yrRecover

Note

Constraint: When users define their own yrRecover, the function signature must match the interface prototype. Otherwise, the cloud will not be able to find the corresponding function and execute it.

Interface description

public void yrRecover()

Users can use this interface to perform state recovery, initialization of state, and other operations. In actors executed in the cloud, add a hook function named yrRecover. The function supports calling the openYuanrong interface. The yrRecover function will be executed in the following scenarios:

1. When the runtime receives a recover request (for example, when a user on-premises configures recoverRetryTimes > 0 in InvokeOptions, and the cloud instance exits abnormally).

Case 1:

// Define yrRecover in the stateful function.
public class Counter {
    private int cnt = 0;

    public static long getPid () {
        String processName = ManagementFactory.getRuntimeMXBean().getName();
        long pid = Long.parseLong(processName.split("@")[0]);
        return pid;
    }

    public void yrRecover() throws YRException {
        SetParam setParam = new SetParam.Builder().writeMode(WriteMode.NONE_L2_CACHE_EVICT).build();
        YR.kv().set("myKey", "myValue".getBytes(StandardCharsets.UTF_8), setParam);
    }
}

public void main(String[] args) throws Exception {
    YR.kv().del("myKey");
    InstanceHandler ins = YR.instance(Counter::new).invoke();
    ObjectRef ref = ins.function(Counter::getPid).invoke();
    long pid = (long)YR.get(ref, 10000);

    ProcessBuilder pb = new ProcessBuilder("kill", "-9", String.valueOf(pid));
    pb.inheritIO();
    pb.start().waitFor();

    byte[] byteArray = YR.kv().get("myKey", 30);
    String recoverValue = new String(byteArray, StandardCharsets.UTF_8);
    Assert.assertEquals(recoverValue, "myValue");
    YR.Finalize();
}

Case 2:

// yrRecover is not defined in the stateful function.
public class Counter {
    private int cnt = 0;

    public int add() {
        this.cnt += 1;
        return this.cnt;
    }

    public static long getPid () {
        String processName = ManagementFactory.getRuntimeMXBean().getName();
        long pid = Long.parseLong(processName.split("@")[0]);
        return pid;
    }

    public boolean saveState() throws YRException {
        YR.saveState();
        return true;
    }
}

public void main(String[] args) throws Exception {
    InstanceHandler ins = YR.instance(Counter::new).invoke();
    ObjectRef ref = ins.function(Counter::add).invoke();
    YR.get(ref, 10);

    ref = ins.function(Counter::saveState).invoke();
    YR.get(ref, 10);

    ref = ins.function(Counter::getPid).invoke();
    long pid = (long)YR.get(ref, 10000);

    ProcessBuilder pb = new ProcessBuilder("kill", "-9", String.valueOf(pid));
    pb.inheritIO();
    pb.start().waitFor();

    ref = ins.function(Counter::add).invoke();
    int res = (int)YR.get(ref, 10);
    Assert.assertEquals(res, 2);
    YR.Finalize();
}