async fn start_poll_upstream(
    backend: &Backend,
    key: &ImageKey,
) -> Result<UpstreamResponse, Box<dyn std::error::Error>> {
    use std::str::FromStr;

    let url = {
        let info = backend.ping_info.load();
        let upstream_url = Option::as_ref(&info)
            .map(|x| &x.upstream_url)
            .ok_or(NoUpstreamError)?;

        url::Url::options()
            .base_url(Some(upstream_url))
            .parse(&format!(
                "/{}/{}/{}",
                key.archive_name(),
                key.chapter(),
                key.image()
            ))?
    };

    let res = HTTP_CLIENT.get(url).send().await?;
    let status = res.status();

    // get the mime type from upstream, or try to guess
    let content_type = res
        .headers()
        .get(header::CONTENT_TYPE)
        .and_then(|x| x.to_str().ok())
        .and_then(|x| x.parse::<mime::Mime>().ok())
        // if this entire process fails for whatever reason, then just assume that the image is a
        // PNG and move on with life
        .unwrap_or(mime::IMAGE_PNG);

    // get the last modified date from upstream, or else just use now
    let last_modified = res
        .headers()
        .get(header::LAST_MODIFIED)
        .and_then(|x| x.to_str().ok())
        .and_then(|x| HttpDate::from_str(x).ok())
        .unwrap_or_else(|| HttpDate::from(time::SystemTime::now()));

    let size_hint = res.content_length().map(|x| x as usize);
    Ok(UpstreamResponse {
        stream: Box::new(res.bytes_stream()),
        size_hint,

        status,
        content_type,
        last_modified,
    })
}
/// Starts a connection with the upstream server with the request resource.
///
/// This will return the required headers to stream back to the client as well as the stream of
/// bytes representing the body of the request.
///
/// This function will return on first byte received
Starts a connection with the upstream server with the request resource.
This will return the required headers to stream back to the client as well as the stream of
bytes representing the body of the request.

This function will return on first byte received
Starts a connection with the upstream server with the request resource . This will return the required headers to stream back to the client as well as the stream of bytes representing the body of the request . This function will return on first byte received
async fn start_poll_upstream(
    backend: &Backend,
    key: &ImageKey,
) -> Result<UpstreamResponse, Box<dyn std::error::Error>> {
    use std::str::FromStr;
    let url = {
        let info = backend.ping_info.load();
        let upstream_url = Option::as_ref(&info)
            .map(|x| &x.upstream_url)
            .ok_or(NoUpstreamError)?;
        url::Url::options()
            .base_url(Some(upstream_url))
            .parse(&format!(
                "/{}/{}/{}",
                key.archive_name(),
                key.chapter(),
                key.image()
            ))?
    };
    let res = HTTP_CLIENT.get(url).send().await?;
    let status = res.status();
    // get the mime type from upstream, or try to guess
    let content_type = res
        .headers()
        .get(header::CONTENT_TYPE)
        .and_then(|x| x.to_str().ok())
        .and_then(|x| x.parse::<mime::Mime>().ok())
        // if this entire process fails for whatever reason, then just assume that the image is a
        // PNG and move on with life
        .unwrap_or(mime::IMAGE_PNG);
    // get the last modified date from upstream, or else just use now
    let last_modified = res
        .headers()
        .get(header::LAST_MODIFIED)
        .and_then(|x| x.to_str().ok())
        .and_then(|x| HttpDate::from_str(x).ok())
        .unwrap_or_else(|| HttpDate::from(time::SystemTime::now()));
    let size_hint = res.content_length().map(|x| x as usize);
    Ok(UpstreamResponse {
        stream: Box::new(res.bytes_stream()),
        size_hint,
        status,
        content_type,
        last_modified,
    })
}
async fn start_poll_upstream ( backend : & Backend , key : & ImageKey , ) -> Result < UpstreamResponse , Box < dyn std :: error :: Error > > { use std :: str :: FromStr ; let url = { let info = backend . ping_info . load ( ) ; let upstream_url = Option :: as_ref ( & info ) . map ( | x | & x . upstream_url ) . ok_or ( NoUpstreamError ) ? ; url :: Url :: options ( ) . base_url ( Some ( upstream_url ) ) . parse ( & format ! ( " " key archive_name ( ) key chapter ( ) key image ( ) ) ) ? } ; let res = HTTP_CLIENT . get ( url ) . send ( ) . await ? ; let status = res . status ( ) ; // get the mime type from upstream, or try to guess let content_type = res . headers ( ) . get ( header :: CONTENT_TYPE ) . and_then ( | x | x . to_str ( ) . ok ( ) ) . and_then ( | x | x . parse :: < mime :: Mime > ( ) . ok ( ) ) // if this entire process fails for whatever reason, then just assume that the image is a // PNG and move on with life . unwrap_or ( mime :: IMAGE_PNG ) ; // get the last modified date from upstream, or else just use now let last_modified = res . headers ( ) . get ( header :: LAST_MODIFIED ) . and_then ( | x | x . to_str ( ) . ok ( ) ) . and_then ( | x | HttpDate :: from_str ( x ) . ok ( ) ) . unwrap_or_else ( | | HttpDate :: from ( time :: SystemTime :: now ( ) ) ) ; let size_hint = res . content_length ( ) . map ( | x | x as usize ) ; Ok ( UpstreamResponse { stream : Box :: new ( res . bytes_stream ( ) ) , size_hint , status , content_type , last_modified , } ) }
Starts a connection with the upstream server with the request resource.
Starts a connection with the upstream server with the request resource .
backend
&Backend
key
&ImageKey