First off, hello! My name is Cory Klein and this marks my first
interaction with this group. I've read through the email guidelines
and I think I have something productive to discuss here.
In looking at GenericObjectPool I came across a process that I believe
could be improved upon and I wanted to get some early feedback on this
approach before investing the time to create a full pull request.
The general approach for using an object pool is to borrow an object,
use it to do something, and then return it. For example:
Resource resource = objectPool.borrowObject();
String result = doSomething(resource);
objectPool.returnObject(resource);
In this case, objectPool owns instances of Resource and lends them
out. However, the object pool abstraction gets slightly leaky when you
consider that the consumer has a responsibility to return the object,
and other consumers might be adversely affected if objects aren't
returned properly.
I propose augmenting ObjectPool with the following method. This code
is merely demonstrative and not intended to be final:
public class <T> ObjectPool {
...
public R run(Function<T,R> function) {
T obj = null;
try {
obj = borrowObject();
} catch (Exception e) {
throw new RuntimeException("Unable to get object from pool");
}
R returnVal = null;
try {
returnVal = function(T);
} catch (Exception e) {
throw new RuntimeException("Supplied lambda produced an exception");
} finally {
this.returnObject(obj);
return returnVal;
}
}
}
With this idea, consumers can instead provide the object pool with a
function to run using the required resource, leaving the object pool
complete ownership of the resource and ensuring that resources can
always be returned to the pool. The borrow/return example from above
becomes merely:
String result = objectPool.run((resource) -> doSomething(resource));
In summary, some positive reasons I can think of to make this change are:
* Improve a leaky abstraction
* Less code needed on the consuming side
* Improved reliability
I'm having a harder time coming up with reasons why this change is
bad, but I think this may be due to a lack of intimacy with the
library as it exists now. Are there any reasons that are immediately
apparent to you?
Thanks,
Cory Klein
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