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👉 cffuCompletableFuture-Fu 🦝)是一个小小的CompletableFuture(CF)辅助增强库,提升CF使用体验并减少误用,在业务中更方便高效安全地使用CF。😋🚀🦺

欢迎 👏 💖

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🔧 功能

提供的功能有:

更多cffu的使用方式与功能说明详见 User Guide

关于CompletableFuture

如何管理并发执行是个复杂易错的问题,业界有大量的工具、框架可以采用。

并发工具、框架的广度了解,可以看看如《七周七并发模型》、《Java虚拟机并发编程》、《Scala并发编程(第2版)》;更多关于并发主题的书籍参见书单

其中CompletableFuture(CF)有其优点:

和其它并发工具、框架一样,CompletableFuture用于

值得更深入地了解和应用。 💕

👥 User Guide

1. cffu的使用方式

cffu的使用方式:

cffu也支持Kotlin扩展方法的使用方式,参见cffu-kotlin/README.md;使用方式对比示例参见docs/usage-mode-demo.md

2. cffu功能介绍

2.1 返回多个CF的整体运行结果

CompletableFutureallOf方法不返回多个CF的运行结果(方法返回类型是CF<Void>)。

不能方便地获取多个CF的运行结果:

cffuallResultsFailFastOf / allResultsOf / mostSuccessResultsOf等方法提供了返回多个CF运行结果的功能。

使用这些方法获取多个CF的整体运行结果:

示例代码如下:

public class AllResultsOfDemo {
  public static final Executor myBizExecutor = Executors.newCachedThreadPool();
  public static final CffuFactory cffuFactory = CffuFactory.builder(myBizExecutor).build();

  public static void main(String[] args) throws Exception {
    //////////////////////////////////////////////////
    // CffuFactory#allResultsOf
    //////////////////////////////////////////////////
    Cffu<Integer> cffu1 = cffuFactory.completedFuture(21);
    Cffu<Integer> cffu2 = cffuFactory.completedFuture(42);

    Cffu<Void> all = cffuFactory.allOf(cffu1, cffu2);
    // Result type is Void!
    //
    // the result can be got by input argument `cf1.get()`, but it's cumbersome.
    // so we can see a lot of util methods to enhance `allOf` with result in our project.

    Cffu<List<Integer>> allResults = cffuFactory.allResultsOf(cffu1, cffu2);
    System.out.println(allResults.get());

    //////////////////////////////////////////////////
    // or CompletableFutureUtils#allResultsOf
    //////////////////////////////////////////////////
    CompletableFuture<Integer> cf1 = CompletableFuture.completedFuture(21);
    CompletableFuture<Integer> cf2 = CompletableFuture.completedFuture(42);

    CompletableFuture<Void> all2 = CompletableFuture.allOf(cf1, cf2);
    // Result type is Void!

    CompletableFuture<List<Integer>> allResults2 = allResultsOf(cf1, cf2);
    System.out.println(allResults2.get());
  }
}

# 完整可运行的Demo代码参见AllResultsOfDemo.java

上面是多个相同结果类型的CFcffu还提供了返回多个不同类型CF结果的allTupleFailFastOf / allTupleOf / mSupplyTupleFailFastAsync等方法。

示例代码如下:

public class AllTupleOfDemo {
  public static final Executor myBizExecutor = Executors.newCachedThreadPool();
  public static final CffuFactory cffuFactory = CffuFactory.builder(myBizExecutor).build();

  public static void main(String[] args) throws Exception {
    //////////////////////////////////////////////////
    // allTupleFailFastOf / allTupleOf
    //////////////////////////////////////////////////
    Cffu<String> cffu1 = cffuFactory.completedFuture("21");
    Cffu<Integer> cffu2 = cffuFactory.completedFuture(42);

    Cffu<Tuple2<String, Integer>> allTuple = cffuFactory.allTupleFailFastOf(cffu1, cffu2);
    System.out.println(allTuple.get());

    //////////////////////////////////////////////////
    // or CompletableFutureUtils.allTupleFailFastOf / allTupleOf
    //////////////////////////////////////////////////
    CompletableFuture<String> cf1 = CompletableFuture.completedFuture("21");
    CompletableFuture<Integer> cf2 = CompletableFuture.completedFuture(42);

    CompletableFuture<Tuple2<String, Integer>> allTuple2 = allTupleFailFastOf(cf1, cf2);
    System.out.println(allTuple2.get());
  }
}

# 完整可运行的Demo代码参见AllTupleOfDemo.java

2.2 支持设置缺省的业务线程池并封装携带

结果就是,

示例代码如下:

public class NoDefaultExecutorSettingForCompletableFuture {
  public static final Executor myBizExecutor = Executors.newCachedThreadPool();

  public static void main(String[] args) {
    CompletableFuture<Void> cf1 = CompletableFuture.runAsync(
        () -> System.out.println("doing a long time work!"),
        myBizExecutor);

    CompletableFuture<Void> cf2 = CompletableFuture
        .supplyAsync(
            () -> {
              System.out.println("doing another long time work!");
              return 42;
            },
            myBizExecutor)
        .thenAcceptAsync(
            i -> System.out.println("doing third long time work!"),
            myBizExecutor);

    CompletableFuture.allOf(cf1, cf2).join();
  }
}

# 完整可运行的Demo代码参见NoDefaultExecutorSettingForCompletableFuture.java

Cffu支持设置缺省的业务线程池,规避上面的繁琐与危险。示例代码如下:

public class DefaultExecutorSettingForCffu {
  public static final Executor myBizExecutor = Executors.newCachedThreadPool();
  public static final CffuFactory cffuFactory = CffuFactory.builder(myBizExecutor).build();

  public static void main(String[] args) {
    Cffu<Void> cf1 = cffuFactory.runAsync(() -> System.out.println("doing a long time work!"));

    Cffu<Void> cf2 = cffuFactory.supplyAsync(() -> {
      System.out.println("doing another long time work!");
      return 42;
    }).thenAcceptAsync(i -> System.out.println("doing third long time work!"));

    cffuFactory.allOf(cf1, cf2).join();
  }
}

# 完整可运行的Demo代码参见DefaultExecutorSettingForCffu.java

2.3 高效灵活的并发执行策略(AllFailFast / AnySuccess / AllSuccess / MostSuccess

📔 关于多个CF的并发执行策略,可以看看JavaScript规范Promise Concurrency;在JavaScript中,Promise即对应CompletableFuture

JavaScript Promise提供了4个并发执行方法:

PS:JavaScript Promise的方法命名真考究~ 👍

cffu新加2个方法后,对齐了JavaScript Promise规范的并发方法~ 👏

示例代码如下:

public class ConcurrencyStrategyDemo {
  public static final Executor myBizExecutor = Executors.newCachedThreadPool();
  public static final CffuFactory cffuFactory = CffuFactory.builder(myBizExecutor).build();

  public static void main(String[] args) throws Exception {
    ////////////////////////////////////////////////////////////////////////
    // CffuFactory#allResultsFailFastOf
    // CffuFactory#anySuccessOf
    // CffuFactory#mostSuccessResultsOf
    ////////////////////////////////////////////////////////////////////////
    final Cffu<Integer> successAfterLongTime = cffuFactory.supplyAsync(() -> {
      sleep(3000); // sleep LONG time
      return 42;
    });
    final Cffu<Integer> failed = cffuFactory.failedFuture(new RuntimeException("Bang!"));

    Cffu<List<Integer>> failFast = cffuFactory.allResultsFailFastOf(successAfterLongTime, failed);
    // fail fast without waiting successAfterLongTime
    System.out.println(failFast.exceptionNow());

    Cffu<Integer> anySuccess = cffuFactory.anySuccessOf(successAfterLongTime, failed);
    System.out.println(anySuccess.get());

    Cffu<List<Integer>> mostSuccess = cffuFactory.mostSuccessResultsOf(
        0, 100, TimeUnit.MILLISECONDS, successAfterLongTime, failed);
    System.out.println(mostSuccess.get());

    ////////////////////////////////////////////////////////////////////////
    // or CompletableFutureUtils#allResultsFailFastOf
    //    CompletableFutureUtils#anySuccessOf
    //    CompletableFutureUtils#mostSuccessResultsOf
    ////////////////////////////////////////////////////////////////////////
    final CompletableFuture<Integer> successAfterLongTimeCf = CompletableFuture.supplyAsync(() -> {
      sleep(3000); // sleep LONG time
      return 42;
    });
    final CompletableFuture<Integer> failedCf = failedFuture(new RuntimeException("Bang!"));

    CompletableFuture<List<Integer>> failFast2 = allResultsFailFastOf(successAfterLongTimeCf, failedCf);
    // fail fast without waiting successAfterLongTime
    System.out.println(exceptionNow(failFast2));

    CompletableFuture<Integer> anySuccess2 = anySuccessOf(successAfterLongTimeCf, failedCf);
    System.out.println(anySuccess2.get());

    CompletableFuture<List<Integer>> mostSuccess2 = mostSuccessResultsOf(
        0, 100, TimeUnit.MILLISECONDS, successAfterLongTime, failed);
    System.out.println(mostSuccess2.get());
  }
}

# 完整可运行的Demo代码参见ConcurrencyStrategyDemo.java

2.4 支持直接运行多个Action,而不是要先包装成CompletableFuture

CompletableFutureallOf/anyOF方法输入的是CompletableFuture,当业务直接有要编排业务逻辑方法时仍然需要先包装成CompletableFuture再运行:

cffu提供了直接运行多个Action的方法,方便直接明了地表达业务编排流程。

示例代码如下:

public class MultipleActionsDemo {
  static void mRunAsyncDemo() {
    // wrap tasks to CompletableFuture first, AWKWARD! 😖
    CompletableFuture.allOf(
        CompletableFuture.runAsync(() -> System.out.println("task1")),
        CompletableFuture.runAsync(() -> System.out.println("task2")),
        CompletableFuture.runAsync(() -> System.out.println("task3"))
    );

    // just run multiple actions, fresh and cool 😋
    CompletableFutureUtils.mRunAsync(
        () -> System.out.println("task1"),
        () -> System.out.println("task2"),
        () -> System.out.println("task3")
    );
  }
}

这些多Action方法也配套实现了「不同的并发执行策略」与「返回多个运行结果」的支持。

示例代码如下:

public class MultipleActionsDemo {
  static void thenMApplyAsyncDemo() {
    // wrap tasks to CompletableFuture first, AWKWARD! 😖
    completedFuture(42).thenCompose(v ->
        CompletableFutureUtils.allResultsFailFastOf(
            CompletableFuture.supplyAsync(() -> v + 1),
            CompletableFuture.supplyAsync(() -> v + 2),
            CompletableFuture.supplyAsync(() -> v + 3)
        )
    ).thenAccept(System.out::println);
    // output: [43, 44, 45]

    // just run multiple actions, fresh and cool 😋
    CompletableFutureUtils.thenMApplyFailFastAsync(
        completedFuture(42),
        v -> v + 1,
        v -> v + 2,
        v -> v + 3
    ).thenAccept(System.out::println);
    // output: [43, 44, 45]
  }
}

# 完整可运行的Demo代码参见MultipleActionsDemo.java

2.5 支持超时的join的方法

cf.join()会「不超时永远等待」,在业务中很危险❗️当意外出现长时间等待时,会导致:

join(timeout, unit)方法即支持超时的join的方法;就像cf.get(timeout, unit) 之于 cf.get()

这个新方法使用简单类似,不附代码示例。

2.6 Backport支持Java 8

Java 9+高版本的所有CF新功能方法在Java 8低版本直接可用。

其中重要的Backport功能有:

这些backport的方法是CompletableFuture的已有功能,不附代码示例。

2.7 返回具体类型的anyOf方法

CompletableFuture.anyOf方法返回类型是Object,丢失具体类型,不类型安全,使用时需要转型也不方便。

cffu提供的anySuccessOf / anyOf方法,返回具体类型T,而不是返回Object

这个方法使用简单类似,不附代码示例。

2.8 输入宽泛类型的allof/anyOf方法

CompletableFuture#allof/anyOf方法输入参数类型是CompletableFuture,而输入更宽泛的CompletionStage类型;对于CompletionStage类型的输入,则需要调用CompletionStage#toCompletableFuture方法做转换。

cffu提供的allof / anyOf方法输入更宽泛的CompletionStage参数类型,使用更方便。

方法使用简单类似,不附代码示例。

更多功能说明

可以参见:

3. 如何从直接使用CompletableFuture类迁移到Cffu

为了使用cffu增强功能,可以迁移已有直接使用CompletableFuture类的代码到Cffu类。包含2步修改:

之所以可以这样迁移,是因为:

🔌 API Docs

代码示例:

🍪依赖

可以在 central.sonatype.com 查看最新版本与可用版本列表。

📚 更多资料

👋 关于库名

cffuCompletableFuture-Fu的缩写;读作C Fu,谐音Shifu/师傅

嗯嗯,想到了《功夫熊猫》里可爱的小浣熊师傅吧~ 🦝

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