1527. [cleanup] Reduce the number of gettimeofday() calls without

losing necessary timer granularity.

(reviewed by marka and Kurt)

CHANGES

@@ -1,6 +1,7 @@
 1528.	[placeholder]
 
-1527.	[placeholder]
+1527.	[cleanup]	Reduce the number of gettimeofday() calls without
+			losing necessary timer granularity.
 
 1526.	[placeholder]
 

bin/named/client.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: client.c,v 1.216 2003/07/04 04:38:54 marka Exp $ */
+/* $Id: client.c,v 1.217 2003/10/25 00:09:13 jinmei Exp $ */
 
 #include <config.h>
 
@@ -1129,8 +1129,6 @@ client_request(isc_task_t *task, isc_event_t *event) {
 	REQUIRE(NS_CLIENT_VALID(client));
 	REQUIRE(task == client->task);
 
-	UNUSED(task);
-
 	INSIST(client->recursionquota == NULL);
 
 	INSIST(client->state ==
@@ -1174,7 +1172,7 @@ client_request(isc_task_t *task, isc_event_t *event) {
 		goto cleanup;
 	client->state = client->newstate = NS_CLIENTSTATE_WORKING;
 
-	isc_stdtime_get(&client->requesttime);
+	isc_task_getcurrenttime(task, &client->requesttime);
 	client->now = client->requesttime;
 
 	if (result != ISC_R_SUCCESS) {

lib/isc/include/isc/task.h

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: task.h,v 1.49 2001/02/13 04:11:44 gson Exp $ */
+/* $Id: task.h,v 1.50 2003/10/25 00:09:14 jinmei Exp $ */
 
 #ifndef ISC_TASK_H
 #define ISC_TASK_H 1
@@ -58,9 +58,10 @@
  *** Imports.
  ***/
 
-#include <isc/lang.h>
-#include <isc/types.h>
 #include <isc/eventclass.h>
+#include <isc/lang.h>
+#include <isc/stdtime.h>
+#include <isc/types.h>
 
 #define ISC_TASKEVENT_FIRSTEVENT	(ISC_EVENTCLASS_TASK + 0)
 #define ISC_TASKEVENT_SHUTDOWN		(ISC_EVENTCLASS_TASK + 1)
@@ -518,6 +519,19 @@ isc_task_endexclusive(isc_task_t *task);
  *		exclusive access by calling isc_task_spl().
  */
 
+void
+isc_task_getcurrenttime(isc_task_t *task, isc_stdtime_t *t);
+/*
+ * Provide the most recent timestamp on the task.  The timestamp is considered
+ * as the "current time" in the second-order granularity.
+ *
+ * Requires:
+ *	'task' is a valid task.
+ *	't' is a valid non NULL pointer.
+ *
+ * Ensures:
+ *	'*t' has the "current time".
+ */
 
 /*****
  ***** Task Manager.

lib/isc/task.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: task.c,v 1.88 2002/07/19 03:39:43 marka Exp $ */
+/* $Id: task.c,v 1.89 2003/10/25 00:09:13 jinmei Exp $ */
 
 /*
  * Principal Author: Bob Halley
@@ -82,6 +82,7 @@ struct isc_task {
 	isc_eventlist_t			on_shutdown;
 	unsigned int			quantum;
 	unsigned int			flags;
+	isc_stdtime_t			now;
 #ifdef ISC_TASK_NAMES
 	char				name[16];
 	void *				tag;
@@ -196,6 +197,7 @@ isc_task_create(isc_taskmgr_t *manager, unsigned int quantum,
 	INIT_LIST(task->on_shutdown);
 	task->quantum = quantum;
 	task->flags = 0;
+	task->now = 0;
 #ifdef ISC_TASK_NAMES
 	memset(task->name, 0, sizeof(task->name));
 	task->tag = NULL;
@@ -717,6 +719,17 @@ isc_task_gettag(isc_task_t *task) {
 	return (task->tag);
 }
 
+void
+isc_task_getcurrenttime(isc_task_t *task, isc_stdtime_t *t) {
+	REQUIRE(VALID_TASK(task));
+	REQUIRE(t != NULL);
+
+	LOCK(&task->lock);
+
+	*t = task->now;
+
+	UNLOCK(&task->lock);
+}
 
 /***
  *** Task Manager.
@@ -838,6 +851,7 @@ dispatch(isc_taskmgr_t *manager) {
 			task->state = task_state_running;
 			XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
 					      ISC_MSG_RUNNING, "running"));
+			isc_stdtime_get(&task->now);
 			do {
 				if (!EMPTY(task->events)) {
 					event = HEAD(task->events);

lib/isc/unix/app.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: app.c,v 1.48 2002/05/10 06:41:54 marka Exp $ */
+/* $Id: app.c,v 1.49 2003/10/25 00:09:14 jinmei Exp $ */
 
 #include <config.h>
 
@@ -304,12 +304,14 @@ evloop() {
 		fd_set readfds, writefds;
 		int maxfd;
 		isc_boolean_t readytasks;
+		isc_boolean_t call_timer_dispatch = ISC_FALSE;
 
 		readytasks = isc__taskmgr_ready();
 		if (readytasks) {
 			tv.tv_sec = 0;
 			tv.tv_usec = 0;
 			tvp = &tv;
+			call_timer_dispatch = ISC_TRUE;
 		} else {
 			result = isc__timermgr_nextevent(&when);
 			if (result != ISC_R_SUCCESS)
@@ -319,6 +321,8 @@ evloop() {
 
 				TIME_NOW(&now);
 				us = isc_time_microdiff(&when, &now);
+				if (us == 0)
+					call_timer_dispatch = ISC_TRUE;
 				tv.tv_sec = us / 1000000;
 				tv.tv_usec = us % 1000000;
 				tvp = &tv;
@@ -328,7 +332,23 @@ evloop() {
 		isc__socketmgr_getfdsets(&readfds, &writefds, &maxfd);
 		n = select(maxfd, &readfds, &writefds, NULL, tvp);
 
-		isc__timermgr_dispatch();
+		if (n == 0 || call_timer_dispatch) {
+			/*
+			 * We call isc__timermgr_dispatch() only when
+			 * necessary, in order to reduce overhead.  If the
+			 * select() call indicates a timeout, we need the
+			 * dispatch.  Even if not, if we set the 0-timeout 
+			 * for the select() call, we need to check the timer
+			 * events.  In the 'readytasks' case, there may be no
+			 * timeout event actually, but there is no other way
+			 * to reduce the overhead.
+			 * Note that we do not have to worry about the case
+			 * where a new timer is inserted during the select()
+			 * call, since this loop only runs in the non-thread
+			 * mode.
+			 */
+			isc__timermgr_dispatch();
+		}
 		if (n > 0)
 			(void)isc__socketmgr_dispatch(&readfds, &writefds,
 						      maxfd);
@@ -367,16 +387,16 @@ static isc_boolean_t signalled = ISC_FALSE;
 isc_result_t
 isc__nothread_wait_hack(isc_condition_t *cp, isc_mutex_t *mp) {
 	isc_result_t result;
-	
+
 	UNUSED(cp);
 	UNUSED(mp);
-	
+
 	INSIST(!in_recursive_evloop);
 	in_recursive_evloop = ISC_TRUE;
 
 	INSIST(*mp == 1); /* Mutex must be locked on entry. */
 	--*mp;
-	
+
 	result = evloop();
 	if (result == ISC_R_RELOAD)
 		want_reload = ISC_TRUE;
@@ -394,7 +414,7 @@ isc_result_t
 isc__nothread_signal_hack(isc_condition_t *cp) {
 
 	UNUSED(cp);
-	
+
 	INSIST(in_recursive_evloop);
 
 	want_shutdown = ISC_TRUE;