"tail -f"-like Generator in Go
Problem
Tailing a file in Go requires a loop with a sleep on EOF, which can be error-prone and inefficient. Is there a cleaner way to do this?
Solution
Instead of using a goroutine, create a wrapper around a reader that sleeps on EOF:
<code class="go">type tailReader struct {
io.ReadCloser
}
func (t tailReader) Read(b []byte) (int, error) {
for {
n, err := t.ReadCloser.Read(b)
if n > 0 {
return n, nil
} else if err != io.EOF {
return n, err
}
time.Sleep(10 * time.Millisecond)
}
}
func newTailReader(fileName string) (tailReader, error) {
f, err := os.Open(fileName)
if err != nil {
return tailReader{}, err
}
if _, err := f.Seek(0, 2); err != nil {
return tailReader{}, err
}
return tailReader{f}, nil
}</code>
Usage
This reader can be used with any io.Reader, including bufio.Scanner and json.Decoder. For example:
<code class="go">t, err := newTailReader("somefile")
if err != nil {
log.Fatal(err)
}
defer t.Close()
// Use with bufio.Scanner
scanner := bufio.NewScanner(t)
for scanner.Scan() {
fmt.Println(scanner.Text())
}
// Use with json.Decoder
dec := json.NewDecoder(t)
for {
var v SomeType
if err := dec.Decode(&v); err != nil {
log.Fatal(err)
}
fmt.Println("the value is ", v)
}</code>
Advantages
- Easy Shutdown: Just close the file.
- Works with Many Packages: Many packages (like bufio.Scanner and json.Decoder) work with io.Reader.
- Configurable Sleep: Adjust the sleep time to optimize latency or CPU usage.
The above is the detailed content of How Can I Create a \'tail -f\' Like Generator in Go?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1794
16
1739
56
1590
29
1468
72
267
587
Strategies for Integrating Golang Services with Existing Python Infrastructure
Jul 02, 2025 pm 04:39 PM
TointegrateGolangserviceswithexistingPythoninfrastructure,useRESTAPIsorgRPCforinter-servicecommunication,allowingGoandPythonappstointeractseamlesslythroughstandardizedprotocols.1.UseRESTAPIs(viaframeworkslikeGininGoandFlaskinPython)orgRPC(withProtoco
Understanding the Performance Differences Between Golang and Python for Web APIs
Jul 03, 2025 am 02:40 AM
Golangofferssuperiorperformance,nativeconcurrencyviagoroutines,andefficientresourceusage,makingitidealforhigh-traffic,low-latencyAPIs;2.Python,whileslowerduetointerpretationandtheGIL,provideseasierdevelopment,arichecosystem,andisbettersuitedforI/O-bo
Is golang frontend or backend
Jul 08, 2025 am 01:44 AM
Golang is mainly used for back-end development, but it can also play an indirect role in the front-end field. Its design goals focus on high-performance, concurrent processing and system-level programming, and are suitable for building back-end applications such as API servers, microservices, distributed systems, database operations and CLI tools. Although Golang is not the mainstream language for web front-end, it can be compiled into JavaScript through GopherJS, run on WebAssembly through TinyGo, or generate HTML pages with a template engine to participate in front-end development. However, modern front-end development still needs to rely on JavaScript/TypeScript and its ecosystem. Therefore, Golang is more suitable for the technology stack selection with high-performance backend as the core.
How to completely and cleanly uninstall Golang from my system?
Jun 30, 2025 am 01:58 AM
TocompletelyuninstallGolang,firstdeterminehowitwasinstalled(packagemanager,binary,source,etc.),thenremoveGobinariesanddirectories,cleanupenvironmentvariables,anddeleterelatedtoolsandcaches.Beginbycheckinginstallationmethod:commonmethodsincludepackage
How to marshal a golang struct to JSON with custom field names?
Jun 30, 2025 am 01:59 AM
In Go, if you want the structure field to use a custom field name when converting to JSON, you can implement it through the json tag of the structure field. 1. Use the json: "custom_name" tag to specify the key name of the field in JSON. For example, Namestringjson: "username"" will make the Name field output as "username"; 2. Add, omitempty can control that the output is omitted when the field is empty, such as Emailstringjson: "email,omitempty""
How to install Go
Jul 09, 2025 am 02:37 AM
The key to installing Go is to select the correct version, configure environment variables, and verify the installation. 1. Go to the official website to download the installation package of the corresponding system. Windows uses .msi files, macOS uses .pkg files, Linux uses .tar.gz files and unzip them to /usr/local directory; 2. Configure environment variables, edit ~/.bashrc or ~/.zshrc in Linux/macOS to add PATH and GOPATH, and Windows set PATH to Go in the system properties; 3. Use the government command to verify the installation, and run the test program hello.go to confirm that the compilation and execution are normal. PATH settings and loops throughout the process
How do I get environment variables using the os.Getenv() function in Go?
Jun 27, 2025 am 02:04 AM
TogetenvironmentvariablesinGo,useos.Getenv(),butconsiderLookupEnvforexistencechecks.1.Useos.Getenv("VAR_NAME")toretrieveavariable’svalueasastring,returningemptyifunset.2.Useos.LookupEnv()todistinguishbetweenunsetandemptyvariables.3.Provided
How to fix 'go: command not found' after installation?
Jun 30, 2025 am 01:54 AM
"Go:commandnotfound" is usually caused by incorrect configuration of environment variables; 1. Check whether Go has been installed correctly and use whichgo to confirm the path; 2. Manually add Go's bin directory (such as /usr/local/go/bin) to the PATH environment variable; 3. Modify the corresponding shell's configuration file (such as .bashrc or .zshrc) and execute source to make the configuration take effect; 4. Optionally set GOROOT and GOPATH to avoid subsequent module problems. After completing the above steps, run government and verify whether it is repaired.
