[
https://issues.apache.org/jira/browse/LOG4J2-1630?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15558298#comment-15558298
]
Ralph Goers commented on LOG4J2-1630:
-------------------------------------
While your assessment seems to be accurate it is incomplete. First, I dislike
"TimeMachineBuffer". It is just an EventBuffer. With the right options it could
be used for anything.
Second, the discussion so far seems to be missing the fact that a "UnitOfWork"
construct would have to support multiple units of work happening on multiple
threads, which means an EventBuffer would be needed for each unit of work (each
thread?). The challenge for the EventBuffer in the 1137 use case is that when
a triggering event occurs we would want to move the events to a second buffer
for logging so there is no danger of them being overwritten while they are
being logged. I presume that would not be necessary for the unit of work use
case.
Speaking of the unit of work use case, I am still trying to understand when it
would be useful. I could understand the purpose if the goal was to collect
events that are going to be performed when the unit of work is committed, but I
would argue that using a logging framework for that is inappropriate. It sort
of seems strange to say that the events are going to be tossed if the unit of
work is "committed" and logged if it is "rolled back", as that is the opposite
of what a database would do.
It seems to me that creating an EventBuffer that could be attached to various
components, could be configured with a pool of circular buffers with a
configurable way to determine which buffer events should reside in and is
provided with a triggering mechanism, including Script support, would be enough
to satisfy all these use cases.
> Unit of Work Logging
> --------------------
>
> Key: LOG4J2-1630
> URL: https://issues.apache.org/jira/browse/LOG4J2-1630
> Project: Log4j 2
> Issue Type: Story
> Components: API, Core, Filters
> Affects Versions: 2.7
> Reporter: Remko Popma
> Fix For: 2.8
>
>
> h3. Intent
> Provide a way to filter log events, where the decision on whether to discard
> the message or actually log them cannot be made until after the application
> has already logged the message.
> h3. Motivation
> In many systems, particularly event processing applications, log files
> contain a lot of repetitive log messages. Suppose an application needs to do
> some calculation to decide whether or not to react to some event, and a lot
> of detail is logged during this calculation. Imagine that 99% of the time,
> the application decides to take no action. Once the application arrived at
> that conclusion it would be nice if we could go back and undo all the
> detailed logging and print a summary instead. When the application _does_
> decide to take some action, however, we _do_ want the detailed log messages.
> A Unit of Work for logging would allow us to group a set of log messages and
> either discard them or log them together. (Inspired by Martin Fowler's [Unit
> of Work|http://martinfowler.com/eaaCatalog/unitOfWork.html] pattern.)
> This should result in log files where a lot of the "uninteresting" logging is
> filtered out, significantly reducing the amount of data logged.
> Some applications do this in an ad hoc manner, for example by passing a
> Collection to its components, where these components can add log message
> strings to this Collection. When the discard/retain decision is made, the
> application then either clears the Collection or logs the contents of the
> Collection. This works, but having to pass the Collection down the component
> tree is clunky and the result often omits details like logger name, timestamp
> and other details that come for free with normal logging. Log4j can provide a
> reusable and less intrusive way to accomplish this.
> h3. How it works
> There would need to be some API for the application to mark the _start_ of
> the unit of work, and some API to signal whether the log messages that are
> part of that unit of work need to be _discarded_ or _logged_ (retained).
> Not all logging that occurs after a unit of work was started is part of that
> unit of work. The application may want some messages to be logged regardless
> of whether the unit of work was discarded or not. There needs to be a
> flexible way (or multiple ways) to include or exclude logging statements from
> the unit of work.
> The application may also designate multiple units of work, which may be
> sequential, nested or partially overlapping. Each unit of work may define its
> own rules for which log messages are considered included in or excluded from
> the unit of work.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org
For additional commands, e-mail: log4j-dev-h...@logging.apache.org
