DefaultTuple(List) constructor is inefficient, causes List.size()
System.arraycopy() calls (though they are 0 byte copies), DefaultTuple(int)
constructor is a bit misleading wrt time complexity
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Key: PIG-2001
URL: https://issues.apache.org/jira/browse/PIG-2001
Project: Pig
Issue Type: Improvement
Components: impl
Affects Versions: 0.8.0, 0.9.0
Reporter: Woody Anderson
Assignee: Woody Anderson
Priority: Minor
Fix For: 0.10
I was perusing the Tuple created by the default Tuple factory, when I wanted it
to copy my input list.
here i noticed that the List constructor uses List.add(index, element), which
is different from set(index, element) in that it shifts the right side of the
list, with ArrayList this causes an no-op System.arraycopy call which is
completely unnecessary.
Even though the array copy call isn't actually copying any bytes, it's still
unnecessary, and can be easily avoided.
it's also N iterate/add function calls, that can be avoided by using:
{code}
new ArrayList<Object>(c);
{code}
which, is more efficient. For arbitrary collection inputs this is at worst N
iterator calls (same as existing code); when constructing from ArrayLists or
Arrays.asList, the construction is accomplished via a single System.arraycopy
call, which is an actual improvement.
There do not seem to be DefaultTuple tests.
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