Add WL_SOCKET_ACCEPT event to WaitEventSet API.

To be able to handle incoming connections on a server socket with
the WaitEventSet API, we'll need a new kind of event to indicate that
the the socket is ready to accept a connection.

On Unix, it's just the same as WL_SOCKET_READABLE, but on Windows there
is a different underlying kernel event that we need to map our
abstraction to.

No user yet, but a proposed patch would use this.

Reviewed-by: Andres Freund <[email protected]>
Discussion: https://postgr.es/m/CA%2BhUKG%2BZ-HpOj1JsO9eWUP%2Bar7npSVinsC_npxSy%2BjdOMsx%3DGg%40mail.gmail.com

diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
index eb3a569aae14fd8a300a1c7b50d098436835d875..7ced8264f00b82ff642196063c7ce5807d556acb 100644 (file)
--- a/src/backend/storage/ipc/latch.c
+++ b/src/backend/storage/ipc/latch.c
@@ -864,6 +864,9 @@ FreeWaitEventSet(WaitEventSet *set)
  * - WL_SOCKET_CONNECTED: Wait for socket connection to be established,
  *      can be combined with other WL_SOCKET_* events (on non-Windows
  *      platforms, this is the same as WL_SOCKET_WRITEABLE)
+ * - WL_SOCKET_ACCEPT: Wait for new connection to a server socket,
+ *      can be combined with other WL_SOCKET_* events (on non-Windows
+ *      platforms, this is the same as WL_SOCKET_READABLE)
  * - WL_SOCKET_CLOSED: Wait for socket to be closed by remote peer.
  * - WL_EXIT_ON_PM_DEATH: Exit immediately if the postmaster dies
  *
@@ -874,7 +877,7 @@ FreeWaitEventSet(WaitEventSet *set)
  * i.e. it must be a process-local latch initialized with InitLatch, or a
  * shared latch associated with the current process by calling OwnLatch.
  *
- * In the WL_SOCKET_READABLE/WRITEABLE/CONNECTED cases, EOF and error
+ * In the WL_SOCKET_READABLE/WRITEABLE/CONNECTED/ACCEPT cases, EOF and error
  * conditions cause the socket to be reported as readable/writable/connected,
  * so that the caller can deal with the condition.
  *
@@ -1312,6 +1315,8 @@ WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event)
                        flags |= FD_WRITE;
                if (event->events & WL_SOCKET_CONNECTED)
                        flags |= FD_CONNECT;
+               if (event->events & WL_SOCKET_ACCEPT)
+                       flags |= FD_ACCEPT;
 
                if (*handle == WSA_INVALID_EVENT)
                {
@@ -2067,6 +2072,12 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
                        /* connected */
                        occurred_events->events |= WL_SOCKET_CONNECTED;
                }
+               if ((cur_event->events & WL_SOCKET_ACCEPT) &&
+                       (resEvents.lNetworkEvents & FD_ACCEPT))
+               {
+                       /* incoming connection could be accepted */
+                       occurred_events->events |= WL_SOCKET_ACCEPT;
+               }
                if (resEvents.lNetworkEvents & FD_CLOSE)
                {
                        /* EOF/error, so signal all caller-requested socket flags */

diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h
index 68ab740f1618fd86a527143289793ea5a6782cea..c55838db6078e99d0bf1aaf66f2b28e65c4410f1 100644 (file)
--- a/src/include/storage/latch.h
+++ b/src/include/storage/latch.h
@@ -135,9 +135,16 @@ typedef struct Latch
 #define WL_SOCKET_CONNECTED  WL_SOCKET_WRITEABLE
 #endif
 #define WL_SOCKET_CLOSED        (1 << 7)
+#ifdef WIN32
+#define WL_SOCKET_ACCEPT        (1 << 8)
+#else
+/* avoid having to deal with case on platforms not requiring it */
+#define WL_SOCKET_ACCEPT       WL_SOCKET_READABLE
+#endif
 #define WL_SOCKET_MASK         (WL_SOCKET_READABLE | \
                                                         WL_SOCKET_WRITEABLE | \
                                                         WL_SOCKET_CONNECTED | \
+                                                        WL_SOCKET_ACCEPT | \
                                                         WL_SOCKET_CLOSED)
 
 typedef struct WaitEvent