Commit 488e2b00 authored by Nick Mathewson's avatar Nick Mathewson 🏃
Browse files

Refactor the "block the connection on bandwidth" logic

Right now, this patch just introduces and exposes some new
functions. Later, these functions will get a little more complexity.
parent 2bf6f1cd
......@@ -772,8 +772,8 @@ connection_close_immediate(connection_t *conn)
connection_unregister_events(conn);
/* Prevent the event from getting unblocked. */
conn->read_blocked_on_bw =
conn->write_blocked_on_bw = 0;
conn->read_blocked_on_bw = 0;
conn->write_blocked_on_bw = 0;
if (SOCKET_OK(conn->s))
tor_close_socket(conn->s);
......@@ -3052,9 +3052,37 @@ connection_buckets_decrement(connection_t *conn, time_t now,
}
}
/**
* Mark <b>conn</b> as needing to stop reading because bandwidth has been
* exhausted. If <b>is_global_bw</b>, it is closing because global bandwidth
* limit has been exhausted. Otherwise, it is closing because its own
* bandwidth limit has been exhausted.
*/
void
connection_read_bw_exhausted(connection_t *conn, bool is_global_bw)
{
(void)is_global_bw;
conn->read_blocked_on_bw = 1;
connection_stop_reading(conn);
}
/**
* Mark <b>conn</b> as needing to stop reading because write bandwidth has
* been exhausted. If <b>is_global_bw</b>, it is closing because global
* bandwidth limit has been exhausted. Otherwise, it is closing because its
* own bandwidth limit has been exhausted.
*/
void
connection_write_bw_exhausted(connection_t *conn, bool is_global_bw)
{
(void)is_global_bw;
conn->write_blocked_on_bw = 1;
connection_stop_reading(conn);
}
/** If we have exhausted our global buckets, or the buckets for conn,
* stop reading. */
static void
void
connection_consider_empty_read_buckets(connection_t *conn)
{
const char *reason;
......@@ -3062,6 +3090,7 @@ connection_consider_empty_read_buckets(connection_t *conn)
if (!connection_is_rate_limited(conn))
return; /* Always okay. */
bool is_global = true;
if (token_bucket_rw_get_read(&global_bucket) <= 0) {
reason = "global read bucket exhausted. Pausing.";
} else if (connection_counts_as_relayed_traffic(conn, approx_time()) &&
......@@ -3071,17 +3100,17 @@ connection_consider_empty_read_buckets(connection_t *conn)
conn->state == OR_CONN_STATE_OPEN &&
token_bucket_rw_get_read(&TO_OR_CONN(conn)->bucket) <= 0) {
reason = "connection read bucket exhausted. Pausing.";
is_global = false;
} else
return; /* all good, no need to stop it */
LOG_FN_CONN(conn, (LOG_DEBUG, LD_NET, "%s", reason));
conn->read_blocked_on_bw = 1;
connection_stop_reading(conn);
connection_read_bw_exhausted(conn, is_global);
}
/** If we have exhausted our global buckets, or the buckets for conn,
* stop writing. */
static void
void
connection_consider_empty_write_buckets(connection_t *conn)
{
const char *reason;
......@@ -3089,6 +3118,7 @@ connection_consider_empty_write_buckets(connection_t *conn)
if (!connection_is_rate_limited(conn))
return; /* Always okay. */
bool is_global = true;
if (token_bucket_rw_get_write(&global_bucket) <= 0) {
reason = "global write bucket exhausted. Pausing.";
} else if (connection_counts_as_relayed_traffic(conn, approx_time()) &&
......@@ -3098,12 +3128,12 @@ connection_consider_empty_write_buckets(connection_t *conn)
conn->state == OR_CONN_STATE_OPEN &&
token_bucket_rw_get_write(&TO_OR_CONN(conn)->bucket) <= 0) {
reason = "connection write bucket exhausted. Pausing.";
is_global = false;
} else
return; /* all good, no need to stop it */
LOG_FN_CONN(conn, (LOG_DEBUG, LD_NET, "%s", reason));
conn->write_blocked_on_bw = 1;
connection_stop_writing(conn);
connection_write_bw_exhausted(conn, is_global);
}
/** Initialize the global buckets to the values configured in the
......@@ -3768,8 +3798,7 @@ connection_handle_write_impl(connection_t *conn, int force)
/* Make sure to avoid a loop if the receive buckets are empty. */
log_debug(LD_NET,"wanted read.");
if (!connection_is_reading(conn)) {
connection_stop_writing(conn);
conn->write_blocked_on_bw = 1;
connection_write_bw_exhausted(conn, true);
/* we'll start reading again when we get more tokens in our
* read bucket; then we'll start writing again too.
*/
......
......@@ -125,6 +125,10 @@ void connection_bucket_init(void);
void connection_bucket_adjust(const or_options_t *options);
void connection_bucket_refill(time_t now,
uint32_t now_ts);
void connection_read_bw_exhausted(connection_t *conn, bool is_global_bw);
void connection_write_bw_exhausted(connection_t *conn, bool is_global_bw);
void connection_consider_empty_read_buckets(connection_t *conn);
void connection_consider_empty_write_buckets(connection_t *conn);
int connection_handle_read(connection_t *conn);
......
......@@ -1025,19 +1025,22 @@ conn_close_if_marked(int i)
* busy Libevent loops where we keep ending up here and returning
* 0 until we are no longer blocked on bandwidth.
*/
if (connection_is_writing(conn)) {
conn->write_blocked_on_bw = 1;
connection_stop_writing(conn);
connection_consider_empty_read_buckets(conn);
connection_consider_empty_write_buckets(conn);
/* Make sure that consider_empty_buckets really disabled the
* connection: */
if (BUG(connection_is_writing(conn))) {
connection_write_bw_exhausted(conn, true);
}
if (connection_is_reading(conn)) {
if (BUG(connection_is_reading(conn))) {
/* XXXX+ We should make this code unreachable; if a connection is
* marked for close and flushing, there is no point in reading to it
* at all. Further, checking at this point is a bit of a hack: it
* would make much more sense to react in
* connection_handle_read_impl, or to just stop reading in
* mark_and_flush */
conn->read_blocked_on_bw = 1;
connection_stop_reading(conn);
connection_read_bw_exhausted(conn, true/* kludge. */);
}
}
return 0;
......
......@@ -57,6 +57,7 @@
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#include <stdbool.h>
#ifdef _WIN32
#include <winsock2.h>
......
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