Metacat

Use the ServiceFailure to replace the InvalidRequest when it is the read-only mode (CN throws the exception).

In the replicate method, the checking of the read-only mode was moved from MNodeService class to the MNResourceHandler class since it is asynchronized.

The systemmetadataChanged method is asynchronized, so we put the read-only checking on the ResourceHandler class.

Add the code to check if the mn is on the read-only mode.

Add the code to check if the metacat is in the read-only mode.

Add the code to handle the read-only mode.

Add a class to determine if the metacat is in the readonly mode.

Add the check that only the administrator can shrink the connection pool.

Close the sql statements on the four methods - getGUID, getHeadPID, systemMetadataSIDExist and systemMetadataPIDExist.

Close some prepared sql statement in the summarize method.