On Mon, 7 Jul 2025 10:41:58 GMT, Volkan Yazici <vyaz...@openjdk.org> wrote:

>> Adds a new `ofFileChannel(FileChannel channel, long offset, long length)` 
>> method to `java.net.HttpRequest.BodyPublishers` to provide an `HttpClient` 
>> publisher to upload a certain region of a file. The new publisher does not 
>> modify the state of the passed `FileChannel`, streams the file channel bytes 
>> as it publishes (i.e., avoids reading the entire file into the memory), and 
>> can be leveraged to implement sliced uploads. As noted in the Javadoc:
>> 
>>> The file channel will not be closed upon completion. The caller is
>>> expected to manage the life cycle of the channel, and close it
>>> appropriately when not needed anymore.
>> 
>> ### Implementation notes
>> 
>> - `FileChannel` is preferred over `{Readable,Seekable}ByteChannel`, since 
>> the latter does not provide a positional read without modifying the state of 
>> the `FileChannel`, which is necessary to use a single `FileChannel` instance 
>> to implement sliced uploads.
>> - `ofFileChannel(FileChannel,long,long)` is preferred over 
>> `ofPath(Path,long,long)` to avoid overloading the maximum file descriptor 
>> limit of the platform.
>
> Volkan Yazici has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Improve docs on `IndexOutOfBoundsException` thrown
>   
>   Co-authored-by: Daniel Fuchs <67001856+df...@users.noreply.github.com>

src/java.net.http/share/classes/jdk/internal/net/http/RequestPublishers.java 
line 476:

> 474: 
> 475:         @Override
> 476:         public synchronized boolean hasNext() {

In context of the synchronizations in this class, does a single instance of 
`FileChannelIterator` gets accessed concurrently? I haven't fully grasped the 
publisher/subscriber model through which this `FileChannelIterator` instance 
would be handed out and how that then ends up as a `BodyPublisher` that's 
accessed by the application.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/26155#discussion_r2213367083

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