On 09/09/21 12:51 am, Stuart Marks wrote:
On Wed, 8 Sep 2021 09:32:55 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
Jaikiran Pai has updated the pull request incrementally with two additional
commits since the last revision:
- adjust testcases to verify the new semantics
- implement review suggestions:
- Use doPriveleged instead of explicit permission checks, to reduce
complexity
- Use DateTimeFormatter and ZonedDateTime instead of Date.toString()
- Use DateTimeFormatter.RFC_1123_DATE_TIME for formatting
SOURCE_DATE_EPOCH dates
- Use Arrays.sort instead of a TreeMap for ordering property keys
src/java.base/share/classes/java/util/Properties.java line 963:
961: synchronized (this) {
962: var entries = map.entrySet().toArray(new Map.Entry<?, ?>[0]);
963: Arrays.sort(entries, new Comparator<Map.Entry<?, ?>>() {
This part here, intentionally doesn't use a lambda, since from what I remember
seeing in some mail discussion, it was suggested that using lambda in core
parts which get used very early during JVM boostrap, should be avoided. If
that's not a concern here, do let me know and I can change it to a lambda.
This is a fair concern, but writing out a properties file is a pretty
high-level operation that doesn't seem likely to be used during bootstrap.
Also, I observe that the `doPrivileged` block above uses a lambda. So I think
we're probably ok to use a lambda here. But if you get an inexplicable error at
build time or at startup time, this would be the reason why.
Good catch about the doPriveleged block currently using the lambda. I
had overlooked that part.
Assuming we're ok with lambdas, it might be easier to use collections instead
of arrays in order to preserve generic types.
That usage of lambda in doPriveleged hasn't caused any issues (due to
the lazy/delayed implementation this PR uses to parse the environment
variable). So I think using lambdas in the store() implementation should
be fine then.
Unfortunately the map is `Map<Object, Object>` so we have to do some fancy
casting to get the right type. But then we can use `Map.Entry.comparingByKey()` as
the comparator. (Note that this uses lambda internally.)
Something like this might work:
@SuppressWarnings("unchecked")
var entries = new ArrayList<>(((Map<String,
String>)(Map)map).entrySet());
entries.sort(Map.Entry.comparingByKey());
Thank you for this snippet (learned something new :)). I've now updated
the PR to use this version instead of the Arrays.sort(...) one. I've
rerun a modified JMH benchmark, comparing this version with the
Arrays.sort(...) version and this one performs slightly better too, so
performance shouldn't be a concern here.
package org.myapp;
import org.openjdk.jmh.annotations.Benchmark;
import java.util.*;
import java.util.concurrent.*;
import org.openjdk.jmh.annotations.*;
public class MyBenchmark {
@State(Scope.Thread)
public static class TestData {
static final Map<Object, Object> tenItems;
static final Map<Object, Object> hundredItems;
static final Map<Object, Object> thousandItems;
static {
tenItems = new ConcurrentHashMap<>(8);
hundredItems = new ConcurrentHashMap<>(8);
thousandItems = new ConcurrentHashMap<>(8);
for (int i = 0; i < 1000; i++) {
thousandItems.put("foo" + i, "bar");
if (i < 100) {
hundredItems.put("hello" + i, "world");
}
if (i < 10) {
tenItems.put("good" + i, "morning");
}
}
System.out.println("Test data created with " +
tenItems.size() + ", "
+ hundredItems.size() + " and " + thousandItems.size()
+ " Map keys");
}
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testTenItemsCollectionSorting(TestData testData) {
@SuppressWarnings("unchecked")
var entries = new ArrayList<>(((Map<String, String>) (Map)
testData.tenItems).entrySet());
entries.sort(Map.Entry.comparingByKey());
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testHundredItemsCollectionSorting(TestData testData) {
@SuppressWarnings("unchecked")
var entries = new ArrayList<>(((Map<String, String>) (Map)
testData.hundredItems).entrySet());
entries.sort(Map.Entry.comparingByKey());
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testThousandItemsCollectionSorting(TestData testData) {
@SuppressWarnings("unchecked")
var entries = new ArrayList<>(((Map<String, String>) (Map)
testData.thousandItems).entrySet());
entries.sort(Map.Entry.comparingByKey());
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testTenItemsArraySorting(TestData testData) {
var entries = testData.tenItems.entrySet().toArray(new
Map.Entry<?, ?>[0]);
Arrays.sort(entries, new Comparator<Map.Entry<?, ?>>() {
@Override
public int compare(Map.Entry<?, ?> o1, Map.Entry<?, ?> o2) {
return ((String) o1.getKey()).compareTo((String)
o2.getKey());
}
});
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testHundredItemsArraySorting(TestData testData) {
var entries = testData.hundredItems.entrySet().toArray(new
Map.Entry<?, ?>[0]);
Arrays.sort(entries, new Comparator<Map.Entry<?, ?>>() {
@Override
public int compare(Map.Entry<?, ?> o1, Map.Entry<?, ?> o2) {
return ((String) o1.getKey()).compareTo((String)
o2.getKey());
}
});
}
@Benchmark
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void testThousandItemsArraySorting(TestData testData) {
var entries = testData.thousandItems.entrySet().toArray(new
Map.Entry<?, ?>[0]);
Arrays.sort(entries, new Comparator<Map.Entry<?, ?>>() {
@Override
public int compare(Map.Entry<?, ?> o1, Map.Entry<?, ?> o2) {
return ((String) o1.getKey()).compareTo((String)
o2.getKey());
}
});
}
}
Benchmark Mode Cnt Score Error
Units
MyBenchmark.testHundredItemsArraySorting avgt 25 8.375 ±
0.119 us/op
MyBenchmark.testHundredItemsCollectionSorting avgt 25 7.608 ±
0.118 us/op
MyBenchmark.testTenItemsArraySorting avgt 25 0.261 ±
0.004 us/op
MyBenchmark.testTenItemsCollectionSorting avgt 25 0.234 ±
0.004 us/op
MyBenchmark.testThousandItemsArraySorting avgt 25 150.934 ±
2.865 us/op
MyBenchmark.testThousandItemsCollectionSorting avgt 25 149.356 ±
4.381 us/op
-Jaikiran
