Java tutorial
/* * Copyright (c) 2015 Spotify AB. * * 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 com.spotify.heroic; import com.google.common.collect.ImmutableList; import com.spotify.heroic.shell.CoreInterface; import com.spotify.heroic.shell.QuoteParser; import com.spotify.heroic.shell.ShellIO; import com.spotify.heroic.shell.Tasks; import com.spotify.heroic.shell.protocol.CommandDefinition; import eu.toolchain.async.AsyncFuture; import jline.console.ConsoleReader; import jline.console.UserInterruptException; import jline.console.completer.StringsCompleter; import jline.console.history.FileHistory; import lombok.RequiredArgsConstructor; import lombok.extern.slf4j.Slf4j; import org.apache.commons.lang3.StringUtils; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import java.util.concurrent.ExecutionException; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; @Slf4j @RequiredArgsConstructor public class HeroicInteractiveShell { final ConsoleReader reader; final List<CommandDefinition> commands; final FileHistory history; boolean running = true; // mutable state, a.k.a. settings int timeout = 10; public void run(final CoreInterface core) throws Exception { final PrintWriter out = new PrintWriter(reader.getOutput()); while (running) { final String raw; try { raw = reader.readLine(); } catch (UserInterruptException e) { out.println("Interrupted"); break; } if (raw == null) { break; } final List<List<String>> lines; try { lines = QuoteParser.parse(raw); } catch (Exception e) { log.error("Line syntax invalid", e); return; } lines.forEach(command -> { if (command.isEmpty()) { return; } final String commandName = command.iterator().next(); if ("exit".equals(commandName)) { running = false; return; } if ("help".equals(commandName)) { printTasksHelp(out); return; } if ("clear".equals(commandName)) { try { reader.clearScreen(); } catch (IOException e) { log.error("Failed to clear screen", e); } return; } if ("timeout".equals(commandName)) { internalTimeoutTask(out, command); return; } final ShellIO io = new DirectShellIO(out); final long start = System.nanoTime(); try { runTask(command, io, core); } catch (Exception e) { e.printStackTrace(); } final long diff = System.nanoTime() - start; out.println(String.format("time: %s", Tasks.formatTimeNanos(diff))); }); } out.println(); out.println("Exiting..."); } public void shutdown() throws IOException { if (history != null) { history.flush(); } reader.shutdown(); } void printTasksHelp(PrintWriter out) { out.println("Available commands:"); for (final CommandDefinition c : commands) { out.println(String.format("%s - %s", c.getName(), c.getUsage())); if (!c.getAliases().isEmpty()) { out.println(String.format(" aliases: %s", StringUtils.join(", ", c.getAliases()))); } } } void internalTimeoutTask(PrintWriter out, List<String> args) { if (args.size() < 2) { if (this.timeout == 0) { out.println("timeout disabled"); } else { out.println(String.format("timeout = %d", this.timeout)); } return; } final int timeout; try { timeout = Integer.parseInt(args.get(1)); } catch (Exception e) { out.println(String.format("not a valid integer value: %s", args.get(1))); return; } if (timeout <= 0) { out.println("Timeout disabled"); this.timeout = 0; } else { out.println(String.format("Timeout updated to %d seconds", timeout)); this.timeout = timeout; } } void runTask(List<String> command, final ShellIO io, final CoreInterface core) throws Exception { final AsyncFuture<Void> t; try { t = core.evaluate(command, io); } catch (Exception e) { io.out().println("Command failed"); e.printStackTrace(io.out()); return; } if (t == null) { io.out().flush(); return; } try { awaitFinished(t); } catch (TimeoutException e) { io.out().println(String.format("Command timed out (current timeout = %ds)", timeout)); t.cancel(true); } catch (Exception e) { io.out().println("Command failed"); e.printStackTrace(io.out()); return; } io.out().flush(); } Void awaitFinished(final AsyncFuture<Void> t) throws InterruptedException, ExecutionException, TimeoutException { if (timeout > 0) { return t.get(timeout, TimeUnit.SECONDS); } log.warn(String.format("Waiting forever for task (timeout = %d)", timeout)); return t.get(); } public static HeroicInteractiveShell buildInstance(final List<CommandDefinition> commands, FileInputStream input) throws Exception { final ConsoleReader reader = new ConsoleReader("heroicsh", input, System.out, null); final FileHistory history = setupHistory(reader); if (history != null) { reader.setHistory(history); } reader.setPrompt(String.format("heroic> ")); reader.addCompleter( new StringsCompleter(ImmutableList.copyOf(commands.stream().map((d) -> d.getName()).iterator()))); reader.setHandleUserInterrupt(true); return new HeroicInteractiveShell(reader, commands, history); } private static FileHistory setupHistory(final ConsoleReader reader) throws IOException { final String home = System.getProperty("user.home"); if (home == null) { return null; } return new FileHistory(new File(home, ".heroicsh-history")); } }