# `Membrane.Logger`
[🔗](https://github.com/membraneframework/membrane-core/blob/v1.2.6/lib/membrane/logger.ex#L1)

Wrapper around the Elixir logger. Adds Membrane prefixes and handles verbose logging.

## Prefixes

By default, this wrapper prepends each log with a prefix containing the context
of the log, such as element name. This can be turned off via configuration:

    use Mix.Config
    config :membrane_core, :logger, prefix: false

Regardless of the config, the prefix is passed to `Logger` metadata under `:mb_prefix` key.
Prefixes are passed via process dictionary, so they have process-wide scope,
but it can be extended with `get_prefix/0` and `set_prefix/1`.

## Verbose logging

For verbose debug logs that should be silenced by default, use `debug_verbose/2`
macro. Verbose logs are purged in the compile time, unless turned on via configuration:

    use Mix.Config
    config :membrane_core, :logger, verbose: true

Verbose debugs should be used for logs that are USUALLY USEFUL for debugging,
but printed so often that they make the output illegible. For example, it may
be a good idea to debug_verbose from within `c:Membrane.WithInputPads.handle_buffer/4`
or `c:Membrane.Element.WithOutputPads.handle_demand/5` callbacks.

# `bare_log`

```elixir
@spec bare_log(Logger.level(), Logger.message(), Logger.metadata()) :: :ok
```

Wrapper around `Logger.bare_log/3` that adds Membrane prefix.

For details, see the 'prefixes' section of the moduledoc.

# `debug`
*macro* 

Wrapper around `Logger.debug/2` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

# `debug_verbose`
*macro* 

Macro for verbose debug logs, that are silenced by default.

For details, see the ['verbose logging'](#module-verbose-logging) section of the moduledoc.

# `error`
*macro* 

Wrapper around `Logger.error/2` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

# `get_config`

```elixir
@spec get_config() :: Keyword.t()
```

Returns the Membrane logger config.

# `get_config`

```elixir
@spec get_config(key, value) :: value when key: atom(), value: any()
```

Returns value at given key in the Membrane logger config.

# `get_prefix`

```elixir
@spec get_prefix() :: String.t()
```

Returns the logger prefix.

Returns an empty string if no prefix is set.

# `info`
*macro* 

Wrapper around `Logger.info/2` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

# `log`
*macro* 

Wrapper around `Logger.log/3` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

# `set_prefix`

```elixir
@spec set_prefix(prefix :: String.t()) :: :ok
```

Sets the logger prefix. Avoid using in Membrane-managed processes.

This function is intended to enable setting prefix obtained in a Membrane-managed
process via `get_prefix/1`. If some custom data needs to be prepended to logs,
please use `Logger.metadata/1`.

Prefixes in Membrane-managed processes are set automatically and using this
function there would overwrite them, which is usually unintended.

# `warn`
*macro* 

Wrapper around `Logger.warn/2` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

# `warning`
*macro* 

Wrapper around `Logger.warning/2` that adds Membrane prefix.

For details, see the ['prefixes'](#module-prefixes) section of the moduledoc.

---

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