This simple PR optimizes the observable `ArrayList` creation by using the
ArrayList constructor/array size so that the underlying array will be
initialized at the correct size which will speed up the creation as the array
does not need to grow as a result of the `addAll` call.
I also added tests which will succeed before and after to verify that nothing
got broken by this change.
Also I made a benchmark test. Results:
Old: `ListBenchmark.init thrpt 25 722,842 ± 26,930 ops/s`
New: `ListBenchmark.init thrpt 25 29262,274 ± 2088,712 ops/s`
<details><summary>Benchmark code</summary>
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.TearDown;
import java.util.ArrayList;
import java.util.List;
@State(Scope.Benchmark)
public class ListBenchmark {
List<String> strings;
@Setup
public void setup() {
strings = new ArrayList<>();
for(int i = 0; i< 100000;i++) {
strings.add("abc: " + i);
}
}
@TearDown
public void tearDown() {
strings = null;
}
@Benchmark
public ObservableList<String> init() {
return FXCollections.observableArrayList(strings);
}
}
</details>
-------------
Commit messages:
- 8283346: Optimized observable array list creation
Changes: https://git.openjdk.java.net/jfx/pull/758/files
Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=758&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8283346
Stats: 47 lines in 2 files changed: 41 ins; 2 del; 4 mod
Patch: https://git.openjdk.java.net/jfx/pull/758.diff
Fetch: git fetch https://git.openjdk.java.net/jfx pull/758/head:pull/758
PR: https://git.openjdk.java.net/jfx/pull/758
