Using the core `NotInmplementedError` is not desireable since its
documentation includes:
> Note that if `fork` raises a `NotImplementedError`, then
> `respond_to?(:fork)` returns `false`.
Since we are responding to the method but still raise an error, our
usage of the exception does not fulfill its documentation.
A custom error instead of a default `NoMethodError` is still desireable
since it significantly helps with debugging. With a different Exception,
we make it clear that a method is expected to be there and just wasn't
implemented by a subclass as opposed to the caller just using an object
wrong and calling entirely unexpected methods on it.
During normal operation, the Flows will rescue all exceptions and log
them to the special error_flow. By default, we will write JSON logs to
STDERR.
The log location and format can either be change globally by setting (or
changing) the Rackstash.error_flow or for each Flow for a Logger
individually by setting Flow#error_flow.
These methods do not rescue any thrown errors. The usual loggers will
always want to use the non-bang methods which rescue errors and attempt
to log them.
A single BufferStack object is only ever accessed by a single thread.
This is guaranteed by the Logger. Exceptions to the rule are not special
enough to break the rules.
The optional keyword arguments are already cleaned by the keyword splat
in BufferStack#push. They are automatically unsplatted when calling
Buffer#initialize anyway.
A single Sink is tied to a single Logger. It is responsible to:
* Create a log event from a Buffer on #write and send it to each of the
flows independently.
* Forward all actions to all of the defined Flows.
The Sink provides access to all configured data of the Logger which is
used for persisting the Buffers.
A single Buffer can be send to one or more flows which in turn each
write to a different adapter. A Flow object is responsible for
filtering, encoding, and finally persisting the event to an adapter.
Each Flow object can be configured differently which allows to write a
single log event to multiple targets as required.
Previously, we have counted successivly equal lines. However, we want to
count the number of lines with different content to ensure proper
concurrency during the test.
