There is no distributed locking of this sort in JCS. This kind of thing is typically better handled at the application level.
Aaron --- Horton Simon <[EMAIL PROTECTED]> wrote: > Hi Aaron, > > Does the JCSWorker function across JVM's sharing a > remote cache? > > Or is it just the same local cache in the same JVM? > > Thanks, > Simon > > -----Original Message----- > From: Aaron Smuts [mailto:[EMAIL PROTECTED] > Sent: Friday, June 23, 2006 9:59 PM > To: JCS Users List > Subject: Re: JCS thread safe question. > > There is a utility called jcs worker that will do > what > you need. > > http://svn.apache.org/viewvc/jakarta/jcs/trunk/src/java/org/apache/jcs/utils/access/JCSWorker.java?revision=332196&view=markup > > > > > > --- emily chen <[EMAIL PROTECTED]> wrote: > > > Hi Aaron, > > > > If I don't use a lock, thread 1 gets the report > > from cache by key, not data found, so it goes to > DB > > to get the report; before it puts the report into > > cache, thread 2 accesses the cache by the same > key, > > and can not find the report, so it goes to DB to > get > > the data again. That means two thread will access > DB > > twice. But I want they just acces DB only one time > > to get the same report. > > > > In my web application, it takes serval mins to > run > > a long report. Does it make sense to use a lock to > > reduce DB access? > > > > Thanks, > > > > Lucy > > > > > > > > Aaron Smuts <[EMAIL PROTECTED]> wrote: > > I don't understand what you need a lock for. You > > can > > go get the report, and then put it in the cache > > under > > the same key. You don't need to lock the key. > Until > > the new report is ready, client will get the old > one > > from the cache. Simply put the new value in the > > cache > > under the smae key name and it will replace the > old > > value. > > > > Aaron > > > > --- emily chen wrote: > > > > > Hi Aaron, > > > > > > I got you. I will implement the lock in my web > > > application. > > > > > > Many thanks, > > > > > > Lucy > > > > > > Aaron Smuts wrote: > > > Of course JCS is Thread safe, if you mean that > it > > > can > > > handle multiple threads accessing the same > regions > > > at > > > the same time. > > > > > > It doesn't work the way you described, but it is > > > thread safe. You won't get a corrupted value for > a > > > key. > > > > > > As for the memory cache, it is a reference > cache. > > It > > > returns references to objects in memory. It does > > not > > > clone the values. If you are manipulating > objects > > > that are in the cache, any other Thread could > get > > a > > > reference to that same object. . .. It is best > to > > > clone objects that are retrieved from the cache > > > prior > > > to modifying them or just don't modify objects > > that > > > have been put in the cache. > > > > > > Aaron > > > > > > --- emily chen wrote: > > > > > > > Hi there, > > > > > > > > I want to use JCS for my web application, and > > have > > > > some thread safe question. > > > > > > > > Here is scenario: > > > > > > > > I have a JCS cache named > > > �ePINBatchReportCache�? > > > > which is used to save the ePIN Batch Report > > data. > > > > > > > > Thread 1: > > > > 1) Get report data from Cache for key. > > > > 2) If not data found in the cache, then lock > > > > the cache for that key. > > > > 3) Get report data from database. > > > > 4) Put the report data in cache for key > > > > 5) Release lock for that key. > > > > > > > > Thread 2: > > > > 1) Get the data from cache for key. > > > > 2) Wait for lock to be released (should have > > > > max wait time here). > > > > 3) Get the data from cache. > > > > > > > > Does JCS have the above functionality -- lock > > the > > > > key of cache? Or I have to put lock on the key > > in > > > > my web application source code? > > > > > > > > Thank for your help. > > > > > > > > Lucy > > > > > > > > > > > > --------------------------------- > > > > Yahoo! Messenger with Voice. Make PC-to-Phone > > > Calls > > > > to the US (and 30+ countries) for 2�?min or > > less. > > > > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: > > > [EMAIL PROTECTED] > > > For additional commands, e-mail: > > > [EMAIL PROTECTED] > > > > > > > > > > > > > > > --------------------------------- > > > Yahoo! Messenger with Voice. PC-to-Phone calls > for > > > ridiculously low rates. > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: > > [EMAIL PROTECTED] > > For additional commands, e-mail: > > [EMAIL PROTECTED] > > > > > > > > > > --------------------------------- > > Ring'em or ping'em. Make PC-to-phone calls as low > > as 1�/min with Yahoo! Messenger with Voice. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > > === message truncated === --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
