Operator Pushdown Development

As described below, the @HafTarget annotation indicates that the function needs to be pushed down to an offload node.

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;
        }
    }
}

During function pushdown, Fast Serialization (FST) is used to serialize the parameters specified by this and to of the current object. If there are types of objects that cannot be directly serialized by FST, write a serializer based on FST and use the @HafSerializer annotation to specify the serializer.

As described below, if the Page class is a serialized object that is not supported by FST:

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 +
                '}';
    }
}

To create an FST serializer for the Page class, you only need to inherit the FSTBasicObjectSerializer class and rewrite the writeObject and instantiate method.

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);
    }
}

For a serializer that is ready, use the @HafSerializer annotation to use the serializer. See the following information:

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

The @HafSerializer annotation contains two fields:

• clazz: indicates the class that uses the serializer.
• serializer: indicates the customized serializer used.