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Hadoop >> mail # user >> how to unit test my RawComparator

Jane Wayne 2012-03-31, 04:23
Chris White 2012-03-31, 21:18
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Re: how to unit test my RawComparator

1. thanks, that approach to converting my custom key to byte[] works.

2. on the issue of pass by reference or pass by value, (it's been a while
since i've visited this issue), i'm pretty sure java is pass by value
(regardless of whether the parameters are primitives or objects). when i
put the code into debugger, the ids of byte[] b1 and byte[] b2 are equal.
if this is indeed the same byte array, why not just pass it as one
parameter instead of two? unless in some cases, b1 and b2 are not the same.
this second issue is not terribly too important, because the interface
defines two byte arrays to be passed in, and so there's not much i (we) can
do about it.

thanks for the help!

On Sat, Mar 31, 2012 at 5:18 PM, Chris White <[EMAIL PROTECTED]>wrote:

> You can serialize your Writables to a ByteArrayOutputStream and then
> get it's underlying byte array:
> ByteArrayOutputStream baos = new ByteArrayOutputStream();
> DataOutputStream dos = new DataOutputStream(baos);
> Writable myWritable = new Text("text");
> myWritable.write(dos);
> byte[] bytes = baos.toByteArray();
> I would recommend writing a few bytes to the DataOutputStream first -
> i always forget to respect the offset variables (s1 / s2), and this,
> depending on how well you write your unit test, should allow you to
> test that you are respecting them.
> The huge bytes arrays store the other Writables in the stream the are
> about to be run by the comparator.
> Finally, arrays in java are objects, so you're passing a reference to
> a byte array, not making a copy of the array.
> Chris
> On Sat, Mar 31, 2012 at 12:23 AM, Jane Wayne <[EMAIL PROTECTED]>
> wrote:
> > i have a RawComparator that i would like to unit test (using mockito and
> > mrunit testing packages). i want to test the method,
> >
> > public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2)
> >
> > how do i convert my custom key into a byte[] array? is there a util class
> > to help me do this?
> >
> > also, when i put the code into the debugger, i notice that the byte[]
> > arrays (b1 and b2) are HUGE (the lengths of each array are huge, in the
> > thousands). what is actually in these byte[] arrays? intuitively, it does
> > not seem like these byte[] arrays only represent my keys.
> >
> > lastly, why are such huge byte[] arrays being passed around? one would
> > think that since Java is pass-by-value, there would be a large overhead
> > with passing such large byte arrays around.
> >
> > your help is appreciated.
Chris White 2012-04-01, 17:33
Tom Melendez 2012-03-31, 22:50
Chris White 2012-03-31, 23:13