RFR: 8292562: (fc) Use copy_file_range in FileChannel::transferTo on Linux
Alan Bateman
alanb at openjdk.org
Fri Aug 19 06:47:44 UTC 2022
On Thu, 18 Aug 2022 18:50:30 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:
> Add `copy_file_range(2)` to the native Linux implementation of `FileChannel::transferTo`.
src/java.base/unix/native/libnio/ch/FileChannelImpl.c line 182:
> 180: jlong n;
> 181: if (my_copy_file_range_func != NULL) {
> 182: n = my_copy_file_range_func(srcFD, &offset, dstFD, NULL, count, 0);
I assume count will need to be cast to size_t for this to compile on all architectures.
src/java.base/unix/native/libnio/ch/FileChannelImpl.c line 186:
> 184: switch (errno) {
> 185: case EINTR:
> 186: case EINVAL:
For EINVAL we could return IOS_INTERRUPTED if you want.
src/java.base/unix/native/libnio/ch/FileChannelImpl.c line 192:
> 190: default:
> 191: JNU_ThrowIOExceptionWithLastError(env, "Copy failed");
> 192: return IOS_THROWN;
Would you mind checking if we have tests that exercise transferTo when the target WritableByteChannel is to a file opened in append mode? Asking because copy_file_range will fall and I'm wondering what the existing behavior is.
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PR: https://git.openjdk.org/jdk/pull/9925
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