From ab96b5f3f5247c7c7500a64536ceb345e0b8a65f Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Mon, 9 Nov 2009 18:30:33 +0000
Subject: [PATCH] Add an option to disable the timeval cache.

svn:r1518
---
 ChangeLog              |  2 +-
 event-internal.h       |  2 ++
 event.c                | 28 +++++++++++++++++++++-------
 include/event2/event.h |  6 +++++-
 4 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b06128fe..c720db76 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -40,7 +40,7 @@ Changes in 2.0.3-alpha:
  o Add a new bufferevent_socket_connect_hostname() to encapsulate the resolve-then-connect operation.
  o Build kqueue.c correctly on GNU/kFreeBSD platforms. Patch pulled upstream from Debian.
  o Alternative queue-based timeout algorithm for programs that use a large number of timeouts with the same value.
-
+ o New event_base_config option to disable the timeval cache entirely.
 
 Changes in 2.0.2-alpha:
  o Add a new flag to bufferevents to make all callbacks automatically deferred.
diff --git a/event-internal.h b/event-internal.h
index 662e23d6..4fef73c1 100644
--- a/event-internal.h
+++ b/event-internal.h
@@ -181,6 +181,8 @@ struct event_base {
 	struct event_iocp_port *iocp;
 #endif
 
+        enum event_base_config_flag flags;
+
 	/* Notify main thread to wake up break, etc. */
 	int th_notify_fd[2];
 	struct event th_notify;
diff --git a/event.c b/event.c
index 2f1a8429..327546e2 100644
--- a/event.c
+++ b/event.c
@@ -180,6 +180,20 @@ gettime(struct event_base *base, struct timeval *tp)
 	return (evutil_gettimeofday(tp, NULL));
 }
 
+static inline void
+clear_time_cache(struct event_base *base)
+{
+	base->tv_cache.tv_sec = 0;
+}
+
+static inline void
+update_time_cache(struct event_base *base)
+{
+	base->tv_cache.tv_sec = 0;
+	if (!(base->flags & EVENT_BASE_FLAG_NO_CACHE_TIME))
+	    gettime(base, &base->tv_cache);
+}
+
 struct event_base *
 event_init(void)
 {
@@ -281,6 +295,8 @@ event_base_new_with_config(struct event_config *cfg)
 	event_deferred_cb_queue_init(&base->defer_queue);
 	base->defer_queue.notify_fn = notify_base_cbq_callback;
 	base->defer_queue.notify_arg = base;
+	if (cfg)
+		base->flags = cfg->flags;
 
 	evmap_io_initmap(&base->io);
 	evmap_signal_initmap(&base->sigmap);
@@ -1054,8 +1070,7 @@ event_base_loop(struct event_base *base, int flags)
 	 * as we invoke user callbacks. */
 	EVBASE_ACQUIRE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
 
-	/* clear time cache */
-	base->tv_cache.tv_sec = 0;
+	clear_time_cache(base);
 
 	if (base->sig.ev_signal_added)
 		evsig_base = base;
@@ -1099,14 +1114,14 @@ event_base_loop(struct event_base *base, int flags)
 		/* update last old time */
 		gettime(base, &base->event_tv);
 
-		/* clear time cache */
-		base->tv_cache.tv_sec = 0;
+		clear_time_cache(base);
 
 		res = evsel->dispatch(base, tv_p);
 
 		if (res == -1)
 			return (-1);
-		gettime(base, &base->tv_cache);
+
+		update_time_cache(base);
 
 		timeout_process(base);
 
@@ -1118,8 +1133,7 @@ event_base_loop(struct event_base *base, int flags)
 			done = 1;
 	}
 
-	/* clear time cache */
-	base->tv_cache.tv_sec = 0;
+	clear_time_cache(base);
 
 	EVBASE_RELEASE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
 
diff --git a/include/event2/event.h b/include/event2/event.h
index 4cc9bff8..7fe6dc73 100644
--- a/include/event2/event.h
+++ b/include/event2/event.h
@@ -167,7 +167,11 @@ enum event_base_config_flag {
 	    an event_base. */
 	EVENT_BASE_FLAG_IGNORE_ENV = 0x02,
 	/** Windows only: enable the IOCP dispatcher at startup */
-	EVENT_BASE_FLAG_STARTUP_IOCP = 0x04
+	EVENT_BASE_FLAG_STARTUP_IOCP = 0x04,
+	/** Instead of checking the current time every time the event loop is
+	    ready to run timeout callbacks, check after each timeout callback.
+	 */
+	EVENT_BASE_FLAG_NO_CACHE_TIME = 0x08
 };
 
 /**
-- 
2.40.0