Re: libpgtcl: pq_recvbuf: unexpected EOF on client connection

Gerhard Hintermayer <g(dot)hintermayer(at)inode(dot)at> writes:
> I don't understand what you're thinking of, because the unregistering
> triggers the call to PgDelConnectionId, so who will close the
> connection if you remove the unregister call ?

I meant the unregister of the notifier_channel, which is not
Pg_disconnect's business anyway. Unfortunately, it seems this fixes
your problem but creates a bigger one: Tcl dumps core if you shut down
the interpreter without having done pg_disconnect.

As a compromise I've applied the attached patch, which seems to suppress
the "unexpected EOF" problem at the cost of leaking a small amount of
memory for each disconnect.

regards, tom lane

*** src/interfaces/libpgtcl/pgtclCmds.c.orig Mon Sep 2 17:51:47 2002
--- src/interfaces/libpgtcl/pgtclCmds.c Mon Sep 2 18:03:35 2002
***************
*** 399,405 ****
int
Pg_disconnect(ClientData cData, Tcl_Interp *interp, int argc, char *argv[])
{
- Pg_ConnectionId *connid;
PGconn *conn;
Tcl_Channel conn_chan;

--- 399,404 ----
***************
*** 413,427 ****
if (conn_chan == NULL)
{
Tcl_ResetResult(interp);
! Tcl_AppendResult(interp, argv[1], " is not a valid connection\n", 0);
return TCL_ERROR;
}

! #if TCL_MAJOR_VERSION >= 8
! conn = PgGetConnectionId(interp, argv[1], &connid);
! if (connid->notifier_channel != NULL)
! Tcl_UnregisterChannel(interp, connid->notifier_channel);
! #endif

return Tcl_UnregisterChannel(interp, conn_chan);
}
--- 412,425 ----
if (conn_chan == NULL)
{
Tcl_ResetResult(interp);
! Tcl_AppendResult(interp, argv[1], " is not a valid connection", 0);
return TCL_ERROR;
}

! /* Check that it is a PG connection and not something else */
! conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId **) NULL);
! if (conn == (PGconn *) NULL)
! return TCL_ERROR;

return Tcl_UnregisterChannel(interp, conn_chan);
}
*** src/interfaces/libpgtcl/pgtclId.c.orig Mon Sep 2 17:51:47 2002
--- src/interfaces/libpgtcl/pgtclId.c Mon Sep 2 19:38:22 2002
***************
*** 193,199 ****

#if TCL_MAJOR_VERSION >= 8
connid->notifier_channel = Tcl_MakeTcpClientChannel((ClientData) PQsocket(conn));
! Tcl_RegisterChannel(interp, connid->notifier_channel);
#else
connid->notifier_socket = -1;
#endif
--- 194,200 ----

#if TCL_MAJOR_VERSION >= 8
connid->notifier_channel = Tcl_MakeTcpClientChannel((ClientData) PQsocket(conn));
! Tcl_RegisterChannel(NULL, connid->notifier_channel);
#else
connid->notifier_socket = -1;
#endif
***************
*** 286,291 ****
--- 289,313 ----
connid->conn = NULL;

/*
+ * Kill the notifier channel, too. We must not do this until after
+ * we've closed the libpq connection, because Tcl will try to close
+ * the socket itself!
+ *
+ * XXX Unfortunately, while this works fine if we are closing due to
+ * explicit pg_disconnect, Tcl versions through 8.3.3 dump core if we
+ * try to do it during interpreter shutdown. Not clear why, or if
+ * there is a workaround. For now, accept leakage of the (fairly
+ * small) amount of memory taken for the channel state representation.
+ * Note we are not leaking a socket, since libpq closed that already.
+ */
+ #ifdef NOT_USED
+ #if TCL_MAJOR_VERSION >= 8
+ if (connid->notifier_channel != NULL)
+ Tcl_UnregisterChannel(NULL, connid->notifier_channel);
+ #endif
+ #endif
+
+ /*
* We must use Tcl_EventuallyFree because we don't want the connid
* struct to vanish instantly if Pg_Notify_EventProc is active for it.
* (Otherwise, closing the connection from inside a pg_listen callback