lib/table: add route_table_get_next() and iterator
* lib/table.[ch]
- Add a function (route_table_get_next()) to get the route_node in
a tree that succeeds a given prefix in iteration order.
This allows one to reliably walk nodes in a tree while allowing
modifications, and is useful for achieving scale and
performance. Other approaches are also possible -- the main plus
point of this one is that it does not require any state about
the walk to be maintained in the table data structures.
- Add an iterator for walking the nodes in a tree. This introduces
a new structure (route_table_iter_t) and the following main
functions.
route_table_iter_init()
route_table_iter_pause()
route_table_iter_next()
route_table_iter_cleanup()
The iterator normally uses node pointers and the existing
route_next() function to walk nodes efficiently. When an
iteration is 'paused' with route_table_iter_pause(), it stores
the last prefix processed. The next call to
route_table_iter_next() transparently invokes
route_table_get_next() with the prefix to resume iteration.
* bgpd/bgp_table.[ch]
Add wrappers for the new table features described above.
* tests/table_test.c
Add tests for the new table code.
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/lib/table.h b/lib/table.h
index 4d3eddb..ab357a0 100644
--- a/lib/table.h
+++ b/lib/table.h
@@ -98,6 +98,43 @@
#define l_right link[1]
};
+typedef struct route_table_iter_t_ route_table_iter_t;
+
+typedef enum
+{
+ RT_ITER_STATE_INIT,
+ RT_ITER_STATE_ITERATING,
+ RT_ITER_STATE_PAUSED,
+ RT_ITER_STATE_DONE
+} route_table_iter_state_t;
+
+/*
+ * route_table_iter_t
+ *
+ * Structure that holds state for iterating over a route table.
+ */
+struct route_table_iter_t_
+{
+
+ route_table_iter_state_t state;
+
+ /*
+ * Routing table that we are iterating over. The caller must ensure
+ * that that table outlives the iterator.
+ */
+ struct route_table *table;
+
+ /*
+ * The node that the iterator is currently on.
+ */
+ struct route_node *current;
+
+ /*
+ * The last prefix that the iterator processed before it was paused.
+ */
+ struct prefix pause_prefix;
+};
+
/* Prototypes. */
extern struct route_table *route_table_init (void);
@@ -125,4 +162,93 @@
#endif /* HAVE_IPV6 */
extern unsigned long route_table_count (const struct route_table *);
+
+extern struct route_node *
+route_table_get_next (const struct route_table *table, struct prefix *p);
+extern int
+route_table_prefix_iter_cmp (struct prefix *p1, struct prefix *p2);
+
+/*
+ * Iterator functions.
+ */
+extern void route_table_iter_init (route_table_iter_t *iter,
+ struct route_table *table);
+extern void route_table_iter_pause (route_table_iter_t *iter);
+extern void route_table_iter_cleanup (route_table_iter_t *iter);
+
+/*
+ * Inline functions.
+ */
+
+/*
+ * route_table_iter_next
+ *
+ * Get the next node in the tree.
+ */
+static inline struct route_node *
+route_table_iter_next (route_table_iter_t * iter)
+{
+ struct route_node *node;
+
+ switch (iter->state)
+ {
+
+ case RT_ITER_STATE_INIT:
+
+ /*
+ * We're just starting the iteration.
+ */
+ node = route_top (iter->table);
+ break;
+
+ case RT_ITER_STATE_ITERATING:
+ node = route_next (iter->current);
+ break;
+
+ case RT_ITER_STATE_PAUSED:
+
+ /*
+ * Start with the node following pause_prefix.
+ */
+ node = route_table_get_next (iter->table, &iter->pause_prefix);
+ break;
+
+ case RT_ITER_STATE_DONE:
+ return NULL;
+
+ default:
+ assert (0);
+ }
+
+ iter->current = node;
+ if (node)
+ iter->state = RT_ITER_STATE_ITERATING;
+ else
+ iter->state = RT_ITER_STATE_DONE;
+
+ return node;
+}
+
+/*
+ * route_table_iter_is_done
+ *
+ * Returns TRUE if the iteration is complete.
+ */
+static inline int
+route_table_iter_is_done (route_table_iter_t *iter)
+{
+ return iter->state == RT_ITER_STATE_DONE;
+}
+
+/*
+ * route_table_iter_started
+ *
+ * Returns TRUE if this iterator has started iterating over the tree.
+ */
+static inline int
+route_table_iter_started (route_table_iter_t *iter)
+{
+ return iter->state != RT_ITER_STATE_INIT;
+}
+
#endif /* _ZEBRA_TABLE_H */