算子下推开发

如下所示，使用注解@HafTarget表示该函数为需要下推到卸载节点运算的函数。

package com.haf.test.testapp;

import com.huawei.haf.annotations.HafTarget;

public class TestAppMain {

    private String ip;

    private int val;

    public TestAppMain(String ip) {
        val = 0;
        this.ip = ip;
    }

    @HafTarget(target = "127.0.0.1")
    public void jarOffloadVoidTest() {
        System.out.println("void test");
    }

    @HafTarget(target = "ip", to = {"a", "b"}, app = "add", exception = Exception.class)
    public int jarOffloadAddTest(int a, int b) {
        System.out.println("call add func");
        return a + b;
    }

    @HafTarget(target = "ip", to = {"a", "b"}, from = "val", timeout = "300", runInHostIfFailed = false, exception = Exception.class, app = "add")
    public int jarOffload(int a, int b) throws Exception {
        System.out.println("");
        val++;
        return a + b;
    }

    public static void main(String[] args) {
        String addIp;
        int numA = 0;
        int numB = 0;
        try {
            addIp = args[0];
            numA = Integer.valueOf(args[1]).intValue();
            numB = Integer.valueOf(args[2]).intValue();
        } catch (Exception e) {
            System.out.println(e.fillInStackTrace());
            return;
        }
        TestAppMain testAppMain = new TestAppMain(addIp);
        System.out.println(testAppMain.jarOffloadAddTest(numA, numB));
        testAppMain.jarOffloadVoidTest();
        try {
            testAppMain.jarOffload(numA, numB);
        } catch (Exception e) {
            System.out.println(e.fillInStackTrace());
            return;
        }
    }
}

函数下推的过程中，是使用FST序列化当前对象this和to指定的参数，如果存在FST无法直接序列化的对象类型，需自行根据FST写序列化器，并使用注解@HafSerializer指定序列化器。

如下所示，假设类Page是FST不支持的序列化对象。

public class Page {
    private String name;
    private int age;
    public Page(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Page{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

针对类Page创建FST的序列化器仅需继承FST的类FSTBasicObjectSerializer，并重写writeObject和instantiate方法。

public class PageSerializer extends FSTBasicObjectSerializer {

    @Override
    public void writeObject(FSTObjectOutput out,
                            Object toWrite,
                            FSTClazzInfo clzInfo,
                            FSTClazzInfo.FSTFieldInfo referencedBy,
                            int streamPosition) throws IOException {
        if (toWrite instanceof Page) {
            Page page = (Page) toWrite;
            out.writeInt(page.getAge());
            out.writeStringUTF(page.getName());
        }
    }

    @Override
    public Object instantiate(Class objectClass,
                              FSTObjectInput in,
                              FSTClazzInfo serializationInfo,
                              FSTClazzInfo.FSTFieldInfo referencee,
                              int streamPosition) throws Exception {
        int age = in.readInt();
        String name = in.readStringUTF();
        return new Page(name, age);
    }
}

对于写好的序列化器，使用注解@HafSerializer使用该序列化器。如下所示：

@HafSerializer(clazz = Page.class, serializer = PageSerializer.class)
@HafTarget(target = "127.0.0.1")
public Page getPage() {
	Page page = new Page("test", 0);
	return page;
}

注解@HafSerializer包含两个字段：

• clazz表示需要使用序列化器的类。
• serializer表示使用的自定义序列化器。