The noCopy strategy you should know in Golang

In Go development, we often encounternoCopyThis structure is accompanied by a common annotation 'must not be copied after first use'. This article will explore in depthnoCopyThe role of Go Vet and how it can help us avoid potential errors.

sync.noCopyThe role of

sync.noCopyStructures are usually associated withsync.WaitGroupWait for synchronization primitives to appear together, for example:

type WaitGroup struct {
    noCopy noCopy    state atomic.Uint64 // high 32 bits are counter, low 32 bits are waiter count.
    sema  uint32
}

noCopyThe structure itself is an empty structure, which implementsLockandUnlockMethod, both of these methods are null operations. It does not have actual functional attributes, but its existence is of great significance.

Go Vet and ‘Locks Erroneously Passed by Value’

In addition to synchronization primitives,noCopyIt can also be used in other scenarios where copying needs to be prevented, such as:

• Connection Pool: Connection pools usually need to avoid copying connection objects, as copying can cause connection failures.
• Resource Management: Resource management objects typically need to avoid replication as it can lead to resource leaks.
• Cache: Cache objects usually need to avoid copying, as copying can cause cache invalidation.

summary

noCopyIt is a simple mechanism, but it can effectively prevent developers from mistakenly copying structures containing locks or other important data, thereby avoiding potential errors.

When we seenoCopyWhen constructing a structure, one should be aware of its purpose and carefully examine the code to ensure that no structures containing locks or other important data have been copied incorrectly.