# `Rho.Dyn.LogGuard`
[🔗](https://github.com/GenericJam/rho/blob/v0.1.0/lib/rho/dyn/log_guard.ex#L1)

A primary `:logger` filter that keeps Dyn terms away from the logger's
formatting, in whatever process logs them.

A plain process that dies with an error is reported by the emulator, and
that report is formatted in OTP's `:logger_proxy`: Elixir's translator
(itself a primary filter) calls the exception's `message/1` there and
inspects the reason. A Dyn process (`spawn(fn -> raise MyError end)`)
would so get its own code run in a process every crash report of the VM
goes through, and a `message/1` that throws or exits there makes OTP
remove the translator VM-wide (later crash logs come out untranslated).
This filter runs before the translator (`:logger` runs the newest
primary filter first, and the Keeper installs it when it starts, after
Logger) and, for any log event that holds a struct of a Dyn module
(`Rho.Untrusted.untrusted?/1`), replaces the message with its
`Rho.Untrusted.describe/2` text and keeps only the metadata that holds
no Dyn term. It reads terms as data (no protocol of any struct runs) and
looks at most 10,000 terms of an event; a bigger event is let through
unchecked.

Best effort, like `Rho.Dyn.Check`: it lowers the chance that a Dyn
process's crash takes a logger process down; it does not stop code that
sets out to reach the logger (a `report_cb` sent to `:logger_proxy` as a
raw message, a filter added after this one, Logger restarted without it).

# `install`

```elixir
@spec install() :: :ok
```

Installs the filter (once; a second call is a no-op).

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*Consult [api-reference.md](api-reference.md) for complete listing*