build: Migrate to flat project structure

This change updates the project structure to become flattened.
Previously, the simulator, frontend and API each lived into their own
directory.

With this change, all modules of the project live in the top-level
directory of the repository. This should improve discoverability of
modules of the project.

1 files changed, 121 insertions, 0 deletions

diff --git a/opendc-harness/src/main/kotlin/org/opendc/harness/engine/ExperimentEngineLauncher.kt b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/ExperimentEngineLauncher.kt
new file mode 100644
index 00000000..ddd30483
--- /dev/null
+++ b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/ExperimentEngineLauncher.kt
@@ -0,0 +1,121 @@
+/*
+ * 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.harness.engine
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.runBlocking
+import org.opendc.harness.api.ExperimentDefinition
+import org.opendc.harness.engine.scheduler.ExperimentScheduler
+import org.opendc.harness.engine.scheduler.ThreadPoolExperimentScheduler
+import org.opendc.harness.engine.strategy.CartesianExperimentStrategy
+import org.opendc.harness.engine.strategy.ExperimentStrategy
+import org.opendc.harness.internal.CompositeExperimentExecutionListener
+
+/**
+ * A builder class for conducting experiments via the [ExperimentEngine].
+ */
+public class ExperimentEngineLauncher private constructor(
+    private val strategy: ExperimentStrategy?,
+    private val scheduler: ExperimentScheduler?,
+    private val listeners: List<ExperimentExecutionListener>,
+    private val repeats: Int
+) {
+    /**
+     * Construct an [ExperimentEngineLauncher] instance.
+     */
+    public constructor() : this(null, null, emptyList(), 1)
+
+    /**
+     * Create an [ExperimentEngineLauncher] with the specified [strategy].
+     */
+    public fun withScheduler(strategy: ExperimentStrategy): ExperimentEngineLauncher {
+        return ExperimentEngineLauncher(strategy, scheduler, listeners, repeats)
+    }
+
+    /**
+     * Create an [ExperimentEngineLauncher] with the specified [scheduler].
+     */
+    public fun withScheduler(scheduler: ExperimentScheduler): ExperimentEngineLauncher {
+        return ExperimentEngineLauncher(strategy, scheduler, listeners, repeats)
+    }
+
+    /**
+     * Create an [ExperimentEngineLauncher] with the specified [listener] added.
+     */
+    public fun withListener(listener: ExperimentExecutionListener): ExperimentEngineLauncher {
+        return ExperimentEngineLauncher(strategy, scheduler, listeners + listener, repeats)
+    }
+
+    /**
+     * Create an [ExperimentEngineLauncher] with the specified number of repeats.
+     */
+    public fun withRepeats(repeats: Int): ExperimentEngineLauncher {
+        require(repeats > 0) { "Invalid number of repeats; must be greater than zero. " }
+        return ExperimentEngineLauncher(strategy, scheduler, listeners, repeats)
+    }
+
+    /**
+     * Launch the specified experiments via the [ExperimentEngine] and block execution until finished.
+     */
+    public suspend fun run(experiments: Flow<ExperimentDefinition>) {
+        val engine = ExperimentEngine(createStrategy(), createScheduler(), createListener(), repeats)
+        experiments.collect { experiment -> engine.execute(experiment) }
+    }
+
+    /**
+     * Launch the specified experiments via the [ExperimentEngine] and block the current thread until finished.
+     */
+    public fun runBlocking(experiments: Flow<ExperimentDefinition>) {
+        runBlocking {
+            run(experiments)
+        }
+    }
+
+    /**
+     * Return a string representation of this instance.
+     */
+    public override fun toString(): String = "ExperimentEngineLauncher"
+
+    /**
+     * Create the [ExperimentStrategy] that explores the experiment design space.
+     */
+    private fun createStrategy(): ExperimentStrategy {
+        return strategy ?: CartesianExperimentStrategy
+    }
+
+    /**
+     * Create the [ExperimentScheduler] that schedules the trials over the compute resources.
+     */
+    private fun createScheduler(): ExperimentScheduler {
+        return scheduler ?: ThreadPoolExperimentScheduler(Runtime.getRuntime().availableProcessors())
+    }
+
+    /**
+     * Create the [ExperimentExecutionListener] that listens the to the execution of the experiments.
+     */
+    private fun createListener(): ExperimentExecutionListener {
+        require(listeners.isNotEmpty()) { "No listeners registered." }
+        return CompositeExperimentExecutionListener(listeners)
+    }
+}