effect-io-ai

Package: effect
Module: Metric

Metric.snapshotUnsafe

Captures a snapshot of all registered metrics synchronously using the provided service context.

When to use

Use to read metric snapshots from an explicit Context in low-level integrations, exporters, or debugging tools that already have the context.

Details

This is the “unsafe” version that bypasses Effect’s safety guarantees and requires manual handling of the services context. Use the safe snapshot function for normal application code.

Example (Capturing snapshots from a context)

import { Data, Effect, Metric } from "effect"

class UnsafeSnapshotError extends Data.TaggedError("UnsafeSnapshotError")<{
  readonly operation: string
}> {}

// Use unsafeSnapshot in performance-critical scenarios or internal implementations
const performanceMetricsExporter = Effect.gen(function*() {
  // Create some metrics first
  const requestCounter = Metric.counter("http_requests", {
    description: "Total HTTP requests"
  })
  const responseTime = Metric.gauge("response_time_ms", {
    description: "Current response time"
  })

  // Update metrics
  yield* Metric.update(requestCounter, 1)
  yield* Metric.update(responseTime, 150)

  // Get services context for unsafe operations
  const services = yield* Effect.context()

  // Use snapshotUnsafe for direct, synchronous access
  const snapshots = Metric.snapshotUnsafe(services)
  const exportBatchCreatedAt = 1_700_000_000_000

  // Process snapshots immediately (useful for exporters, debugging tools)
  const exportData = snapshots.map((snapshot) => ({
    name: snapshot.id,
    type: snapshot.type,
    value: snapshot.state,
    timestamp: exportBatchCreatedAt
  }))

  // This is synchronous and doesn't involve Effect overhead
  // Useful for performance-critical metric export operations
  return exportData
})

// For normal application use, prefer the safe snapshot function:
const safeSnapshotExample = Effect.gen(function*() {
  // This automatically handles the services context
  const snapshots = yield* Metric.snapshot
  return snapshots
})

Signature

declare const snapshotUnsafe: (context: Context.Context<never>) => ReadonlyArray<Metric.Snapshot>

Source

Since v4.0.0