This fizes a Ruby warning generated when running the tests for
Rackstash::Adaptes::Logger. The warning was:
> warning: instance variable @closed not initialized
The Sink was a vehicle to transport some shared state between the logger
instance and the buffers, most notably the default fields and default
tags.
It turns out however, that error handling during merging of the
default_fields and default_tags is non trivial since there, the buffer
is in sime kind of limbo: users won't write to it anymore (and thus
don't expect exceptions there) while the error handling of the
individual flows is not yet reached. Since users can specify procs in
default_fields, they can still raise for whatever user-defined reason.
Luckily, the insertion of default fields and default tags can easily be
done by a filter later anyway, under the protection of the flow's error
handling in Flow#write. This allows us just remove the whole concept of
the sink and just pass the Flows object to the Buffer.
Not having to merge default_fields during event creation significantly
simplifies Buffer#to_event which was rather ugly to begin with but now
turned out quite beatifully.
If messages are removed by the final cut step (but not when applying the
selectors), we insert an ellipsis, by default a Message with the
contents of "[...]\n", at the place where we removed messages. This
helps the investigating human who reads the logs to understand that
there were logs messages removed from the event.
This can be used to achieve similar results as
ActiveSupport::TaggedLogger. With our implementation, the "tags" are
prepended to each line (instead of each message) and we add the same
tags to all message lines.
If required, you can still use ActiveSupport::TaggedLogger with
Rackstash to add tags at the time of adding the log message.
This resolves the following warning:
> spec/rackstash/encoders/logstash_spec.rb:18: warning: ambiguous first
> argument; put parentheses or a space even after `/' operator
This allows to configure the last (and often only) flow on creation of
the Logger without having to manually create the object. We can thus use
the following shortcut to e.g. set a custom encoder:
Rackstash::Logger.new(STDOUT) do
encoder Rackstash::Encoder::Message.new
end
That way, we ensure that the error_flow receives an expected event and
doesn;t have to deal with different data formats which might result in
additional (then quietly hidden) errors.
The encoder is then responsible to format it as it pleases. Commonly,
encoders can use Rackstash::Encoders::Helpers::Message#normalize_message
to create a single combined message string.
If the encoder is not interested in using the message, it can jsut get
rid if it without incuring any overhead.
With the change to allow ading fields to the Buffer with a Logger
interface in the previous commit, we should also flush those Buffers
with fields set that way by default.
With this interface, the user adds fields the same way they would add
messages. The implicit assumption here is that the buffer is handled the
same way. Thus, if the current buffer is non-buffering, we will
automatically flush it to the sink and clear it, just the same way as we
would have done it for a message.
This new name better reflects what this option actually does: it allows
to flush a Buffer even if there were just added fields or tags. A tryely
empty Buffer, i.e., one which has neither added messages, fields, or
tags is never flushed.
This field is only relevant when actually sending JSON to Logstash.
Other formats don't need it. It is thus more desireable to only include
this field in a specific logstash JSON encoder.
