Commit a1a9c66c authored by Nick Mathewson's avatar Nick Mathewson
Browse files

r11717@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.


svn:r9531
parent 69def349
......@@ -14,6 +14,10 @@ Changes in version 0.1.2.8-alpha - 2007-??-??
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
......
......@@ -954,17 +954,24 @@ smartlist_choose_by_bandwidth(smartlist_t *sl, int for_exit, int statuses)
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 @@ smartlist_choose_by_bandwidth(smartlist_t *sl, int for_exit, int statuses)
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 @@ smartlist_choose_by_bandwidth(smartlist_t *sl, int for_exit, int statuses)
/* 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 @@ smartlist_choose_by_bandwidth(smartlist_t *sl, int for_exit, int statuses)
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 @@ compute_recommended_versions(time_t now, int client,
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 @@ routers_update_all_from_networkstatus(void)
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 @@ routers_update_all_from_networkstatus(void)
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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