maedhroz commented on code in PR #24: URL: https://github.com/apache/cassandra-harry/pull/24#discussion_r1418054105
########## harry-core/src/harry/checker/ModelChecker.java: ########## @@ -0,0 +1,230 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package harry.checker; + +import java.util.ArrayList; +import java.util.List; +import java.util.Random; +import java.util.function.Consumer; + +import harry.generators.EntropySource; +import harry.generators.JdkRandomEntropySource; + +public class ModelChecker<STATE> +{ + private final List<StepExecutor<STATE>> steps; + private final List<Precondition<STATE>> invariants; + private Precondition<STATE> exitCondition; + private Consumer<STATE> beforeAll; + private Consumer<STATE> afterAll; + private STATE init; + + public ModelChecker() + { + steps = new ArrayList<>(); + invariants = new ArrayList<>(); + } + + public void run() throws Throwable + { + run(Integer.MAX_VALUE, System.currentTimeMillis()); + } + + public void run(int maxSteps, long seed) throws Throwable + { + assert init != null : "Initial condition is not specified"; + + Ref<STATE> state = new Ref<>(init); + EntropySource entropySource = new JdkRandomEntropySource(new Random(seed)); + if (beforeAll != null) + beforeAll.accept(state.get()); + + for (int i = 0; i < maxSteps; i++) + { + if (exitCondition != null && exitCondition.test(state.get())) + return; + + // TODO: add randomisation / probability for triggering a specific step + steps.get(entropySource.nextInt(steps.size())).execute(state, entropySource.derive()); + for (Precondition<STATE> invariant : invariants) + invariant.test(state.get()); + } + + if (afterAll != null) + afterAll.accept(state.get()); + } + public ModelChecker<STATE> init(STATE state) + { + this.init = state; + return this; + } + + public ModelChecker<STATE> beforeAll(Consumer<STATE> precondition) + { + this.beforeAll = precondition; + return this; + } + + public ModelChecker<STATE> afterAll(Consumer<STATE> postcondition) + { + this.afterAll = postcondition; + return this; + } + + public ModelChecker<STATE> exitCondition(Precondition<STATE> precondition) + { + this.exitCondition = precondition; + return this; + } + + public ModelChecker<STATE> step(Precondition<STATE> precondition, Step<STATE> step) + { + steps.add((ref, entropySource) -> { + ref.map(state -> { + if (!precondition.test(state)) + return state; + + return step.next(state, entropySource); + }); + }); + + return this; + } + + public ModelChecker<STATE> invariant(Precondition<STATE> invariant) + { + invariants.add(invariant); + return this; + } + + public ModelChecker<STATE> step(Step<STATE> step) + { + return step(Precondition.alwaysTrue(), step); + } + + public ModelChecker<STATE> step(StatePrecondition<STATE> precondition, ThrowingFunction<STATE, STATE> step) + { + steps.add((ref, entropySource) -> { + ref.map(state -> { + if (!precondition.test(state)) + return state; + + return step.apply(state); + }); + }); + + return this; + } + + public ModelChecker<STATE> step(ThrowingConsumer<STATE> step) + { + return step((t, entropySource) -> { + step.consume(t); + return t; + }); + } + public ModelChecker<STATE> step(ThrowingFunction<STATE, STATE> step) + { + return step((t, entropySource) -> { + return step.apply(t); + }); + } + + static interface StepExecutor<STATE> + { + void execute(Ref<STATE> state, EntropySource entropySource) throws Throwable; + } + + public static interface StatePrecondition<STATE> + { + boolean test(STATE state) throws Throwable; + } + + public static interface Precondition<STATE> + { + boolean test(STATE state) throws Throwable; + + public static <STATE> Precondition<STATE> alwaysTrue() + { + return (a) -> true; + } + } + + public static interface Step<STATE> Review Comment: nit: None of the interfaces need the `static` keyword -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
