QOF  0.7.5
Error: Extensible error handling.

Files

file  qoferror.h
 Extensible error handling.
 

Macros

#define QOF_MOD_ERROR   "qof-error-module"
 
#define QOF_SUCCESS   0
 
#define QOF_FATAL   -1
 general error value More...
 

Typedefs

typedef struct QofError_s QofError
 

Functions

QofErrorId qof_error_register (const gchar *err_message, gboolean use_file)
 Generate and register a new error. More...
 
void qof_error_unregister (QofErrorId id)
 Unregister an error. More...
 
void qof_error_set (QofSession *session, QofErrorId error)
 Add an error to the stack for this session. More...
 
void qof_error_set_be (QofBackend *be, QofErrorId error)
 
void qof_error_clear (QofSession *session)
 clear the error stack for the session. More...
 
QofErrorId qof_error_check_be (QofBackend *be)
 Check for errors. More...
 
QofErrorId qof_error_check (QofSession *session)
 
QofTimeqof_error_get_time_be (QofBackend *be)
 Get the time of the most recent error. More...
 
QofTimeqof_error_get_time (QofSession *session)
 Alternative for applications.
 
QofErrorId qof_error_get_id_be (QofBackend *be)
 Pop the most recent error from the backend stack. More...
 
QofErrorId qof_error_get_id (QofSession *session)
 Alternative for applications.
 
const gchar * qof_error_get_message_be (QofBackend *be)
 Pop the most recent error and get the message. More...
 
const gchar * qof_error_get_message (QofSession *session)
 Alternative for applications.
 

Detailed Description

QofError supports the creation of new error codes (complete with error strings) along the lines of GdaError. Applications and backends can generate their own QofError values and register them with QofError. Any function can then set this error value and retrieve the error with qof_error_get_id or qof_error_get_message. The main advantage is that applications can set error states that are unrelated to the old QofBackendError values but retrieve all errors in the same manner.

An error must be registered to be set. Registered errors can be set repeatedly into an error stack for the relevant session. Setting an error copies the registered error to the error stack and sets a time index in the copy.

Once an error has been unregistered, it cannot be set later. If the error has already been set on the error stack, the stack is not changed and the error remains readable.

Each error stack is specific to one QofSession.

Registered errors can be set in any session (if the QofErrorId is known) but most errors are specific to one session.

Applications can register new error values with qof_error_register passing the error message string, already marked for translation - a new QofErrorId will be returned. Error values are unregistered when the session ends or can be unregistered manually.

Each backend can also generate specific QofError values, in which case the translation is done within QOF.

Set an error by passing the QofErrorId (or the deprecated QofBackendError) to qof_error_set.

To check the error condition use qof_error_check - if an error has been set, qof_error_check returns the QofErrorId of that error without clearing the error from the stack.

To retrieve an error and clear it from the stack, use qof_error_get_id or qof_error_get_message.

Precise values of QofErrorId are not to be stored in applications as values (other than deprecated values) may change at any time.

There are no default errors - previous QofBackendError values are retained only as deprecated macros. Until libqof2, QofErrorId is guaranteed not to overlap a previous QofBackendError value but once deprecated code is removed in libqof2, any value can be used.

This deliberately makes it harder to re-use the same error time after time. The purpose is to encourage more detailed error reporting by supporting an unlimited number of error values.

Applications and backends can store the QofErrorId in a context or static values if the error must be set from multiple locations, otherwise an error can be registered and set locally.

If a subsystem or dependency generates an error message of it's own, this can also be passed to qof_error_register to generate a new error within the session, complete with the (translated) message direct from the subsystem. This increases the detail and clarity of the messages presented to the user. Programming errors and complex errors should still be logged using QofLog - QofError is for messages destined for the end user of the application using QOF.

Many applications already include message strings for the previous QofBackendError values but all are welcome to move to the new QofError strings.

QofError strings remain the property of QofError and should not be freed.

Since
0.7.2

Macro Definition Documentation

#define QOF_FATAL   -1

general error value

Can be returned by any function handling QofErrorId to indicate a fatal error, e.g. g_return_val_if_fail

Definition at line 131 of file qoferror.h.

#define QOF_MOD_ERROR   "qof-error-module"

QofError log_module name.

Definition at line 121 of file qoferror.h.

#define QOF_SUCCESS   0

success value

Definition at line 124 of file qoferror.h.

Typedef Documentation

typedef struct QofError_s QofError

opaque QofError type.

Definition at line 118 of file qoferror.h.

Function Documentation

QofErrorId qof_error_check ( QofSession session)

alternative for applications.

Definition at line 227 of file qoferror.c.

228 {
229  g_return_val_if_fail (session, QOF_FATAL);
230  return qof_error_check_be (session->backend);
231 }
QofErrorId qof_error_check_be ( QofBackend be)

Check for errors.

Parameters
beThe backend to check.
Returns
QOF_SUCCESS if no errors have been set, otherwise the QofErrorId of the most recently set error.

Definition at line 234 of file qoferror.c.

235 {
236  QofError * qerr;
237  GList * first;
238 
239  if (!be)
240  return QOF_FATAL;
241  if (g_list_length (be->error_stack) == 0)
242  return QOF_SUCCESS;
243  first = g_list_first (be->error_stack);
244  qerr = (QofError*)first->data;
245  if (!qerr)
246  return QOF_FATAL;
247  return qerr->id;
248 }
void qof_error_clear ( QofSession session)

clear the error stack for the session.

Applications should clear the stack once errors have been presented to the user.

Definition at line 209 of file qoferror.c.

210 {
211  g_return_if_fail (session);
212  if (!session->backend)
213  return;
214  g_list_foreach (session->backend->error_stack, clear_list, NULL);
215  g_list_free (session->backend->error_stack);
216  session->backend->error_stack = NULL;
217  if (session->error_message)
218  g_free (session->error_message);
219  session->error_message = NULL;
220  session->last_err = QOF_SUCCESS;
221 #ifndef QOF_DISABLE_DEPRECATED
222  session->backend->last_err = QOF_SUCCESS;
223 #endif
224 }
QofErrorId qof_error_get_id_be ( QofBackend be)

Pop the most recent error from the backend stack.

Returns and clears the most recently set error for this backend, if any.

Parameters
beThe Backend that recorded the error.
Returns
QOF_SUCCESS if no errors have been set, otherwise the QofErrorId of the most recently set error.

Definition at line 314 of file qoferror.c.

315 {
316  QofError * qerr;
317  GList * first;
318 
319  if (!be)
320  return QOF_FATAL;
321  if (g_list_length (be->error_stack) == 0)
322  return QOF_SUCCESS;
323  first = g_list_first (be->error_stack);
324  qerr = (QofError*)first->data;
325  if (!qerr)
326  return QOF_FATAL;
327  be->error_stack =
328  g_list_remove (be->error_stack, qerr);
329 #ifndef QOF_DISABLE_DEPRECATED
330  set_previous_error (be);
331 #endif
332  return qerr->id;
333 }
const gchar* qof_error_get_message_be ( QofBackend be)

Pop the most recent error and get the message.

Clears the most recently set error for this backend and returns the error message, if any.

Parameters
beThe Backend that recorded the error.
Returns
NULL if no errors have been set, otherwise the translated message for the most recently set error.

Definition at line 364 of file qoferror.c.

365 {
366  QofError * qerr;
367  GList * first;
368 
369  g_return_val_if_fail (be, NULL);
370  if (g_list_length (be->error_stack) == 0)
371  {
372  DEBUG (" empty error stack");
373  return NULL;
374  }
375  first = g_list_first (be->error_stack);
376  qerr = (QofError*)first->data;
377  if (!qerr)
378  {
379  DEBUG (" empty QofError value");
380  return NULL;
381  }
382  DEBUG (" qerr->message=%s", qerr->message);
383  be->error_stack =
384  g_list_remove (be->error_stack, qerr);
385 #ifndef QOF_DISABLE_DEPRECATED
386  be->error_msg = qerr->message;
387  set_previous_error (be);
388 #endif
389  return qerr->message;
390 }
QofTime* qof_error_get_time_be ( QofBackend be)

Get the time of the most recent error.

All QofError values are timestamped at the moment that the error is set.

Parameters
beThe Backend where the error was set.
Returns
NULL if no error exists, otherwise the QofTime that the error was set.

Definition at line 251 of file qoferror.c.

252 {
253  QofError * qerr;
254  GList * first;
255 
256  if (g_list_length(be->error_stack) == 0)
257  return NULL;
258  first = g_list_first (be->error_stack);
259  qerr = (QofError*)first->data;
260  return qerr->qt;
261 }
QofErrorId qof_error_register ( const gchar *  err_message,
gboolean  use_file 
)

Generate and register a new error.

Parameters
err_messageThe user-friendly string to add as an error, already marked for translation.
use_fileTRUE if the session filename should be substituted in the string - err_message must contain a bare string format specifier: s. Note that flags, width, precision or size specifiers are not accepted and the filename is output in full, complete with the access_method. e.g. file:/home/user/app/data.xml

To use a different presentation of the filename or other customised strings, prepare the error message before registering it with QofError.

Registered errors are cleared when the session is destroyed.

Applications need to plan the use of locally registered error codes so that the same errors are not repeatedly registered.

Returns
The QofErrorId of this error.

Definition at line 91 of file qoferror.c.

92 {
93  QofError * qerr;
94 
95  ENTER (" ");
96  qerr = g_new0 (QofError, 1);
97  count++;
98 #ifndef QOF_DISABLE_DEPRECATED
99  count += ERR_LAST;
100 #endif
101  qerr->id = count;
102  if (use_file)
103  {
104  gchar * spec;
105 
106  spec = g_strrstr (err_message, "%s");
107  use_file = (spec) ? TRUE : FALSE;
108  }
109  qerr->use_file = use_file;
110  qerr->message = g_strdup (err_message);
111  g_hash_table_insert (error_table, GINT_TO_POINTER(qerr->id), qerr);
112  LEAVE (" ");
113  return qerr->id;
114 }
void qof_error_set ( QofSession session,
QofErrorId  error 
)

Add an error to the stack for this session.

Parameters
sessionThe session that raised the error.
errorThe QofErrorId of the error to be recorded.

Definition at line 133 of file qoferror.c.

134 {
135  QofError * qerr, * set;
136 
137  g_return_if_fail (session);
138  if (error == QOF_SUCCESS)
139  {
140  DEBUG (" passed success, not error.");
141  return;
142  }
143  qerr = g_hash_table_lookup (error_table, GINT_TO_POINTER(error));
144  if (!qerr)
145  {
146  DEBUG (" failed hash table lookup");
147  return;
148  }
149  session->last_err = error;
150  if (session->error_message)
151  g_free (session->error_message);
152  if (qerr->use_file)
153  session->error_message = g_strdup_printf (qerr->message,
154  qof_session_get_url (session));
155  else
156  session->error_message = g_strdup (qerr->message);
157  if (!session->backend)
158  return;
159  /* create a new error for the list */
160  set = g_new0 (QofError, 1);
161  if (qerr->use_file)
162  set->message = g_strdup_printf (qerr->message,
163  qof_session_get_file_path (session));
164  else
165  set->message = g_strdup (qerr->message);
166  set->id = error;
167  set->qt = qof_time_get_current ();
168  session->backend->error_stack =
169  g_list_prepend (session->backend->error_stack, set);
170 #ifndef QOF_DISABLE_DEPRECATED
171  session->backend->last_err = error;
172 #endif
173 }
void qof_error_unregister ( QofErrorId  id)

Unregister an error.

Registered errors are normally freed when the session ends. Errors can also be unregistered (and freed) directly.

An unregistered error can not be set later.

Definition at line 117 of file qoferror.c.

118 {
119  QofError * qerr;
120  gboolean result;
121 
122  ENTER (" ");
123  qerr = g_hash_table_lookup (error_table, GINT_TO_POINTER(id));
124  qof_error_free (qerr);
125  result = g_hash_table_remove (error_table,
126  GINT_TO_POINTER(id));
127  if (!result)
128  LEAVE ("unable to remove registered error.");
129  LEAVE (" ok.");
130 }