Reorder the asynchronous libpq calls for replication connection

Per libpq documentation, the initial state must be
PGRES_POLLING_WRITING.  Failing to do that appears to cause some issues
on some Windows systems.

From: Petr Jelinek <petr.jelinek@2ndquadrant.com>

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 048d2aaa76b8cca5bfd02d2487f5827c2879301a..ebadf3680f62708fcdf4abe71d092d6c48a97e35 100644 (file)
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -155,12 +155,16 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
        return NULL;
    }
 
-   /* Poll connection. */
-   do
+   /*
+    * Poll connection until we have OK or FAILED status.
+    *
+    * Note that the initial state after PQconnectStartParams is
+    * PGRES_POLLING_WRITING.
+    */
+   for (status = PGRES_POLLING_WRITING;
+        status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED;
+        status = PQconnectPoll(conn->streamConn))
    {
-       /* Determine current state of the connection. */
-       status = PQconnectPoll(conn->streamConn);
-
        /* Sleep a bit if waiting for socket. */
        if (status == PGRES_POLLING_READING ||
            status == PGRES_POLLING_WRITING)
@@ -188,9 +192,7 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
            if (rc & WL_LATCH_SET)
                CHECK_FOR_INTERRUPTS();
        }
-
-       /* Otherwise loop until we have OK or FAILED status. */
-   } while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
+   }
 
    if (PQstatus(conn->streamConn) != CONNECTION_OK)
    {