fix: better robustness of commands

deployment/src/main/java/io/quarkiverse/power/deployment/devui/commands/StartCommand.java

@@ -27,13 +27,18 @@ public StartCommand(PowerMeasurer<? extends SensorMeasure> sensor) {
     @Override
     public CommandResult doExecute(CommandInvocation commandInvocation) throws CommandException, InterruptedException {
         try {
-            if (duration > 0) {
-                commandInvocation.println("Measuring power for " + duration + " seconds, every " + frequency + " milliseconds");
+            if (!sensor.isRunning()) {
+                if (duration > 0) {
+                    commandInvocation
+                            .println("Measuring power for " + duration + " seconds, every " + frequency + " milliseconds");
+                } else {
+                    commandInvocation.println("Measuring power every " + frequency
+                            + " milliseconds. Execute 'power stop' to stop measurements and get the results.");
+                }
+                sensor.start(duration, frequency, commandInvocation::println);
             } else {
-                commandInvocation.println("Measuring power every " + frequency
-                        + " milliseconds. Execute 'power stop' to stop measurements and get the results.");
+                commandInvocation.println("Power measurement is already ongoing. Execute 'power stop' to stop it now.");
             }
-            sensor.start(duration, frequency, commandInvocation::println);
         } catch (Exception e) {
             commandInvocation.println("Couldn't start power measure: " + e.getMessage());
             return CommandResult.FAILURE;

deployment/src/main/java/io/quarkiverse/power/deployment/devui/commands/StopCommand.java

@@ -20,7 +20,11 @@ public StopCommand(PowerMeasurer<? extends SensorMeasure> sensor) {
 
     @Override
     public CommandResult doExecute(CommandInvocation commandInvocation) throws CommandException, InterruptedException {
-        sensor.stop(commandInvocation::println);
+        if (sensor.isRunning()) {
+            sensor.stop(commandInvocation::println);
+        } else {
+            commandInvocation.println("Power measurement hasn't started. Execute 'power start' to start it first.");
+        }
 
         return CommandResult.SUCCESS;
     }

runtime/src/main/java/io/quarkiverse/power/runtime/PowerMeasurer.java

@@ -8,10 +8,7 @@
 
 import com.sun.management.OperatingSystemMXBean;
 
-import io.quarkiverse.power.runtime.sensors.IncrementableMeasure;
-import io.quarkiverse.power.runtime.sensors.OngoingPowerMeasure;
-import io.quarkiverse.power.runtime.sensors.PowerSensor;
-import io.quarkiverse.power.runtime.sensors.PowerSensorProducer;
+import io.quarkiverse.power.runtime.sensors.*;
 
 public class PowerMeasurer<M extends IncrementableMeasure> {
     public static final OperatingSystemMXBean osBean;
@@ -24,6 +21,7 @@ public class PowerMeasurer<M extends IncrementableMeasure> {
     private ScheduledFuture<?> scheduled;
     private final PowerSensor<M> sensor;
     private OngoingPowerMeasure<M> measure;
+    private StoppedPowerMeasure<M> lastMeasure;
 
     private final static PowerMeasurer<? extends SensorMeasure> instance = new PowerMeasurer<>(
             PowerSensorProducer.determinePowerSensor());
@@ -36,8 +34,12 @@ public PowerMeasurer(PowerSensor<M> sensor) {
         this.sensor = sensor;
     }
 
+    public boolean isRunning() {
+        return measure != null;
+    }
+
     public void start(long duration, long frequency, PowerSensor.Writer out) throws Exception {
-        if (measure == null) {
+        if (!isRunning()) {
             measure = sensor.start(duration, frequency, out);
 
             if (duration > 0) {
@@ -55,23 +57,34 @@ private void update(PowerSensor.Writer out) {
         measure.incrementSamples();
     }
 
-    public PowerMeasure<M> stop(PowerSensor.Writer out) {
-        if (measure != null) {
+    public void stop(PowerSensor.Writer out) {
+        if (isRunning()) {
             sensor.stop();
             scheduled.cancel(true);
+            outputConsumptionSinceStarted(out);
+            lastMeasure = new StoppedPowerMeasure<>(measure);
+            measure = null;
         }
-        outputConsumptionSinceStarted(out);
-        return measure;
     }
 
     public PowerMeasure<M> current() {
-        return measure;
+        // use the ongoing power measure if it exists
+        if (measure == null) {
+            // or use the last recorded measure if we have one
+            if (lastMeasure != null) {
+                return lastMeasure;
+            } else {
+                throw new IllegalStateException("No power measure found. Please start it first.");
+            }
+        } else {
+            return measure;
+        }
     }
 
     private void outputConsumptionSinceStarted(PowerSensor.Writer out) {
         out = out == null ? System.out::println : out;
         out.println("Consumed " + measure.total() + " mW over " + (measure.duration() / 1000)
                 + " seconds (" + measure.numberOfSamples() + " samples)");
-        sensor.additionalInfo(out);
+        sensor.additionalInfo(measure, out);
     }
 }

runtime/src/main/java/io/quarkiverse/power/runtime/sensors/PowerSensor.java

@@ -1,5 +1,7 @@
 package io.quarkiverse.power.runtime.sensors;
 
+import io.quarkiverse.power.runtime.PowerMeasure;
+
 public interface PowerSensor<T extends IncrementableMeasure> {
 
     OngoingPowerMeasure<T> start(long duration, long frequency, Writer out) throws Exception;
@@ -9,7 +11,7 @@ default void stop() {
 
     void update(OngoingPowerMeasure<T> ongoingMeasure, Writer out);
 
-    default void additionalInfo(Writer out) {
+    default void additionalInfo(PowerMeasure<T> measure, Writer out) {
     }
 
     interface Writer {

runtime/src/main/java/io/quarkiverse/power/runtime/sensors/StoppedPowerMeasure.java

@@ -0,0 +1,53 @@
+package io.quarkiverse.power.runtime.sensors;
+
+import java.util.Optional;
+
+import io.quarkiverse.power.runtime.PowerMeasure;
+import io.quarkiverse.power.runtime.SensorMeasure;
+
+public class StoppedPowerMeasure<M extends SensorMeasure> implements SensorMeasure, PowerMeasure<M> {
+    private final M measure;
+    private final long duration;
+    private final int samples;
+
+    public StoppedPowerMeasure(PowerMeasure<M> powerMeasure) {
+        this.measure = powerMeasure.sensorMeasure();
+        this.duration = powerMeasure.duration();
+        this.samples = powerMeasure.numberOfSamples();
+    }
+
+    @Override
+    public double cpu() {
+        return measure.cpu();
+    }
+
+    @Override
+    public Optional<Double> gpu() {
+        return measure.gpu();
+    }
+
+    @Override
+    public Optional<Double> byKey(String key) {
+        return measure.byKey(key);
+    }
+
+    @Override
+    public double total() {
+        return measure.total();
+    }
+
+    @Override
+    public int numberOfSamples() {
+        return samples;
+    }
+
+    @Override
+    public long duration() {
+        return duration;
+    }
+
+    @Override
+    public M sensorMeasure() {
+        return measure;
+    }
+}

runtime/src/main/java/io/quarkiverse/power/runtime/sensors/macos/powermetrics/MacOSPowermetricsSensor.java

@@ -6,6 +6,7 @@
 import java.io.InputStream;
 import java.io.InputStreamReader;
 
+import io.quarkiverse.power.runtime.PowerMeasure;
 import io.quarkiverse.power.runtime.sensors.OngoingPowerMeasure;
 import io.quarkiverse.power.runtime.sensors.PowerSensor;
 import io.quarkiverse.power.runtime.sensors.macos.AppleSiliconMeasure;
@@ -14,7 +15,7 @@ public class MacOSPowermetricsSensor implements PowerSensor<AppleSiliconMeasure>
     private Process powermetrics;
     public static PowerSensor<AppleSiliconMeasure> instance = new MacOSPowermetricsSensor();
     private final static String pid = " " + ProcessHandle.current().pid() + " ";
-    private double accumulatedCPUShareDiff;
+    private double accumulatedCPUShareDiff = 0.0;
 
     private static class ProcessRecord {
         final double cpu;
@@ -117,6 +118,7 @@ public OngoingPowerMeasure<AppleSiliconMeasure> start(long duration, long freque
         powermetrics = Runtime.getRuntime()
                 .exec("sudo powermetrics --samplers cpu_power,tasks --show-process-samp-norm --show-process-gpu -i "
                         + freq);
+        accumulatedCPUShareDiff = 0.0;
         return new OngoingPowerMeasure<>(new AppleSiliconMeasure());
     }
 
@@ -125,7 +127,8 @@ public void stop() {
         powermetrics.destroy();
     }
 
-    public void additionalInfo(Writer out) {
+    @Override
+    public void additionalInfo(PowerMeasure<AppleSiliconMeasure> measure, Writer out) {
         out.println("Powermetrics vs JMX CPU share accumulated difference: " + accumulatedCPUShareDiff);
     }
 }