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.

4 files changed, 184 insertions, 0 deletions

diff --git a/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategy.kt b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategy.kt
new file mode 100644
index 00000000..e5e08003
--- /dev/null
+++ b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategy.kt
@@ -0,0 +1,55 @@
+/*
+ * 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.strategy
+
+import org.opendc.harness.api.ExperimentDefinition
+import org.opendc.harness.api.Parameter
+import org.opendc.harness.api.Scenario
+import org.opendc.harness.internal.ScenarioImpl
+
+/**
+ * An [ExperimentStrategy] that takes the cartesian product of the parameters and evaluates every combination.
+ */
+public object CartesianExperimentStrategy : ExperimentStrategy {
+    /**
+     * Build the trials of an experiment.
+     */
+    override fun generate(experiment: ExperimentDefinition): Sequence<Scenario> {
+        return experiment.parameters
+            .asSequence()
+            .map { param -> mapParameter(param).map { value -> listOf(param to value) } }
+            .reduce { acc, param ->
+                acc.flatMap { x -> param.map { y -> x + y } }
+            }
+            .mapIndexed { id, values -> ScenarioImpl(id, experiment, values.toMap()) }
+    }
+
+    /**
+     * Instantiate a parameter and return a sequence of possible values.
+     */
+    private fun <T> mapParameter(param: Parameter<T>): Sequence<T> {
+        return when (param) {
+            is Parameter.Generic<T> -> param.values.asSequence()
+        }
+    }
+}
diff --git a/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategyProvider.kt b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategyProvider.kt
new file mode 100644
index 00000000..f18795a3
--- /dev/null
+++ b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/CartesianExperimentStrategyProvider.kt
@@ -0,0 +1,32 @@
+/*
+ * 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.strategy
+
+/**
+ * An [ExperimentStrategyProvider] for constructing a [CartesianExperimentStrategy].
+ */
+public class CartesianExperimentStrategyProvider : ExperimentStrategyProvider {
+    override val id: String = "cartesian"
+
+    override fun create(): ExperimentStrategy = CartesianExperimentStrategy
+}
diff --git a/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategy.kt b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategy.kt
new file mode 100644
index 00000000..3a0148ad
--- /dev/null
+++ b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategy.kt
@@ -0,0 +1,40 @@
+/*
+ * 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.strategy
+
+import org.opendc.harness.api.ExperimentDefinition
+import org.opendc.harness.api.Scenario
+
+/**
+ * The [ExperimentStrategy] is responsible for traversing the design space of an [ExperimentDefinition] based on its
+ * parameters, generating concrete points in the space represented as [Scenario]s.
+ */
+public interface ExperimentStrategy {
+    /**
+     * Generate the points in the design space of the specified [experiment] to explore.
+     *
+     * @param experiment The experiment design space to explore.
+     * @return A sequence of [Scenario]s which may be explored by the [ExperimentEngine].
+     */
+    public fun generate(experiment: ExperimentDefinition): Sequence<Scenario>
+}
diff --git a/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategyProvider.kt b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategyProvider.kt
new file mode 100644
index 00000000..7fa05f34
--- /dev/null
+++ b/opendc-harness/src/main/kotlin/org/opendc/harness/engine/strategy/ExperimentStrategyProvider.kt
@@ -0,0 +1,57 @@
+/*
+ * 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.strategy
+
+import java.util.*
+
+/**
+ * A factory for constructing an [ExperimentStrategy].
+ */
+public interface ExperimentStrategyProvider {
+    /**
+     * A unique identifier for this strategy implementation.
+     *
+     * Each experiment strategy must provide a unique ID, so that they can be selected by the user.
+     * When in doubt, you may use the fully qualified name of your custom [ExperimentStrategy] implementation class.
+     */
+    public val id: String
+
+    /**
+     * Factory method for creating a new [ExperimentStrategy] instance.
+     */
+    public fun create(): ExperimentStrategy
+
+    public companion object {
+        /**
+         * The available [ExperimentStrategyProvider]s.
+         */
+        private val providers by lazy { ServiceLoader.load(ExperimentStrategyProvider::class.java) }
+
+        /**
+         * Obtain the [ExperimentStrategy] with the specified [id] or return `null`.
+         */
+        public fun findById(id: String): ExperimentStrategyProvider? {
+            return providers.find { it.id == id }
+        }
+    }
+}