry>
+      <entry>shared memory allocations tracked in the DSM registry</entry>
+     </row>
+
      <row>
       <entry><link linkend="view-pg-file-settings"><structname>pg_file_settings</structname></link></entry>
       <entry>summary of configuration file contents</entry>
@@ -1086,6 +1091,75 @@ AND c1.path[c2.level] = c2.path[c2.level];
 
  </sect1>
 
+ <sect1 id="view-pg-dsm-registry-allocations">
+  <title><structname>pg_dsm_registry_allocations</structname></title>
+
+  <indexterm zone="view-pg-dsm-registry-allocations">
+   <primary>pg_dsm_registry_allocations</primary>
+  </indexterm>
+
+  <para>
+   The <structname>pg_dsm_registry_allocations</structname> view shows shared
+   memory allocations tracked in the dynamic shared memory (DSM) registry.
+   This includes memory allocated by extensions using the mechanisms detailed
+   in <xref linkend="xfunc-shared-addin-after-startup" />.
+  </para>
+
+  <table>
+   <title><structname>pg_dsm_registry_allocations</structname> Columns</title>
+   <tgroup cols="1">
+    <thead>
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       Column Type
+      </para>
+      <para>
+       Description
+      </para></entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>name</structfield> <type>text</type>
+      </para>
+      <para>
+       The name of the allocation in the DSM registry.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>type</structfield> <type>text</type>
+      </para>
+      <para>
+       The type of allocation.  Possible values are <literal>segment</literal>,
+       <literal>area</literal>, and <literal>hash</literal>, which correspond
+       to dynamic shared memory segments, areas, and hash tables, respectively.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>size</structfield> <type>int8</type>
+      </para>
+      <para>
+       Size of the allocation in bytes.  NULL for entries of type
+       <literal>area</literal> and <literal>hash</literal>.
+      </para></entry>
+     </row>
+    </tbody>
+   </tgroup>
+  </table>
+
+  <para>
+   By default, the <structname>pg_dsm_registry_allocations</structname> view
+   can be read only by superusers or roles with privileges of the
+   <literal>pg_read_all_stats</literal> role.
+  </para>
+ </sect1>
+
  <sect1 id="view-pg-file-settings">
   <title><structname>pg_file_settings</structname></title>
 

src/backend/catalog/system_views.sql

@@ -666,6 +666,14 @@ GRANT SELECT ON pg_shmem_allocations_numa TO pg_read_all_stats;
 REVOKE EXECUTE ON FUNCTION pg_get_shmem_allocations_numa() FROM PUBLIC;
 GRANT EXECUTE ON FUNCTION pg_get_shmem_allocations_numa() TO pg_read_all_stats;
 
+CREATE VIEW pg_dsm_registry_allocations AS
+    SELECT * FROM pg_get_dsm_registry_allocations();
+
+REVOKE ALL ON pg_dsm_registry_allocations FROM PUBLIC;
+GRANT SELECT ON pg_dsm_registry_allocations TO pg_read_all_stats;
+REVOKE EXECUTE ON FUNCTION pg_get_dsm_registry_allocations() FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_get_dsm_registry_allocations() TO pg_read_all_stats;
+
 CREATE VIEW pg_backend_memory_contexts AS
     SELECT * FROM pg_get_backend_memory_contexts();
 

src/backend/storage/ipc/dsm_registry.c

@@ -40,10 +40,12 @@
 
 #include "postgres.h"
 
+#include "funcapi.h"
 #include "lib/dshash.h"
 #include "storage/dsm_registry.h"
 #include "storage/lwlock.h"
 #include "storage/shmem.h"
+#include "utils/builtins.h"
 #include "utils/memutils.h"
 
 #define DSMR_NAME_LEN				128
@@ -88,6 +90,13 @@ typedef enum DSMREntryType
 	DSMR_ENTRY_TYPE_DSH,
 } DSMREntryType;
 
+static const char *const DSMREntryTypeNames[] =
+{
+	[DSMR_ENTRY_TYPE_DSM] = "segment",
+	[DSMR_ENTRY_TYPE_DSA] = "area",
+	[DSMR_ENTRY_TYPE_DSH] = "hash",
+};
+
 typedef struct DSMRegistryEntry
 {
 	char		name[DSMR_NAME_LEN];
@@ -435,3 +444,43 @@ GetNamedDSHash(const char *name, const dshash_parameters *params, bool *found)
 
 	return ret;
 }
+
+Datum
+pg_get_dsm_registry_allocations(PG_FUNCTION_ARGS)
+{
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	DSMRegistryEntry *entry;
+	MemoryContext oldcontext;
+	dshash_seq_status status;
+
+	InitMaterializedSRF(fcinfo, MAT_SRF_USE_EXPECTED_DESC);
+
+	/* Be sure any local memory allocated by DSM/DSA routines is persistent. */
+	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+	init_dsm_registry();
+	MemoryContextSwitchTo(oldcontext);
+
+	dshash_seq_init(&status, dsm_registry_table, false);
+	while ((entry = dshash_seq_next(&status)) != NULL)
+	{
+		Datum		vals[3];
+		bool		nulls[3] = {0};
+
+		vals[0] = CStringGetTextDatum(entry->name);
+		vals[1] = CStringGetTextDatum(DSMREntryTypeNames[entry->type]);
+
+		/*
+		 * Since we can't know the size of DSA/dshash entries without first
+		 * attaching to them, return NULL for those.
+		 */
+		if (entry->type == DSMR_ENTRY_TYPE_DSM)
+			vals[2] = Int64GetDatum(entry->data.dsm.size);
+		else
+			nulls[2] = true;
+
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, vals, nulls);
+	}
+	dshash_seq_term(&status);
+
+	return (Datum) 0;
+}

src/include/catalog/pg_proc.dat

@@ -8572,6 +8572,13 @@
   proargnames => '{name,numa_node,size}',
   prosrc => 'pg_get_shmem_allocations_numa' },
 
+{ oid => '9314', descr => 'allocations tracked in the DSM registry',
+  proname => 'pg_get_dsm_registry_allocations', prorows => '50',
+  proretset => 't', provolatile => 'v', prorettype => 'record',
+  proargtypes => '', proallargtypes => '{text,text,int8}',
+  proargmodes => '{o,o,o}', proargnames => '{name,type,size}',
+  prosrc => 'pg_get_dsm_registry_allocations' },
+
 # memory context of local backend
 { oid => '2282',
   descr => 'information about all memory contexts of local backend',

src/test/modules/test_dsm_registry/expected/test_dsm_registry.out

@@ -1,3 +1,10 @@
+SELECT name, type, size IS DISTINCT FROM 0 AS size
+FROM pg_dsm_registry_allocations
+WHERE name like 'test_dsm_registry%' ORDER BY name;
+ name | type | size 
+------+------+------
+(0 rows)
+
 CREATE EXTENSION test_dsm_registry;
 SELECT set_val_in_shmem(1236);
  set_val_in_shmem 
@@ -24,3 +31,14 @@ SELECT get_val_in_hash('test');
  1414
 (1 row)
 
+\c
+SELECT name, type, size IS DISTINCT FROM 0 AS size
+FROM pg_dsm_registry_allocations
+WHERE name like 'test_dsm_registry%' ORDER BY name;
+          name          |  type   | size 
+------------------------+---------+------
+ test_dsm_registry_dsa  | area    | t
+ test_dsm_registry_dsm  | segment | t
+ test_dsm_registry_hash | hash    | t
+(3 rows)
+

src/test/modules/test_dsm_registry/sql/test_dsm_registry.sql

@@ -1,6 +1,13 @@
+SELECT name, type, size IS DISTINCT FROM 0 AS size
+FROM pg_dsm_registry_allocations
+WHERE name like 'test_dsm_registry%' ORDER BY name;
 CREATE EXTENSION test_dsm_registry;
 SELECT set_val_in_shmem(1236);
 SELECT set_val_in_hash('test', '1414');
 \c
 SELECT get_val_in_shmem();
 SELECT get_val_in_hash('test');
+\c
+SELECT name, type, size IS DISTINCT FROM 0 AS size
+FROM pg_dsm_registry_allocations
+WHERE name like 'test_dsm_registry%' ORDER BY name;

src/test/regress/expected/privileges.out

@@ -3220,7 +3220,8 @@ REVOKE MAINTAIN ON lock_table FROM regress_locktable_user;
 DROP TABLE lock_table;
 DROP USER regress_locktable_user;
 -- test to check privileges of system views pg_shmem_allocations,
--- pg_shmem_allocations_numa and pg_backend_memory_contexts.
+-- pg_shmem_allocations_numa, pg_dsm_registry_allocations, and
+-- pg_backend_memory_contexts.
 -- switch to superuser
 \c -
 CREATE ROLE regress_readallstats;
@@ -3248,6 +3249,12 @@ SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations_numa','S
  f
 (1 row)
 
+SELECT has_table_privilege('regress_readallstats','pg_dsm_registry_allocations','SELECT'); -- no
+ has_table_privilege 
+---------------------
+ f
+(1 row)
+
 GRANT pg_read_all_stats TO regress_readallstats;
 SELECT has_table_privilege('regress_readallstats','pg_aios','SELECT'); -- yes
  has_table_privilege 
@@ -3273,6 +3280,12 @@ SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations_numa','S
  t
 (1 row)
 
+SELECT has_table_privilege('regress_readallstats','pg_dsm_registry_allocations','SELECT'); -- yes
+ has_table_privilege 
+---------------------
+ t
+(1 row)
+
 -- run query to ensure that functions within views can be executed
 SET ROLE regress_readallstats;
 SELECT COUNT(*) >= 0 AS ok FROM pg_aios;

src/test/regress/expected/rules.out

@@ -1340,6 +1340,10 @@ pg_cursors| SELECT name,
     is_scrollable,
     creation_time
    FROM pg_cursor() c(name, statement, is_holdable, is_binary, is_scrollable, creation_time);
+pg_dsm_registry_allocations| SELECT name,
+    type,
+    size
+   FROM pg_get_dsm_registry_allocations() pg_get_dsm_registry_allocations(name, type, size);
 pg_file_settings| SELECT sourcefile,
     sourceline,
     seqno,

src/test/regress/sql/privileges.sql

@@ -1948,7 +1948,8 @@ DROP TABLE lock_table;
 DROP USER regress_locktable_user;
 
 -- test to check privileges of system views pg_shmem_allocations,
--- pg_shmem_allocations_numa and pg_backend_memory_contexts.
+-- pg_shmem_allocations_numa, pg_dsm_registry_allocations, and
+-- pg_backend_memory_contexts.
 
 -- switch to superuser
 \c -
@@ -1959,13 +1960,15 @@ SELECT has_table_privilege('regress_readallstats','pg_aios','SELECT'); -- no
 SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- no
 SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- no
 SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations_numa','SELECT'); -- no
+SELECT has_table_privilege('regress_readallstats','pg_dsm_registry_allocations','SELECT'); -- no
 
 GRANT pg_read_all_stats TO regress_readallstats;
 
 SELECT has_table_privilege('regress_readallstats','pg_aios','SELECT'); -- yes
 SELECT has_table_privilege('regress_readallstats','pg_backend_memory_contexts','SELECT'); -- yes
 SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations','SELECT'); -- yes
 SELECT has_table_privilege('regress_readallstats','pg_shmem_allocations_numa','SELECT'); -- yes
+SELECT has_table_privilege('regress_readallstats','pg_dsm_registry_allocations','SELECT'); -- yes
 
 -- run query to ensure that functions within views can be executed
 SET ROLE regress_readallstats;