On Sun, Dec 4, 2016 at 11:00 PM, Mithun Cy <mithun...@enterprisedb.com> wrote:
> On Fri, Dec 2, 2016 at 8:54 PM, Robert Haas <robertmh...@gmail.com> wrote:
>> Couldn't this just be a variable in PQconnectPoll(), instead of adding
>> a new structure member?
>
> I have fixed same with a local variable in PQconnectPoll, Initally I thought
> savedMessage should have same visiblitly as errorMessage so we can restore
> the errorMessage even outside PQconnectPoll. But that seems not required.
> Attacting the new patch which fixes the same.
I think that you need a restoreErrorMessage call here:
/* Skip any remaining addresses for this host. */
conn->addr_cur = NULL;
if (conn->whichhost + 1 < conn->nconnhost)
{
conn->status = CONNECTION_NEEDED;
restoreErrorMessage(conn, &savedMessage);
goto keep_going;
}
Updated patch attached with that change, the removal of a useless
hunk, and the removal of "inline" from the new functions, which seems
like second-guessing of whatever decision the compiler chooses to
make.
Thoughts?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 3b9b263..24fc12d 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1762,6 +1762,39 @@ connectDBComplete(PGconn *conn)
}
}
+/*
+ * This subroutine saves conn->errorMessage, which will be restored back by
+ * restoreErrorMessage subroutine.
+ */
+static bool
+saveErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
+{
+ initPQExpBuffer(savedMessage);
+ if (PQExpBufferBroken(savedMessage))
+ {
+ printfPQExpBuffer(&conn->errorMessage,
+ libpq_gettext("out of memory\n"));
+ return false;
+ }
+
+ appendPQExpBufferStr(savedMessage,
+ conn->errorMessage.data);
+ resetPQExpBuffer(&conn->errorMessage);
+ return true;
+}
+
+/*
+ * Restores saved error messages back to conn->errorMessage.
+ */
+static void
+restoreErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
+{
+ appendPQExpBufferStr(savedMessage, conn->errorMessage.data);
+ resetPQExpBuffer(&conn->errorMessage);
+ appendPQExpBufferStr(&conn->errorMessage, savedMessage->data);
+ termPQExpBuffer(savedMessage);
+}
+
/* ----------------
* PQconnectPoll
*
@@ -1795,6 +1828,7 @@ PQconnectPoll(PGconn *conn)
PGresult *res;
char sebuf[256];
int optval;
+ PQExpBufferData savedMessage;
if (conn == NULL)
return PGRES_POLLING_FAILED;
@@ -2792,11 +2826,26 @@ keep_going: /* We will come back to here until there is
if (conn->target_session_attrs != NULL &&
strcmp(conn->target_session_attrs, "read-write") == 0)
{
+ /*
+ * We are yet to make a connection. Save all existing error
+ * messages until we make a successful connection state.
+ * This is important because PQsendQuery is going to reset
+ * conn->errorMessage and we will loose error messages
+ * related to previous hosts we have tried to connect and
+ * failed.
+ */
+ if (!saveErrorMessage(conn, &savedMessage))
+ goto error_return;
+
conn->status = CONNECTION_OK;
if (!PQsendQuery(conn,
"show transaction_read_only"))
+ {
+ restoreErrorMessage(conn, &savedMessage);
goto error_return;
+ }
conn->status = CONNECTION_CHECK_WRITABLE;
+ restoreErrorMessage(conn, &savedMessage);
return PGRES_POLLING_READING;
}
@@ -2841,11 +2890,18 @@ keep_going: /* We will come back to here until there is
if (conn->target_session_attrs != NULL &&
strcmp(conn->target_session_attrs, "read-write") == 0)
{
+ if (!saveErrorMessage(conn, &savedMessage))
+ goto error_return;
+
conn->status = CONNECTION_OK;
if (!PQsendQuery(conn,
"show transaction_read_only"))
+ {
+ restoreErrorMessage(conn, &savedMessage);
goto error_return;
+ }
conn->status = CONNECTION_CHECK_WRITABLE;
+ restoreErrorMessage(conn, &savedMessage);
return PGRES_POLLING_READING;
}
@@ -2858,13 +2914,20 @@ keep_going: /* We will come back to here until there is
case CONNECTION_CHECK_WRITABLE:
{
+ if (!saveErrorMessage(conn, &savedMessage))
+ goto error_return;
+
conn->status = CONNECTION_OK;
if (!PQconsumeInput(conn))
+ {
+ restoreErrorMessage(conn, &savedMessage);
goto error_return;
+ }
if (PQisBusy(conn))
{
conn->status = CONNECTION_CHECK_WRITABLE;
+ restoreErrorMessage(conn, &savedMessage);
return PGRES_POLLING_READING;
}
@@ -2878,6 +2941,7 @@ keep_going: /* We will come back to here until there is
if (strncmp(val, "on", 2) == 0)
{
PQclear(res);
+ restoreErrorMessage(conn, &savedMessage);
/* Not writable; close connection. */
appendPQExpBuffer(&conn->errorMessage,
@@ -2895,6 +2959,7 @@ keep_going: /* We will come back to here until there is
if (conn->whichhost + 1 < conn->nconnhost)
{
conn->status = CONNECTION_NEEDED;
+ restoreErrorMessage(conn, &savedMessage);
goto keep_going;
}
@@ -2902,6 +2967,7 @@ keep_going: /* We will come back to here until there is
goto error_return;
}
PQclear(res);
+ termPQExpBuffer(&savedMessage);
/* We can release the address lists now. */
release_all_addrinfo(conn);
@@ -2917,6 +2983,7 @@ keep_going: /* We will come back to here until there is
*/
if (res)
PQclear(res);
+ restoreErrorMessage(conn, &savedMessage);
appendPQExpBuffer(&conn->errorMessage,
libpq_gettext("test \"show transaction_read_only\" failed "
" on \"%s:%s\" \n"),
--
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