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Posted to issues@drill.apache.org by "Paul Rogers (JIRA)" <ji...@apache.org> on 2017/05/08 22:42:04 UTC
[jira] [Updated] (DRILL-5488) Useless code in VectorTrimmer
[ https://issues.apache.org/jira/browse/DRILL-5488?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Paul Rogers updated DRILL-5488:
-------------------------------
Description:
Consider this code in a generated fixed-width vector, such as UInt4Vector:
{code}
@Override
public void setValueCount(int valueCount) {
...
final int idx = (VALUE_WIDTH * valueCount);
...
VectorTrimmer.trim(data, idx);
data.writerIndex(valueCount * VALUE_WIDTH);
}
{code}
Consider the {{trim()}} method:
{code}
public class VectorTrimmer {
...
public static void trim(ByteBuf data, int idx) {
data.writerIndex(idx);
if (data instanceof DrillBuf) {
// data.capacity(idx);
data.writerIndex(idx);
}
}
}
{code}
This method is called {{trim}}, but it actually sets the writer index in the buffer (though we never use that index.) Since all buffers we use are {{DrillBuf}}, the if-statement is a no-op: we simply set the writer index twice.
But, notice that the {{setValueCount()}} method itself calls the same {{writerIndex()}} method, so it is actually being called three times.
It seems this code can simply be discarded: it is called from only two places; neither of which end up using the writer index.
was:
Consider this code in a generated fixed-width vector, such as UInt4Vector:
{code}
@Override
public void setValueCount(int valueCount) {
...
final int idx = (VALUE_WIDTH * valueCount);
...
VectorTrimmer.trim(data, idx);
data.writerIndex(valueCount * VALUE_WIDTH);
}
{code}
Consider the {{trim()}} method:
{code}
public class VectorTrimmer {
...
public static void trim(ByteBuf data, int idx) {
data.writerIndex(idx);
if (data instanceof DrillBuf) {
// data.capacity(idx);
data.writerIndex(idx);
}
}
}
{code}
This method is called {{trim}}, but it actually sets the writer index in the buffer (though we never use that index.) Since all buffers we use are {{DrillBuf}}, the if-statement is a no-op: we simply set the writer index twice.
It seems this code can simply be discarded: it is called from only two places; neither of which end up using the writer index.
> Useless code in VectorTrimmer
> -----------------------------
>
> Key: DRILL-5488
> URL: https://issues.apache.org/jira/browse/DRILL-5488
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.10.0
> Reporter: Paul Rogers
> Priority: Trivial
>
> Consider this code in a generated fixed-width vector, such as UInt4Vector:
> {code}
> @Override
> public void setValueCount(int valueCount) {
> ...
> final int idx = (VALUE_WIDTH * valueCount);
> ...
> VectorTrimmer.trim(data, idx);
> data.writerIndex(valueCount * VALUE_WIDTH);
> }
> {code}
> Consider the {{trim()}} method:
> {code}
> public class VectorTrimmer {
> ...
> public static void trim(ByteBuf data, int idx) {
> data.writerIndex(idx);
> if (data instanceof DrillBuf) {
> // data.capacity(idx);
> data.writerIndex(idx);
> }
> }
> }
> {code}
> This method is called {{trim}}, but it actually sets the writer index in the buffer (though we never use that index.) Since all buffers we use are {{DrillBuf}}, the if-statement is a no-op: we simply set the writer index twice.
> But, notice that the {{setValueCount()}} method itself calls the same {{writerIndex()}} method, so it is actually being called three times.
> It seems this code can simply be discarded: it is called from only two places; neither of which end up using the writer index.
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