[tor-commits] [tor/master] Add an API for a scheduled/manually activated event in the mainloop
nickm at torproject.org
nickm at torproject.org
Fri Apr 6 12:51:50 UTC 2018
commit 871ff0006d052967534fb6ce31465b55021888f0
Author: Nick Mathewson <nickm at torproject.org>
Date: Tue Oct 3 10:44:45 2017 -0400
Add an API for a scheduled/manually activated event in the mainloop
Using this API lets us remove event2/event.h usage from half a dozen
modules, to better isolate libevent. Implements part of ticket
23750.
---
src/common/compat_libevent.c | 115 +++++++++++++++++++++++++++++++++++++++++++
src/common/compat_libevent.h | 11 +++++
src/common/timers.c | 18 +++----
src/or/control.c | 20 +++-----
src/or/main.c | 11 ++---
src/or/periodic.c | 21 +++-----
src/or/periodic.h | 5 +-
src/or/scheduler.c | 25 ++++------
src/or/scheduler.h | 4 +-
src/or/scheduler_kist.c | 4 +-
src/or/scheduler_vanilla.c | 4 +-
11 files changed, 170 insertions(+), 68 deletions(-)
diff --git a/src/common/compat_libevent.c b/src/common/compat_libevent.c
index 735385557..f453a8e87 100644
--- a/src/common/compat_libevent.c
+++ b/src/common/compat_libevent.c
@@ -221,6 +221,121 @@ periodic_timer_free_(periodic_timer_t *timer)
tor_free(timer);
}
+/**
+ * Type used to represent events that run directly from the main loop,
+ * either because they are activated from elsewhere in the code, or
+ * because they have a simple timeout.
+ *
+ * We use this type to avoid exposing Libevent's API throughout the rest
+ * of the codebase.
+ *
+ * This type can't be used for all events: it doesn't handle events that
+ * are triggered by signals or by sockets.
+ */
+struct mainloop_event_t {
+ struct event *ev;
+ void (*cb)(mainloop_event_t *, void *);
+ void *userdata;
+};
+
+/**
+ * Internal: Implements mainloop event using a libevent event.
+ */
+static void
+mainloop_event_cb(evutil_socket_t fd, short what, void *arg)
+{
+ (void)fd;
+ (void)what;
+ mainloop_event_t *mev = arg;
+ mev->cb(mev, mev->userdata);
+}
+
+/**
+ * Create and return a new mainloop_event_t to run the function <b>cb</b>.
+ *
+ * When run, the callback function will be passed the mainloop_event_t
+ * and <b>userdata</b> as its arguments. The <b>userdata</b> pointer
+ * must remain valid for as long as the mainloop_event_t event exists:
+ * it is your responsibility to free it.
+ *
+ * The event is not scheduled by default: Use mainloop_event_activate()
+ * or mainloop_event_schedule() to make it run.
+ */
+mainloop_event_t *
+mainloop_event_new(void (*cb)(mainloop_event_t *, void *),
+ void *userdata)
+{
+ tor_assert(cb);
+
+ struct event_base *base = tor_libevent_get_base();
+ mainloop_event_t *mev = tor_malloc_zero(sizeof(mainloop_event_t));
+ mev->ev = tor_event_new(base, -1, 0, mainloop_event_cb, mev);
+ tor_assert(mev->ev);
+ mev->cb = cb;
+ mev->userdata = userdata;
+ return mev;
+}
+
+/**
+ * Schedule <b>event</b> to run in the main loop, immediately. If it is
+ * not scheduled, it will run anyway. If it is already scheduled to run
+ * later, it will run now instead. This function will have no effect if
+ * the event is already scheduled to run.
+ *
+ * This function may only be called from the main thread.
+ */
+void
+mainloop_event_activate(mainloop_event_t *event)
+{
+ tor_assert(event);
+ event_active(event->ev, EV_READ, 1);
+}
+
+/** Schedule <b>event</b> to run in the main loop, after a delay of <b>tv</b>.
+ *
+ * If the event is scheduled for a different time, cancel it and run
+ * after this delay instead. If the event is currently pending to run
+ * <em>now</b>, has no effect.
+ *
+ * Do not call this function with <b>tv</b> == NULL -- use
+ * mainloop_event_activate() instead.
+ *
+ * This function may only be called from the main thread.
+ */
+int
+mainloop_event_schedule(mainloop_event_t *event, const struct timeval *tv)
+{
+ tor_assert(event);
+ if (BUG(tv == NULL)) {
+ // LCOV_EXCL_START
+ mainloop_event_activate(event);
+ return 0;
+ // LCOV_EXCL_STOP
+ }
+ return event_add(event->ev, tv);
+}
+
+/** Cancel <b>event</b> if it is currently active or pending. (Do nothing if
+ * the event is not currently active or pending.) */
+void
+mainloop_event_cancel(mainloop_event_t *event)
+{
+ if (!event)
+ return;
+ event_del(event->ev);
+}
+
+/** Cancel <b>event</b> and release all storage associated with it. */
+void
+mainloop_event_free_(mainloop_event_t *event)
+{
+ if (!event)
+ return;
+ tor_event_free(event->ev);
+ memset(event, 0xb8, sizeof(*event));
+ tor_free(event);
+}
+
int
tor_init_libevent_rng(void)
{
diff --git a/src/common/compat_libevent.h b/src/common/compat_libevent.h
index 318697864..711c3a2eb 100644
--- a/src/common/compat_libevent.h
+++ b/src/common/compat_libevent.h
@@ -34,6 +34,17 @@ void periodic_timer_free_(periodic_timer_t *);
#define periodic_timer_free(t) \
FREE_AND_NULL(periodic_timer_t, periodic_timer_free_, (t))
+typedef struct mainloop_event_t mainloop_event_t;
+mainloop_event_t *mainloop_event_new(void (*cb)(mainloop_event_t *, void *),
+ void *userdata);
+void mainloop_event_activate(mainloop_event_t *event);
+int mainloop_event_schedule(mainloop_event_t *event,
+ const struct timeval *delay);
+void mainloop_event_cancel(mainloop_event_t *event);
+void mainloop_event_free_(mainloop_event_t *event);
+#define mainloop_event_free(event) \
+ FREE_AND_NULL(mainloop_event_t, mainloop_event_free_, (event))
+
#define tor_event_base_loopexit event_base_loopexit
#define tor_event_base_loopbreak event_base_loopbreak
diff --git a/src/common/timers.c b/src/common/timers.c
index 552080b11..a90817da1 100644
--- a/src/common/timers.c
+++ b/src/common/timers.c
@@ -37,8 +37,6 @@
#include "torlog.h"
#include "util.h"
-#include <event2/event.h>
-
struct timeout_cb {
timer_cb_fn_t cb;
void *arg;
@@ -69,7 +67,7 @@ struct timeout_cb {
#include "src/ext/timeouts/timeout.c"
static struct timeouts *global_timeouts = NULL;
-static struct event *global_timer_event = NULL;
+static struct mainloop_event_t *global_timer_event = NULL;
static monotime_t start_of_time;
@@ -147,7 +145,7 @@ libevent_timer_reschedule(void)
if (delay > MIN_CHECK_TICKS)
delay = MIN_CHECK_TICKS;
timeout_to_tv(delay, &d);
- event_add(global_timer_event, &d);
+ mainloop_event_schedule(global_timer_event, &d);
}
/** Run the callback of every timer that has expired, based on the current
@@ -170,10 +168,9 @@ timers_run_pending(void)
* have fired, activate their callbacks, and reschedule the libevent timer.
*/
static void
-libevent_timer_callback(evutil_socket_t fd, short what, void *arg)
+libevent_timer_callback(mainloop_event_t *ev, void *arg)
{
- (void)fd;
- (void)what;
+ (void)ev;
(void)arg;
timers_run_pending();
@@ -203,9 +200,8 @@ timers_initialize(void)
monotime_init();
monotime_get(&start_of_time);
- struct event *timer_event;
- timer_event = tor_event_new(tor_libevent_get_base(),
- -1, 0, libevent_timer_callback, NULL);
+ mainloop_event_t *timer_event;
+ timer_event = mainloop_event_new(libevent_timer_callback, NULL);
tor_assert(timer_event);
global_timer_event = timer_event;
@@ -219,7 +215,7 @@ void
timers_shutdown(void)
{
if (global_timer_event) {
- tor_event_free(global_timer_event);
+ mainloop_event_free(global_timer_event);
global_timer_event = NULL;
}
if (global_timeouts) {
diff --git a/src/or/control.c b/src/or/control.c
index 5cac0e172..5a2fae64e 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -83,8 +83,6 @@
#include <sys/resource.h>
#endif
-#include <event2/event.h>
-
#include "crypto_s2k.h"
#include "procmon.h"
@@ -216,7 +214,7 @@ static void orconn_target_get_name(char *buf, size_t len,
static int get_cached_network_liveness(void);
static void set_cached_network_liveness(int liveness);
-static void flush_queued_events_cb(evutil_socket_t fd, short what, void *arg);
+static void flush_queued_events_cb(mainloop_event_t *event, void *arg);
static char * download_status_to_string(const download_status_t *dl);
@@ -691,7 +689,7 @@ static tor_mutex_t *queued_control_events_lock = NULL;
/** An event that should fire in order to flush the contents of
* queued_control_events. */
-static struct event *flush_queued_events_event = NULL;
+static mainloop_event_t *flush_queued_events_event = NULL;
void
control_initialize_event_queue(void)
@@ -703,9 +701,8 @@ control_initialize_event_queue(void)
if (flush_queued_events_event == NULL) {
struct event_base *b = tor_libevent_get_base();
if (b) {
- flush_queued_events_event = tor_event_new(b,
- -1, 0, flush_queued_events_cb,
- NULL);
+ flush_queued_events_event =
+ mainloop_event_new(flush_queued_events_cb, NULL);
tor_assert(flush_queued_events_event);
}
}
@@ -781,7 +778,7 @@ queue_control_event_string,(uint16_t event, char *msg))
*/
if (activate_event) {
tor_assert(flush_queued_events_event);
- event_active(flush_queued_events_event, EV_READ, 1);
+ mainloop_event_activate(flush_queued_events_event);
}
}
@@ -863,10 +860,9 @@ queued_events_flush_all(int force)
/** Libevent callback: Flushes pending events to controllers that are
* interested in them. */
static void
-flush_queued_events_cb(evutil_socket_t fd, short what, void *arg)
+flush_queued_events_cb(mainloop_event_t *event, void *arg)
{
- (void) fd;
- (void) what;
+ (void) event;
(void) arg;
queued_events_flush_all(0);
}
@@ -7608,7 +7604,7 @@ control_free_all(void)
smartlist_free(queued_events);
}
if (flush_queued_events_event) {
- tor_event_free(flush_queued_events_event);
+ mainloop_event_free(flush_queued_events_event);
flush_queued_events_event = NULL;
}
bootstrap_percent = BOOTSTRAP_STATUS_UNDEF;
diff --git a/src/or/main.c b/src/or/main.c
index a0d2ae075..9f26732a2 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -1060,9 +1060,8 @@ conn_close_if_marked(int i)
* reason.
*/
static void
-directory_all_unreachable_cb(evutil_socket_t fd, short event, void *arg)
+directory_all_unreachable_cb(mainloop_event_t *event, void *arg)
{
- (void)fd;
(void)event;
(void)arg;
@@ -1082,7 +1081,7 @@ directory_all_unreachable_cb(evutil_socket_t fd, short event, void *arg)
control_event_general_error("DIR_ALL_UNREACHABLE");
}
-static struct event *directory_all_unreachable_cb_event = NULL;
+static mainloop_event_t *directory_all_unreachable_cb_event = NULL;
/** We've just tried every dirserver we know about, and none of
* them were reachable. Assume the network is down. Change state
@@ -1099,12 +1098,11 @@ directory_all_unreachable(time_t now)
if (!directory_all_unreachable_cb_event) {
directory_all_unreachable_cb_event =
- tor_event_new(tor_libevent_get_base(),
- -1, EV_READ, directory_all_unreachable_cb, NULL);
+ mainloop_event_new(directory_all_unreachable_cb, NULL);
tor_assert(directory_all_unreachable_cb_event);
}
- event_active(directory_all_unreachable_cb_event, EV_READ, 1);
+ mainloop_event_activate(directory_all_unreachable_cb_event);
}
/** This function is called whenever we successfully pull down some new
@@ -3525,6 +3523,7 @@ tor_free_all(int postfork)
periodic_timer_free(refill_timer);
tor_event_free(shutdown_did_not_work_event);
tor_event_free(initialize_periodic_events_event);
+ mainloop_event_free(directory_all_unreachable_cb_event);
#ifdef HAVE_SYSTEMD_209
periodic_timer_free(systemd_watchdog_timer);
diff --git a/src/or/periodic.c b/src/or/periodic.c
index 6896b41c8..fa40965de 100644
--- a/src/or/periodic.c
+++ b/src/or/periodic.c
@@ -16,8 +16,6 @@
#include "config.h"
#include "periodic.h"
-#include <event2/event.h>
-
/** We disable any interval greater than this number of seconds, on the
* grounds that it is probably an absolute time mistakenly passed in as a
* relative time.
@@ -34,17 +32,16 @@ periodic_event_set_interval(periodic_event_item_t *event,
struct timeval tv;
tv.tv_sec = next_interval;
tv.tv_usec = 0;
- event_add(event->ev, &tv);
+ mainloop_event_schedule(event->ev, &tv);
}
/** Wraps dispatches for periodic events, <b>data</b> will be a pointer to the
* event that needs to be called */
static void
-periodic_event_dispatch(evutil_socket_t fd, short what, void *data)
+periodic_event_dispatch(mainloop_event_t *ev, void *data)
{
- (void)fd;
- (void)what;
periodic_event_item_t *event = data;
+ tor_assert(ev == event->ev);
time_t now = time(NULL);
const or_options_t *options = get_options();
@@ -74,7 +71,7 @@ periodic_event_dispatch(evutil_socket_t fd, short what, void *data)
// log_debug(LD_GENERAL, "Scheduling %s for %d seconds", event->name,
// next_interval);
struct timeval tv = { next_interval , 0 };
- event_add(event->ev, &tv);
+ mainloop_event_schedule(ev, &tv);
}
/** Schedules <b>event</b> to run as soon as possible from now. */
@@ -93,10 +90,8 @@ periodic_event_setup(periodic_event_item_t *event)
tor_assert(0);
}
- event->ev = tor_event_new(tor_libevent_get_base(),
- -1, 0,
- periodic_event_dispatch,
- event);
+ event->ev = mainloop_event_new(periodic_event_dispatch,
+ event);
tor_assert(event->ev);
}
@@ -111,7 +106,7 @@ periodic_event_launch(periodic_event_item_t *event)
}
// Initial dispatch
- periodic_event_dispatch(-1, EV_TIMEOUT, event);
+ periodic_event_dispatch(event->ev, event);
}
/** Release all storage associated with <b>event</b> */
@@ -120,7 +115,7 @@ periodic_event_destroy(periodic_event_item_t *event)
{
if (!event)
return;
- tor_event_free(event->ev);
+ mainloop_event_free(event->ev);
event->last_action_time = 0;
}
diff --git a/src/or/periodic.h b/src/or/periodic.h
index 8baf3994e..285400b8b 100644
--- a/src/or/periodic.h
+++ b/src/or/periodic.h
@@ -14,13 +14,14 @@
typedef int (*periodic_event_helper_t)(time_t now,
const or_options_t *options);
-struct event;
+struct mainloop_event_t;
/** A single item for the periodic-events-function table. */
typedef struct periodic_event_item_t {
periodic_event_helper_t fn; /**< The function to run the event */
time_t last_action_time; /**< The last time the function did something */
- struct event *ev; /**< Libevent callback we're using to implement this */
+ struct mainloop_event_t *ev; /**< Libevent callback we're using to implement
+ * this */
const char *name; /**< Name of the function -- for debug */
} periodic_event_item_t;
diff --git a/src/or/scheduler.c b/src/or/scheduler.c
index 382b3e3ca..da894294b 100644
--- a/src/or/scheduler.c
+++ b/src/or/scheduler.c
@@ -13,8 +13,6 @@
#define TOR_CHANNEL_INTERNAL_
#include "channeltls.h"
-#include <event2/event.h>
-
/**
* \file scheduler.c
* \brief Channel scheduling system: decides which channels should send and
@@ -169,7 +167,7 @@ STATIC smartlist_t *channels_pending = NULL;
* This event runs the scheduler from its callback, and is manually
* activated whenever a channel enters open for writes/cells to send.
*/
-STATIC struct event *run_sched_ev = NULL;
+STATIC struct mainloop_event_t *run_sched_ev = NULL;
static int have_logged_kist_suddenly_disabled = 0;
@@ -203,10 +201,9 @@ get_scheduler_type_string(scheduler_types_t type)
* if any scheduling work was created during the event loop.
*/
static void
-scheduler_evt_callback(evutil_socket_t fd, short events, void *arg)
+scheduler_evt_callback(mainloop_event_t *event, void *arg)
{
- (void) fd;
- (void) events;
+ (void) event;
(void) arg;
log_debug(LD_SCHED, "Scheduler event callback called");
@@ -487,10 +484,7 @@ scheduler_free_all(void)
log_debug(LD_SCHED, "Shutting down scheduler");
if (run_sched_ev) {
- if (event_del(run_sched_ev) < 0) {
- log_warn(LD_BUG, "Problem deleting run_sched_ev");
- }
- tor_event_free(run_sched_ev);
+ mainloop_event_free(run_sched_ev);
run_sched_ev = NULL;
}
@@ -589,7 +583,7 @@ scheduler_ev_add(const struct timeval *next_run)
{
tor_assert(run_sched_ev);
tor_assert(next_run);
- if (BUG(event_add(run_sched_ev, next_run) < 0)) {
+ if (BUG(mainloop_event_schedule(run_sched_ev, next_run) < 0)) {
log_warn(LD_SCHED, "Adding to libevent failed. Next run time was set to: "
"%ld.%06ld", next_run->tv_sec, (long)next_run->tv_usec);
return;
@@ -598,10 +592,10 @@ scheduler_ev_add(const struct timeval *next_run)
/** Make the scheduler event active with the given flags. */
void
-scheduler_ev_active(int flags)
+scheduler_ev_active(void)
{
tor_assert(run_sched_ev);
- event_active(run_sched_ev, flags, 1);
+ mainloop_event_activate(run_sched_ev);
}
/*
@@ -618,11 +612,10 @@ scheduler_init(void)
IF_BUG_ONCE(!!run_sched_ev) {
log_warn(LD_SCHED, "We should not already have a libevent scheduler event."
"I'll clean the old one up, but this is odd.");
- tor_event_free(run_sched_ev);
+ mainloop_event_free(run_sched_ev);
run_sched_ev = NULL;
}
- run_sched_ev = tor_event_new(tor_libevent_get_base(), -1,
- 0, scheduler_evt_callback, NULL);
+ run_sched_ev = mainloop_event_new(scheduler_evt_callback, NULL);
channels_pending = smartlist_new();
set_scheduler();
diff --git a/src/or/scheduler.h b/src/or/scheduler.h
index aeba9e2b7..08b02e286 100644
--- a/src/or/scheduler.h
+++ b/src/or/scheduler.h
@@ -155,12 +155,12 @@ void scheduler_bug_occurred(const channel_t *chan);
smartlist_t *get_channels_pending(void);
MOCK_DECL(int, scheduler_compare_channels,
(const void *c1_v, const void *c2_v));
-void scheduler_ev_active(int flags);
+void scheduler_ev_active(void);
void scheduler_ev_add(const struct timeval *next_run);
#ifdef TOR_UNIT_TESTS
extern smartlist_t *channels_pending;
-extern struct event *run_sched_ev;
+extern struct mainloop_event_t *run_sched_ev;
extern const scheduler_t *the_scheduler;
void scheduler_touch_channel(channel_t *chan);
#endif /* defined(TOR_UNIT_TESTS) */
diff --git a/src/or/scheduler_kist.c b/src/or/scheduler_kist.c
index 6d6490077..c6e9b72c4 100644
--- a/src/or/scheduler_kist.c
+++ b/src/or/scheduler_kist.c
@@ -3,8 +3,6 @@
#define SCHEDULER_KIST_PRIVATE
-#include <event2/event.h>
-
#include "or.h"
#include "buffers.h"
#include "config.h"
@@ -553,7 +551,7 @@ kist_scheduler_schedule(void)
/* Re-adding an event reschedules it. It does not duplicate it. */
scheduler_ev_add(&next_run);
} else {
- scheduler_ev_active(EV_TIMEOUT);
+ scheduler_ev_active();
}
}
diff --git a/src/or/scheduler_vanilla.c b/src/or/scheduler_vanilla.c
index 7a83b9da1..b674d8256 100644
--- a/src/or/scheduler_vanilla.c
+++ b/src/or/scheduler_vanilla.c
@@ -1,8 +1,6 @@
/* Copyright (c) 2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
-#include <event2/event.h>
-
#include "or.h"
#include "config.h"
#define TOR_CHANNEL_INTERNAL_
@@ -42,7 +40,7 @@ vanilla_scheduler_schedule(void)
}
/* Activate our event so it can process channels. */
- scheduler_ev_active(EV_TIMEOUT);
+ scheduler_ev_active();
}
static void
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