How to develop golang plug-ins

With the popularity of Go language and the continuous expansion of application scenarios, more and more enterprises and developers are beginning to adopt Go language for development. Among them, writing Go plug-ins has become a hot topic. Go plug-in is an independent binary file that can be loaded into the Go program at runtime to extend the program and enhance its functionality. This article will introduce how to develop golang plug-ins.

1. Understand the Go plug-in

Go plug-in is an extension mechanism officially provided by the Go language. It allows binary files to be dynamically loaded while the program is running, thereby extending the program and enhancing its functionality. Go plug-ins can be independently compiled into binaries and then dynamically loaded at runtime without compiling source code. Go plugins usually contain one or more functions, and only allow exported functions.

2. Compilation of plug-ins

Go plug-ins can be compiled like ordinary Go programs. Just use the -buildmode parameter to specify the plug-in mode during compilation. For example:

go build -buildmode=plugin plugin.so plugin.go

Among them, plugin.so is the output plug-in file name, and plugin.go is the Go source file containing the plug-in code. After successful compilation, a separate .so file will be generated.

3. Plug-in export function

Go plug-in can export one or more functions for the main program to call. The method of exporting a function is the same as that of a normal function, just add the export keyword before the function.

package main

import (
    "log"
)

// 普通函数
func Add(a, b int) int {
    return a + b
}

// 导出函数
// 必须符合如下形式：func 函数名(参数类型) 返回值类型
func ExportAdd(a, b int) int {
    log.Println("调用了插件函数ExportAdd")
    return Add(a, b)
}

Note: The naming rule for exported functions is that the first letter is capitalized and can be exported.

4. Loading plug-ins

The Go program can load the plug-in through the plugin.Open function, which returns a *plugin.Plugin type structure , through which the exported functions in the plug-in can be called. The following is a sample code that uses the plugin.Open function to load and call the plug-in:

package main

import (
    "log"
    "plugin"
)

func main() {
    // 加载插件
    p, err := plugin.Open("./plugin.so")
    if err != nil {
        log.Fatalf("打开插件失败：%v
", err)
    }

    // 查找插件中的导出函数
    add, err := p.Lookup("ExportAdd")
    if err != nil {
        log.Fatalf("查找导出函数失败：%v
", err)
    }

    // 调用导出函数
    result := add.(func(int, int) int)(1, 2)
    log.Println("Result: ", result)
}

5. Notes

1. The plug-in only supports Linux, macOS, FreeBSD and Windows operating system.
2. The plug-in must be compiled under the same architecture as the main program, that is, the operating system and CPU architecture of the plug-in and the main program must be consistent, otherwise the plug-in will not be loaded.
3. All dependencies used in the plug-in must be statically linked, otherwise it will cause failure to load the plug-in.
4. The exported function of the Go plug-in must comply with the specification of func function name (parameter type) return value type, and the first letter of the function name must be capitalized.
5. Go plug-ins are independently compiled binaries, so the plug-in code must be included in the same package and cannot span files in multiple packages.

6. Summary

The Go language provides a complete plug-in mechanism, and developers can achieve dynamic expansion and functional enhancement of programs through plug-ins. When writing Go plug-ins, you need to pay attention to the compilation mode of the plug-in, the naming convention of exported functions, and the same architecture of the plug-in and the main program. Through the introduction of this article, I believe that everyone has a deeper understanding of the development of Go plug-ins, and you can try to write your own Go plug-ins to achieve more extended functions.

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