Rename BUFFERPIN wait event class to BUFFER

In an upcoming patch more wait events will be added to the wait event
class (for buffer locking), making the current name too
specific. Alternatively we could introduce a dedicated wait event class for
those, but it seems somewhat confusing to have a BUFFERPIN and a BUFFER wait
event class.

Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff

doc/src/sgml/monitoring.sgml

@@ -1053,11 +1053,9 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       </entry>
      </row>
      <row>
-      <entry><literal>BufferPin</literal></entry>
-      <entry>The server process is waiting for exclusive access to
-       a data buffer.  Buffer pin waits can be protracted if
-       another process holds an open cursor that last read data from the
-       buffer in question. See <xref linkend="wait-event-bufferpin-table"/>.
+      <entry><literal>Buffer</literal></entry>
+      <entry>The server process is waiting for access to a data buffer.
+      See <xref linkend="wait-event-buffer-table"/>.
       </entry>
      </row>
      <row>

src/backend/storage/buffer/bufmgr.c

@@ -5799,7 +5799,7 @@ LockBufferForCleanup(Buffer buffer)
 			SetStartupBufferPinWaitBufId(-1);
 		}
 		else
-			ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
+			ProcWaitForSignal(WAIT_EVENT_BUFFER_CLEANUP);
 
 		/*
 		 * Remove flag marking us as waiter. Normally this will not be set

src/backend/storage/ipc/standby.c

@@ -840,7 +840,7 @@ ResolveRecoveryConflictWithBufferPin(void)
 	 * SIGHUP signal handler, etc cannot do that because it uses the different
 	 * latch from that ProcWaitForSignal() waits on.
 	 */
-	ProcWaitForSignal(WAIT_EVENT_BUFFER_PIN);
+	ProcWaitForSignal(WAIT_EVENT_BUFFER_CLEANUP);
 
 	if (got_standby_delay_timeout)
 		SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);

src/backend/utils/activity/wait_event.c

@@ -29,7 +29,7 @@
 
 
 static const char *pgstat_get_wait_activity(WaitEventActivity w);
-static const char *pgstat_get_wait_bufferpin(WaitEventBufferPin w);
+static const char *pgstat_get_wait_buffer(WaitEventBuffer w);
 static const char *pgstat_get_wait_client(WaitEventClient w);
 static const char *pgstat_get_wait_ipc(WaitEventIPC w);
 static const char *pgstat_get_wait_timeout(WaitEventTimeout w);
@@ -389,8 +389,8 @@ pgstat_get_wait_event_type(uint32 wait_event_info)
 		case PG_WAIT_LOCK:
 			event_type = "Lock";
 			break;
-		case PG_WAIT_BUFFERPIN:
-			event_type = "BufferPin";
+		case PG_WAIT_BUFFER:
+			event_type = "Buffer";
 			break;
 		case PG_WAIT_ACTIVITY:
 			event_type = "Activity";
@@ -453,11 +453,11 @@ pgstat_get_wait_event(uint32 wait_event_info)
 		case PG_WAIT_INJECTIONPOINT:
 			event_name = GetWaitEventCustomIdentifier(wait_event_info);
 			break;
-		case PG_WAIT_BUFFERPIN:
+		case PG_WAIT_BUFFER:
 			{
-				WaitEventBufferPin w = (WaitEventBufferPin) wait_event_info;
+				WaitEventBuffer w = (WaitEventBuffer) wait_event_info;
 
-				event_name = pgstat_get_wait_bufferpin(w);
+				event_name = pgstat_get_wait_buffer(w);
 				break;
 			}
 		case PG_WAIT_ACTIVITY:

src/backend/utils/activity/wait_event_names.txt

@@ -279,12 +279,12 @@ WAL_WRITE	"Waiting for a write to a WAL file."
 ABI_compatibility:
 
 #
-# Wait Events - Buffer Pin
+# Wait Events - Buffer
 #
 
-Section: ClassName - WaitEventBufferPin
+Section: ClassName - WaitEventBuffer
 
-BUFFER_PIN	"Waiting to acquire an exclusive pin on a buffer."
+BUFFER_CLEANUP	"Waiting to acquire an exclusive pin on a buffer. Buffer pin waits can be protracted if another process holds an open cursor that last read data from the buffer in question."
 
 ABI_compatibility:
 

src/include/utils/wait_classes.h

@@ -17,7 +17,7 @@
  */
 #define PG_WAIT_LWLOCK				0x01000000U
 #define PG_WAIT_LOCK				0x03000000U
-#define PG_WAIT_BUFFERPIN			0x04000000U
+#define PG_WAIT_BUFFER				0x04000000U
 #define PG_WAIT_ACTIVITY			0x05000000U
 #define PG_WAIT_CLIENT				0x06000000U
 #define PG_WAIT_EXTENSION			0x07000000U

src/test/recovery/t/048_vacuum_horizon_floor.pl

@@ -194,7 +194,7 @@ $node_primary->poll_query_until(
 	qq[
 	SELECT count(*) >= 1 FROM pg_stat_activity
 		WHERE pid = $vacuum_pid
-		AND wait_event = 'BufferPin';
+		AND wait_event = 'BufferCleanup';
 	],
 	't');
 

src/test/regress/expected/sysviews.out

@@ -182,7 +182,7 @@ select type, count(*) > 0 as ok FROM pg_wait_events
    type    | ok 
 -----------+----
  Activity  | t
- BufferPin | t
+ Buffer    | t
  Client    | t
  Extension | t
  IO        | t

src/tools/pgindent/typedefs.list

@@ -3270,7 +3270,7 @@ WSANETWORKEVENTS
 WSAPROTOCOL_INFO
 WaitEvent
 WaitEventActivity
-WaitEventBufferPin
+WaitEventBuffer
 WaitEventClient
 WaitEventCustomCounterData
 WaitEventCustomEntryByInfo