In case of key collision broken implementation will likely attribute
measurements to the wrong key and therefore it is better to have
non-zero value to end up with a wrong average value.
When all measurements are zero then averages are also zero even
when attributed to the wrong keys.
Updates #91
* Added tests for endian-calculations (had these in a different class, perhaps handy for others to see as well)
Inlined the hash function, runs locally in 2.4sec now, hopefully endian issues fix
Added equals to support any city name up to 1024 in length, don't rely on hash
* For clarity I've updated the code so endian doesn't change the hashes, easier to debug.
* Fixing bug in array check
Simple is faster
* Also spotted the diff, not just the big exception
Fixed buffer limit issue
Input created via
```sh
bash -c 'for i in {1..10000} ; do echo "id$i;0.0" ; done' >./src/test/resources/samples/measurements-10000-unique-keys.txt
```
and output via baseline implementation.
Keys are short and very similar which improves chances for collision
and hence are good for testing.
Fixes#91
* Use open-addressing scheme to deal with hash table collisions. Reduce concurrency from 16 to 8. Use bit mask rather than mod operator to confine hash code to table range.
* Properly handle file partitions that reside entirely within a line.
* Reorder statements in doProcessBuffer.
Adds test samples that can be used for unit tests or to verify
implementations via:
```bash
for sample in $(ls src/test/resources/samples/*.txt)
do
echo "Validating $sample"
rm -f measurements.txt
ln -s $sample measurements.txt
diff <(./calculate_average.sh) ${sample%.txt}.out
done
rm measurements.txt
```
For #61
Added SWAR (SIMD Within A Register) code to increase bytebuffer processing/throughput
Delaying the creation of the String by comparing hash, segmenting like spullara, improved EOL finding
Co-authored-by: Gunnar Morling <gunnar.morling@googlemail.com>
* Initial implementation using Shenandoah GC and parallel iteration
* Use memory mapped files
* Iterate the buffer once and use BigDecimal parsing instead of Double.parseDouble
* Add information about Graal
* Add sdk use to calculate script
* Memory mapped file, single-pass parsing, custom hash map, fixed thread pool
The threading was a hasty addition and needs work
* Used arraylist instead of treemap to reduce a little overhead
We only need it sorted for output, so only construct a treemap for output
* Attempt to speed up double conversion
* Cap core count for low-core systems
* Fix wrong exponent
* Accumulate measurement value in double, seems marginally faster
Benchmark Mode Cnt Score Error Units
DoubleParsingBenchmark.ourToDouble thrpt 10 569.771 ± 7.065 ops/us
DoubleParsingBenchmark.ourToDoubleAccumulateInToDouble thrpt 10 648.026 ± 7.741 ops/us
DoubleParsingBenchmark.ourToDoubleDivideInsteadOfMultiply thrpt 10 570.412 ± 9.329 ops/us
DoubleParsingBenchmark.ourToDoubleNegative thrpt 10 512.618 ± 8.580 ops/us
DoubleParsingBenchmark.ourToDoubleNegativeAccumulateInToDouble thrpt 10 565.043 ± 18.137 ops/us
DoubleParsingBenchmark.ourToDoubleNegativeDivideInsteadOfMultiply thrpt 10 511.228 ± 13.967 ops/us
DoubleParsingBenchmark.stringToDouble thrpt 10 52.310 ± 1.351 ops/us
DoubleParsingBenchmark.stringToDoubleNegative thrpt 10 50.785 ± 1.252 ops/us
