[libgda/LIBGDA_5.2] gda-connection: improved multi-thread behavior

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 253c0fd80692d1a1cd05c3c6d98cda5272018e44
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Sep 26 13:48:16 2018 -0500

    gda-connection: improved multi-thread behavior
    
    Now a GdaConnection holds a reference of a statement if it has an associated
    prepared statement.
    
    Internally remove the use of g_object_weak_* methods, causing
    problems in multi-threading environments

 libgda/gda-connection.c | 59 +++++++++++++++++++++++++++++++------------------
 1 file changed, 38 insertions(+), 21 deletions(-)
---
diff --git a/libgda/gda-connection.c b/libgda/gda-connection.c
index 71e9d74ec..a971394d8 100644
--- a/libgda/gda-connection.c
+++ b/libgda/gda-connection.c
@@ -20,7 +20,7 @@
  * Copyright (C) 2008 Johannes Schmid <jschmid openismus com>
  * Copyright (C) 2010 David King <davidk openismus com>
  * Copyright (C) 2010 Jonh Wendell <jwendell gnome org>
- * Copyright (C) 2011 Daniel Espinosa <despinosa src gnome org>
+ * Copyright (C) 2011,2018 Daniel Espinosa <esodan gmail com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -6390,39 +6390,47 @@ gda_connection_internal_reset_transaction_status (GdaConnection *cnc)
  */
 
 static void prepared_stmts_stmt_reset_cb (GdaStatement *gda_stmt, GdaConnection *cnc);
-static void statement_weak_notify_cb (GdaConnection *cnc, GdaStatement *stmt);
 
-static void 
+static void
 prepared_stmts_stmt_reset_cb (GdaStatement *gda_stmt, GdaConnection *cnc)
 {
        gda_connection_lock ((GdaLockable*) cnc);
+       g_object_ref (gda_stmt);
 
        g_signal_handlers_disconnect_by_func (gda_stmt, G_CALLBACK (prepared_stmts_stmt_reset_cb), cnc);
-       g_object_weak_unref (G_OBJECT (gda_stmt), (GWeakNotify) statement_weak_notify_cb, cnc);
        g_assert (cnc->priv->prepared_stmts);
        g_hash_table_remove (cnc->priv->prepared_stmts, gda_stmt);
 
+       g_object_unref (gda_stmt);
        gda_connection_unlock ((GdaLockable*) cnc);
 }
 
 static void
 prepared_stms_foreach_func (GdaStatement *gda_stmt, G_GNUC_UNUSED GdaPStmt *prepared_stmt, GdaConnection 
*cnc)
 {
+       g_object_ref (gda_stmt);
        g_signal_handlers_disconnect_by_func (gda_stmt, G_CALLBACK (prepared_stmts_stmt_reset_cb), cnc);
-       g_object_weak_unref (G_OBJECT (gda_stmt), (GWeakNotify) statement_weak_notify_cb, cnc);
+       g_object_unref (gda_stmt);
 }
 
-static void
-statement_weak_notify_cb (GdaConnection *cnc, GdaStatement *stmt)
-{
-       g_rec_mutex_lock (& cnc->priv->rmutex);
-
-       g_assert (cnc->priv->prepared_stmts);
-       g_hash_table_remove (cnc->priv->prepared_stmts, stmt);
+typedef struct {
+       GdaStatement   *statement;
+       GdaPStmt       *prepared_stmt;
+} PreparedStatementRef;
 
-       g_rec_mutex_unlock (& cnc->priv->rmutex);
+PreparedStatementRef*
+_gda_prepared_estatement_new (GdaStatement *stmt, GdaPStmt *pstmt) {
+       PreparedStatementRef *nps = g_new0(PreparedStatementRef,1);
+       nps->statement = g_object_ref (stmt);
+       nps->prepared_stmt = g_object_ref (pstmt);
+       return nps;
 }
 
+void
+_gda_prepared_estatement_free (PreparedStatementRef *ps) {
+       g_object_unref (ps->statement);
+       g_object_unref (ps->prepared_stmt);
+}
 
 /**
  * gda_connection_add_prepared_statement:
@@ -6442,21 +6450,25 @@ gda_connection_add_prepared_statement (GdaConnection *cnc, GdaStatement *gda_stm
        g_return_if_fail (GDA_IS_CONNECTION (cnc));
        g_return_if_fail (GDA_IS_STATEMENT (gda_stmt));
        g_return_if_fail (GDA_IS_PSTMT (prepared_stmt));
+       // Hold a reference until the end of the method
+       g_object_ref (prepared_stmt);
+       g_object_ref (gda_stmt);
 
        gda_connection_lock ((GdaLockable*) cnc);
 
        if (!cnc->priv->prepared_stmts)
                cnc->priv->prepared_stmts = g_hash_table_new_full (g_direct_hash, g_direct_equal,
-                                                                  NULL, g_object_unref);
+                                                                  NULL, _gda_prepared_estatement_free);
        g_hash_table_remove (cnc->priv->prepared_stmts, gda_stmt);
-       g_hash_table_insert (cnc->priv->prepared_stmts, gda_stmt, g_object_ref (prepared_stmt));
-       
-       /* destroy the prepared statement if gda_stmt is destroyed, or changes */
-       g_object_weak_ref (G_OBJECT (gda_stmt), (GWeakNotify) statement_weak_notify_cb, cnc);
+       PreparedStatementRef *ref = _gda_prepared_estatement_new (gda_stmt, prepared_stmt);
+       g_hash_table_insert (cnc->priv->prepared_stmts, gda_stmt, ref);
+
        g_signal_connect (G_OBJECT (gda_stmt), "reset",
                          G_CALLBACK (prepared_stmts_stmt_reset_cb), cnc);
 
        gda_connection_unlock ((GdaLockable*) cnc);
+       g_object_unref (prepared_stmt);
+       g_object_unref (gda_stmt);
 }
 
 /**
@@ -6477,8 +6489,11 @@ gda_connection_get_prepared_statement (GdaConnection *cnc, GdaStatement *gda_stm
        g_return_val_if_fail (GDA_IS_CONNECTION (cnc), NULL);
 
        gda_connection_lock ((GdaLockable*) cnc);
-       if (cnc->priv->prepared_stmts) 
-               retval = g_hash_table_lookup (cnc->priv->prepared_stmts, gda_stmt);
+       if (cnc->priv->prepared_stmts) {
+               PreparedStatementRef *ref = g_hash_table_lookup (cnc->priv->prepared_stmts, gda_stmt);
+               if (ref)
+                       retval = ref->prepared_stmt;
+       }
        gda_connection_unlock ((GdaLockable*) cnc);
 
        return retval;
@@ -6495,12 +6510,14 @@ gda_connection_get_prepared_statement (GdaConnection *cnc, GdaStatement *gda_stm
 void
 gda_connection_del_prepared_statement (GdaConnection *cnc, GdaStatement *gda_stmt)
 {
-       g_return_if_fail (GDA_IS_CONNECTION (cnc));
+       g_return_if_fail (cnc != NULL);
 
        gda_connection_lock ((GdaLockable*) cnc);
        g_return_if_fail (GDA_IS_CONNECTION (cnc));
+       g_object_ref (gda_stmt);
        if (gda_connection_get_prepared_statement (cnc, gda_stmt))
                prepared_stmts_stmt_reset_cb (gda_stmt, cnc);
+       g_object_unref (gda_stmt);
        gda_connection_unlock ((GdaLockable*) cnc);
 }