How to implement sticking and unpacking in Swoole

In network programming, packet sticking and unpacking are common problems. This is because in the process of transmitting data, in order to improve transmission efficiency, multiple messages are often merged into one large data packet and sent, which will As a result, the receiving end cannot correctly identify the boundaries of each message, resulting in packet sticking and unpacking problems.

Swoole is a high-performance network communication framework based on PHP language, supporting TCP/UDP protocol, HTTP/WebSocket protocol and other network communication methods. In the Swoole framework, the problem of packet sticking and unpacking is solved by setting the data packet header.

1. What are packet sticking and unpacking

Sticking packets and unpacking refer to the situation where the receiver cannot correctly distinguish the data packets due to the special nature of the transmitted data during network transmission. boundary, resulting in incomplete reception or multiple packets being received.

1. The sticky packet problem

The sticky packet problem means that the sender merges multiple messages into one large data packet and sends it, and the receiving end cannot identify the boundaries of each message. caused problems. For example, the sender sends three messages "A", "B", and "C", but the data received by the receiving end may be different combinations such as "ABC" or "AB" and "C".

2. Unpacking problem

Unpacking problem refers to the problem caused by the sender’s data packet being large and the receiving end not receiving it completely at one time. For example, for example The sender sends a large data packet, but due to network transmission reasons, the receiving end only receives part of the data packet, and it requires multiple receptions to fully receive the sender's data packet.

2. How to solve the problems of packet sticking and unpacking

In network programming, we can solve the problems of packet sticking and unpacking by setting the data packet header. The data packet header means that when sending data, a fixed-length identifier is added to the beginning of each data packet to identify the length of the data packet. When receiving data, we can intercept a complete data packet in the buffer based on the length information of the data packet header after receiving the data packet header.

In the Swoole framework, we can solve the problems of sticking and unpacking by setting the protocol.

3. Implementing sticking and unpacking in Swoole

In Swoole, we can solve the problems of sticking and unpacking by setting the Swoole protocol. Swoole supports TCP and UDP protocols, and the functions used are also different.

1. TCP protocol

In the TCP protocol, we can set a data packet header to indicate the length of the data packet, and then when receiving the data, read Take the packet header to get the length of the packet, then receive the complete packet.

The following is a simple example:

<?php
$server = new swoole_server("127.0.0.1", 9501);

$server->set(array(
    'open_length_check' => true,  //开启数据包头
    'package_max_length' => 8192, //最大长度
    'package_length_type' => 'n', //数据包头长度标识所占字节数
    'package_length_offset' => 0,
    'package_body_offset' => 2,   //数据包头长度标识结束后的位置
));

$server->on('receive', function (swoole_server $server, $fd, $reactor_id, $data) {
    //处理数据
});

$server->start();
?>

In the above example, we enable the data packet header by setting the protocol parameters, and set the maximum length of the data packet header and the length identifier. The number of bytes, the starting position of the length identifier and the position of the packet body after the end of the data packet header length identifier. In this way, the receiving end can receive the complete data packet according to the data packet header.

2. UDP protocol

In the UDP protocol, we can set a data packet header to indicate the length of the data packet, and then when receiving the data, read Take the packet header to get the length of the packet, then receive the complete packet. It is also necessary to turn on the data packet header through protocol parameters.

The following is a simple example:

<?php
$server = new swoole_server("127.0.0.1", 9502, SWOOLE_PROCESS, SWOOLE_SOCK_UDP);

$server->set(array(
    'open_length_check' => true,
    'package_max_length' => 8192,
    'package_length_type' => 'n',
    'package_length_offset' => 0,
    'package_body_offset' => 2,
));

$server->on('Packet', function (swoole_server $server, $data, $client_info) {
    //处理数据
});

$server->start();
?>

In the above example, we enable the data packet header by setting the protocol parameters, and set the length and position of the data packet header. In this way, the receiving end can receive the complete data packet according to the data packet header.

4. Summary

By setting the Swoole protocol, we can more easily solve the problems of sticking and unpacking. Using the Swoole framework allows us to avoid the complexity of underlying network communication, focus on the implementation of business logic, and improve development efficiency.

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