0001-Make-Windows-FD_CLOSE-reporting-sticky.patch

From d3cfff53911ce068d4a31fe7ac7933958936d1b0 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Mon, 10 Jan 2022 14:45:05 +1300
Subject: [PATCH] Make Windows FD_CLOSE reporting sticky.

XXX Just testing an idea...
---
 src/backend/storage/ipc/latch.c | 16 ++++++++++++++++
 src/include/storage/latch.h     |  1 +
 2 files changed, 17 insertions(+)

diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
index 1d893cf863..4a61b31cd5 100644
--- a/src/backend/storage/ipc/latch.c
+++ b/src/backend/storage/ipc/latch.c
@@ -899,6 +899,7 @@ AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
 	event->user_data = user_data;
 #ifdef WIN32
 	event->reset = false;
+	event->closed = false;
 #endif
 
 	if (events == WL_LATCH_SET)
@@ -1882,6 +1883,20 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
 				return 1;
 			}
 		}
+
+		/*
+		 * XXX: HYPOTHESIS TO TEST
+		 * Windows only reports FD_CLOSE once.  If we've seen that already,
+		 * continue to report it.
+		 */
+		if ((cur_event & WL_SOCKET_MASK) && cur_event->closed)
+		{
+			occurred_events->pos = cur_event->pos;
+			occurred_events->user_data = cur_event->user_data;
+			occurred_events->events = (cur_event->events & WL_SOCKET_MASK);
+			occurred_events->fd = cur_event->fd;
+			return 1;
+		}
 	}
 
 	/*
@@ -2002,6 +2017,7 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
 		{
 			/* EOF/error, so signal all caller-requested socket flags */
 			occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
+			cur_event->closed = true;
 		}
 
 		if (occurred_events->events != 0)
diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h
index 44f9368c64..c24f46dc37 100644
--- a/src/include/storage/latch.h
+++ b/src/include/storage/latch.h
@@ -147,6 +147,7 @@ typedef struct WaitEvent
 	void	   *user_data;		/* pointer provided in AddWaitEventToSet */
 #ifdef WIN32
 	bool		reset;			/* Is reset of the event required? */
+	bool		closed;			/* Has FD_CLOSE event been reported? */
 #endif
 } WaitEvent;
 
-- 
2.33.1