commit ed636de4cc71fb2936358da27f211fb6a255cd9d
parent be9f0e5f20e37d2176ce0663b71b532c44c10c28
Author: Nick Mathewson <nickm@torproject.org>
Date: Thu, 3 May 2018 11:59:31 -0400
Merge remote-tracking branch 'github/ticket25951'
Diffstat:
7 files changed, 59 insertions(+), 4 deletions(-)
diff --git a/changes/ticket25951 b/changes/ticket25951
@@ -0,0 +1,9 @@
+ o Minor features (mainloop):
+ - Move responsibility for
+ flushing log callbacks
+ from a once-per-second callback to a callback that is only scheduled as
+ needed. Once enough items are removed from our once-per-second
+ callback, we can eliminate it entirely to conserve CPU when idle.
+ Closes ticket
+ 25951.
+
diff --git a/src/common/log.c b/src/common/log.c
@@ -170,6 +170,9 @@ typedef struct pending_log_message_t {
/** Log messages waiting to be replayed onto callback-based logs */
static smartlist_t *pending_cb_messages = NULL;
+/** Callback to invoke when pending_cb_messages becomes nonempty. */
+static pending_callback_callback pending_cb_cb = NULL;
+
/** Log messages waiting to be replayed once the logging system is initialized.
*/
static smartlist_t *pending_startup_messages = NULL;
@@ -538,6 +541,9 @@ logfile_deliver(logfile_t *lf, const char *buf, size_t msg_len,
smartlist_add(pending_cb_messages,
pending_log_message_new(severity,domain,NULL,msg_after_prefix));
*callbacks_deferred = 1;
+ if (smartlist_len(pending_cb_messages) == 1 && pending_cb_cb) {
+ pending_cb_cb();
+ }
}
} else {
lf->callback(severity, domain, msg_after_prefix);
@@ -825,6 +831,7 @@ logs_free_all(void)
logfiles = NULL;
messages = pending_cb_messages;
pending_cb_messages = NULL;
+ pending_cb_cb = NULL;
messages2 = pending_startup_messages;
pending_startup_messages = NULL;
UNLOCK_LOGS();
@@ -988,6 +995,24 @@ add_temp_log(int min_severity)
}
/**
+ * Register "cb" as the callback to call when there are new pending log
+ * callbacks to be flushed with flush_pending_log_callbacks().
+ *
+ * Note that this callback, if present, can be invoked from any thread.
+ *
+ * This callback must not log.
+ *
+ * It is intentional that this function contains the name "callback" twice: it
+ * sets a "callback" to be called on the condition that there is a "pending
+ * callback".
+ **/
+void
+logs_set_pending_callback_callback(pending_callback_callback cb)
+{
+ pending_cb_cb = cb;
+}
+
+/**
* Add a log handler to send messages in <b>severity</b>
* to the function <b>cb</b>.
*/
diff --git a/src/common/torlog.h b/src/common/torlog.h
@@ -154,6 +154,8 @@ int add_android_log(const log_severity_list_t *severity,
const char *android_identity_tag);
#endif // HAVE_ANDROID_LOG_H.
int add_callback_log(const log_severity_list_t *severity, log_callback cb);
+typedef void (*pending_callback_callback)(void);
+void logs_set_pending_callback_callback(pending_callback_callback cb);
void logs_set_domain_logging(int enabled);
int get_min_log_level(void);
void switch_logs_debug(void);
diff --git a/src/or/config.c b/src/or/config.c
@@ -1552,6 +1552,7 @@ options_act_reversible(const or_options_t *old_options, char **msg)
tor_malloc_zero(sizeof(log_severity_list_t));
close_temp_logs();
add_callback_log(severity, control_event_logmsg);
+ logs_set_pending_callback_callback(control_event_logmsg_pending);
control_adjust_event_log_severity();
tor_free(severity);
tor_log_update_sigsafe_err_fds();
diff --git a/src/or/control.c b/src/or/control.c
@@ -803,6 +803,9 @@ queued_event_free_(queued_event_t *ev)
static void
queued_events_flush_all(int force)
{
+ /* Make sure that we get all the pending log events, if there are any. */
+ flush_pending_log_callbacks();
+
if (PREDICT_UNLIKELY(queued_control_events == NULL)) {
return;
}
@@ -6186,7 +6189,7 @@ control_event_logmsg(int severity, uint32_t domain, const char *msg)
int event;
/* Don't even think of trying to add stuff to a buffer from a cpuworker
- * thread. */
+ * thread. (See #25987 for plan to fix.) */
if (! in_main_thread())
return;
@@ -6232,6 +6235,23 @@ control_event_logmsg(int severity, uint32_t domain, const char *msg)
}
}
+/**
+ * Logging callback: called when there is a queued pending log callback.
+ */
+void
+control_event_logmsg_pending(void)
+{
+ if (! in_main_thread()) {
+ /* We can't handle this case yet, since we're using a
+ * mainloop_event_t to invoke queued_events_flush_all. We ought to
+ * use a different mechanism instead: see #25987.
+ **/
+ return;
+ }
+ tor_assert(flush_queued_events_event);
+ mainloop_event_activate(flush_queued_events_event);
+}
+
/** Called whenever we receive new router descriptors: tell any
* interested control connections. <b>routers</b> is a list of
* routerinfo_t's.
diff --git a/src/or/control.h b/src/or/control.h
@@ -60,6 +60,7 @@ int control_event_conn_bandwidth(connection_t *conn);
int control_event_conn_bandwidth_used(void);
int control_event_circuit_cell_stats(void);
void control_event_logmsg(int severity, uint32_t domain, const char *msg);
+void control_event_logmsg_pending(void);
int control_event_descriptors_changed(smartlist_t *routers);
int control_event_address_mapped(const char *from, const char *to,
time_t expires, const char *error,
diff --git a/src/or/main.c b/src/or/main.c
@@ -1711,9 +1711,6 @@ run_scheduled_events(time_t now)
*/
consider_hibernation(now);
- /* 0c. If we've deferred log messages for the controller, handle them now */
- flush_pending_log_callbacks();
-
/* Maybe enough time elapsed for us to reconsider a circuit. */
circuit_upgrade_circuits_from_guard_wait();
