[HBASE-5827] [Coprocessors] Observer notifications on exceptions

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: Coprocessors
• Assignee: Unassigned
• Reporter: Andrew Kyle Purtell
• Created: 19/Apr/12 01:52
• Updated: 13/Jun/22 16:05
• Resolved: 11/Jun/22 23:28

Description

Benjamin Busjaeger wrote on dev@:

Is there a reason that RegionObservers are not notified when a get/put/delete fails? Suppose I maintain some (transient) state in my Coprocessor that is created during preGet and discarded during postGet. If the get fails, postGet is not invoked, so I cannot remove the state.

If there is a good reason, is there any other way to achieve the same thing? If not, would it be possible to add something the snippet below to the code base?

    // pre-get CP hook
    if (withCoprocessor && (coprocessorHost != null)) {
      if (coprocessorHost.preGet(get, results)) {
        return results;
      }
    }
+    try{
    ...
+    } catch (Throwable t) {
+        // failed-get CP hook
+        if (withCoprocessor && (coprocessorHost != null)) {
+          coprocessorHost.failedGet(get, results);
+        }
+        rethrow t;
+    }

    // post-get CP hook
    if (withCoprocessor && (coprocessorHost != null)) {
      coprocessorHost.postGet(get, results);
    }

Issue Links

• relates to: HBASE-11125 Introduce a higher level interface for registering interest in coprocessor upcalls