Apache Gora
  1. Apache Gora
  2. GORA-105

DataStoreFactory does not properly support multiple stores

    Details

    • Type: Bug Bug
    • Status: Closed
    • Priority: Blocker Blocker
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.2
    • Component/s: schema, storage
    • Labels:
      None

      Description

      DataStoreFactory has a single, static properties field. This is completely unacceptable, because that way when multiple stores are instantiated in the same JVM, the last store instance will overwrite the "default.schema" property. This causes that all the previous stores will read a misconfigured default schema property. Beside this it may cause several other nasty future bugs. In my opinion this is a blocker because the methods on DataStoreFactory suggest that it can handle multiple stores, when as a matter fact it doesn't.

      I will attach and commit a patch that fixes this problem. It only modifies gora-core. All stores directly benefit from this bugfix because of DataStoreBase. This patch fixes the following property related problems.

      -It introduces a static method createProps in DataStoreFactory. This is the equivalent of Configuration.create(). Everyone can create a new properties object and set everything interesting on it and pass it on to whatever stores they like, instead of ALL stores.
      -It fixes the method javadoc of DataStoreBase#getSchemaName(String mappingSchemaName, Class<?> persistentClass). The previous description was simply wrong.
      -It SERIALIZES the properties field of DataStoreBase instead of grabbing the static DataStoreFactory.properties field. This has the additional benefit of making sure that the store can be used correctly with runtime modified properties in a mapreduce context.
      -It removes the caching functionality of DataStoreFactory. Because of the dynamic configuration in the Properties and Configuration object, it is very difficult to implement a correct key hash for the cache. At the moment it only uses the triple

      {datastoreClass, keyClass,valueClass} as a key hash. Multiple stores cannot be properly supported when the factory uses badly implemented hash keys. (For example, one might instantiate 2 SqlStores, both using the exact same {datastoreClass, keyClass,valueClass}

      triple, but pointing to different databases. When one is about the instantiate the second datastore, it will faulty return the first datastore from cache). We can always reintroduce caching functionality when we can implement a proper key.

      The patch passes all tests. Will commit when there are no objections.

      1. GORA-105.patch
        17 kB
        Ferdy Galema
      2. GORA-105-v2.patch
        24 kB
        Ferdy Galema

        Issue Links

          Activity

          Hide
          Lewis John McGibbney added a comment -

          This arguement you've created here in this issue is about flexibility and usability and is a real great catch at this late stage in the day so to speak.
          I've followed your commentary as above and only have the following comments:

          • Would be great to see the new static createProps() annotated with something along the lines of "Everyone can create a new properties object and set everything interesting on it and pass it on to whatever stores they like, instead of ALL stores. ", this provides a neat justification for the change.
          • Can you please expand on what you mean by {bq} We can always reintroduce caching functionality when we can implement a proper key. {bq}

            ?
            Does this require us to log the issue just now and act on it at a later stage?

          All in all I'm very happy with the issue and of course the proposed solution. It's a real nice catch and can only get better once it's implemented and tested more.

          Show
          Lewis John McGibbney added a comment - This arguement you've created here in this issue is about flexibility and usability and is a real great catch at this late stage in the day so to speak. I've followed your commentary as above and only have the following comments: Would be great to see the new static createProps() annotated with something along the lines of "Everyone can create a new properties object and set everything interesting on it and pass it on to whatever stores they like, instead of ALL stores. ", this provides a neat justification for the change. Can you please expand on what you mean by {bq} We can always reintroduce caching functionality when we can implement a proper key. {bq} ? Does this require us to log the issue just now and act on it at a later stage? All in all I'm very happy with the issue and of course the proposed solution. It's a real nice catch and can only get better once it's implemented and tested more.
          Hide
          Ferdy Galema added a comment -

          "the new static createProps() annotated"
          That's a good idea. It's going to be an important method after all. Will include it in the next patch.

          "Does this require us to log the issue just now and act on it at a later stage? "
          Yes that is what I propose. I will create an issue that is for implementing caching, the right way. Because this needs to be very well thought out, I did not intend to include it with this issue. Simply disabling cache should be right for now because this will prevent unexpected behaviour. (Like the scenario I sketched above with the two different databases). I do not expect this change to have negative impact.

          In any case I am more than happy to also provide annotations for the "createDataStore" methods to clarify their exact behaviour.

          Show
          Ferdy Galema added a comment - "the new static createProps() annotated" That's a good idea. It's going to be an important method after all. Will include it in the next patch. "Does this require us to log the issue just now and act on it at a later stage? " Yes that is what I propose. I will create an issue that is for implementing caching, the right way. Because this needs to be very well thought out, I did not intend to include it with this issue. Simply disabling cache should be right for now because this will prevent unexpected behaviour. (Like the scenario I sketched above with the two different databases). I do not expect this change to have negative impact. In any case I am more than happy to also provide annotations for the "createDataStore" methods to clarify their exact behaviour.
          Hide
          Ferdy Galema added a comment -

          Done. Annotating the various creator methods was... inspiring. To reduce the levels of indirection I made sure that all methods directly call the "end creator method", that is the method that actually creates and initializes the store. That should help with debugging and maintaining the code.

          Show
          Ferdy Galema added a comment - Done. Annotating the various creator methods was... inspiring. To reduce the levels of indirection I made sure that all methods directly call the "end creator method", that is the method that actually creates and initializes the store. That should help with debugging and maintaining the code.
          Hide
          Ferdy Galema added a comment -

          committed.

          Show
          Ferdy Galema added a comment - committed.
          Hide
          Hudson added a comment -

          Integrated in gora-trunk #198 (See https://builds.apache.org/job/gora-trunk/198/)
          GORA-105 DataStoreFactory does not properly support multiple stores (Revision 1306866)

          Result = SUCCESS
          ferdy :
          Files :

          • /gora/trunk/CHANGES.txt
          • /gora/trunk/gora-core/src/main/java/org/apache/gora/store/DataStoreFactory.java
          • /gora/trunk/gora-core/src/main/java/org/apache/gora/store/impl/DataStoreBase.java
          • /gora/trunk/gora-core/src/main/java/org/apache/gora/util/WritableUtils.java
          • /gora/trunk/gora-core/src/test/java/org/apache/gora/GoraTestDriver.java
          • /gora/trunk/gora-core/src/test/java/org/apache/gora/avro/mapreduce/TestDataFileAvroStoreMapReduce.java
          • /gora/trunk/gora-core/src/test/java/org/apache/gora/avro/store/TestAvroStore.java
          • /gora/trunk/gora-core/src/test/java/org/apache/gora/store/TestDataStoreFactory.java
          • /gora/trunk/gora-core/src/test/java/org/apache/gora/util/TestWritableUtils.java
          Show
          Hudson added a comment - Integrated in gora-trunk #198 (See https://builds.apache.org/job/gora-trunk/198/ ) GORA-105 DataStoreFactory does not properly support multiple stores (Revision 1306866) Result = SUCCESS ferdy : Files : /gora/trunk/CHANGES.txt /gora/trunk/gora-core/src/main/java/org/apache/gora/store/DataStoreFactory.java /gora/trunk/gora-core/src/main/java/org/apache/gora/store/impl/DataStoreBase.java /gora/trunk/gora-core/src/main/java/org/apache/gora/util/WritableUtils.java /gora/trunk/gora-core/src/test/java/org/apache/gora/GoraTestDriver.java /gora/trunk/gora-core/src/test/java/org/apache/gora/avro/mapreduce/TestDataFileAvroStoreMapReduce.java /gora/trunk/gora-core/src/test/java/org/apache/gora/avro/store/TestAvroStore.java /gora/trunk/gora-core/src/test/java/org/apache/gora/store/TestDataStoreFactory.java /gora/trunk/gora-core/src/test/java/org/apache/gora/util/TestWritableUtils.java
          Hide
          Hudson added a comment -

          Integrated in goraOracle #6 (See https://builds.apache.org/job/goraOracle/6/)
          GORA-105 DataStoreFactory does not properly support multiple stores (Revision 9701ea398ba8a9fea6e84b84eb99dd0d405021ff)

          Result = FAILURE
          ferdy :
          Files :

          • gora-core/src/main/java/org/apache/gora/store/impl/DataStoreBase.java
          • gora-core/src/test/java/org/apache/gora/avro/mapreduce/TestDataFileAvroStoreMapReduce.java
          • gora-core/src/main/java/org/apache/gora/util/WritableUtils.java
          • gora-core/src/test/java/org/apache/gora/avro/store/TestAvroStore.java
          • gora-core/src/main/java/org/apache/gora/store/DataStoreFactory.java
          • gora-core/src/test/java/org/apache/gora/util/TestWritableUtils.java
          • gora-core/src/test/java/org/apache/gora/store/TestDataStoreFactory.java
          • gora-core/src/test/java/org/apache/gora/GoraTestDriver.java
          • CHANGES.txt
          Show
          Hudson added a comment - Integrated in goraOracle #6 (See https://builds.apache.org/job/goraOracle/6/ ) GORA-105 DataStoreFactory does not properly support multiple stores (Revision 9701ea398ba8a9fea6e84b84eb99dd0d405021ff) Result = FAILURE ferdy : Files : gora-core/src/main/java/org/apache/gora/store/impl/DataStoreBase.java gora-core/src/test/java/org/apache/gora/avro/mapreduce/TestDataFileAvroStoreMapReduce.java gora-core/src/main/java/org/apache/gora/util/WritableUtils.java gora-core/src/test/java/org/apache/gora/avro/store/TestAvroStore.java gora-core/src/main/java/org/apache/gora/store/DataStoreFactory.java gora-core/src/test/java/org/apache/gora/util/TestWritableUtils.java gora-core/src/test/java/org/apache/gora/store/TestDataStoreFactory.java gora-core/src/test/java/org/apache/gora/GoraTestDriver.java CHANGES.txt

            People

            • Assignee:
              Unassigned
              Reporter:
              Ferdy Galema
            • Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:

                Development