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netty: Eliminate buffer release when there is an error as caller still owns the buffer. #10537

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merged 6 commits into from
Sep 15, 2023
Original file line number Diff line number Diff line change
Expand Up @@ -204,16 +204,9 @@ static void mergeWithCompositeTail(
composite.addFlattenedComponents(true, newTail);
// New tail's ownership transferred to the composite buf.
newTail = null;
in.release();
in = null;
// Restore the reader. In case it fails we restore the reader after releasing/forgetting
// the input and the new tail so that finally block can handles them properly.
composite.readerIndex(prevReader);
in.release(); // Successful so took over ownership of in
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} finally {
// Input buffer was merged with the tail.
if (in != null) {
in.release();
}
// If new tail's ownership isn't transferred to the composite buf.
// Release it to prevent a leak.
if (newTail != null) {
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Original file line number Diff line number Diff line change
Expand Up @@ -536,8 +536,8 @@ public CompositeByteBuf addFlattenedComponents(boolean increaseWriterIndex,
fail("Cumulator didn't throw");
} catch (UnsupportedOperationException actualError) {
assertSame(expectedError, actualError);
// Input must be released unless its ownership has been to the composite cumulation.
assertEquals(0, in.refCnt());
// Because of error, ownership shouldn't have changed so should not have been released.
assertEquals(1, in.refCnt());
// Tail released
assertEquals(0, tail.refCnt());
// Composite cumulation is retained
Expand All @@ -546,6 +546,7 @@ public CompositeByteBuf addFlattenedComponents(boolean increaseWriterIndex,
assertEquals(0, compositeThrows.numComponents());
} finally {
compositeThrows.release();
in.release();
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I think we should keep it abovefail("Cumulator didn't throw");

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It is expected the in the case of an error that the ownership remained with the calling method so it is this method's responsibility to do the release.

}
}

Expand All @@ -572,8 +573,8 @@ public CompositeByteBuf addFlattenedComponents(boolean increaseWriterIndex,
fail("Cumulator didn't throw");
} catch (UnsupportedOperationException actualError) {
assertSame(expectedError, actualError);
// Input must be released unless its ownership has been to the composite cumulation.
assertEquals(0, in.refCnt());
// Because of error, ownership shouldn't have changed so should not have been released.
assertEquals(1, in.refCnt());
// New buffer released
assertEquals(0, newTail.refCnt());
// Composite cumulation is retained
Expand All @@ -582,6 +583,7 @@ public CompositeByteBuf addFlattenedComponents(boolean increaseWriterIndex,
assertEquals(0, compositeRo.numComponents());
} finally {
compositeRo.release();
in.release();
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I think we should keep it abovefail("Cumulator didn't throw");

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We need to release when there is an error since the new paradigm is that only successes change ownership.

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Discussed IRL, we do want to move it, but to another place

}
}
}
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