Research on the underlying data structure principles of Golang functions

Golang is an open source concurrent programming language with high running speed and low memory usage. In Golang, functions play an extremely important role. Functions can not only encapsulate functions and reuse code, but also help decompose large programs into small modules to facilitate the organization and management of code. However, for regular programmers, they often only care about the implementation of functions, but do not understand the underlying principles of the functions. Below, we will explore the underlying data structure of Golang functions to better understand the working mechanism of Golang.

1. Data structure definition of function

Let’s first take a look at the data structure definition of function in Golang:

type Func struct {
  Type *rtype        // 函数类型
  PC   uintptr       // 函数指针
  Entry uintptr      // 入口指针
  Name string        // 函数名字
  File string        // 文件名字
  Line int           // 行号
  Args int           // 参数个数
  Frame int          // 栈帧大小
  Free []*_type      // 自由变量类型
  Gc   []byte        // GC 标记
  }}

This is a very concise data structure (struct ), only 10 fields. Among them, only the first two fields are critical. The Type field saves the pointer of the function type, which contains the function signature (parameter type and return value type, etc.) and function implementation (function code). The PC field stores the function pointer, that is, the memory address of the function in the program.

2. Function type definition

Next, let’s take a look at the data structure definition of function type in Golang:

type Func struct {
  in      []in      // 参数列表
  out     []out     // 返回值列表
  variadic bool     // 是否是可变参函数
}
type in struct {
  name string       // 参数名称
  type Type         // 参数类型
}
type out struct {
  name string       // 返回值名称
  type Type         // 返回值类型
}

The function type specifies the type of function parameters and return value type. In Golang, the function type is actually an interface, and its implementation can be analogous to struct. It contains three fields: parameter list in, return value list out and variadic (whether it is a variable parameter function). The parameter list and return value list are defined in a struct-like manner, containing the names and types of parameters and return values ​​respectively.

3. Exploring the underlying principles of functions

With the data structure and type definition of the function, we can further explore the underlying principles of the function. For function calling, Golang adopts a method similar to the function pointer of C language, that is, calling the function as a pointer (function pointer), thus avoiding frequent stack operations during function calling.

When calling a function, you first need to push the function parameters into the operating system stack, and then jump to the memory address where the function code is located (that is, the function pointer), so that the program execution flow is transferred to the function. When the function returns, the return value needs to be popped from the stack and then jump to the "return address", which is the call point of the previous function.

It is worth mentioning that because Golang uses an automatic garbage collection mechanism, when the function is executed, the memory space used can be immediately recycled, thereby releasing resources and avoiding problems such as memory leaks.

4. Summary

Golang’s function is one of the core components of the entire program. For this important part, we need to have an in-depth understanding of its underlying data structure and principles. This article explores the function's data structure and type definition from two perspectives, striving to give readers a deeper understanding and mastery of Golang's function implementation mechanism.

It should be noted that although Golang has an efficient automatic garbage collection mechanism, we still need to pay attention to program optimization issues, especially during function calls, frequent stack operations should be avoided as much as possible. To improve program execution efficiency.

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