Add wait event type "InjectionPoint", a custom type like "Extension".

Both injection points and customization of type "Extension" are new in
v17, so this just changes a detail of an unreleased feature.

Reported by Robert Haas.  Reviewed by Michael Paquier.

Discussion: https://postgr.es/m/CA+TgmobfMU5pdXP36D5iAwxV5WKE_vuDLtp_1QyH+H5jMMt21g@mail.gmail.com

Author: nmisch

doc/src/sgml/monitoring.sgml

@@ -1063,6 +1063,14 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
        See <xref linkend="wait-event-extension-table"/>.
       </entry>
      </row>
+     <row>
+      <entry><literal>InjectionPoint</literal></entry>
+      <entry>The server process is waiting for an injection point to reach an
+       outcome defined in a test.  See
+       <xref linkend="xfunc-addin-injection-points"/> for more details.  This
+       type has no predefined wait points.
+      </entry>
+     </row>
      <row>
       <entry><literal>IO</literal></entry>
       <entry>The server process is waiting for an I/O operation to complete.
@@ -1139,8 +1147,8 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
    <note>
     <para>
-     Extensions can add <literal>Extension</literal> and
-     <literal>LWLock</literal> events
+     Extensions can add <literal>Extension</literal>,
+     <literal>InjectionPoint</literal>. and <literal>LWLock</literal> events
      to the lists shown in <xref linkend="wait-event-extension-table"/> and
      <xref linkend="wait-event-lwlock-table"/>. In some cases, the name
      of an <literal>LWLock</literal> assigned by an extension will not be

doc/src/sgml/xfunc.sgml

@@ -3643,7 +3643,11 @@ extern void InjectionPointAttach(const char *name,
 static void
 custom_injection_callback(const char *name, const void *private_data)
 {
+    uint32 wait_event_info = WaitEventInjectionPointNew(name);
+
+    pgstat_report_wait_start(wait_event_info);
     elog(NOTICE, "%s: executed custom callback", name);
+    pgstat_report_wait_end();
 }
 </programlisting>
      This callback prints a message to server error log with severity

src/backend/storage/ipc/ipci.c

@@ -149,7 +149,7 @@ CalculateShmemSize(int *num_semaphores)
 	size = add_size(size, SyncScanShmemSize());
 	size = add_size(size, AsyncShmemSize());
 	size = add_size(size, StatsShmemSize());
-	size = add_size(size, WaitEventExtensionShmemSize());
+	size = add_size(size, WaitEventCustomShmemSize());
 	size = add_size(size, InjectionPointShmemSize());
 	size = add_size(size, SlotSyncShmemSize());
 #ifdef EXEC_BACKEND
@@ -355,7 +355,7 @@ CreateOrAttachShmemStructs(void)
 	SyncScanShmemInit();
 	AsyncShmemInit();
 	StatsShmemInit();
-	WaitEventExtensionShmemInit();
+	WaitEventCustomShmemInit();
 	InjectionPointShmemInit();
 }
 

src/backend/utils/activity/generate-wait_event_types.pl

@@ -181,9 +181,10 @@
 	foreach my $waitclass (sort { uc($a) cmp uc($b) } keys %hashwe)
 	{
 		# Don't generate the pgstat_wait_event.c and wait_event_types.h files
-		# for Extension, LWLock and Lock, these are handled independently.
+		# for types handled independently.
 		next
 		  if ( $waitclass eq 'WaitEventExtension'
+			|| $waitclass eq 'WaitEventInjectionPoint'
 			|| $waitclass eq 'WaitEventLWLock'
 			|| $waitclass eq 'WaitEventLock');