BitLogger/docs/api/async-logger-with-patch.md

name, group, category, update-time, description, key-word

name	group	category	update-time	description	key-word
async-logger-with-patch	api	async	20260512	Attach record transformation logic to an async logger before records reach the queue.	async logger patch public

Async-logger-with-patch

Attach a record patch to an async logger so each record is transformed before filtering and enqueue. This is the main API for async record rewriting without changing the sink implementation.

Interface

pub fn[S] AsyncLogger::with_patch(
  self : AsyncLogger[S],
  patch : @bitlogger.RecordPatch,
) -> AsyncLogger[S] {}

input

• self : AsyncLogger[S] - Base async logger to wrap.
• patch : RecordPatch - Transformation applied to each record before enqueue.

output

• AsyncLogger[S] - A new async logger that rewrites each record before filtering and queue insertion.

Explanation

Detailed rules explaining key parameters and behaviors

• Patch logic runs after record creation and field merging but before filtering and enqueue.
• Existing patch logic is preserved and composed so the new patch wraps the current one.
• The original async logger is not mutated.
• Patching can normalize, redact, or enrich records before they consume queue capacity.

How to Use

Here are some specific examples provided.

When Need Async Record Enrichment

When records should gain stable extra data before enqueue:

let logger = async_logger(console_sink())
  .with_patch(@bitlogger.append_fields([
    @bitlogger.field("channel", "async"),
  ]))

In this example, the added fields are part of the record before filtering and queue insertion.

When Need Redaction Before Queueing

When sensitive fields should be removed early:

let logger = async_logger(console_sink())
  .with_patch(@bitlogger.redact_fields(["token", "password"]))

In this example, sensitive values are rewritten before they enter the async pipeline.

Error Case

e.g.:

• If the patch removes or rewrites important data incorrectly, later filters and sinks will only see the patched version.

• If callers need selection logic rather than transformation, with_filter(...) should be used instead.

Notes

1. Use patches for transformation, not filtering decisions.

2. Redaction before enqueue helps keep sensitive data out of the queued pipeline.