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close other consensus fetches when we get a consensus

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not once per second, and only do it when a consensus arrives
This commit is contained in:
Roger Dingledine 2016-04-13 02:54:31 -04:00
parent 59da060f10
commit a7665df2f8
3 changed files with 30 additions and 105 deletions
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123
src/or/directory.c
View File

@ -96,6 +96,9 @@ static void directory_initiate_command_rend(
time_t if_modified_since,
const rend_data_t *rend_query);
static void connection_dir_close_consensus_fetches(
dir_connection_t *except_this_one, const char *resource);
/********* START VARIABLES **********/
/** How far in the future do we allow a directory server to tell us it is
@ -2028,6 +2031,10 @@ connection_dir_client_reached_eof(dir_connection_t *conn)
networkstatus_consensus_download_failed(0, flavname);
return -1;
}
/* If we launched other fetches for this consensus, cancel them. */
connection_dir_close_consensus_fetches(conn, flavname);
/* launches router downloads as needed */
routers_update_all_from_networkstatus(now, 3);
update_microdescs_from_networkstatus(now);
@ -3680,7 +3687,7 @@ connection_dir_finished_flushing(dir_connection_t *conn)
}
/* A helper function for connection_dir_close_consensus_conn_if_extra()
* and connection_dir_close_extra_consensus_conns() that returns 0 if
* that returns 0 if
* we can't have, or don't want to close, excess consensus connections. */
STATIC int
connection_dir_would_close_consensus_conn_helper(void)
@ -3797,103 +3804,33 @@ connection_dir_close_consensus_conn_if_extra(dir_connection_t *conn)
return 0;
}
/* Clean up excess consensus download connection attempts.
* During bootstrap, or when the bootstrap consensus has just been downloaded,
* if we have more than one active consensus connection:
* - if we don't have a consensus, and we're downloading a consensus, keep an
* earlier connection, or a connection to a fallback directory, and close
* all other connections;
* - if we have just downloaded the bootstrap consensus, and have other
* consensus connections left over, close all of them.
/* We just got a new consensus! If there are other in-progress requests
* for this consensus flavor (for example because we launched several in
* parallel), cancel them.
*
* Post-bootstrap consensus connection attempts are initiated one at a time.
* So this function won't close any consensus connection attempts that
* are initiated after bootstrap.
* We do this check here (not just in
* connection_ap_handshake_attach_circuit()) to handle the edge case where
* a consensus fetch begins and ends before some other one tries to attach to
* a circuit, in which case the other one won't know that we're all happy now.
*
* Don't mark the conn that just gave us the consensus -- otherwise we
* would end up double-marking it when it cleans itself up.
*/
void
connection_dir_close_extra_consensus_conns(void)
static void
connection_dir_close_consensus_fetches(dir_connection_t *except_this_one,
const char *resource)
{
/* Only cleanup connections if there is more than one consensus connection,
* and at least one of those connections is already downloading
* (during bootstrap), or connecting (just after the bootstrap consensus is
* downloaded).
* Post-bootstrap consensus connection attempts won't be cleaned up, because
* they only occur one at a time. */
if (!connection_dir_would_close_consensus_conn_helper()) {
return;
}
int we_are_bootstrapping = networkstatus_consensus_is_bootstrapping(
time(NULL));
const char *usable_resource = networkstatus_get_flavor_name(
usable_consensus_flavor());
smartlist_t *consens_usable_conns =
connection_dir_list_by_purpose_and_resource(
DIR_PURPOSE_FETCH_CONSENSUS,
usable_resource);
/* If we want to keep a connection that's downloading, find a connection to
* keep, favouring:
* - connections opened earlier (they are likely to have progressed further)
* - connections to fallbacks (to reduce the load on authorities) */
dir_connection_t *kept_download_conn = NULL;
int kept_is_authority = 0;
if (we_are_bootstrapping) {
SMARTLIST_FOREACH_BEGIN(consens_usable_conns,
dir_connection_t *, d) {
tor_assert(d);
int d_is_authority = router_digest_is_trusted_dir(d->identity_digest);
/* keep the first connection that is past the connecting state, but
* prefer fallbacks. */
if (d->base_.state != DIR_CONN_STATE_CONNECTING) {
if (!kept_download_conn || (kept_is_authority && !d_is_authority)) {
kept_download_conn = d;
kept_is_authority = d_is_authority;
/* we've found the earliest fallback, and want to keep it regardless
* of any other connections */
if (!kept_is_authority)
break;
}
}
} SMARTLIST_FOREACH_END(d);
}
SMARTLIST_FOREACH_BEGIN(consens_usable_conns,
dir_connection_t *, d) {
tor_assert(d);
/* don't close this connection if it's the one we want to keep */
if (kept_download_conn && d == kept_download_conn)
smartlist_t *conns_to_close =
connection_dir_list_by_purpose_and_resource(DIR_PURPOSE_FETCH_CONSENSUS,
resource);
SMARTLIST_FOREACH_BEGIN(conns_to_close, dir_connection_t *, d) {
if (d == except_this_one)
continue;
/* mark all other connections for close */
if (!d->base_.marked_for_close) {
connection_close_immediate(&d->base_);
connection_mark_for_close(&d->base_);
}
log_info(LD_DIR, "Closing consensus fetch (to %s) since one "
"has just arrived.", TO_CONN(d)->address);
connection_mark_for_close(TO_CONN(d));
} SMARTLIST_FOREACH_END(d);
smartlist_free(consens_usable_conns);
consens_usable_conns = NULL;
/* make sure we've closed all excess connections */
const int final_connecting_conn_count =
connection_dir_count_by_purpose_resource_and_state(
DIR_PURPOSE_FETCH_CONSENSUS,
usable_resource,
DIR_CONN_STATE_CONNECTING);
if (final_connecting_conn_count > 0) {
log_warn(LD_BUG, "Expected 0 consensus connections connecting after "
"cleanup, got %d.", final_connecting_conn_count);
}
const int expected_final_conn_count = (we_are_bootstrapping ? 1 : 0);
const int final_conn_count =
connection_dir_count_by_purpose_and_resource(
DIR_PURPOSE_FETCH_CONSENSUS,
usable_resource);
if (final_conn_count > expected_final_conn_count) {
log_warn(LD_BUG, "Expected %d consensus connections after cleanup, got "
"%d.", expected_final_conn_count, final_connecting_conn_count);
}
smartlist_free(conns_to_close);
}
/** Connected handler for directory connections: begin sending data to the

1
src/or/directory.h
View File

@ -80,7 +80,6 @@ void directory_initiate_command(const tor_addr_t *or_addr, uint16_t or_port,
time_t if_modified_since);
int connection_dir_avoid_extra_connection_for_purpose(unsigned int purpose);
int connection_dir_close_consensus_conn_if_extra(dir_connection_t *conn);
void connection_dir_close_extra_consensus_conns(void);
#define DSR_HEX (1<<0)
#define DSR_BASE64 (1<<1)

11
src/or/main.c
View File

@ -1484,17 +1484,6 @@ run_scheduled_events(time_t now)
dirvote_act(options, now);
}
/* 2d. Cleanup excess consensus bootstrap connections every second.
* connection_dir_close_consensus_conn_if_extra() closes some connections
* that are clearly excess, but this check is more thorough.
* This only closes connections if there is more than one consensus
* connection, and at least one of those connections is already downloading
* (during bootstrap), or connecting (just after the bootstrap consensus is
* downloaded).
* It won't close any consensus connections initiated after bootstrap,
* because those attempts are made one at a time. */
connection_dir_close_extra_consensus_conns();
/* 3a. Every second, we examine pending circuits and prune the
* ones which have been pending for more than a few seconds.
* We do this before step 4, so it can try building more if