RFR: 8299518: HotSpotVirtualMachine shared code across different platforms [v3]

[Yi Yang]

On Thu, 5 Jan 2023 05:44:23 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Good suggestion.
>> However, I wonder why the `fd` is casted from `long` to `int` on Unix. The Unix versions of SocketInputStream had `int fd`.
>> So, the following code also needs to cast `fd` to `int`:
>> 
>> +        public synchronized int read(byte[] bs, int off, int len) throws IOException {
>> +            if ((off < 0) || (off > bs.length) || (len < 0) ||
>> +                ((off + len) > bs.length) || ((off + len) < 0)) {
>> +                throw new IndexOutOfBoundsException();
>> +            } else if (len == 0) {
>> +                return 0;
>> +            }
>> +            return read(fd, bs, off, len);       <== ???
>> +        }
>> +
>> +        public synchronized void close() throws IOException {
>> +            if (fd != -1) {
>> +                close(fd);                  <== ???
>> +            }
>
> Looks like Windows needs a long fd so the shared API takes long and we then cast to int for the Unix native methods. A little messy but fixable.

> If you add read/close methods for Windows that then call readPipe/closePipe, then we don't need to subclass and override.

Sorry, I don't understand what this means. VirtualMachineImpl is platform-dependent while HotSpotVirtualMachine is shared, we always need to sub-class socket input stream in order to call platform-depend read/close.

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PR: https://git.openjdk.org/jdk/pull/11823