add date parsing method that returns epochMillis instead of date object

pdb-ui/src/test/java/org/lucares/pdbui/date/FastISODateParserTest.java

@@ -1,7 +1,17 @@
 package org.lucares.pdbui.date;
 
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.time.Instant;
 import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
 
 import org.testng.Assert;
 import org.testng.annotations.DataProvider;
@@ -43,7 +53,7 @@ public class FastISODateParserTest {
 	@Test(dataProvider = "providerValidDate")
 	public void testParseValidDate(final String date) {
 
-		final OffsetDateTime actualDate = FastISODateParser.parse(date);
+		final OffsetDateTime actualDate = new FastISODateParser().parse(date);
 
 		final OffsetDateTime expectedDate = OffsetDateTime.from(DateTimeFormatter.ISO_DATE_TIME.parse(date));
 		Assert.assertEquals(actualDate, expectedDate);
@@ -81,6 +91,104 @@ public class FastISODateParserTest {
 
 	@Test(expectedExceptions = IllegalArgumentException.class, dataProvider = "providerParseInvalidDate")
 	public void testParseInvalidDate(final String invalidDate) {
-		FastISODateParser.parse(invalidDate);
+		new FastISODateParser().parse(invalidDate);
+	}
+
+	@DataProvider(name = "providerDateToTimestamp")
+	public Object[][] providerDateToTimestamp() {
+		return new Object[][] { //
+				{ "2018-11-18T14:42:49.123Z" }, //
+				// There are no leap seconds in java-time:
+				// In reality, UTC has a leap second 2016-12-31T23:59:60Z, but java handles
+				// this differently. This makes it a little bit easier for us, because we do not
+				// have to handle this.
+				{ "2016-12-31T23:59:59.999Z" }, // before leap second
+				{ "2017-01-01T00:00:00.000Z" }, // after leap second
+
+				// normal leap days exist
+				{ "2016-02-28T23:59:59.999Z" }, // before leap day
+				{ "2016-02-29T00:00:00.000Z" }, // leap day
+				{ "2016-02-29T23:59:59.999Z" }, // leap day
+				{ "2016-03-01T00:00:00.000Z" }, // after leap day
+
+				// dates with non-UTC timezones
+				{ "2018-11-18T14:42:49.123+12:34" }, //
+				{ "2018-11-18T02:34:56.123+12:34" }, //
+
+				// dates with non-UTC timezones and leap days
+				{ "2016-02-29T00:59:59.999+01:00" }, // before leap day
+				{ "2016-02-29T01:00:00.000+01:00" }, // leap day
+				{ "2016-03-01T00:59:59.999+01:00" }, // leap day
+				{ "2016-03-01T01:00:00.000+01:00" }, // after leap day
+		};
+	}
+
+	@Test(dataProvider = "providerDateToTimestamp")
+	public void testDateToTimestamp(final String date) {
+
+		final long actualEpochMilli = new FastISODateParser().parseAsTimestamp(date);
+
+		final OffsetDateTime expectedDate = OffsetDateTime.from(DateTimeFormatter.ISO_DATE_TIME.parse(date));
+		final long expectedEpochMilli = expectedDate.toInstant().toEpochMilli();
+		Assert.assertEquals(actualEpochMilli, expectedEpochMilli);
+	}
+
+	@Test(enabled = false)
+	public void test() {
+
+		final OffsetDateTime expectedDate = OffsetDateTime
+				.from(DateTimeFormatter.ISO_DATE_TIME.parse("2016-12-31T23:00:00.000Z"));
+
+		final long epochMilli = expectedDate.toInstant().toEpochMilli();
+
+		for (int i = 0; i < 1000; i++) {
+
+			final long timestamp = epochMilli + i * 10000;
+			final OffsetDateTime date = Instant.ofEpochMilli(timestamp).atOffset(ZoneOffset.UTC);
+
+			System.out.println(timestamp + " " + date.format(DateTimeFormatter.ISO_OFFSET_DATE_TIME));
+		}
+	}
+
+	public static void main(final String[] args) throws IOException, InterruptedException {
+		final Path path = Path.of("/home/andi/ws/performanceDb/data/production/dates2.csv");
+
+		for (int i = 0; i < 15; i++) {
+			final List<String> dates = new ArrayList<>();
+
+			try (final BufferedReader reader = new BufferedReader(
+					new FileReader(path.toFile(), StandardCharsets.UTF_8))) {
+				String line;
+				while ((line = reader.readLine()) != null) {
+					dates.add(line);
+				}
+			}
+
+			System.gc();
+			TimeUnit.MILLISECONDS.sleep(100);
+			System.gc();
+			TimeUnit.MILLISECONDS.sleep(100);
+			System.gc();
+			TimeUnit.MILLISECONDS.sleep(100);
+			System.gc();
+
+			TimeUnit.SECONDS.sleep(1);
+
+			final long start = System.nanoTime();
+			final FastISODateParser fastISODateParser = new FastISODateParser();
+
+			for (final String date : dates) {
+				fastISODateParser.parseAsTimestamp(date);
+				// final long timestamp =
+				// fastISODateParser.parse(date).toInstant().toEpochMilli();
+//					final long timestamp = OffsetDateTime.parse(date, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+//							.toInstant().toEpochMilli();
+				// sum += timestamp;
+			}
+
+			final double millis = (System.nanoTime() - start) / 1_000_000.0;
+			final long datesPerSecond = (long) (dates.size() / (millis / 1000.0));
+			System.out.println("duration: " + millis + "ms ; speed: " + datesPerSecond + " dates/s");
+		}
 	}
 }