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Accumulo >> mail # dev >> Bug In Text Class - getLength() and getBytes().length are different.


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David Medinets 2012-11-13, 18:00
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Marc Parisi 2012-11-13, 18:13
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Keith Turner 2012-11-13, 18:13
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Re: Bug In Text Class - getLength() and getBytes().length are different.
This is not a bug. A Text object is a reusable object which prevents
repeated creation of byte arrays, so it will use the same byte array,
resizing it if necessary, and writing over the previous values. Doing any
operation based on Text.getBytes().length has a strong potential to provide
inaccurate results. Text.getLength() is the appropriate way to get the
length of the underlying byte array that you care about.

John
On Tue, Nov 13, 2012 at 1:00 PM, David Medinets <[EMAIL PROTECTED]>wrote:

> The following code (the TextTest class) displays:
>
> cq: [5000000000000000]
> cq: [16]
> cq: [16]
> cq: [5000000000000000]
> cq: [16]
> cq: [17]
>
> You'll notice that the last two numbers are different, but they should
> both be 16. This bug affects Accumulo because of the following code in
> Mutation:
>
>   private void put(byte b[]) {
>     buffer.writeVLong(b.length);
>     buffer.add(b, 0, b.length);
>   }
>
>   private void put(Text t) {
>     buffer.writeVLong(t.getLength());
>     buffer.add(t.getBytes(), 0, t.getLength());
>   }
>
> I should be able to call either of the following to get the same
> result but I can't.
>
>   put("5000000000000000".getBytes());
>   put(new Text("5000000000000000"));
>
> Has anyone else run into this issue? Any workarounds or fixes?
>
> ----
>
> package com.codebits.accumulo;
>
> import org.apache.hadoop.io.Text;
>
> public class TextTest {
>
>   public static void main(String[] args) {
>     String s = "5000000000000000";
>     System.out.println("cq: [" + s + "]");
>     System.out.println("cq: [" + s.length() + "]");
>     System.out.println("cq: [" + s.getBytes().length + "]");
>
>     Text cq = new Text(s);
>     System.out.println("cq: [" + cq + "]");
>     System.out.println("cq: [" + cq.getLength() + "]");
>     System.out.println("cq: [" + cq.getBytes().length + "]");
>   }
>
> }
>
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David Medinets 2012-11-13, 18:50