ctxdownload

ctxdownload

Update: this repo is no longer maintained. Use iocopy instead.

ctxdownload is a Golang package which provides helper functions for performing context-aware download task.

Google's Context

• Context type, which carries deadlines, cancelation signals, and other request-scoped values across API boundaries and between processes.
• References:
• https://godoc.org/golang.org/x/net/context
• http://blog.golang.org/context

Context-aware

• ctxdownload.Download()'s first parameter is Context type.
• Download() will stop if context's cancel() function is called in other goroutines.
• Download() will stop if context's deadline exceeded.

Example

// Run "go test -c && ./ctxdownload.test"
func ExampleDownload() {
    // Download a zip file to test ctxdownload.Download().
    url := "https://github.com/northbright/plants/archive/master.zip"
    outDir := "./download"
    fileName := "" // If file name is empty, it will try to detect file name in response Header in Download().

    // Set total timeout. You'll get "deadline exceeded" error as expected.
    // To make download successful, set it to 300 or longer.
    totalTimeoutSeconds := 30
    totalTimeout := time.Duration(time.Duration(totalTimeoutSeconds) * time.Second)

    // Make a context to carry a deadline(timeout).
    // See http://blog.golang.org/context to for more information.
    ctx, cancel := context.WithTimeout(context.Background(), totalTimeout)
    defer cancel()

    // HTTP request timeout(NOT download timeout).
    requestTimeoutSeconds := 5

    // Make buffer.
    buf := make([]byte, 2*1024*1024)

    // Start download.
    // It will cancel download if cancel() is called in other goroutines.
    // It will stop download if deadline is exceeded(timeout).
    downloadedFileName, err := ctxdownload.Download(ctx, url, outDir, fileName, buf, requestTimeoutSeconds)
    if err != nil {
        fmt.Fprintf(os.Stderr, "ctxdownload.Download() err: %v\n", err)
    } else {
        fmt.Fprintf(os.Stderr, "ctxdownload.Download() succeeded.\nDownloaded File: %v\n", downloadedFileName)
    }

    // Output:
}

Go Version Requirement

• Go 1.5 and later
• See Fix the *http.Request has no field or method Cancel Issue

Documentation

• API References

License

• MIT License

References

• https://godoc.org/golang.org/x/net/context
• http://blog.golang.org/context
• https://github.com/golang/net/tree/master/context