Struct FillStreams 

struct FillStreams {
    open: usize,
    opened: u64,
    group_order: GroupOrder,
}

What one subscription’s fill fetch streams amount to, from the point of view of an endpoint that has to attribute an arriving FETCH_HEADER and count the streams a PUBLISH_DONE reports.

There is no state machine here on purpose. A fill fetch stream has no FETCH_OK and no REQUEST_ERROR (Section 5.1.3.1), so it has none of the states FetchStateMachine exists to keep apart: it is opened, it carries objects, and it ends with a FIN meaning the fill is complete or a reset meaning it failed. Neither ending touches the subscription — “Resetting or cancelling a fill fetch stream, by either endpoint, does not affect the subscription, which continues to deliver objects using subscribe subgroups and datagrams.”

Fields

open: usize

How many of this subscription’s fill fetch streams are open.

opened: u64

How many have been opened over the life of the subscription, ended or not.

Section 10.12 makes the count a PUBLISH_DONE field: Stream Count is the total the publisher opened, “including streams that contained no Objects (e.g., an empty Subgroup) and including any fill fetch streams”. So the number that matters is cumulative and the open count cannot answer it.

group_order: GroupOrder

The Group Order the fill’s Objects arrive in, resolved from the request that asked for the fill by fill::group_order.

Held here because nothing on a fill fetch stream says which direction its Group ID Deltas count in (Section 11.4.4.1) and the answer is in a control message the stream never sees. Kept per subscription rather than per stream for the reason the field above is: a fill fetch stream carries its subscription’s Request ID and nothing else, so two of them cannot be told apart here. A REQUEST_UPDATE that asks for a second fill with a different order replaces this, which is right for the stream it opens and wrong for one still running under the older order; a caller in that position restarts the reader itself with begin_fetch_objects.

Trait Implementations

impl Clone for FillStreams

fn clone(&self) -> FillStreams

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for FillStreams

impl Debug for FillStreams

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for FillStreams

impl PartialEq for FillStreams

fn eq(&self, other: &FillStreams) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for FillStreams