README
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Speculation Dependency Limit
Vendor-agnostic "how much" policy that bounds how many active (in-flight, non-terminal) dependencies a batch may speculate over.
See the Speculation RFC for the end-to-end design and how limits fit into the two-layer speculation model.
Dependency Limit
Speculation splits into decision seams (what to build) and limit policies (how much to allow). The dependency limit is the first limit: it is the eligibility gate for speculation. A batch becomes eligible to enumerate only when its count of active dependencies is at or below the current limit; otherwise it waits. Nothing is dropped — as dependencies land they leave the active set, the count shrinks, and the batch is admitted. The gate applies even to the fully-stacked happy path, so a very long chain is not speculated in full at once.
The value is signal-driven, not a fixed constant. Its primary input is the build system's available capacity, so a period of CI pressure can shrink how deep the queue speculates, but a policy may also weigh historical pass rates, cost budgets, time of day, or an experiment toggle. Because the value is dynamic, a change to the limit alone — not only a landing dependency or a DAG change — can newly admit a waiting batch.
Unlike the selection and prioritization limits, the dependency limit is not injected into a decision seam. It gates eligibility before enumeration and needs active-dependency reconciliation, which is controller orchestration — so the controller holds it, consults it on every respeculate, and applies it, keeping the enumerator pure.
Factory
A per-queue factory returns the limit policy for a queue, following the repo's extension contract. It is handed only the queue identity; the signals a policy weighs — a capacity feed, historical metrics, config — are injected at construction by the integrator in the wiring layer. Computing the limit itself takes no further inputs.
Documentation
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Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Config ¶
type Config struct {
// QueueName identifies the queue this DependencyLimit serves.
QueueName string
}
Config carries the per-queue identity handed to a Factory. The system knows only the queue name; everything a policy needs to compute the limit (a capacity feed, historical metrics, config) is injected at construction by the integrator.
type DependencyLimit ¶
type DependencyLimit interface {
// Limit returns the current maximum number of active dependencies a batch
// may speculate over. The controller compares a batch's active-dependency
// count against this to decide eligibility. It takes no parameters; anything
// an implementation needs is injected at construction.
Limit(ctx context.Context) (int, error)
}
DependencyLimit is the "how much" policy that bounds how many active (in-flight, non-terminal) dependencies a batch may speculate over.
It is the eligibility gate for speculation: a batch becomes eligible to enumerate only when its count of active dependencies is at or below the current limit; otherwise it waits, and is admitted later as predecessors land and leave the active set. The limit is a bound, not a trim — nothing is dropped from a batch's base.
The value is dynamic: it may change between calls — not only when a dependency lands — so a change alone can newly admit a waiting batch, and the controller re-consults it on every respeculate rather than caching it.
This limit is the exception among the speculation limits: it gates eligibility *before* enumeration and needs active-dependency reconciliation, which is controller orchestration — so the controller holds and applies it, rather than it being injected into a decision seam. The enumerator stays pure.
type Factory ¶
type Factory interface {
// For returns the DependencyLimit for the given queue.
For(cfg Config) (DependencyLimit, error)
}
Factory builds the DependencyLimit for a queue. Implementations are provided by integrators (and tests) and inject whatever signals they need at construction.
Source Files
Directories
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| Path | Synopsis |
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Package fake provides a programmable dependencylimit.DependencyLimit for tests and examples.
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Package fake provides a programmable dependencylimit.DependencyLimit for tests and examples. |
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Package mock is a generated GoMock package.
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Package mock is a generated GoMock package. |
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Package static provides a dependencylimit.DependencyLimit that always returns a fixed, construction-time value.
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Package static provides a dependencylimit.DependencyLimit that always returns a fixed, construction-time value. |