mysql

var Classifier errs.Classifier = classifier{}

Classifier implements errs.Classifier for MySQL-related errors. It recognises:

• *gomysql.MySQLError values, dispatching on the server-reported error number to one of InfraRetryable (transient server / lock / connection issues) or Infra (everything else the driver reports — schema bugs, constraint violations, programmer errors).
• driver.ErrBadConn and sql.ErrConnDone — pooled connection failures that are safe to retry on a fresh connection.
• sql.ErrTxDone — a programming error, non-retryable.
• net.Error values (including *net.OpError, *net.DNSError) — transient network failures while talking to the server, retryable.

Anything else returns errs.Unknown so the surrounding classifier-processor walker can keep looking down the unwrap chain.

The classifier never returns errs.User. Constraint violations and similar codes that a caller might want to surface as user errors must be wrapped explicitly with errs.NewUserError at the controller — only the controller knows whether a duplicate key, FK violation, etc. reflects bad input from the user or an internal invariant being broken. The framework-wrap check in the classifier-processor short-circuits before this classifier runs, so an explicit controller wrap always wins.

The classifier is stateless; this package-level singleton is the canonical handle. Pass it as one of the variadic classifiers to errs.NewClassifierProcessor; the resulting processor is what gets handed to consumer.New.