On 19.09.2011, at 22:09, ralph.goers @dslextreme.com wrote:
>
>
> On Mon, Sep 19, 2011 at 1:07 PM, ralph.goers @dslextreme.com
> <ralph.go...@dslextreme.com> wrote:
>
>
> On Mon, Sep 19, 2011 at 10:07 AM, John Vasileff <john.li...@gmail.com> wrote:
>
> What do you think about an optional LazyRenderMessage interface (I'm sure
> there is a better name for this) that could be used by Message types that
> have expensive constructers?
>
> interface LazyRenderMessage {
> void render();
> }
>
> The logger would call render() immediately after checking isEnabled for level
> and marker. So, this should not affect serialization - the object will
> either be fully constructed or discarded right away.
>
> This would allow ThreadDumpMessage Thread.getAllStackTraces() work to be
> avoided unless logging will actually occur (or is likely to occur in the case
> of complex filters).
>
> The benefit of course is that trace(THREAD_DUMP_MARKER, new
> ThreadDumpMessage()) could be left in production code without if
> isTraceEnabled(...) { ... }, and with very little overhead - creating a short
> lived object that does nothing in the constructor is pretty cheap these days.
>
> This would also help for Message types like ParameterizedMessage to avoid
> parseArguments(arguments) when they are created by application code.
>
> I see some merit in this idea. But you are right, it really needs a better
> name.
>
> One other point, though, is that there should always be a constructor that
> allows immediate rendering. I could easily see the ThreadDumpMessage being
> used for other purposes and never being passed to a logger. For example, I
> could create two ThreadDumpMessages at slightly different points in time and
> then only print the differences between them.
>
But the whole idea of the Message interface was the lazy evaluation of the
expensive String creation with the suggestion to also cache those strings for
reuse. Otherwise using toString() wouldn't make a big difference...
Printing the differences between two ThreadDumpMessages would be an additional
functionality, of course. I guess that something like a populate() method
filling in the stacktrace (separate from string creation) would make sense.
That could be called automatically if it wasn't called explicitly before
execution of getFormattedMessage()...
Joern.
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