Struct FetchSession 

pub struct FetchSession { /* private fields */ }

Drives the fetchurl client protocol as a state machine.

Determines which URLs to try and in what order: servers first (with source URLs forwarded as X-Source-Urls), then direct source URLs in random order.

The caller iterates through attempts, makes HTTP requests with their preferred library, and reports results back to the session.

Implementations

impl FetchSession

pub fn new( algo: &str, hash: &str, source_urls: &[impl AsRef<str>], ) -> Result<Self, Error>

Create a new fetch session.

• algo: hash algorithm name (e.g. "sha256")
• hash: expected hash in hex
• source_urls: direct source URLs (tried after servers, in random order)

pub fn next_attempt(&mut self) -> Option<FetchAttempt>

Get the next attempt to try.

Returns None when all attempts are exhausted or the session is finished (after report_success or report_partial).

If the HTTP request fails without writing any bytes, just call next_attempt() again to try the next source.

pub fn report_success(&mut self)

Report that the current attempt succeeded. Stops the session.

pub fn report_partial(&mut self)

Report that bytes were already written to the output before a failure. Stops the session — no further attempts since the output is tainted.

pub fn succeeded(&self) -> bool

Whether the session completed with a successful download.

pub fn verifier<W: Write>(&self, writer: W) -> HashVerifier<W>

Create a HashVerifier wrapping the given writer.

Pipe the HTTP response body through the verifier, then call HashVerifier::finish to check the hash.