Crate fast_telemetry 

Fast, thread-sharded counters and histograms for high-performance telemetry.

OpenTelemetry counters use atomic operations with global synchronization, which causes cache-line bouncing across cores. This crate provides thread-local sharded counters that:

• Increment with no cross-thread contention (just a thread-local write)
• Are cache-line padded to avoid false sharing (using crossbeam’s CachePadded)
• Aggregate on read (sum all shards)

Labeled Metrics

For dimensional metrics (counters/gauges/histograms broken down by label), use the Labeled* types with a LabelEnum implementation. These provide O(1) lookup via array indexing instead of HashMap lookups.

use fast_telemetry::{LabeledCounter, LabelEnum};

#[derive(Copy, Clone, Debug)]
enum HttpMethod { Get, Post, Put, Delete }

impl LabelEnum for HttpMethod { /* ... */ }

let counter: LabeledCounter<HttpMethod> = LabeledCounter::new(4);
counter.inc(HttpMethod::Get);  // O(1) array index, no hashing

Re-exports

pub use span::CompletedSpan;

pub use span::Span;

pub use span::SpanAttribute;

pub use span::SpanCollector;

pub use span::SpanEvent;

pub use span::SpanId;

pub use span::SpanKind;

pub use span::SpanStatus;

pub use span::SpanValue;

pub use span::TraceId;

pub use span::current_span_id;

pub use span::current_trace_id;

Modules

clickhouse

otlp

span

Standalone distributed tracing for fast-telemetry.

Structs

ClickHouseMetricBatch

OTel-standard ClickHouse rows built directly from fast-telemetry primitives.

Counter

A sharded atomic counter.

CounterSet

A grouped set of related sharded counters.

CounterSetBuffer

A local write buffer for a CounterSet.

Distribution

Exponential histogram distribution for high-performance metric recording.

DynamicCounter

Counter keyed by runtime label sets.

DynamicCounterSeries

A reusable handle to a dynamic-label counter series.

DynamicCounterSet

Runtime-label grouped counters.

DynamicCounterSetSeries

A reusable handle to one dynamic-label grouped counter series.

DynamicDistribution

Distribution keyed by runtime label sets.

DynamicDistributionSeries

A reusable handle to a dynamic-label distribution series.

DynamicGauge

Gauge keyed by runtime label sets.

DynamicGaugeI64

Signed integer gauge keyed by runtime label sets.

DynamicGaugeI64Series

A reusable handle to a dynamic-label i64 gauge series.

DynamicGaugeSeries

A reusable handle to a dynamic-label gauge series.

DynamicHistogram

Histogram keyed by runtime label sets.

DynamicHistogramSeries

A reusable handle to a dynamic-label histogram series.

DynamicLabelSet

Canonicalized runtime label set.

Gauge

A cache-padded atomic gauge for point-in-time measurements.

GaugeF64

A cache-padded atomic gauge for floating-point point-in-time measurements.

Histogram

A fixed-bucket histogram with thread-sharded counters.

LabeledCounter

A counter indexed by an enum label, providing O(1) dimensional metrics.

LabeledGauge

A gauge indexed by an enum label, providing O(1) dimensional metrics.

LabeledHistogram

A histogram indexed by an enum label, providing O(1) dimensional metrics.

LabeledSampledTimer

Label-indexed sampled timer with O(1) lookup.

MaxGauge

A thread-sharded maximum tracker exported as a gauge.

MaxGaugeF64

A thread-sharded maximum tracker for floating-point values.

MetricLabel

One borrowed metric label pair.

MetricLabels

Borrowed labels for one metric observation.

MetricLabelsIter

Iterator over borrowed metric labels.

MetricMeta

Immutable metadata for one metric observation.

MetricScope

Logical scope for a registered metric group.

MinGauge

A thread-sharded minimum tracker exported as a gauge.

MinGaugeF64

A thread-sharded minimum tracker for floating-point values.

RegisteredMetrics

Direct handles to a metric group registered with a Runtime.

Runtime

Shared telemetry runtime.

RuntimeConfig

Configuration for Runtime.

SampledTimer

Counts every timed operation and samples elapsed latency into a histogram.

SampledTimerGuard

RAII guard returned by SampledTimer::start and LabeledSampledTimer::start.

Enums

MetricKind

Coarse semantic kind for a metric observation.

Temporality

Aggregation temporality used during export.

Traits

ClickHouseExport

Direct ClickHouse export trait for metric primitives.

DistributionSnapshot

Borrowed snapshot view for exponential-bucket distributions.

DogStatsDExport

Trait for exporting a metric in DogStatsD format.

ExportMetrics

Structured export surface implemented by metric groups.

HistogramSnapshot

Borrowed snapshot view for fixed-bucket histograms.

LabelEnum

Trait for label enums used with LabeledCounter, LabeledGauge, etc.

MetricVisitor

Visitor for structured cumulative metric observations.

OtlpExport

Trait for exporting a metric as OTLP protobuf Metric messages.

PrometheusExport

Trait for exporting a metric in Prometheus text exposition format.

Functions

advance_cycle

Advance the eviction cycle by 1 and return the new value.

current_cycle

Get the current eviction cycle.

Derive Macros

DeriveLabel

Derive macro for implementing LabelEnum on enums.

ExportMetrics

Derive macro for exporting metrics in Prometheus, DogStatsD, and OTLP formats.