[HBASE-18770] Remove bypass method in ObserverContext and implement the 'bypass' logic case by case

• Type: Sub-task
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.0.0-alpha-4, 2.0.0
• Component/s: Coprocessors
• Hadoop Flags: Reviewed

Release Note

Removes blanket bypass mechanism (Observer#bypass). Instead, a curated subset of methods are bypassable.

    Changes Coprocessor ObserverContext 'bypass' semantic. We flip the
    default so bypass is NOT supported on Observer invocations; only a
    couple of preXXX methods in RegionObserver allow it: e.g. preGet
    and prePut but not preFlush, etc. Everywhere else, we throw
    a Exception if a Coprocessor Observer tries to invoke bypass. Master
    Observers can no longer stop or change move, split, assign, create table, etc.
    preBatchMutate can no longer be bypassed (bypass the finer-grained
    prePut, preDelete, etc. instead)

    Ditto on complete, the mechanism that allowed a Coprocessor
    rule that all subsequent Coprocessors are skipped in an
    invocation chain; now, complete is only available to
    bypassable methods (and Coprocessors will get an exception if
    they try to 'complete' when it is not allowed).

    See javadoc for whether a Coprocessor Observer method supports
    'bypass'. If no mention, 'bypass' is NOT supported.

The below methods have been marked deprecated in hbase2. We would have liked to have removed them because they use IA.Private parameters but they are in use by CoreCoprocessors or are critical to downstreamers and we have no alternatives to provide currently.

@Deprecated public boolean prePrepareTimeStampForDeleteVersion(final Mutation mutation, final Cell kv, final byte[] byteNow, final Get get) throws IOException {
              
@Deprecated public boolean preWALRestore(final RegionInfo info, final WALKey logKey, final WALEdit logEdit) throws IOException {

@Deprecated public void postWALRestore(final RegionInfo info, final WALKey logKey, final WALEdit logEdit) throws IOException {
       
@Deprecated public DeleteTracker postInstantiateDeleteTracker(DeleteTracker result) throws IOException

Metrics are updated now even if the Coprocessor does a bypass; e.g. The put count is updated even if a Coprocessor bypasses the core put operation (We do it this way so no need for Coprocessors to have access to our core metrics system).

• Assignee: Michael Stack
• Reporter: Duo Zhang
• Created: 07/Sep/17 08:17
• Updated: 17/Jun/22 05:21
• Resolved: 31/Oct/17 19:50

Description

http://search-hadoop.com/m/HBase/YGbbXd0RDCIHSC1

Issue Links

• contains: HBASE-15071 Cleanup bypass semantic in MasterCoprocessorHost
• is related to: HBASE-19122 preCompact and preFlush can bypass by returning null scanner; shut it down
• relates to: HBASE-19123 Purge 'complete' support from Coprocesor Observers
• links to: Review Board (master)