Simplify QofSession to own only exactly one QofBook.

No more, no less. This object isn't used in any other way in gnucash, so
we better get rid of the extra potential complexity here.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@21548 57a11ea4-9604-0410-9ed3-97b8803252fd

src/libqof/qof/qofsession-p.h

@@ -41,8 +41,8 @@ struct _QofSession
     QofInstance entity;
 
     /* A book holds pointers to the various types of datasets.
-     * A session may have multiple books. */
+     * A session has exactly one book. */
-    GList *books;
+    QofBook *book;
 
     /* The requested book id, in the form or a URI, such as
      * file:/some/where, or sql:server.host.com:555

src/libqof/qof/qofsession.c

@@ -214,7 +214,7 @@ qof_session_init (QofSession *session)
     if (!session) return;
 
     session->entity.e_type = QOF_ID_SESSION;
-    session->books = g_list_append (NULL, qof_book_new ());
+    session->book = qof_book_new ();
     session->book_id = NULL;
     session->backend = NULL;
     session->lock = 1;
@@ -235,14 +235,17 @@ qof_session_get_book (const QofSession *session)
 {
     GList *node;
     if (!session) return NULL;
+    if (!session->book) return NULL;
 
-    for (node = session->books; node; node = node->next)
+    if ('y' == session->book->book_open)
     {
-        QofBook *book = node->data;
+        return session->book;
-        if ('y' == book->book_open) return book;
     }
+    else
+    {
         return NULL;
     }
+}
 
 QofBackend *
 qof_session_get_backend (const QofSession *session)
@@ -295,14 +298,10 @@ static void
 qof_session_load_backend(QofSession * session, const char * access_method)
 {
     GSList *p;
-    GList *node;
     QofBackendProvider *prov;
-    QofBook *book;
     char *msg;
-    gint num;
     gboolean prov_type;
     gboolean (*type_check) (const char*);
-    gchar *libdir_from_env = NULL;
 
     ENTER (" list=%d, initted=%s", g_slist_length(provider_list),
            qof_providers_initialized ? "true" : "false");
@@ -340,12 +339,8 @@ qof_session_load_backend(QofSession * session, const char * access_method)
             /* Use the providers creation callback */
             session->backend = (*(prov->backend_new))();
             session->backend->provider = prov;
-            /* Tell the books about the backend that they'll be using. */
+            /* Tell the book about the backend that they'll be using. */
-            for (node = session->books; node; node = node->next)
+            qof_book_set_backend (session->book, session->backend);
-            {
-                book = node->data;
-                qof_book_set_backend (book, session->backend);
-            }
             LEAVE (" ");
             return;
         }
@@ -494,8 +489,7 @@ void
 qof_session_load (QofSession *session,
                   QofPercentageFunc percentage_func)
 {
-    QofBook *newbook, *ob;
+    QofBook *newbook, *oldbook;
-    QofBookList *oldbooks, *node;
     QofBackend *be;
     QofBackendError err;
 
@@ -508,14 +502,14 @@ qof_session_load (QofSession *session,
     /* At this point, we should are supposed to have a valid book
     * id and a lock on the file. */
 
-    oldbooks = session->books;
+    oldbook = session->book;
 
     /* XXX why are we creating a book here? I think the books
     * need to be handled by the backend ... especially since
     * the backend may need to load multiple books ... XXX. FIXME.
     */
     newbook = qof_book_new();
-    session->books = g_list_append (NULL, newbook);
+    session->book = newbook;
     PINFO ("new book=%p", newbook);
 
     qof_session_clear_error (session);
@@ -560,18 +554,12 @@ qof_session_load (QofSession *session,
         /* Something broke, put back the old stuff */
         qof_book_set_backend (newbook, NULL);
         qof_book_destroy (newbook);
-        g_list_free (session->books);
+        session->book = oldbook;
-        session->books = oldbooks;
         LEAVE("error from backend %d", qof_session_get_error(session));
         return;
     }
-    for (node = oldbooks; node; node = node->next)
+    qof_book_set_backend (oldbook, NULL);
-    {
+    qof_book_destroy (oldbook);
-        ob = node->data;
-        qof_book_set_backend (ob, NULL);
-        qof_book_destroy (ob);
-    }
-    g_list_free (oldbooks);
 
     LEAVE ("sess = %p, book_id=%s", session, session->book_id
            ? session->book_id : "(null)");
@@ -597,12 +585,11 @@ void
 qof_session_save (QofSession *session,
                   QofPercentageFunc percentage_func)
 {
-    GList *node;
     QofBackend *be;
     gboolean partial, change_backend;
     QofBackendProvider *prov;
     GSList *p;
-    QofBook *book, *abook;
+    QofBook *book;
     int err;
     gint num;
     char *msg = NULL;
@@ -688,12 +675,8 @@ qof_session_save (QofSession *session,
                         msg = NULL;
                     }
                 }
-                /* Tell the books about the backend that they'll be using. */
+                /* Tell the book about the backend that they'll be using. */
-                for (node = session->books; node; node = node->next)
+                qof_book_set_backend (session->book, session->backend);
-                {
-                    book = node->data;
-                    qof_book_set_backend (book, session->backend);
-                }
                 p = NULL;
             }
             if (p)
@@ -723,19 +706,16 @@ qof_session_save (QofSession *session,
     be = session->backend;
     if (be)
     {
-        for (node = session->books; node; node = node->next)
-        {
-            abook = node->data;
         /* if invoked as SaveAs(), then backend not yet set */
-            qof_book_set_backend (abook, be);
+        qof_book_set_backend (session->book, be);
         be->percentage = percentage_func;
         if (be->sync)
         {
-                (be->sync)(be, abook);
+            (be->sync)(be, session->book);
             if (save_error_handler(be, session))
                 goto leave;
         }
-        }
+
         /* If we got to here, then the backend saved everything
         * just fine, and we are done. So return. */
         /* Return the book_id to previous value. */
@@ -812,7 +792,6 @@ qof_session_end (QofSession *session)
 void
 qof_session_destroy (QofSession *session)
 {
-    GList *node;
     if (!session) return;
 
     ENTER ("sess=%p book_id=%s", session, session->book_id
@@ -823,14 +802,9 @@ qof_session_destroy (QofSession *session)
     /* destroy the backend */
     qof_session_destroy_backend(session);
 
-    for (node = session->books; node; node = node->next)
+    qof_book_set_backend (session->book, NULL);
-    {
+    qof_book_destroy (session->book);
-        QofBook *book = node->data;
+    session->book  = NULL;
-        qof_book_set_backend (book, NULL);
-        qof_book_destroy (book);
-    }
-
-    session->books  = NULL;
 
     g_free (session);
 
@@ -843,29 +817,21 @@ qof_session_destroy (QofSession *session)
 void
 qof_session_swap_data (QofSession *session_1, QofSession *session_2)
 {
-    GList *books_1, *books_2, *node;
+    QofBook *book_1, *book_2;
 
     if (session_1 == session_2) return;
     if (!session_1 || !session_2) return;
 
     ENTER ("sess1=%p sess2=%p", session_1, session_2);
 
-    books_1 = session_1->books;
+    book_1 = session_1->book;
-    books_2 = session_2->books;
+    book_2 = session_2->book;
 
-    session_1->books = books_2;
+    session_1->book = book_2;
-    session_2->books = books_1;
+    session_2->book = book_1;
 
-    for (node = books_1; node; node = node->next)
-    {
-        QofBook *book_1 = node->data;
     qof_book_set_backend (book_1, session_2->backend);
-    }
-    for (node = books_2; node; node = node->next)
-    {
-        QofBook *book_2 = node->data;
     qof_book_set_backend (book_2, session_1->backend);
-    }
 
     LEAVE (" ");
 }