SortedList, now faster

• FilterList's Barcode simply stores boolean 'filtered' or 'unfiltered' state and provides methods to convert between filtered and unfiltered indices.
• SortedList's IndexedTree allows nodes to be inserted either by index or in sorted order using a comparator. Individual nodes in an otherwise sorted tree can be made unsorted in order to preserve the location of edited values.
• ListEvent's BC2 Tree stores nodes in one of four states - inserted, updated, deleted and unchanged. In addition, it needs to offset between the 'before' tree and the 'after' tree. In the future we plan to store deleted elements in the nodes.

1. give up, go back to IndexedTree
2. accept the performance regression
3. cut and paste the BC2.java class and strip out the unneeded fields

The result of all my hackery? SortedList is 5-10% faster than before.

# posted by Jesse Wilson on Sunday, June 25, 2006  0 comments   post a comment

Wanna download iTunes shared tracks? Get Git!

# posted by Jesse Wilson on Saturday, June 24, 2006  1 comments   post a comment

Using m4 as a macro processor for Java, the nice way

public class HelloNTimes {
    public static void main(String[] args) {
        forloop(`i', 1, HELLO_COUNT, `System.out.println("Hello i");
        ')
    }
}

public class HelloNTimes {
    public static void main(String[] args) {
        System.out.println("Hello 1");
        System.out.println("Hello 2");
        System.out.println("Hello 3");
        System.out.println("Hello 4");
    }
}

public class HelloNTimes {
    public static void main(String[] args) {
        /* BEGIN_M4_MACRO
        forloop(`i', 1, HELLO_COUNT, `System.out.println("Hello i");
        ')
        END_M4_MACRO */
        // BEGIN_M4_ALTERNATE
        System.out.println("Hello 1");
        System.out.println("Hello 2");
        // END_M4_ALTERNATE
    }
}

define(`BEGIN_M4_MACRO', ` BEGIN M4 MACRO GENERATED CODE *'`/')
define(`END_M4_MACRO', `/'`* END M4 MACRO GENERATED CODE ')
define(`BEGIN_M4_ALTERNATE', `BEGIN M4 ALTERNATE CODE
/'`* ')
define(`END_M4_ALTERNATE', `END ALTERNATE CODE *'`/')

public class HelloNTimes {
    public static void main(String[] args) {
        /*  BEGIN M4 MACRO GENERATED CODE */
        System.out.println("Hello 1");
        System.out.println("Hello 2");
        System.out.println("Hello 3");
        System.out.println("Hello 4");
        
        /* END M4 MACRO GENERATED CODE  */ 
        // BEGIN M4 ALTERNATE CODE
/* 
        System.out.println("Hello 1");
        System.out.println("Hello 2");
        // END ALTERNATE CODE */
    }
}

Fine grained events: for performance

JSR 295: the future of observable lists?

# posted by Jesse Wilson on Tuesday, June 13, 2006  0 comments   post a comment

Why there's no String.getCharset()

byte[] characters = { 83, 87, 65, 78, 75, 46, 67, 65 };
String myString = new String(characters, "ISO 8859-1");

byte[] theBytes = myString.getBytes();
String theCharset = myString.getCharsetName()

public static String decodeBytes(byte[], charset)

Tuning Java Performance? Think Japex

Repeat the tests. If my change turns out to be slower, I check out the original implementation from CVS and redo the executions to confirm the data in the spreadsheet. Finally, I rollback the change.

But there hasn't really been alternatives to this ad-hoc approach. Although tools like Netbeans Profiler and JProbe can analyze the performance of a single component, they're not good at comparing different implementations of the same component because they only work with one implementation at a time.

Enter Japex. This fantastic tool is to performance testing what JUnit is to unit testing. Here's my new strategy, which is a much more efficient:

Canonical path of a file in Bash

#!/bin/bash
cd -P -- "$(dirname -- "$1")" &&
printf '%s\n' "$(pwd -P)/$(basename -- "$1")"

chixdiglinux:jessewilson$ canonicalize ./bash_profile
/Users/jessewilson/.bash_profile
chixdiglinux:jessewilson$ export JESSES_PROFILE=`canonicalize ./bash_profile`
chixdiglinux:jessewilson$ cd ~kevinmaltby
chixdiglinux:kevinmaltby$ diff $JESSES_PROFILE ./bash_profile
....

# posted by Jesse Wilson on Sunday, June 04, 2006  6 comments   post a comment