[Powertop] [PATCH 05/10] power_meter: introduce discharging member measurement: report total global_time_left()

report total capacity and discahrge rate if at least one power_meter
reports that is's discharging. previously we reported only discharging
power_meters, thus user was not aware of total time left in case of
N batteries. this is the reason why power_meter discharging member
(with getter and setter one-liners were introduced) -- we need
capacity and rate for every power_meter, regardless the fact whether
its /sys/class/power_supply/*/status reports "Discharging" or not.
report total "The battery discharge rate" and "The estimated remaining
time" back to user when at least one power_meter is discharging.

Reported-and-tested-by: Maksim Melnikau <maxposedon(a)gmail.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com>
---
 src/measurement/measurement.cpp | 32 ++++++++++++++------------------
 src/measurement/measurement.h   | 24 +++++++++++++++++-------
 src/measurement/sysfs.cpp       |  7 ++++---
 3 files changed, 35 insertions(+), 28 deletions(-)

diff --git a/src/measurement/measurement.cpp b/src/measurement/measurement.cpp
index 0b68940..8b63eb3 100644
--- a/src/measurement/measurement.cpp
+++ b/src/measurement/measurement.cpp
@@ -54,23 +54,6 @@ double power_meter::joules_consumed(void)
 	return 0.0;
 }
 
-double power_meter::time_left(void)
-{
-	double cap, rate;
-
-	cap = dev_capacity();
-	rate = joules_consumed();
-
-	if (cap < 0.001)
-		return 0.0;
-
-	/* return 0.0 instead of INF+ */
-	if (rate < 0.001)
-		return 0.0;
-
-	return cap / rate;
-}
-
 vector<class power_meter *> power_meters;
 
 void start_power_measurement(void)
@@ -88,10 +71,17 @@ void end_power_measurement(void)
 
 double global_joules_consumed(void)
 {
+	bool global_discharging = false;
 	double total = 0.0;
 	unsigned int i;
-	for (i = 0; i < power_meters.size(); i++)
+
+	for (i = 0; i < power_meters.size(); i++) {
+		global_discharging |= power_meters[i]->is_discharging();
 		total += power_meters[i]->joules_consumed();
+	}
+	/* report global time left if at least one battery is discharging */
+	if (!global_discharging)
+		return 0.0;
 
 	all_results.power = total;
 	if (total < min_power && total > 0.01)
@@ -101,13 +91,19 @@ double global_joules_consumed(void)
 
 double global_time_left(void)
 {
+	bool global_discharging = false;
 	double total_capacity = 0.0;
 	double total_rate = 0.0;
 	unsigned int i;
 	for (i = 0; i < power_meters.size(); i++) {
+		global_discharging |= power_meters[i]->is_discharging();
 		total_capacity += power_meters[i]->dev_capacity();
 		total_rate += power_meters[i]->joules_consumed();
 	}
+	/* report global time left if at least one battery is discharging */
+	if (!global_discharging)
+		return 0.0;
+
 	/* return 0.0 instead of INF+ */
 	if (total_rate < 0.001)
 		return 0.0;
diff --git a/src/measurement/measurement.h b/src/measurement/measurement.h
index 5bcd8e2..83ffc34 100644
--- a/src/measurement/measurement.h
+++ b/src/measurement/measurement.h
@@ -30,18 +30,29 @@
 using namespace std;
 
 class power_meter {
+	bool discharging;
 public:
+	virtual ~power_meter() {};
+
 	virtual void start_measurement(void);
 	virtual void end_measurement(void);
-
 	virtual double joules_consumed(void);
-	virtual double dev_capacity(void) { return 0.0;};  /* in Joules */
 
-	virtual double time_left(void);
+	virtual double dev_capacity(void)
+	{
+		return 0.0; /* in Joules */
+	}
 
-	virtual ~power_meter() {};
-};
+	virtual void set_discharging(bool d)
+	{
+		discharging = d;
+	}
 
+	virtual bool is_discharging()
+	{
+		return discharging;
+	}
+};
 
 extern vector<class power_meter *> power_meters;
 
@@ -53,7 +64,6 @@ extern double global_time_left(void);
 extern void detect_power_meters(void);
 extern void extech_power_meter(const char *devnode);
 
-
 extern double min_power;
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/measurement/sysfs.cpp b/src/measurement/sysfs.cpp
index 66cb1cd..ed42ed4 100644
--- a/src/measurement/sysfs.cpp
+++ b/src/measurement/sysfs.cpp
@@ -126,11 +126,13 @@ void sysfs_power_meter::measure()
 
 	rate = 0.0;
 	capacity = 0.0;
+	this->set_discharging(false);
 
 	if (!is_present())
 		return;
-	if (read_sysfs_string("/sys/class/power_supply/%s/status", name) != "Discharging")
-		return;
+	/** do not jump over. we may have discharging battery */
+	if (read_sysfs_string("/sys/class/power_supply/%s/status", name) == "Discharging")
+		this->set_discharging(true);
 
 	got_rate = set_rate_from_power();
 	got_capacity = set_capacity_from_energy();
@@ -146,7 +148,6 @@ void sysfs_power_meter::measure()
 	}
 }
 
-
 void sysfs_power_meter::end_measurement(void)
 {
 	measure();
-- 
1.8.4.679.g0a1a803