Struct EntityResync 

pub struct EntityResync { /* private fields */ }

The projector’s way back to the VM its mutations come from.

The entity cache is bounded. A patch for a key it does not hold carries only the fields that changed and cannot rebuild the entity, unless it is the mutation that created the entity. A linked VM marks those (WholeEntity::Created), so the cache stores a creation and refuses any other patch for a key it lacks, whether it evicted the key or never held it. The projector then asks the VM, which holds the whole entity, to send all of it at the end of its next batch of mutations, whether or not the key changes in it (see WholeEntityRequests).

A resend is the entity again, not a change, so it must not take the position (_seq) of the batch it arrives in: in a view ordered by recency it would rank ahead of entities that really changed there. The projector remembers the position of each requested key’s latest change — the refused patch, or any change it sees for the key after it — and stamps the resend with that, in the cache, in derived views and on the upsert it publishes. It learns a key’s changes in stream order, which the VM cannot: positions are assigned per batch, after the VM has emitted it. A resend with no remembered position (one past the bound, or from a source without a VM, which sends whole entities as changes) takes its batch’s. For an account-owned entity it also remembers the explicit account position at request time, so a whole entity produced for an old lifetime cannot land after deletion and recreation.

The generated runtime hands its VM over through crate::snapshot::register_runtime, inside Self::scope, before it emits anything. A mutation source that registers no VM marks nothing and cannot be asked: the cache takes a patch for a key it lacks for a new entity unless it remembers evicting the key, and a remembered key stays out until the source sends a mutation marked whole (arete_interpreter::Mutation::mark_whole_entity) or a source delete.

Implementations

impl EntityResync

pub fn new() -> Self

pub async fn scope<F: Future>(&self, future: F) -> F::Output

Run a mutation source (the generated parser) so that the VM it registers answers this projector’s requests.

pub fn link(&self, vm: &Arc<StdMutex<VmContext>>)

Answer requests from vm.

pub fn is_linked(&self) -> bool

pub fn requests(&self) -> &WholeEntityRequests

The request set, for inspection.

Trait Implementations

impl Clone for EntityResync

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for EntityResync

fn default() -> Self

Returns the “default value” for a type.