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LUCENE-10605: fix error in 32bit jvm object alignment gap calculation (#949)

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Sun WuQiang 2022-06-10 09:07:37 +08:00 committed by GitHub
parent b1eddec821
commit 26f21ae36d
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2 changed files with 13 additions and 7 deletions
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2
lucene/CHANGES.txt
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@ -99,6 +99,8 @@ Bug Fixes
* LUCENE-10563: Fix failure to tessellate complex polygon (Craig Taverner)
* LUCENE-10605: Fix error in 32bit jvm object alignment gap calculation (Sun Wuqiang)
Other
---------------------

18
lucene/core/src/java/org/apache/lucene/util/ArrayUtil.java
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@ -191,17 +191,21 @@ public final class ArrayUtil {
return newSize;
}
} else {
// round up to 4 byte alignment in 64bit env
// In 32bit jvm, it's still 8-byte aligned,
// but the array header is 12 bytes, not a multiple of 8.
// So saving 4,12,20,28... bytes of data is the most cost-effective.
switch (bytesPerElement) {
case 2:
// round up to multiple of 2
return (newSize + 1) & 0x7ffffffe;
case 1:
// round up to multiple of 4
return (newSize + 3) & 0x7ffffffc;
// align with size of 4,12,20,28...
return ((newSize + 3) & 0x7ffffff8) + 4;
case 2:
// align with size of 6,10,14,18...
return ((newSize + 1) & 0x7ffffffc) + 2;
case 4:
// align with size of 5,7,9,11...
return (newSize & 0x7ffffffe) + 1;
case 8:
// no rounding
// no processing required
default:
// odd (invalid?) size
return newSize;