On Mon, 2008-08-25 at 20:23 -0400, Vadim Gritsenko wrote: > On Aug 25, 2008, at 6:40 AM, Thorsten Scherler wrote: ... > Yes, ObjectModelHelper.REQUEST_OBJECT object is always unique. It is > actually unique in any environment. And since it is unique, it does > not make sense to lock on it at all - lock on unique object serves no > purpose :-)
Makes me wonder since HttpServletRequest is always unique as well due to the headers, so does not violate as well the whole locking? > You could, for example, have same effect with code: > > // Avoids NPE, does nothing > if (lock == null) lock = new Object(); > > > To get back to the problem... The original goal of pipeline locking > was to prevent separate external requests to start generating cached > response for the same resource-intensive resource. In other words, if > too external requests both (directly or through aggregation) hit '/ > slow/cached/foo' resource, only one request will trigger this > pipeline, while another will wait for the first to complete. > > This logic, in turn, had to be augmented to exclude single external > request hitting the same slow resource twice due to aggregation (and > parallel aggregation), hence locking against top level external > request was implemented. > Understand but I am confused due to the above fact that the HttpServletRequest is as well unique as it is my understanding. > Now, in situation when CommandLineEnvironment is used from the, ahem, > command line, two external requests will not happen. Which means that > whole pipeline locking thing is irrelevant and can be omitted > completely (like in 'lock = new Object()' snippet above). But, the > same CommandLineEnvironment stuff can be used in multi threaded > environment which uses the CocoonBean class. So, strictly speaking, in > this scenario locking still should be performed against external > request object, and not against any RequestWrapper which is unique for > each sub-request. I now are using the url as lock key since as I understand it perfectly qualifies as lock key. The patch is attached to COCOON-2241. As soon you are ok with it I will commit it. Thanks for your patience. salu2 > > Hope now it all makes more sense. > > Regards, > Vadim > > > > In comparison the HttpEnvironment has in the constructor: > > this.objectModel.put(HTTP_REQUEST_OBJECT, req); > > where HttpServletRequest req. > > > > The uniqueness in both cases are, as I understand, the headers. > > > > salu2 > -- Thorsten Scherler thorsten.at.apache.org Open Source Java consulting, training and solutions
