How to Achieve Streaming HTTP Responses and Disable Buffering in Go?

Streaming HTTP Responses in Go: Disable Buffering in http.ResponseWriter

Streaming HTTP responses allows for data to be sent to the client incrementally, rather than waiting for the entire request to be processed. This approach enhances the user experience by providing immediate feedback and reducing perceived latency. In Go, the http.ResponseWriter interface is responsible for sending responses to the client. However, by default, it buffers data until the request is complete.

Solution: Utilize the Flusher Interface

To disable buffering and stream responses, we can leverage the Flusher interface implemented by some ResponseWriter types. The Flusher interface allows us to manually flush any buffered data to the client.

import (
    "fmt"
    "log"
    "net/http"
    "time"
)

func handle(res http.ResponseWriter, req *http.Request) {
    fmt.Fprintf(res, "sending first line of data")

    // Check if ResponseWriter implements Flusher interface
    if f, ok := res.(http.Flusher); ok {
        f.Flush()
    } else {
        log.Println("Damn, no flush")
    }

    time.Sleep(10 * time.Second) // Simulate a delay

    fmt.Fprintf(res, "sending second line of data")
}

By incorporating the Flusher interface, we can explicitly flush the buffered data after writing each chunk of the response. This ensures that the data is sent immediately to the client, resulting in a streamed response.

Alternative Solution: Hijack the Connection

Another approach is to hijack the underlying TCP connection of the HTTP request. This allows for direct interaction with the socket and customization of the data transfer process, including disabling buffering. However, this approach is more complex and requires a deeper understanding of the underlying network layer.

Autoflushing: Not a Built-in Feature

Unfortunately, Go's http.ResponseWriter does not provide an autoflush feature. This means that the developer is responsible for manually flushing the data as needed. However, some frameworks or third-party libraries may offer autoflushing capabilities.

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