Skip to content

toByteArray should return a copy not a reference#3729

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Fokko merged 3 commits into from
Aug 31, 2026
+7 −24
Merged

toByteArray should return a copy not a reference #3729

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
7cd4c21
BytesInput.copy(BytesInput) should return a copy
dossett Aug 17, 2026
455e12b
make tests clearer
dossett Aug 26, 2026
ce79ef3
Remove unsafe BytesInput toByteArray override
dossett Aug 31, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
15 changes: 0 additions & 15 deletions parquet-common/src/main/java/org/apache/parquet/bytes/BytesInput.java
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -690,21 +690,6 @@ public ByteBuffer toByteBuffer() throws IOException {
return java.nio.ByteBuffer.wrap(in, offset, length);
}

/**
* Zero-copy override: returns the backing array directly when fully used,
* skipping the base-class BAOS allocation + copy on every decompressor call.
* Returning the mutable array is safe — the base class already exposes a
* mutable {@code BAOS.getBuf()}.

@dossettdossettAug 17, 2026

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think Returning the mutable array is safe is the key. The array was mutable before, but it was a mutable copy of the original array.

@FokkoFokkoAug 31, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Should we revert the whole toByteArray method? This effectively reverts the part in:

https://github.com/apache/parquet-java/pull/3565/changes#diff-49155017f14a28333fad01fe81e8c7cd353cdc73824360db5d8ba15b7e7dd6daR693-R707

It is also deprecated

@dossettdossettAug 31, 2026

Copy link
Copy Markdown
ContributorAuthor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Done!

*/
@SuppressWarnings("deprecation")
@Override
public byte[] toByteArray() {
if (offset == 0 && length == in.length) {
return in;
}
return Arrays.copyOfRange(in, offset, offset + length);
}

@Override
public long size() {
return length;
Expand Down
16 changes: 7 additions & 9 deletions parquet-common/src/test/java/org/apache/parquet/bytes/TestBytesInput.java
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -123,16 +123,14 @@ public void testFromByteArray(ByteBufferAllocator innerAllocator) throws IOExcep

@ParameterizedTest(name = "{0}")
@MethodSource("parameters")
public void testFromByteArrayToByteArrayZeroCopy(ByteBufferAllocator innerAllocator) throws IOException {
public void testCopyDoesNotAliasSourceBytes(ByteBufferAllocator innerAllocator) throws IOException {
initAllocator(innerAllocator);
// Full array (offset=0, length=array.length): toByteArray() returns the backing array directly
byte[] data = new byte[1000];
RANDOM.nextBytes(data);
BytesInput bi = BytesInput.from(data, 0, data.length);
byte[] result = bi.toByteArray();
assertThat(result)
.as("toByteArray() should return the backing array when offset=0 and length=full")
.isSameAs(data);
byte[] source = {'a'};
BytesInput copied = BytesInput.copy(BytesInput.from(source));

source[0] = 'b';

assertThat(copied.toByteArray()).isEqualTo(new byte[] {'a'});
}

@ParameterizedTest(name = "{0}")
Expand Down
Loading