[External] : Re: Introduce constructor for PriorityQueue with existing collection and custom comparator

[Pavel Rappo]

You might want to use this older, unresolved, duplicated bug for your PR: https://bugs.openjdk.org/browse/JDK-6356745

> On 13 Dec 2023, at 23:37, Valeh Hajiyev <valeh.hajiyev at gmail.com> wrote:
> 
> Hi Pavel,
> 
> Thanks for the reply. If I understand correctly, I need this change to be discussed in one of the mailing lists there, so that someone would sponsor me to create a tracking issue in JBS. Do you know which mailing list is the most relevant for me to propose the change?
> 
> Thanks,
> Valeh
> 
> On Thu, Dec 14, 2023 at 12:26 AM Pavel Rappo <pavel.rappo at oracle.com> wrote:
> Sorry, there's a necessary process that a PR must follow. You seem to have signed OCA already. For the rest, see this resource: https://openjdk.org/guide/. In particular, this part: https://openjdk.org/guide/#contributing-to-an-openjdk-project.
> 
> -Pavel
> 
> > On 13 Dec 2023, at 23:09, Valeh Hajiyev <valeh.hajiyev at gmail.com> wrote:
> > 
> > Hi all,
> > 
> > I have raised the following PR, could someone please help me to get it merged?
> > 
> > https://github.com/openjdk/jdk/pull/17045
> > 
> > More details:
> > 
> > This commit addresses the current limitation in the `PriorityQueue` implementation, which lacks a constructor to efficiently create a priority queue with a custom comparator and an existing collection. In order to create such a queue, we currently need to initialize a new queue with custom comparator, and after that populate the queue using `addAll()` method, which in the background calls `add()` method (which takes `O(logn)` time) for each element of the collection (`n` times).  This is resulting in an overall time complexity of `O(nlogn)`. 
> > 
> > ```
> > PriorityQueue<String> pq = new PriorityQueue<>(customComparator);
> > pq.addAll(existingCollection);
> > ```
> > 
> > The pull request introduces a new constructor to streamline this process and reduce the time complexity to `O(n)`.  If you create the queue above using the new constructor, the contents of the collection will be copied (which takes `O(n)` time) and then later  `heapify()` operation (Floyd's algorithm) will be called once (another `O(n)` time). Overall the operation will be reduced from `O(nlogn)` to `O(2n)` -> `O(n)` time.
> > 
> > ```
> > PriorityQueue<String> pq = new PriorityQueue<>(existingCollection, customComparator);
> > ```
> > 
> > Best regards,
> > Valeh Hajiyev
> > 
>