Hi, all,
I am trying to learn how to share data between two coprocessors. I have one
Observer coprocessor and one Endpoint coprocessor. In the observer, it overload
the prePut/preDelete to maintain a counter. And I want the Endpoint coprocessor
to read that counter and return to client caller. So I want to use the
getSharedData() method in RegionCoprocessorEnvironment, but I cannot make it
work. Could anybody help me here?
In the Observer Coprocessor :
During start(), create the shared object "counter":
-----------------------------------------------------------------
public void start(CoprocessorEnvironment envi) throws IOException {
Env.getSharedData().put("counter", new Long(0) ); //create the counter
-----------------------------------------------------------------
In the Endpoint coprocessor:
During start(), try to read the shared "counter" , but failed.
------------------------------------------------------------------
public void start(CoprocessorEnvironment envi) throws IOException {
LOG.info("The size of sharedData map is: " + envi.getSharedData().size()
); //try to get the counter
------------------------------------------------------------------
Here it print 0, if I use evni.getSharedData().containsKey("counter"), it will
return false.
When creating table, I call addCoprocessor() method to add Observer first, then
Endpoint coprocessor. I confirmed that by checking the hbase log file message.
I only have one region for that table during the run. I confirmed by hbase
shell status 'detailed' command.
There is not much example I can find about how to use getSharedData(), could
someone help me here? What is missing in my simple code? Thanks very much in
advance!
Thanks,
Ming
