> I remember Andrew saying same thing about CoprocessorEnvironment#getTable functions during the review of HBASE-17732, that we should get rid of them and let CP do their own table resource management like all other things.
Yes > The above 'trick' is now commonplace in servers as the Master and RegionServer always make Connections that will short-circuit if an opportunity No need for CoprocessorHConnection, then. On Wed, Oct 18, 2017 at 3:12 PM, Apekshit Sharma <a...@cloudera.com> wrote: > +1 > I remember Andrew saying same thing about CoprocessorEnvironment#getTable > functions during the review of HBASE-17732, that we should get rid of them > and let CP do their own table resource management like all other things. > > On Wed, Oct 18, 2017 at 2:45 PM, Stack <st...@duboce.net> wrote: > > > tl;dr I believe the original intent for TableWrapper and > > CoprocessorHConnection can now be gotten elsewhere so we should purge > these > > classes. > > > > In base CoprocessorEnvironment, there are methods to return a Table > > instance. There are none to return an Admin. In our code base, the only > > user is the AccessController. Phoenix uses it twice in its Indexer > > implementation. > > > > When you call CE#getTable, the default implementation in > > BaseEnvironemnt calls HTableWrapper.createWrapper which takes a > > BaseEnvironment List in which we keep all Table instances. On shutdown of > > the coprocessor, the list is iterated and all tables are closed. > > > > Going via TableWrapper, the class comment says: > > > > * A wrapper for HTable. Can be used to restrict privilege. > > * > > * Currently it just helps to track tables opened by a Coprocessor and > > * facilitate close of them if it is aborted. > > * > > * We also disallow row locking. > > * > > * There is nothing now that will stop a coprocessor from using HTable > > * objects directly instead of this API, but in the future we intend to > > * analyze coprocessor implementations as they are loaded and reject those > > * which attempt to use objects and methods outside the Environment > > * sandbox. > > > > > > TableWrapper by my reading delegates all calls to a Table instance with > no > > interception (there is not rowlocking to override anymore). On open, we > do > > ensure the Table is up on a CoprocessorHConnection which does the > > following: > > > > * Connection to an HTable from within a Coprocessor. We can do some > > nice tricks since we know we > > * are on a regionserver, for instance skipping the full > > serialization/deserialization of objects > > * when talking to the server. > > > > > > The above 'trick' is now commonplace in servers as the Master and > > RegionServer always make Connections that will short-circuit if an > > opportunity. > > > > As I read TableWrapper and CoprocessorHConnection, they were written at > > another time when Table construction was heavyweight and Table#close was > > not expected of clients and before the introduction of the general > > Server-side short-circuit Connection facility. > > > > Unless objection, I think we should purge them. > > > > Writing here in case I'm missing some key facility they provide. > > > > Thanks, > > St.Ack > > > > > > -- > > -- Appy > -- Best regards, Andrew Words like orphans lost among the crosstalk, meaning torn from truth's decrepit hands - A23, Crosstalk
