[or-cvs] r9531: Clear up some XXX012s in routerlist.c: make smartlist_choose (in tor/trunk: . src/or)
nickm at seul.org
nickm at seul.org
Thu Feb 8 19:44:59 UTC 2007
Author: nickm
Date: 2007-02-08 14:44:55 -0500 (Thu, 08 Feb 2007)
New Revision: 9531
Modified:
tor/trunk/
tor/trunk/ChangeLog
tor/trunk/src/or/routerlist.c
Log:
r11717 at catbus: nickm | 2007-02-08 14:44:30 -0500
Clear up some XXX012s in routerlist.c: make smartlist_choose_by_bandwidth handle statuses with no corresponding routers much better.
Property changes on: tor/trunk
___________________________________________________________________
svk:merge ticket from /tor/trunk [r11717] on 8246c3cf-6607-4228-993b-4d95d33730f1
Modified: tor/trunk/ChangeLog
===================================================================
--- tor/trunk/ChangeLog 2007-02-08 19:44:48 UTC (rev 9530)
+++ tor/trunk/ChangeLog 2007-02-08 19:44:55 UTC (rev 9531)
@@ -14,6 +14,10 @@
o Minor bugfixes (other):
- Display correct results when reporting which versions are recommended,
and how recommended they are. (Resolves bug 383.)
+ - Improve our estimates for directory bandwidth to be less random: guess
+ that an unrecognized directory will have the average bandwidth from all
+ known directories, not that it will have the average bandwidth from
+ those directories earlier than it on the list.
o Minor features:
- Warn the user when an application uses the obsolete binary v0 control
Modified: tor/trunk/src/or/routerlist.c
===================================================================
--- tor/trunk/src/or/routerlist.c 2007-02-08 19:44:48 UTC (rev 9530)
+++ tor/trunk/src/or/routerlist.c 2007-02-08 19:44:55 UTC (rev 9531)
@@ -954,17 +954,24 @@
int i;
routerinfo_t *router;
routerstatus_t *status;
- uint32_t *bandwidths;
+ int32_t *bandwidths;
uint32_t this_bw, is_exit;
uint64_t total_nonexit_bw = 0, total_exit_bw = 0, total_bw = 0;
uint64_t rand_bw, tmp;
double exit_weight;
+ int n_unknown = 0;
/* First count the total bandwidth weight, and make a list
- * of each value. */
- bandwidths = tor_malloc(sizeof(uint32_t)*smartlist_len(sl));
+ * of each value. <0 means "unknown; no routerinfo." We use the
+ * bits of negative values to remember whether the router was fast (-x)&1
+ * and whether it was an exit (-x)&2. Yes, it's a hack. */
+ bandwidths = tor_malloc(sizeof(int32_t)*smartlist_len(sl));
+
+ /* Iterate over all the routerinfo_t or routerstatus_t, and */
for (i = 0; i < smartlist_len(sl); ++i) {
/* first, learn what bandwidth we think i has */
+ int is_known = 1;
+ int32_t flags = 0;
if (statuses) {
/* need to extract router info */
status = smartlist_get(sl, i);
@@ -973,18 +980,9 @@
if (router) {
this_bw = router_get_advertised_bandwidth(router);
} else { /* guess */
- uint64_t partial = for_exit ? total_exit_bw+total_nonexit_bw :
- total_nonexit_bw;
- if (!i) /* no hints; _really_ guess */
- this_bw = status->is_fast ? 40000 : 20000;
- else /* assume it'll be the average we've seen so far */
- this_bw = (uint32_t)(partial/i);
- /*XXXX012 The above calculation is an awful hack, and makes our
- * algorithm hard to describe sanely. Could we do better with a second
- * pass through the list? -NM
- * Sure, fine by me. I fear this thing becoming too intensive,
- * but nobody has mentioned it in profiling yet. -RD
- */
+ is_known = 0;
+ flags = status->is_fast ? 1 : 0;
+ flags |= is_exit ? 2 : 0;
}
} else {
router = smartlist_get(sl, i);
@@ -994,23 +992,60 @@
/* if they claim something huge, don't believe it */
if (this_bw > MAX_BELIEVABLE_BANDWIDTH)
this_bw = MAX_BELIEVABLE_BANDWIDTH;
- bandwidths[i] = this_bw;
- if (is_exit)
- total_exit_bw += this_bw;
- else
- total_nonexit_bw += this_bw;
+ if (is_known) {
+ bandwidths[i] = (int32_t) this_bw; // safe since MAX_BELIEVABLE<INT32_MAX
+ if (is_exit)
+ total_exit_bw += this_bw;
+ else
+ total_nonexit_bw += this_bw;
+ } else {
+ ++n_unknown;
+ bandwidths[i] = -flags;
+ }
}
+
+ /* Now, fill in the unknown values. */
+ if (n_unknown) {
+ int32_t avg_fast, avg_slow;
+ if (total_exit_bw+total_nonexit_bw) {
+ avg_fast = avg_slow =
+ (total_exit_bw+total_nonexit_bw)/(smartlist_len(sl)-n_unknown);
+ } else {
+ avg_fast = 40000;
+ avg_slow = 20000;
+ }
+ for (i=0; i<smartlist_len(sl); ++i) {
+ int32_t bw = bandwidths[i];
+ if (bw>=0)
+ continue;
+ is_exit = ((-bw)&2);
+ bandwidths[i] = ((-bw)&1) ? avg_fast : avg_slow;
+ if (is_exit)
+ total_exit_bw += bandwidths[i];
+ else
+ total_nonexit_bw += bandwidths[i];
+ }
+ }
+
+ /* If there's no bandwidth at all, pick at random. */
if (!(total_exit_bw+total_nonexit_bw)) {
tor_free(bandwidths);
return smartlist_choose(sl);
}
+
+ /* Figure out how to weight exits. */
if (for_exit) {
+ /* If we're choosing an exit node, exit bandwidth counts fully. */
exit_weight = 1.0;
total_bw = total_exit_bw + total_nonexit_bw;
} else if (total_exit_bw < total_nonexit_bw / 2) {
+ /* If we're choosing a relay and exits are greatly outnumbered, ignore
+ * them. */
exit_weight = 0.0;
total_bw = total_nonexit_bw;
} else {
+ /* If we're choosing a relay and exits aren't outnumbered use the formula
+ * from path-spec. */
uint64_t leftover = (total_exit_bw - total_nonexit_bw / 2);
exit_weight = U64_TO_DBL(leftover) /
U64_TO_DBL(leftover + total_nonexit_bw);
@@ -1025,8 +1060,9 @@
U64_PRINTF_ARG(total_nonexit_bw), exit_weight, for_exit);
*/
- /* Second, choose a random value from the bandwidth weights. */
+ /* Almost done: choose a random value from the bandwidth weights. */
rand_bw = crypto_rand_uint64(total_bw);
+
/* Last, count through sl until we get to the element we picked */
tmp = 0;
for (i=0; i < smartlist_len(sl); i++) {
@@ -3128,6 +3164,13 @@
return result;
}
+/** How many times do we have to fail at getting a networkstatus we can't find
+ * before we're willing to believe it's okay to set up router statuses? */
+#define N_NS_ATTEMPTS_TO_SET_ROUTERS 4
+/** How many times do we have to fail at getting a networkstatus we can't find
+ * before we're willing to believe it's okay to check our version? */
+#define N_NS_ATTEMPTS_TO_CHECK_VERSION 4
+
/** If the network-status list has changed since the last time we called this
* function, update the status of every routerinfo from the network-status
* list.
@@ -3151,7 +3194,7 @@
me = router_get_my_routerinfo();
if (me && !have_warned_about_invalid_status &&
- have_tried_downloading_all_statuses(4)) {
+ have_tried_downloading_all_statuses(N_NS_ATTEMPTS_TO_SET_ROUTERS)) {
int n_recent = 0, n_listing = 0, n_valid = 0, n_named = 0, n_naming = 0;
routerstatus_t *rs;
SMARTLIST_FOREACH(networkstatus_list, networkstatus_t *, ns,
@@ -3190,7 +3233,7 @@
entry_guards_compute_status();
if (!have_warned_about_old_version &&
- have_tried_downloading_all_statuses(4)) { /*XXXX012This 4 is too magic.*/
+ have_tried_downloading_all_statuses(N_NS_ATTEMPTS_TO_CHECK_VERSION)) {
combined_version_status_t st;
int is_server = server_mode(get_options());
char *recommended;
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