Golang efficient function writing guide

Follow these guidelines to write efficient Go functions: Avoid using global variables. Pass by value for small value types; pass by pointer for large value types. Assign values ​​only when necessary. Use inline functions. Reduce the number of parameters.

Go Guide to Writing Efficient Functions

Efficient functions are the key to writing efficient Go programs. By following these guidelines, you can write functions that are both efficient and readable.

1. Avoid global variables

Global variables make code difficult to maintain and test because it can be modified from anywhere in the program. Instead, restrict variables to specific functions or types.

2. Use value passing

Functions in Go are passed by value by default. This means that a copy of the variable passed to the function will be passed to the function. This is more efficient for small value types such as int, float, or string. For large value types (such as arrays or slices), pointer passing should be used instead.

3. Passing using pointers

Passing large values ​​through pointers allows functions to directly modify the original value, thus avoiding the overhead of copying the entire value. When a value needs to be modified in a function, use a pointer to pass it.

4. Reduce the number of parameters

The more parameters a function has, the worse the readability and debuggability of the program will be. If a function requires multiple parameters, consider creating a structure or combining related parameters into a single value.

5. Avoid unnecessary allocation

Allocation of new values ​​will cause performance overhead. Assign values ​​only when necessary. For example, use a buffer in a loop instead of assigning new values ​​for each iteration.

6. Use inline functions

Inline functions insert the function body directly into the call point. This can reduce the overhead of function calls, especially when the function body is small.

Practical case:

The following example compares the performance of passing by value and passing by pointer:

package main

import "testing"

type Data struct {
    Value int
}

func passByValue(d Data) {
    d.Value += 1
}

func passByPointer(d *Data) {
    d.Value += 1
}

func BenchmarkPassByValue(b *testing.B) {
    d := Data{Value: 0}
    for i := 0; i < b.N; i++ {
        passByValue(d)
    }
}

func BenchmarkPassByPointer(b *testing.B) {
    d := Data{Value: 0}
    for i := 0; i < b.N; i++ {
        passByPointer(&d)
    }
}

The running score results show that the ratio of pointer passing is Passing by value is much faster:

BenchmarkPassByValue-8              10000000               148 ns/op
BenchmarkPassByPointer-8           100000000                24.2 ns/op

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