# yamq

**Repository Path**: RonxBulld/yamq

## Basic Information

- **Project Name**: yamq
- **Description**: This is the single head file that implement message queue framework.
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 1
- **Created**: 2021-04-29
- **Last Updated**: 2022-05-25

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

yamq - Yet Another Message Queue
---
This is the single head file that implement message queue framework.

## Basics

```c++
#include <yamq.h>
```

Create a `Observer` template class inherit from `ObserverBase`, and override `Invoke`.

```c++
class Observer : public yamq::ObserverBase {
public:
    Observer() = default ;
    ~Observer() override = default ;
    void Invoke(const yamq::KVdb &kvdb) override {
        std::cout << kvdb[""] << std::endl;
    }
};
```

Then, create a serial or parallel `PubSub` instance,

```c++
yamq::PubSub<yamq::SerialSlot> pubsub;
```

or

```c++
yamq::PubSub<yamq::ParallelSlot> pubsub(32);
```

and `Observer` instance.

```c++
Observer obi;
```

After that, register this observer instance.

```c++
pubsub.Subscribe("", obi);
```

Alternatively, you can use lambda expressions instead of observer instances.

```c++
pubsub.Subscribe("aaa", [](const yamq::KVdb &kvdb) {
    std::cout << "Lambda recived: " << kvdb[""] << std::endl;
});
```

Finally, you can broadcast your defined message by calling the `yamq::PubSub::Publish` interface.

```c++
yamq::KVdb kvdb;
kvdb[""] = "Resolved.";
pubsub.Publish("", kvdb);
```

To subscribe to other message channel, you can modify the first stuff of calling `Subscribe`.

Similarly, it can only receive messages with the same first parameter of `Publish`.

```c++
pubsub.Subscribe("other", obi);
pubsub.Publish("other", kvdb);
```

## Deregister observer

When the observer object is released, `ObserverBase` will automatically notify all related
PubSub objects to deregister it.

And, you can use `Disconnect` and `DisconnectAll` to manually control unbinding from
any PubSub object.

```c++
obi.DisconnectAll();
obi.Disconnect(&pubsub);
```

## While destruct

When the object is ready for destruction, you need to pay attention to whether your task has stopped,
otherwise it will cause some uncertain problems.

You can use `DisableAndWait` before this to avoid this problem.

```c++
obk->DisableAndWait();
delete obk;
```

## Full example

Putting all together:

```c++
#include <iostream>
#include <yamq.h>

class ConsoleOut {
private:
    std::string prompt_;
public:
    explicit ConsoleOut(const std::string &prompt = "") : prompt_(prompt) {}
    void WriteOut(const std::string &str) {
        std::cout << prompt_ << ": " << str << std::endl;
    }
};

template <class T>
class Observer : public yamq::ObserverBase {
private:
    ConsoleOut &console_out_;

public:
    explicit Observer(ConsoleOut &CO) : console_out_(CO) {}

    void Invoke(const yamq::KVdb &kvdb) override {
        console_out_.WriteOut(kvdb[""] + kvdb["i"]);
    }

    ~Observer() override = default ;
};

int main() {
    ConsoleOut co("Test");
    ConsoleOut ck("Echo");

    Observer<std::string> obi(co);
    Observer<long> *obk = new Observer<long>(ck);

    yamq::PubSub<yamq::SerialSlot> pubsub;
    pubsub.Subscribe("aaa", obi);
    pubsub.Subscribe("aaa", *obk);
    pubsub.Subscribe("aaa", [](const yamq::KVdb &kvdb) {
        std::cout << "Lambda recived: " << kvdb[""] << std::endl;
    });
    bool obi_reg = true;

    yamq::KVdb kvdb;
    kvdb[""] = "Resolved.";

    int i = 0;
    while(i++ < 10000) {
        kvdb["i"] = std::to_string(i);
        pubsub.Publish("aaa", kvdb);
        if ((i >= 5000) && obk) {
            obk->DisableAndWait();
            delete obk;
            obk = nullptr;
        }
        if (obi_reg && (i >= 1000)) {
            obi.Disconnect(&pubsub);
            obi_reg = false;
        }
    }

    return 0;
}

```

## Linking

This is a header only library.