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https://issues.apache.org/jira/browse/DRILL-8009?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17428344#comment-17428344
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ASF GitHub Bot commented on DRILL-8009:
---------------------------------------
rymarm opened a new pull request #2333:
URL: https://github.com/apache/drill/pull/2333
# [DRILL-8009](https://issues.apache.org/jira/browse/DRILL-8009):
DrillConnectionImpl#isValid() doesn't correspond JDBC API
## Description
I've add ping function which send message with
[RpcMode.PING](http://drill.apache.org/apidocs/org/apache/drill/exec/proto/GeneralRPCProtos.RpcMode.html#PING)
to drillbit and after that waits for a response message with
[RpcMode.PONG](drill.apache.org/apidocs/org/apache/drill/exec/proto/GeneralRPCProtos.RpcMode.html#PONG).
This method is used to validate connection. I add this verification to
[DrillConnectionImpl#isValid(int
timeout)](https://github.com/apache/drill/blob/5f5ae89392471d237605c0b5e1a337e5bc0e10ff/exec/jdbc/src/main/java/org/apache/drill/jdbc/impl/DrillConnectionImpl.java#L522)
as it is required by JDBC API
[documentation](https://docs.oracle.com/en/java/javase/11/docs/api/java.sql/java/sql/Connection.html#isValid(int))
and gives opportunity accurately validate connection:
> The driver shall submit a query on the connection or use some other
mechanism that positively verifies the connection is still valid when this
method is called
Also, I've add to [DrillConnectionImpl#isValid(int
timeout)](https://github.com/apache/drill/blob/5f5ae89392471d237605c0b5e1a337e5bc0e10ff/exec/jdbc/src/main/java/org/apache/drill/jdbc/impl/DrillConnectionImpl.java#L522)
simple check for
[channel#isActive()](https://netty.io/4.1/api/io/netty/channel/Channel.html#isActive--).
[Previously, in
Drill](https://github.com/apache/drill/commit/960f876a1945eee4eeb0d6a98c5c58dfe2eea1a9)
were add `PING` and `PONG` RpcMode's, but they was primarily used for
"hearbeat" function — to let drillbit know, that connection with client is
still alive and now I also used it for client verification of connection to
drillbit.
I've used listener pattern for checking whether client got `PONG` answer or
not. If you think, that this realization is not best, I have ideas how it can
be implemented in other, more "netty's" way.
## Documentation
No doc impact
## Testing
Manual tests with cases:
* server (drillbit) closes connection
* server (drillbit) shut down
* server (drillbit) process has been killed
* client (jdbc) lost network connection
* client (jdbc) temporary lost connection and restored it until JDBC's ping
timeout has been elapsed.
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> DrillConnectionImpl#isValid() doesn't correspond JDBC API
> ---------------------------------------------------------
>
> Key: DRILL-8009
> URL: https://issues.apache.org/jira/browse/DRILL-8009
> Project: Apache Drill
> Issue Type: Bug
> Components: Client - JDBC
> Reporter: Maksym Rymar
> Assignee: Maksym Rymar
> Priority: Major
>
> {{DrillConnectionImpl#isValid()}} doesn't correspond [Java JDBC API
> documentation|https://docs.oracle.com/javase/7/docs/api/java/sql/Connection.html#isValid(int)].
> Current implementation doesn't do actual connection verify and doesn't cover
> cases like drillbit termination and network issues.
> {{java.sql.Connection#isValid()}} (which extends {{DrillConnectionImpl}})
> widely used in JDBC connection pools like HikariCP and without right
> implementation, Drill JDBC driver cannot be used with them, because
> connections will keep alive forever.
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