Roman Puchkovskiy created IGNITE-18049:
------------------------------------------
Summary: Cursor#close() should not declare any exceptions in
throws clause
Key: IGNITE-18049
URL: https://issues.apache.org/jira/browse/IGNITE-18049
Project: Ignite
Issue Type: Improvement
Reporter: Roman Puchkovskiy
Assignee: Roman Puchkovskiy
Fix For: 3.0.0-beta2
When an {{AutoCloseable}} subinterface/implementation declares {{throws
Exception}} in its {{close()}} method, it makes it very inconvenient to work
with such a type using try-with-resources because the using code must use
something like {{catch (Exception e)}} which makes it difficult to process
exceptions that might arise in the {{try}} block.
The suggestion is to make {{Cursor#close()}} not declare any checked
exceptions. Most of the current implementations of {{Cursor}} already obey to
this restriction, and a few that don't can be easily reworked to obey.
The only problem is adapters (when we adapt an {{Iterator}} producing a
{{{}Cursor{}}}). Here, we must be prepared to get an {{Iterator}} that is a
resource itself (is an {{{}AutoCloseable{}}}) and hence needs to be closed when
the cursor is closed. But {{AutoCloseable#close()}} might throw a checked
exception. It is unacceptable to swallow it, and it is not too good to just
automatically wrap it in an unchecked exception.
# The best thing is that developers (who know their resources) write their own
custom {{Cursor}} implementations handling the closure.
# We also need a way to adapt 'safe close' iterators (obtained from in-memory
collections, for example). We should add a method like
{{Cursor#fromPurIterator(Iterator)}} that will check (at the moment of
invocation that the provided iterator is NOT an AutoCloseable and will throw if
it is)
# We can also provide a generic way to adapt a closeable iterator with a
method like {{<IT extends Iterator<T> & AutoCloseable>
Cursor#fromCloseableIterator(IT iterator)}} adding a Javadoc urging the user to
use this method only when absolutely necessary
# We probably should not add an omnivorous method that could adapt both pure
and closeable iterators for now to prevent abuses.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
