Re: Help with understanding caching possibly.

Queries will always read from the database unless you explicitly indicate
you want a cached result. Prefetches are necessary to ensure related
objects are also refreshed by the query, otherwise they may be stale.

On Tue, Oct 29, 2019 at 8:05 PM Andrew Willerding <[email protected]>
wrote:

> I'm not sure what this means in terms of using Cayenne objects. I've
> tried to find some examples and found this reference for Cayenne 3.1
> where exactly the same question I'm asking is sort of addressed.
>
> https://stackoverflow.com/questions/29781605/cayenne-3-1-disable-cache
>
> but let's say I have this
>
>              return ObjectSelect.query(NotifyEvent.class)
>                      .orderBy(STATUS_ID.asc())
>                      .orderBy(D_TSTART.asc())
>                      .select(DBClientBase.getObjectContext());
>
> How would I make sure all the objects that are referenced in NotifyEvent
> (including NotifyEvent) are reread from the database?
>
> There is a .prefetch(String path, int semantics) option but I don't know
> what to put into the parameters.
>
> Are there some better examples?
>
> Or should I just do something like this?
>
> List<NotifyEvent> list = ObjectSelect.query(NotifyEvent.class)
>                      .orderBy(STATUS_ID.asc())
>                      .orderBy(D_TSTART.asc())
>                      .select(DBClientBase.getObjectContext());
> DBClientBase.getObjectContext().invalidateObjects(list);
> return list;
>
>
> On 2019-10-29 11:22 a.m., Andrus Adamchik wrote:
> > You can always use queries (with prefetches for relationships) instead
> of keeping references to objects.
> >
> > Andrus
> >
> >> On Oct 29, 2019, at 5:55 PM, Andrew Willerding <
> [email protected]> wrote:
> >>
> >> Thank you Andrus.  I was chasing down the rabbit hole of looking for
> something like "reload" or "refresh" .
> >>
> >> Is there a way to always force reads from the database?  I'm not
> dealing with a high traffic applications so the caching is not important to
> me (at this point) and the retrieval of up-to-date data from the database
> is my priority.
> >>
> >> Andrew
> >>
> >>
> >> On 2019-10-26 7:58 a.m., Andrus Adamchik wrote:
> >>> Yes, of course:
> >>>
> >>>    context.invalidateObjects(o);
> >>>
> >>> Andrus
> >>>
> >>>
> >>>> On Oct 25, 2019, at 10:41 PM, Andrew Willerding <
> [email protected]> wrote:
> >>>>
> >>>> Is there a way to force a Cayenne object to refresh itself from the
> underlying database?  I have a situation where two *independent*
> Cayenne-based applications are accessing and updating the database and it
> seems that an update from one application is not reflected in the other.
> I'd like to manually force a refresh.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Andrew
> >>>>
> >>>>
> >>>> On 2019-10-11 10:03 a.m., Andrus Adamchik wrote:
> >>>>>>   I think the docs for 4.1 still indicate it's set to true by
> default
> >>>>> Yes, this was wrong. I changed it right after I wrote my reply.
> Should republish soon.
> >>>>>
> >>>>> Andrus
> >>>>>
> >>>>>
> >>>>>> On Oct 11, 2019, at 9:43 AM, Andrew Willerding <
> [email protected]> wrote:
> >>>>>>
> >>>>>> Thank you Andrus!
> >>>>>>
> >>>>>> This has been driving me crazy.  I didn't realize this change was
> made.  I think the docs for 4.1 still indicate it's set to true by default
> >>>>>>
> >>>>>>
> https://cayenne.apache.org/docs/4.1/cayenne-guide/#appendix-a-configuration-properties
> >>>>>>
> >>>>>> *
> >>>>>>
> >>>>>>    |cayenne.server.contexts_sync_strategy| defines whether peer
> >>>>>>    ObjectContexts should receive snapshot events after commits from
> >>>>>>    other contexts. If true (/default/), the contexts would
> >>>>>>    automatically synchronize their state with peers.
> >>>>>>
> >>>>>>      o
> >>>>>>
> >>>>>>        Possible values: true, false
> >>>>>>
> >>>>>>      o
> >>>>>>
> >>>>>>        Default value: true
> >>>>>>
> >>>>>> On 2019-10-11 7:21 a.m., Andrus Adamchik wrote:
> >>>>>>> Hi Andrew,
> >>>>>>>
> >>>>>>> So I assume those two NotifyQueue are in different ObjectContexts?
> >>>>>>>
> >>>>>>> Since 4.1 we stopped doing cross-context state synchronization by
> default. So when you commit in one context, the same object in other
> contexts does not get refreshed until e.g. you run a query. This improves
> both performance and consistency in a typical multi-user application. But
> of course each app has different requirements. So you may turn
> synchronization back on when bootstrapping Cayenne:
> >>>>>>>
> >>>>>>> SererRuntime runtime = ServerRuntime
> >>>>>>>      .builder()
> >>>>>>>      ...
> >>>>>>>      .addModule(b ->
> ServerModule.contributeProperties(b).put(Constants.SERVER_CONTEXTS_SYNC_PROPERTY,
> "true"))
> >>>>>>>      .build();
> >>>>>>>
> >>>>>>> Andrus
> >>>>>>>
> >>>>>>>
> >>>>>>>> On Oct 3, 2019, at 2:43 PM, Andrew Willerding <
> [email protected]> wrote:
> >>>>>>>>
> >>>>>>>> Hi,
> >>>>>>>>
> >>>>>>>> I am getting some strange results in writing/reading with Threads
> using Cayenne and I'm sure it's something I'm not understanding about
> Cayenne's data caching.  I'm hoping to get a solution to force a direct
> read somehow but so far I haven't found anything with Mr. Google.
> >>>>>>>>
> >>>>>>>> I'm using 4.1.B2.
> >>>>>>>>
> >>>>>>>> The issue is that I believe that I am writing a value to the
> database and the database contents reflect the update but subsequent reads
> in other Threads are not picking up the new value.  Here's an example in my
> log file where I log the first Thread update to the object and a subsequent
> read from another Thread
> >>>>>>>>
> >>>>>>>> 2019-10-03,12:38:01:727,INFO
> ,[CAsteriskAMIMgrProxyRemoteIF-Thread-1570],ClientBase,::NotifyQueue -
> PostUpdate NotifyQueue=[Complete](125)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](15)Test call
> >>>>>>>> 2019-10-03,12:38:01:728,INFO
> ,[NotifyTypeHandlerDialer-pool-449-thread-1],ClientBase,::NotifyQueue -
> PostLoad NotifyQueue=[Running](125)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](15)Test call
> >>>>>>>>
> >>>>>>>>    The first line PostUpdate shows that the NotifyQueue item
> (125) is Complete and when I check the database the value is definitely
> showing Complete.  However the next line from a different thread is reading
> the same NotifyQueue record (125) and it's displaying Running.   I don't
> understand how this is possible.  All indications show the PostUpdate is
> working but PostLoad is not picking up the changed value.
> >>>>>>>>
> >>>>>>>> Here's a second example with another pair of NotifyQueue items
> (127,129).  The Web page picks up the correct status values (Complete) as
> indicated in the log below
> >>>>>>>>
> >>>>>>>> 2019-10-03,13:31:07:535,INFO
> ,[http-nio-8080-exec-126],ClientBase,::NotifyQueue - PostLoad
> NotifyQueue=[Complete](127)Test
> call->Phone=416-712-2323::NotifyEvent=[New](17)Test call
> >>>>>>>> 2019-10-03,13:31:07:535,INFO
> ,[http-nio-8080-exec-126],ClientBase,::NotifyQueue - PostLoad
> NotifyQueue=[Complete](129)Test
> call->Phone=416-712-2323::NotifyEvent=[New](19)Test call
> >>>>>>>>
> >>>>>>>> And the background ThreadNotifyEventsForClient again does not
> pickup the updated Complete status (shows Running) more than a few seconds
> later (as opposed to the microseconds in the first logging example).  When
> I do a manual query on the DB, the status is definitely Complete.
> >>>>>>>>
> >>>>>>>> 2019-10-03,13:31:32:265,INFO
> ,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](17)Test
> call::checkForCompletedQueueItems NotifyQueueCount=1
> >>>>>>>>
> 2019-10-03,13:31:32:265,DEBUG,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](17)Test
> call::checkForCompletedQueueItems
> NotifyQueueItem=NotifyQueue=[Running](127)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](17)Test call
> >>>>>>>>
> 2019-10-03,13:31:32:265,DEBUG,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](17)Test
> call::checkForCompletedQueueItems
> INCOMPLETE->NotifyQueue=[Running](127)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](17)Test call DEBUG
> UNCOMMITTED=0
> >>>>>>>>
> >>>>>>>> 2019-10-03,13:31:32:265,INFO
> ,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](19)Test
> call::checkForCompletedQueueItems NotifyQueueCount=1
> >>>>>>>>
> 2019-10-03,13:31:32:265,DEBUG,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](19)Test
> call::checkForCompletedQueueItems
> NotifyQueueItem=NotifyQueue=[Running](129)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](19)Test call
> >>>>>>>>
> 2019-10-03,13:31:32:265,DEBUG,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](19)Test
> call::checkForCompletedQueueItems
> INCOMPLETE->NotifyQueue=[Running](129)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](19)Test call DEBUG
> UNCOMMITTED=0
> >>>>>>>> 2019-10-03,13:31:32:265,INFO
> ,[ThreadNotifyEventsForClient-pool-545-thread-1],NotifyEvent,ThreadNotifyEventsForClient::Callista
> Computer Telephony Inc.::checkForCompletedQueueItems Done
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> I have now made a change in my code for the background
> ThreadNotifyEventsForClient from
> >>>>>>>>
> >>>>>>>> List<NotifyQueue> listQueue = notifyEvent.getListNotifyQueue();
> >>>>>>>>
> >>>>>>>> to what should be the actual underlying transaction generated by
> Cayenne
> >>>>>>>>
> >>>>>>>>              List<NotifyQueue> listQueue =
> ObjectSelect.query(NotifyQueue.class)
> >>>>>>>>                  .where(NotifyQueue.NOTIFY_EVENT.eq(notifyEvent))
> >>>>>>>>                  .select(ClientBaseAdmin.getObjectContext());
> >>>>>>>>
> >>>>>>>> Here's the extract from the map.xml file for the relationship
> >>>>>>>>
> >>>>>>>>      <db-relationship name="listNotifyQueue" source="NotifyEvent"
> target="NotifyQueue" toMany="true">
> >>>>>>>>          <db-attribute-pair source="id" target="notifyEventID"/>
> >>>>>>>>
> >>>>>>>>      <obj-relationship name="listNotifyQueue"
> source="NotifyEvent" target="NotifyQueue" deleteRule="Cascade"
> db-relationship-path="listNotifyQueue"/>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> And guess what.  It works consistently with the explicit code
> change with a difference that I now get a PostLoad event now in the
> ThreadNotifyEventsForClient
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> 2019-10-03,14:12:00:103,INFO
> ,[CAsteriskAMIMgrProxyRemoteIF-Thread-5291],ClientBase,::NotifyQueue -
> PostUpdateNotifyQueue=[Complete](133)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](23)Test call
> >>>>>>>>
> >>>>>>>> 2019-10-03,14:12:00:107,INFO
> ,[ThreadNotifyEventsForClient-pool-758-thread-1],ClientBase,::NotifyQueue -
> PostLoad NotifyQueue=[Complete](133)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](23)Test call
> >>>>>>>> 2019-10-03,14:12:00:107,INFO
> ,[ThreadNotifyEventsForClient-pool-758-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](23)Test
> call::checkForCompletedQueueItems NotifyQueueCount=1
> >>>>>>>>
> 2019-10-03,14:12:00:107,DEBUG,[ThreadNotifyEventsForClient-pool-758-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](23)Test
> call::checkForCompletedQueueItems
> NotifyQueueItem=NotifyQueue=[Complete](133)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](23)Test call
> >>>>>>>> 2019-10-03,14:12:00:107,INFO
> ,[ThreadNotifyEventsForClient-pool-758-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](23)Test
> call::checkForCompletedQueueItems NotifyEvent has been completed
> >>>>>>>>
> 2019-10-03,14:12:00:107,DEBUG,[ThreadNotifyEventsForClient-pool-758-thread-1],NotifyEvent,ThreadNotifyEventsForClient::NotifyEvent=[Running](23)Test
> call::checkForCompletedQueueItems Generating NotifyLog for
> NotifyQueue->NotifyQueue=[Complete](133)Test
> call->Phone=416-712-2323::NotifyEvent=[Running](23)Test call
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Can someone explain why this is the case and how I can "fix it"
> without the code change.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Thanks,
> >>>>>>>>
> >>>>>>>> Andrew
> >>>>>>>>
> >>>>>>>>
>