oh wow! that worked beautifully! at first i was trying to deal with messages that had already been paged in, but then i realized that anything which has not yet been consumed should still be in the store. so it really was as simple as passing a MessageRecoveryListener to the store and I can browse the entire message list.
thanks for your help! christopher.l.shannon wrote > The transaction you are referring to is a transaction on the KahaDB > index and a new one will be created by KahaDB when calling that method > so you don't need to worry about it. In terms of statefulness, you > are correct that the order index tracks state of where it left off. > But I believe it is safe to use the recover() method (which always > resets the cursor and starts at the beginning) as there are things > like duplicate detection in place so it should be able to handle it. > > In fact, if you call browse() on a Topic from JMX it will eventually > end up delegating to the recover method on the Topic Store and it will > return up to the number of messages of the browse page size so it has > been designed to be called multiple times because it will be called > every time you call browse(). Here is how it is used and might be a > good example for basing your code off of: > https://github.com/apache/activemq/blob/activemq-5.14.2/activemq-broker/src/main/java/org/apache/activemq/broker/region/Topic.java#L638 > For recoverNextMessages I don't remember if it would work or not > without taking a closer look. > > Unfortunately I don't think there is really any other methods right > now to try and iterate over the messages in the store. The best thing > to do would be to write a quick test and see if it works for you. > > On Fri, Dec 16, 2016 at 3:26 PM, jahlborn < > jahlborn@ > > wrote: >> So, digging into the message store recoverNextMessages() code, it's tough >> to >> tell what is going in in terms of statefulness. That method certainly >> seems >> like it would get me the information that i'm after. two concerns: 1. it >> looks to be expecting an existing Transaction (maybe i already have one >> in >> place since i'm working off of an existing session). 2. >> "recoverNextMessages" seems to imply that it's basing the notion of >> "next" >> off of current state and calling this method will change that state. do >> i >> need to do something with the store state to ensure that i don't mess up >> this state for normal message consumption? >> >> thanks for your help so far! >> >> >> christopher.l.shannon wrote >>> You should be able to implement your own MessageRecoveryListener and >>> use the recover() or recoverNextMessages() methods on the MessageStore >>> interface. The MessageStore object is part of the region Queue (it is >>> inherited from the parent BaseDestination class) >>> http://activemq.apache.org/maven/apidocs/org/apache/activemq/store/MessageStore.html >>> >>> Calling that method will iterate over each message in the store, load >>> it into memory and then and pass it to the MessageRecoveryListener >>> that you provide. If you are using KahaDB then calling these methods >>> will lock the index and prevent other writes/reads from the store >>> while executing the method. >>> >>> On Thu, Dec 15, 2016 at 11:09 AM, jahlborn < >> >>> jahlborn@ >> >>> > wrote: >>>> We have activemq embedded in our product. Since it runs in the same >>>> jvm, >>>> we >>>> have various resource limits in place. These limits make the browsing >>>> functionality somewhat less than ideal (you can only read so many >>>> messages >>>> in a large queue). I was wondering if someone who has deeper knowledge >>>> of >>>> activemq could suggest a way to read messages directly from the data >>>> store >>>> (or some other way to do unbounded browsing which doesn't use up all >>>> system >>>> memory). >>>> >>>> I already attempted this a bit myself by adding a method to the region >>>> Queue >>>> for first pulling from the "paged in" messages, and then directly from >>>> the >>>> "PendingMessageCursor messages" to read messages. However, despite the >>>> fact >>>> that the cursor is backed by the message store, it still seems to want >>>> to >>>> "page in" messages, and also abides by the resource limits. (i was >>>> borrowing code from Queue.getMessage(String id)). >>>> >>>> Is there any way to "bypass" the "paging in" logic and just read >>>> messages >>>> directly from the message store? i'm okay with this being "slow", i'd >>>> prefer to have a solution which works slowly rather than no solution at >>>> all... >>>> >>>> >>>> >>>> -- >>>> View this message in context: >>>> http://activemq.2283324.n4.nabble.com/Custom-code-to-browse-messages-in-the-message-store-tp4720423.html >>>> Sent from the ActiveMQ - User mailing list archive at Nabble.com. >> >> >> >> >> >> -- >> View this message in context: >> http://activemq.2283324.n4.nabble.com/Custom-code-to-browse-messages-in-the-message-store-tp4720423p4720542.html >> Sent from the ActiveMQ - User mailing list archive at Nabble.com. -- View this message in context: http://activemq.2283324.n4.nabble.com/Custom-code-to-browse-messages-in-the-message-store-tp4720423p4720593.html Sent from the ActiveMQ - User mailing list archive at Nabble.com.
