Skip to content

Async-logger-state-to-json

Convert AsyncLoggerState into a JsonValue. This helper is the structured export path for async logger runtime snapshots or manually constructed state values when callers want machine-readable diagnostics instead of a plain string.

Interface

moonbit
pub fn async_logger_state_to_json(state : AsyncLoggerState) -> @json_parser.JsonValue {}

input

  • state : AsyncLoggerState - Snapshot produced by AsyncLogger::state() or any manually constructed AsyncLoggerState value.

output

  • JsonValue - Structured JSON representation of the async logger snapshot.

Explanation

Detailed rules explaining key parameters and behaviors

  • The JSON includes runtime mode, worker support, queue counters, lifecycle flags, last error, and flush policy.
  • The top-level fields are runtime, pending_count, dropped_count, is_closed, is_running, has_failed, last_error, and flush_policy.
  • The nested runtime field reuses async_runtime_state_to_json(...), and flush_policy is serialized with the canonical labels Never, Batch, or Shutdown.
  • The public helper returns the same internal JSON snapshot shape used by stringify_async_logger_state(...), so both export paths stay aligned without duplicate field assembly logic.
  • This helper is suitable for health endpoints, diagnostics payloads, and custom serialization flows.
  • It shares the same stable field names used by stringify_async_logger_state(...).
  • The state must already have been captured or constructed before serialization.
  • Serialization preserves whatever snapshot combination it receives, including failure flags together with remaining backlog counts.
  • This helper never rereads a logger instance by itself. If callers pass an older or manually constructed AsyncLoggerState, the JSON reflects that provided value exactly rather than refreshing fields from live runtime state.
  • It also does not normalize mixed diagnostic combinations. If the provided snapshot says is_closed=true together with retained has_failed=true, last_error, or non-zero backlog counters, those exact combinations are emitted unchanged.

How to Use

Here are some specific examples provided.

When Need Machine-readable Diagnostics

When the snapshot should be embedded into a JSON payload:

moonbit
let state_json = async_logger_state_to_json(logger.state())

In this example, callers receive a structured value that can be composed into larger JSON objects.

When Need A Snapshot Before Custom Stringify

When another serializer or pipeline expects a JSON value:

moonbit
let payload = async_logger_state_to_json(logger.state())
println(@json_parser.stringify(payload))

In this example, the helper stays useful even outside the built-in stringify wrapper.

Error Case

e.g.:

  • If the snapshot contains no error, last_error is serialized as an empty string.

  • If the queue is empty, pending_count and dropped_count are still serialized normally as numeric values.

  • If has_failed is true, serialization does not force pending_count to 0 or clear last_error; it reports the snapshot exactly as provided.

  • If callers need newer logger data, they must capture a fresh AsyncLogger::state() first instead of expecting JSON conversion itself to refresh stale fields.

Notes

  1. This helper preserves the nested runtime snapshot instead of flattening mode and background_worker onto the top level.

  2. The resulting object matches the compact string form produced by stringify_async_logger_state(...) after JSON stringification.

  3. Use this API when downstream code wants a JSON value rather than a ready-made string.

  4. Pair it with AsyncLogger::state() when you want current logger data, or with AsyncLoggerState::new(...) when tests or adapters are exporting a synthetic snapshot.

Published from the repository docs folder with VitePress.