Parameterize FRAC_USABLE_NEEDED for fraction of circuits

Instead of hardcoding the minimum fraction of possible paths to 0.6, we
take it from the user, and failing that from the consensus, and
failing that we fall back to 0.6.

1 files changed, 17 insertions, 4 deletions

diff --git a/src/or/nodelist.c b/src/or/nodelist.c
index 77e4ae0fe..4d7395b04 100644
--- a/src/or/nodelist.c
+++ b/src/or/nodelist.c
@@ -1387,6 +1387,22 @@ count_loading_descriptors_progress(void)
                BOOTSTRAP_STATUS_LOADING_DESCRIPTORS));
 }
 
+/** Return the fraction of paths needed before we're willing to build
+ * circuits, as configured in <b>options</b>, or in the consensus <b>ns</b>. */
+static double
+get_frac_paths_needed_for_circs(const or_options_t *options,
+                                const networkstatus_t *ns)
+{
+#define DFLT_PCT_USABLE_NEEDED 60
+  if (options->PathsNeededToBuildCircuits >= 1.0) {
+    return options->PathsNeededToBuildCircuits;
+  } else {
+    return networkstatus_get_param(ns, "min_paths_for_circs_pct",
+                                   DFLT_PCT_USABLE_NEEDED,
+                                   25, 95)/100.0;
+  }
+}
+
 /** Change the value of have_min_dir_info, setting it true iff we have enough
  * network and router information to build circuits.  Clear the value of
  * need_to_update_have_min_dir_info. */
@@ -1428,10 +1444,7 @@ update_router_have_minimum_dir_info(void)
                                                 &num_present, &num_usable,
                                                 &status);
 
-/* What fraction of desired paths do we need before we will build circuits? */
-#define FRAC_USABLE_NEEDED .6
-
-    if (paths < FRAC_USABLE_NEEDED) {
+    if (paths < get_frac_paths_needed_for_circs(options,consensus)) {
       tor_snprintf(dir_info_status, sizeof(dir_info_status),
                    "We need more %sdescriptors: we have %d/%d, and "
                    "can only build %02d%% of likely paths. (We have %s.)",