How Can I Efficiently Detect File Changes in Go?

File Change Detection in Go

Detecting file changes is crucial for various applications, such as file editing, version control, and data integrity monitoring. In Go, the standard library doesn't provide a direct equivalent to Unix's fcntl() function for file change notifications. However, there are alternative approaches to accomplish this task.

One cross-platform solution involves using the os.Stat() function to compare the current size and modification time of a file with its initial state obtained at the beginning of the monitoring process. If any discrepancy is found, the file is considered to have changed. A sample implementation of this approach:

func watchFile(filePath string) error {
    initialStat, err := os.Stat(filePath)
    if err != nil {
        return err
    }

    for {
        stat, err := os.Stat(filePath)
        if err != nil {
            return err
        }

        if stat.Size() != initialStat.Size() || stat.ModTime() != initialStat.ModTime() {
            break
        }

        time.Sleep(1 * time.Second)
    }

    return nil
}

This function can be utilized in the following manner:

doneChan := make(chan bool)

go func(doneChan chan bool) {
    defer func() {
        doneChan <- true
    }()

    err := watchFile("/path/to/file")
    if err != nil {
        fmt.Println(err)
    }

    fmt.Println("File has been changed")
}(doneChan)

<-doneChan

While this approach offers simplicity and cross-platform compatibility, it may not be the most efficient solution for scenarios where file changes are frequent. For applications requiring higher performance, platform-specific solutions using system calls or file watchers may be worth exploring.

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