Struct PlanTree

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pub struct PlanTree { /* private fields */ }

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impl PlanTree

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pub fn build(rows: Vec<RoadmapRow>) -> Result<PlanTree, AxError>

Places every row and works out what each one is worth.

§Errors

Fail-closed, in the same shape as crate::locator: a plan that cannot be read is refused rather than guessed at, because every progress figure in the city is divided by it. Five refusals — a repeated index, a node whose parent is missing, a dependency on a node that is not there, a dependency in a circle, and a branch marked done over a child that is not.

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pub fn get(&self, id: &NodeId) -> Option<&PlanNode>

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pub fn nodes(&self) -> impl Iterator<Item = &PlanNode>

Every node, in table order.

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pub fn len(&self) -> usize

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pub fn is_empty(&self) -> bool

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pub fn needs_of(&self, id: &NodeId) -> BTreeSet<NodeId>

What a node waits for, including everything its ancestors wait for. A child of a branch that is waiting is waiting too; answering otherwise would let 2.3.1 start while the reason 2.3 cannot start is still unresolved.

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pub fn ready(&self) -> Vec<NodeId>

What may be started right now: leaves nobody has taken, whose dependencies — their own and their branch’s — are all done.

Pure, and that is the point: a city with no ready nodes and nothing running has finished, and a stop condition that depended on I/O could not be trusted to say so.

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pub fn claim(&self, id: &NodeId) -> Result<Held, AxError>

Takes a node to work on.

§Errors

Refuses everything Self::ready leaves out, and says which of the three reasons applies: the index is not in the table, the node is a branch or already taken, or it is still waiting on something. The third names what it waits for, because “no” sends a model round the loop again while “1.4 is not done” does not.

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pub fn progress(&self) -> Progress

The plan’s own reading of itself: leaves counted, and the share of the whole those leaves carry.

Both figures travel because they answer different questions and mislead alone. A share says how much of the plan is behind you; a leaf count says how many pieces the plan turned out to have, and it is the figure that does not move when somebody divides their own branch generously.