simulator: Add support for emitting VM usage metrics

This change re-enables support for VM usage metrics by adding an adapter
for SimResourceConsumer instances that can export the consumer speed.

1 files changed, 68 insertions, 0 deletions

diff --git a/simulator/opendc-simulator/opendc-simulator-resources/src/main/kotlin/org/opendc/simulator/resources/consumer/SimSpeedConsumerAdapter.kt b/simulator/opendc-simulator/opendc-simulator-resources/src/main/kotlin/org/opendc/simulator/resources/consumer/SimSpeedConsumerAdapter.kt
new file mode 100644
index 00000000..fd4a9ed5
--- /dev/null
+++ b/simulator/opendc-simulator/opendc-simulator-resources/src/main/kotlin/org/opendc/simulator/resources/consumer/SimSpeedConsumerAdapter.kt
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2021 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.simulator.resources.consumer
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import org.opendc.simulator.resources.SimResourceCommand
+import org.opendc.simulator.resources.SimResourceConsumer
+import org.opendc.simulator.resources.SimResourceContext
+import kotlin.math.min
+
+/**
+ * Helper class to expose an observable [speed] field describing the speed of the consumer.
+ */
+public class SimSpeedConsumerAdapter(private val delegate: SimResourceConsumer) : SimResourceConsumer by delegate {
+    /**
+     * The resource processing speed over time.
+     */
+    public val speed: StateFlow<Double>
+        get() = _speed
+    private val _speed = MutableStateFlow(0.0)
+
+    override fun onNext(ctx: SimResourceContext): SimResourceCommand {
+        val command = delegate.onNext(ctx)
+
+        when (command) {
+            is SimResourceCommand.Idle -> _speed.value = 0.0
+            is SimResourceCommand.Consume -> _speed.value = min(ctx.capacity, command.limit)
+            is SimResourceCommand.Exit -> _speed.value = 0.0
+        }
+
+        return command
+    }
+
+    override fun onCapacityChanged(ctx: SimResourceContext, isThrottled: Boolean) {
+        val oldSpeed = _speed.value
+
+        delegate.onCapacityChanged(ctx, isThrottled)
+
+        // Check if the consumer interrupted the consumer and updated the resource consumption. If not, we might
+        // need to update the current speed.
+        if (oldSpeed == _speed.value) {
+            _speed.value = min(ctx.capacity, _speed.value)
+        }
+    }
+
+    override fun toString(): String = "SimSpeedConsumerAdapter[delegate=$delegate]"
+}