merge: Implement multi-flow stages in simulator (#110)

This pull request introduces the new `flow2` multi-flow simulator into the OpenDC codebase
and adjust all existing modules to make use of this new simulator.

The new simulator models flow as a network of components, which can each receive flow
from (potentially) multiple other components. In the previous simulator, the framework itself
supported only single flows between components and required re-implementation of many
components to support multiplexing flows.

Initial benchmarks show performance improvements in the range 2x–4x for large scale experiments
such as the Capelin benchmarks.

## Implementation Notes :hammer_and_pick:

* Add support for multi-flow stages
* Support flow transformations
* Add forwarding flow multiplexer
* Expose metrics on FlowMultiplexer
* Re-implement network sim using flow2
* Re-implement power sim using flow2 
* Re-implement compute sim using flow2
* Optimize workload implementation of SimTrace 
* Remove old flow simulator 
* Add log4j-core dependency 

## External Dependencies :four_leaf_clover:

* N/A

## Breaking API Changes :warning:

* Removal of the `org.opendc.simulator.flow` package. You should now use
   the new flow simulator located in `org.opendc.simulator.flow2`.
* `PowerModel` interface is replaced by the `CpuPowerModel` interface.
* `PowerDriver` interface is replaced by the `SimPsu` and `SimPsuFactory` interfaces.
* Removal of `SimTraceWorkload`. Instead, create a workload from a `SimTrace` using 
  `createWorkload(offset)`.
* `ScalingGovernor` has been split in a `ScalingGovernor` and `ScalingGovernorFactory`.
* All modules in `opendc-simulator` are now written in Java. This means that default 
   parameters are not supported anymore for these modules.

2 files changed, 124 insertions, 137 deletions

diff --git a/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow/FlowBenchmarks.kt b/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow/FlowBenchmarks.kt
deleted file mode 100644
index 58f84d82..00000000
--- a/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow/FlowBenchmarks.kt
+++ /dev/null
@@ -1,137 +0,0 @@
-/*
- * 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.flow
-
-import kotlinx.coroutines.launch
-import org.opendc.simulator.flow.mux.ForwardingFlowMultiplexer
-import org.opendc.simulator.flow.mux.MaxMinFlowMultiplexer
-import org.opendc.simulator.flow.source.TraceFlowSource
-import org.opendc.simulator.kotlin.runSimulation
-import org.openjdk.jmh.annotations.Benchmark
-import org.openjdk.jmh.annotations.Fork
-import org.openjdk.jmh.annotations.Measurement
-import org.openjdk.jmh.annotations.Scope
-import org.openjdk.jmh.annotations.Setup
-import org.openjdk.jmh.annotations.State
-import org.openjdk.jmh.annotations.Warmup
-import java.util.concurrent.ThreadLocalRandom
-import java.util.concurrent.TimeUnit
-
-@State(Scope.Thread)
-@Fork(1)
-@Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
-@Measurement(iterations = 5, time = 3, timeUnit = TimeUnit.SECONDS)
-class FlowBenchmarks {
-    private lateinit var trace: Sequence<TraceFlowSource.Fragment>
-
-    @Setup
-    fun setUp() {
-        val random = ThreadLocalRandom.current()
-        val entries = List(10000) { TraceFlowSource.Fragment(1000, random.nextDouble(0.0, 4500.0)) }
-        trace = entries.asSequence()
-    }
-
-    @Benchmark
-    fun benchmarkSink() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val provider = FlowSink(engine, 4200.0)
-            return@runSimulation provider.consume(TraceFlowSource(trace))
-        }
-    }
-
-    @Benchmark
-    fun benchmarkForward() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val provider = FlowSink(engine, 4200.0)
-            val forwarder = FlowForwarder(engine)
-            provider.startConsumer(forwarder)
-            return@runSimulation forwarder.consume(TraceFlowSource(trace))
-        }
-    }
-
-    @Benchmark
-    fun benchmarkMuxMaxMinSingleSource() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val switch = MaxMinFlowMultiplexer(engine)
-
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-
-            val provider = switch.newInput()
-            return@runSimulation provider.consume(TraceFlowSource(trace))
-        }
-    }
-
-    @Benchmark
-    fun benchmarkMuxMaxMinTripleSource() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val switch = MaxMinFlowMultiplexer(engine)
-
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-
-            repeat(3) {
-                launch {
-                    val provider = switch.newInput()
-                    provider.consume(TraceFlowSource(trace))
-                }
-            }
-        }
-    }
-
-    @Benchmark
-    fun benchmarkMuxExclusiveSingleSource() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val switch = ForwardingFlowMultiplexer(engine)
-
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-
-            val provider = switch.newInput()
-            return@runSimulation provider.consume(TraceFlowSource(trace))
-        }
-    }
-
-    @Benchmark
-    fun benchmarkMuxExclusiveTripleSource() {
-        return runSimulation {
-            val engine = FlowEngine(coroutineContext, clock)
-            val switch = ForwardingFlowMultiplexer(engine)
-
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-            FlowSink(engine, 3000.0).startConsumer(switch.newOutput())
-
-            repeat(2) {
-                launch {
-                    val provider = switch.newInput()
-                    provider.consume(TraceFlowSource(trace))
-                }
-            }
-        }
-    }
-}
diff --git a/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow2/FlowBenchmarks.kt b/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow2/FlowBenchmarks.kt
new file mode 100644
index 00000000..fb112082
--- /dev/null
+++ b/opendc-simulator/opendc-simulator-flow/src/jmh/kotlin/org/opendc/simulator/flow2/FlowBenchmarks.kt
@@ -0,0 +1,124 @@
+/*
+ * 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.flow2
+
+import kotlinx.coroutines.launch
+import org.opendc.simulator.flow2.mux.MaxMinFlowMultiplexer
+import org.opendc.simulator.flow2.sink.SimpleFlowSink
+import org.opendc.simulator.flow2.source.TraceFlowSource
+import org.opendc.simulator.flow2.util.FlowTransformer
+import org.opendc.simulator.flow2.util.FlowTransforms
+import org.opendc.simulator.kotlin.runSimulation
+import org.openjdk.jmh.annotations.Benchmark
+import org.openjdk.jmh.annotations.Fork
+import org.openjdk.jmh.annotations.Measurement
+import org.openjdk.jmh.annotations.Scope
+import org.openjdk.jmh.annotations.Setup
+import org.openjdk.jmh.annotations.State
+import org.openjdk.jmh.annotations.Warmup
+import java.util.concurrent.ThreadLocalRandom
+import java.util.concurrent.TimeUnit
+
+@State(Scope.Thread)
+@Fork(1)
+@Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
+@Measurement(iterations = 5, time = 3, timeUnit = TimeUnit.SECONDS)
+class FlowBenchmarks {
+    private lateinit var trace: TraceFlowSource.Trace
+
+    @Setup
+    fun setUp() {
+        val random = ThreadLocalRandom.current()
+        val traceSize = 10_000_000
+        trace = TraceFlowSource.Trace(
+            LongArray(traceSize) { (it + 1) * 1000L },
+            FloatArray(traceSize) { random.nextFloat(0.0f, 4500.0f) },
+            traceSize
+        )
+    }
+
+    @Benchmark
+    fun benchmarkSink() {
+        return runSimulation {
+            val engine = FlowEngine.create(coroutineContext, clock)
+            val graph = engine.newGraph()
+            val sink = SimpleFlowSink(graph, 4200.0f)
+            val source = TraceFlowSource(graph, trace)
+            graph.connect(source.output, sink.input)
+        }
+    }
+
+    @Benchmark
+    fun benchmarkForward() {
+        return runSimulation {
+            val engine = FlowEngine.create(coroutineContext, clock)
+            val graph = engine.newGraph()
+            val sink = SimpleFlowSink(graph, 4200.0f)
+            val source = TraceFlowSource(graph, trace)
+            val forwarder = FlowTransformer(graph, FlowTransforms.noop())
+
+            graph.connect(source.output, forwarder.input)
+            graph.connect(forwarder.output, sink.input)
+        }
+    }
+
+    @Benchmark
+    fun benchmarkMuxMaxMinSingleSource() {
+        return runSimulation {
+            val engine = FlowEngine.create(coroutineContext, clock)
+            val graph = engine.newGraph()
+            val switch = MaxMinFlowMultiplexer(graph)
+
+            val sinkA = SimpleFlowSink(graph, 3000.0f)
+            val sinkB = SimpleFlowSink(graph, 3000.0f)
+
+            graph.connect(switch.newOutput(), sinkA.input)
+            graph.connect(switch.newOutput(), sinkB.input)
+
+            val source = TraceFlowSource(graph, trace)
+            graph.connect(source.output, switch.newInput())
+        }
+    }
+
+    @Benchmark
+    fun benchmarkMuxMaxMinTripleSource() {
+        return runSimulation {
+            val engine = FlowEngine.create(coroutineContext, clock)
+            val graph = engine.newGraph()
+            val switch = MaxMinFlowMultiplexer(graph)
+
+            val sinkA = SimpleFlowSink(graph, 3000.0f)
+            val sinkB = SimpleFlowSink(graph, 3000.0f)
+
+            graph.connect(switch.newOutput(), sinkA.input)
+            graph.connect(switch.newOutput(), sinkB.input)
+
+            repeat(3) {
+                launch {
+                    val source = TraceFlowSource(graph, trace)
+                    graph.connect(source.output, switch.newInput())
+                }
+            }
+        }
+    }
+}