Module metric_sink 

Render arm for MetricSinkConnection.

A metric sink funnels every row of its source collection to one worker, folds it into a SinkState, and exposes that state to the process’s Prometheus registry through a SinkCollector. SinkState is shared between the timely operator (the sole writer) and SinkCollector::collect (the reader, invoked from whatever thread scrapes the registry) via Arc<Mutex<_>>. Both sides only ever hold the lock across a short, synchronous section: the operator has no await points (it is a synchronous builder_rc operator), and the collector only clones out the data it needs to build MetricFamily protos before releasing the lock.

The planner (optimize::metric_sink::shape_metric_sink_source) does the row-wise shaping: it coalesces labels/help to their identity element and computes the metric_kind and name_valid columns extract_row reads below, so this module no longer parses metric_type strings or validates metric_name itself. Dedup, collision detection, and family-conflict counting stay here because they need the cross-row state of the fold.

Structs

ColumnIndices 🔒

Column indices resolved once from the sink’s source relation.

PendingRegistration 🔒

Active-worker collector registration that tolerates a transient descriptor-id collision with an incarnation of this sink that has not been torn down yet.

SinkCollector 🔒

A prometheus::core::Collector that exposes a metric sink’s SinkState.

SinkState 🔒

Working and published metric state for one metric sink.

Enums

MetricKind 🔒

Retry 🔒

Whether a registration attempt left a collision the caller must arm a retry for.

Constants

REGISTRATION_ESCALATE_AFTER 🔒

How long a collision may persist before it soft-panics.

REGISTRATION_RETRY_INTERVAL 🔒

How long to wait before retrying a collector registration that collided.

Functions

build_families 🔒

Groups published by metric name into one MetricFamily per name, since Prometheus requires a single type and help string per family. Within a group, the entry with the lexicographically smallest label vector wins the family’s type and help string; BTreeMap’s (name, labels) key ordering already sorts each group that way, so the first entry seen for a given name is that winner.

count_conflicts 🔒

Counts published series whose own metric_type/help disagree with their family’s winning type/help. See build_families for how the winner is chosen.

count_skipped 🔒

Counts live working rows dropped for an unsupported metric_type, an invalid Prometheus metric or label name, or a null or empty label value.

extract_row 🔒

Extracts (metric_name, metric_kind, name_valid, sorted labels, value, help) from one shaped source row.

is_publishable_label_value 🔒

Whether a label value can be published as-is. A null (None) has no value to encode, and an empty string reads as absent to Prometheus, so {a => ''} would fold into {}. Both make the row that carries them unpublishable.

is_valid_label_name 🔒

Matches Prometheus’s label name grammar: [a-zA-Z_][a-zA-Z0-9_]*.

rebuild_published 🔒

Collapses the live, representable rows of working into one published entry per (metric_name, labels) series and counts colliding and null-suppressed series.

Type Aliases

PublishedKey 🔒

Key into SinkState::published: a metric name paired with its sorted label vector.

PublishedValue 🔒

Value in SinkState::published: the series’ value, kind, and help string.

RowKey 🔒

Full identity of one source row: metric name, sorted labels, value, metric kind, name validity, and help.