Jerry,
On 9/7/21 15:49, Jerry Malcolm wrote:
On 9/7/2021 2:35 PM, Christopher Schultz wrote:
Jerry, Rémy,
On 9/3/21 07:15, Rémy Maucherat wrote:
On Fri, Sep 3, 2021 at 2:46 AM Jerry Malcolm <techst...@malcolms.com>
wrote:
I have a requirement to start a new log database on the first of every
month. I still need to have access to older monthly log databases. I
do not want to create a bunch of hardcoded manually configured
individual datasources, one for each month. I have a dynamic
datasource
solution that is completely implemented and working except for one
little thing.
I access the BasicDataSource implementation class for the
datasource. I
have an algorithm that substitutes yyyy_MM at the appropriate spot in
the configured URL and then updates the url in the datasource. All of
this works great. I can live with the fact that the datasource can
only
point to one database at a time. My concern is that once I transition
to another database, there are existing connections in the pool that
are
already attached to the old database. I need to clear those out and
start over. But I don't have the luxury of bouncing tomcat to clean
it up.
The apache commons BasicDataSource has a restart() method. But
unfortunately that method is omitted from the Tomcat version. There
is a
close() method on the BasicDataSource. But I don't see anything that
will re-open it after closing. I thought about changing maxActive
to 0,
and waiting for it to drain, then setting it back to the original
value. None of these sound like an ideal solution. Without a
restart()
method, is there any other way to force all existing connections to
close and start clean?
The code is kept in sync with DBCP (with a bit of lag maybe), so these
lifecycle methods were also added to Tomcat one year ago (9.0.38+ and
8.5.58+).
We are using this at $work to bounce our database connection pools
after TLS client certificate changes. This is the code we are using to
reload the pool:
try
{
Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup(getJNDIPath());
if(null == ds)
throw new ServiceException("Cannot obtain DataSource");
if(isInstanceOf(ds, "org.apache.tomcat.dbcp.dbcp2.BasicDataSource")
|| isInstanceOf(ds,
"org.apache.commons.dbcp2.BasicDataSource")) {
return call(ds, "restart");
}
} catch (Exception e) {
org.apache.log4j.Logger.getLogger(this.getClass()).error("Failed to
reload DataSource " + getJNDIPath());
}
The call() method simply encapsulates all of the work to make a
reflective method call to BasicDataSource.restart().
As Rémy points out, it requires a Tomcat version 9.0.38+ or 8.5.58+.
Hope that helps,
-chris
Chris,
I'll definitely try this. But I'm curious about the restart method. Is
it some sort of a hidden method that's only available to reflection?
Seems it would be a lot more straightforward to just make the restart
method public like it is in the apache version of BasicDataSource. I'm
not complaining. If this works, then fine. Just curious.
It's not magic; that method is in there[1][2].
The only reason we call it reflectively is because we don't want to have
compile-time dependencies on the Tomcat internal classes.
-chris
[1]
https://commons.apache.org/proper/commons-dbcp/apidocs/org/apache/commons/dbcp2/BasicDataSource.html#restart--
[2]
https://tomcat.apache.org/tomcat-8.5-doc/api/org/apache/tomcat/dbcp/dbcp2/BasicDataSource.html#restart()
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