pybsddb 4.3.1, adds support for DB.set_bt_compare database btree comparison
functions written in python.
contributed by <frederic.gobry@epfl.ch>
diff --git a/Modules/_bsddb.c b/Modules/_bsddb.c
index 2712e3d..6a39d85 100644
--- a/Modules/_bsddb.c
+++ b/Modules/_bsddb.c
@@ -97,7 +97,7 @@
#error "eek! DBVER can't handle minor versions > 9"
#endif
-#define PY_BSDDB_VERSION "4.3.0"
+#define PY_BSDDB_VERSION "4.3.1"
static char *rcs_id = "$Id$";
@@ -244,6 +244,7 @@
struct behaviourFlags moduleFlags;
#if (DBVER >= 33)
PyObject* associateCallback;
+ PyObject* btCompareCallback;
int primaryDBType;
#endif
#ifdef HAVE_WEAKREF
@@ -741,6 +742,7 @@
self->myenvobj = NULL;
#if (DBVER >= 33)
self->associateCallback = NULL;
+ self->btCompareCallback = NULL;
self->primaryDBType = 0;
#endif
#ifdef HAVE_WEAKREF
@@ -815,6 +817,10 @@
Py_DECREF(self->associateCallback);
self->associateCallback = NULL;
}
+ if (self->btCompareCallback != NULL) {
+ Py_DECREF(self->btCompareCallback);
+ self->btCompareCallback = NULL;
+ }
#endif
PyObject_Del(self);
}
@@ -1959,6 +1965,161 @@
RETURN_NONE();
}
+static int
+_default_cmp (const DBT *leftKey,
+ const DBT *rightKey)
+{
+ int res;
+ int lsize = leftKey->size, rsize = rightKey->size;
+
+ res = memcmp (leftKey->data, rightKey->data,
+ lsize < rsize ? lsize : rsize);
+
+ if (res == 0) {
+ if (lsize < rsize) {
+ res = -1;
+ }
+ else if (lsize > rsize) {
+ res = 1;
+ }
+ }
+ return res;
+}
+
+static int
+_db_compareCallback (DB* db,
+ const DBT *leftKey,
+ const DBT *rightKey)
+{
+ int res = 0;
+ PyObject *args;
+ PyObject *result;
+ PyObject *leftObject;
+ PyObject *rightObject;
+ DBObject *self = (DBObject *) db->app_private;
+
+ if (self == NULL || self->btCompareCallback == NULL) {
+ MYDB_BEGIN_BLOCK_THREADS;
+ PyErr_SetString (PyExc_TypeError,
+ (self == 0
+ ? "DB_bt_compare db is NULL."
+ : "DB_bt_compare callback is NULL."));
+ /* we're in a callback within the DB code, we can't raise */
+ PyErr_Print ();
+ res = _default_cmp (leftKey, rightKey);
+ MYDB_END_BLOCK_THREADS;
+ }
+ else {
+ MYDB_BEGIN_BLOCK_THREADS;
+
+ leftObject = PyString_FromStringAndSize (leftKey->data, leftKey->size);
+ rightObject = PyString_FromStringAndSize (rightKey->data, rightKey->size);
+
+ args = PyTuple_New (3);
+ Py_INCREF (self);
+ PyTuple_SET_ITEM (args, 0, (PyObject *) self);
+ PyTuple_SET_ITEM (args, 1, leftObject); /* steals reference */
+ PyTuple_SET_ITEM (args, 2, rightObject); /* steals reference */
+
+ result = PyEval_CallObject (self->btCompareCallback, args);
+ if (result == 0) {
+ /* we're in a callback within the DB code, we can't raise */
+ PyErr_Print (); // XXX-gps or can we? either way the DB is screwed
+ res = _default_cmp (leftKey, rightKey);
+ }
+ else if (PyInt_Check (result)) {
+ res = PyInt_AsLong (result);
+ }
+ else {
+ PyErr_SetString (PyExc_TypeError,
+ "DB_bt_compare callback MUST return an int.");
+ /* we're in a callback within the DB code, we can't raise */
+ PyErr_Print ();
+ res = _default_cmp (leftKey, rightKey);
+ }
+
+ Py_DECREF (args);
+ Py_XDECREF (result);
+
+ MYDB_END_BLOCK_THREADS;
+ }
+ return res;
+}
+
+static PyObject*
+DB_set_bt_compare (DBObject* self, PyObject* args)
+{
+ int err;
+ PyObject *comparator;
+ PyObject *tuple, *emptyStr, *result;
+
+ if (!PyArg_ParseTuple(args,"O:set_bt_compare", &comparator ))
+ return NULL;
+
+ CHECK_DB_NOT_CLOSED (self);
+
+ if (! PyCallable_Check (comparator)) {
+ makeTypeError ("Callable", comparator);
+ return NULL;
+ }
+
+ /*
+ * Perform a test call of the comparator function with two empty
+ * string objects here. verify that it returns an int (0).
+ * err if not.
+ */
+ tuple = PyTuple_New (3);
+ Py_INCREF (self);
+ PyTuple_SET_ITEM (tuple, 0, (PyObject *) self);
+
+ emptyStr = PyString_FromStringAndSize (NULL, 0);
+ Py_INCREF(emptyStr);
+ PyTuple_SET_ITEM (tuple, 1, emptyStr);
+ PyTuple_SET_ITEM (tuple, 2, emptyStr); /* steals reference */
+ result = PyEval_CallObject (comparator, tuple);
+ Py_DECREF (tuple);
+ if (result == 0 || !PyInt_Check(result)) {
+ PyErr_SetString (PyExc_TypeError,
+ "callback MUST return an int");
+ return NULL;
+ }
+ else if (PyInt_AsLong(result) != 0) {
+ PyErr_SetString (PyExc_TypeError,
+ "callback failed to return 0 on two empty strings");
+ return NULL;
+ }
+
+ /* We don't accept multiple set_bt_compare operations, in order to
+ * simplify the code. This would have no real use, as one cannot
+ * change the function once the db is opened anyway */
+ if (self->btCompareCallback != NULL) {
+ PyErr_SetString (PyExc_RuntimeError, "set_bt_compare () cannot be called more than once");
+ return NULL;
+ }
+
+ Py_INCREF (comparator);
+ self->btCompareCallback = comparator;
+
+ /* This is to workaround a problem with un-initialized threads (see
+ comment in DB_associate) */
+#ifdef WITH_THREAD
+ PyEval_InitThreads();
+#endif
+
+ err = self->db->set_bt_compare (self->db,
+ (comparator != NULL ?
+ _db_compareCallback : NULL));
+
+ if (err) {
+ /* restore the old state in case of error */
+ Py_DECREF (comparator);
+ self->btCompareCallback = NULL;
+ }
+
+ RETURN_IF_ERR ();
+ RETURN_NONE ();
+}
+
static PyObject*
DB_set_cachesize(DBObject* self, PyObject* args)
@@ -4400,6 +4561,7 @@
{"remove", (PyCFunction)DB_remove, METH_VARARGS|METH_KEYWORDS},
{"rename", (PyCFunction)DB_rename, METH_VARARGS},
{"set_bt_minkey", (PyCFunction)DB_set_bt_minkey, METH_VARARGS},
+ {"set_bt_compare", (PyCFunction)DB_set_bt_compare, METH_VARARGS},
{"set_cachesize", (PyCFunction)DB_set_cachesize, METH_VARARGS},
#if (DBVER >= 41)
{"set_encrypt", (PyCFunction)DB_set_encrypt, METH_VARARGS|METH_KEYWORDS},