reduce useless changes on APM battery.remaining_time

Changed update property battery.remaining_time on APM to avoid change the
value every 2 seconds. APM calculate with each poll a new value for
remaining battery time, which could result in high dbus load if a application
listen for the event and check do something over the bus. On the other side
the remaining time from the APM interface is not trustworthy on the most
machines if you poll to often, increase the poll intervall (and emit a new
value to HAL) should smooth the time curve and reduce back and forth jumping
values.

Now the value is updated ever 30 seconds, this should preduce the needless
events.

1 files changed, 19 insertions, 4 deletions

diff --git a/hald/linux2/apm.c b/hald/linux2/apm.c
index 4d74d86a..fc417ae3 100644
--- a/hald/linux2/apm.c
+++ b/hald/linux2/apm.c
@@ -40,6 +40,7 @@ enum {
 	APM_TYPE_AC_ADAPTER
 };
 
+int interval_poll_round = 0;
 
 typedef struct APMDevHandler_s
 {
@@ -201,11 +202,25 @@ battery_refresh (HalDevice *d, APMDevHandler *handler)
 			remaining_time = i.battery_time * 60;
 		}
 
-		/* set the time on discharge, and remove property on charging because unknown on APM */
-		if (remaining_time > 0)
-			hal_device_property_set_int (d, "battery.remaining_time", remaining_time);
-		else
+		/* set the time to discharge, or remove key for charging */
+		if (remaining_time > 0) {
+			/* switched from charging to discharging, set key */
+			if (!is_charging && is_discharging && !hal_device_has_property(d,"battery.remaining_time")) {
+				hal_device_property_set_int (d, "battery.remaining_time", remaining_time);
+				interval_poll_round = 0;
+			}
+			/* after 30 seconds (15*APM_POLL_INTERVAL) set key */
+			else if (interval_poll_round == 15) {
+				hal_device_property_set_int (d, "battery.remaining_time", remaining_time);
+				interval_poll_round = 0;
+			}
+			/* else: only increment counter and set no key to avoid needless events/changes
+			   because APM produce with each read a new value for remaining time */
+			else
+				interval_poll_round++;
+		} else {
 			hal_device_property_remove (d, "battery.remaining_time");
+		}
 
 		/* set the correct charge states */
 		hal_device_property_set_bool (d, "battery.rechargeable.is_charging", is_charging);