Refactor OOM-handling functions for more testability

This patch splits out some of the functions in OOM handling so that
it's easier to check them without involving the rest of Tor or
requiring that the circuits be "wired up".

src/or/circuitlist.c

@@ -1435,9 +1435,9 @@ circuit_mark_all_dirty_circs_as_unusable(void)
  *   - If circ->rend_splice is set (we are the midpoint of a joined
  *     rendezvous stream), then mark the other circuit to close as well.
  */
-void
-circuit_mark_for_close_(circuit_t *circ, int reason, int line,
-                        const char *file)
+MOCK_IMPL(void,
+circuit_mark_for_close_, (circuit_t *circ, int reason, int line,
+                          const char *file))
 {
   int orig_reason = reason; /* Passed to the controller */
   assert_circuit_ok(circ);

src/or/circuitlist.h

@@ -53,8 +53,8 @@ origin_circuit_t *circuit_find_to_cannibalize(uint8_t purpose,
                                               extend_info_t *info, int flags);
 void circuit_mark_all_unused_circs(void);
 void circuit_mark_all_dirty_circs_as_unusable(void);
-void circuit_mark_for_close_(circuit_t *circ, int reason,
-                             int line, const char *file);
+MOCK_DECL(void, circuit_mark_for_close_, (circuit_t *circ, int reason,
+                                          int line, const char *file));
 int circuit_get_cpath_len(origin_circuit_t *circ);
 void circuit_clear_cpath(origin_circuit_t *circ);
 crypt_path_t *circuit_get_cpath_hop(origin_circuit_t *circ, int hopnum);

src/or/relay.c

@@ -2199,12 +2199,19 @@ packed_cell_mem_cost(void)
   return sizeof(packed_cell_t) + MP_POOL_ITEM_OVERHEAD;
 }
 
+/** DOCDOC */
+STATIC size_t
+cell_queues_get_total_allocation(void)
+{
+  return total_cells_allocated * packed_cell_mem_cost();
+}
+
 /** Check whether we've got too much space used for cells.  If so,
  * call the OOM handler and return 1.  Otherwise, return 0. */
-static int
+STATIC int
 cell_queues_check_size(void)
 {
-  size_t alloc = total_cells_allocated * packed_cell_mem_cost();
+  size_t alloc = cell_queues_get_total_allocation();
   alloc += buf_get_total_allocation();
   if (alloc >= get_options()->MaxMemInQueues) {
     circuits_handle_oom(alloc);

src/or/relay.h

@@ -85,6 +85,8 @@ STATIC int connected_cell_parse(const relay_header_t *rh, const cell_t *cell,
                          tor_addr_t *addr_out, int *ttl_out);
 STATIC packed_cell_t *packed_cell_new(void);
 STATIC packed_cell_t *cell_queue_pop(cell_queue_t *queue);
+STATIC size_t cell_queues_get_total_allocation(void);
+STATIC int cell_queues_check_size(void);
 #endif
 
 #endif