Core: Parse floats in epoch millis parser (#34504)

In order to stay BWC compatible with joda time, the epoch millis date
formatter needs to parse dates with a dot like `123.45`. This
adds this functionality for the epoch millis parser in the same way as
for the epoch seconds parser. It also adds support for scientific
notations like `1.0e3` and fixes parsing of negative values for epoch
seconds and epoch millis.

server/src/main/java/org/elasticsearch/common/time/EpochMillisDateFormatter.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.common.time;
 
+import java.math.BigDecimal;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
@@ -27,6 +28,7 @@ import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalField;
 import java.util.Locale;
 import java.util.Map;
+import java.util.regex.Pattern;
 
 /**
  * This is a special formatter to parse the milliseconds since the epoch.
@@ -39,7 +41,8 @@ import java.util.Map;
  */
 class EpochMillisDateFormatter implements DateFormatter {
 
-    public static DateFormatter INSTANCE = new EpochMillisDateFormatter();
+    private static final Pattern SPLIT_BY_DOT_PATTERN = Pattern.compile("\\.");
+    static DateFormatter INSTANCE = new EpochMillisDateFormatter();
 
     private EpochMillisDateFormatter() {
     }
@@ -47,12 +50,33 @@ class EpochMillisDateFormatter implements DateFormatter {
     @Override
     public TemporalAccessor parse(String input) {
         try {
-            return Instant.ofEpochMilli(Long.valueOf(input)).atZone(ZoneOffset.UTC);
+            if (input.contains(".")) {
+                String[] inputs = SPLIT_BY_DOT_PATTERN.split(input, 2);
+                Long milliSeconds = Long.valueOf(inputs[0]);
+                if (inputs[1].length() == 0) {
+                    // this is BWC compatible to joda time, nothing after the dot is allowed
+                    return Instant.ofEpochMilli(milliSeconds).atZone(ZoneOffset.UTC);
+                }
+                // scientific notation it is!
+                if (inputs[1].contains("e")) {
+                    return Instant.ofEpochMilli(Double.valueOf(input).longValue()).atZone(ZoneOffset.UTC);
+                }
+
+                if (inputs[1].length() > 6) {
+                    throw new DateTimeParseException("too much granularity after dot [" + input + "]", input, 0);
+                }
+                Long nanos = new BigDecimal(inputs[1]).movePointRight(6 - inputs[1].length()).longValueExact();
+                if (milliSeconds < 0) {
+                    nanos = nanos * -1;
+                }
+                return Instant.ofEpochMilli(milliSeconds).plusNanos(nanos).atZone(ZoneOffset.UTC);
+            } else {
+                return Instant.ofEpochMilli(Long.valueOf(input)).atZone(ZoneOffset.UTC);
+            }
         } catch (NumberFormatException e) {
-            throw new DateTimeParseException("invalid number", input, 0, e);
+            throw new DateTimeParseException("invalid number [" + input + "]", input, 0, e);
         }
     }
-
     @Override
     public DateFormatter withZone(ZoneId zoneId) {
         if (ZoneOffset.UTC.equals(zoneId) == false) {

server/src/main/java/org/elasticsearch/common/time/EpochSecondsDateFormatter.java

@@ -47,10 +47,17 @@ public class EpochSecondsDateFormatter implements DateFormatter {
                     // this is BWC compatible to joda time, nothing after the dot is allowed
                     return Instant.ofEpochSecond(seconds, 0).atZone(ZoneOffset.UTC);
                 }
+                // scientific notation it is!
+                if (inputs[1].contains("e")) {
+                    return Instant.ofEpochSecond(Double.valueOf(input).longValue()).atZone(ZoneOffset.UTC);
+                }
                 if (inputs[1].length() > 9) {
                     throw new DateTimeParseException("too much granularity after dot [" + input + "]", input, 0);
                 }
                 Long nanos = new BigDecimal(inputs[1]).movePointRight(9 - inputs[1].length()).longValueExact();
+                if (seconds < 0) {
+                    nanos = nanos * -1;
+                }
                 return Instant.ofEpochSecond(seconds, nanos).atZone(ZoneOffset.UTC);
             } else {
                 return Instant.ofEpochSecond(Long.valueOf(input)).atZone(ZoneOffset.UTC);

server/src/test/java/org/elasticsearch/common/joda/JavaJodaTimeDuellingTests.java

@@ -77,11 +77,13 @@ public class JavaJodaTimeDuellingTests extends ESTestCase {
         assertSameDate("1", "epoch_second");
         assertSameDate("-1", "epoch_second");
         assertSameDate("-1522332219", "epoch_second");
+        assertSameDate("1.0e3", "epoch_second");
         assertSameDate("1522332219321", "epoch_millis");
         assertSameDate("0", "epoch_millis");
         assertSameDate("1", "epoch_millis");
         assertSameDate("-1", "epoch_millis");
         assertSameDate("-1522332219321", "epoch_millis");
+        assertSameDate("1.0e3", "epoch_millis");
 
         assertSameDate("20181126", "basic_date");
         assertSameDate("20181126T121212.123Z", "basic_date_time");

server/src/test/java/org/elasticsearch/common/time/DateFormattersTests.java

@@ -37,10 +37,55 @@ import static org.hamcrest.Matchers.sameInstance;
 
 public class DateFormattersTests extends ESTestCase {
 
+    // this is not in the duelling tests, because the epoch millis parser in joda time drops the milliseconds after the comma
+    // but is able to parse the rest
+    // as this feature is supported it also makes sense to make it exact
+    public void testEpochMillisParser() {
+        DateFormatter formatter = DateFormatters.forPattern("epoch_millis");
+        {
+            Instant instant = Instant.from(formatter.parse("12345.6789"));
+            assertThat(instant.getEpochSecond(), is(12L));
+            assertThat(instant.getNano(), is(345_678_900));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("12345"));
+            assertThat(instant.getEpochSecond(), is(12L));
+            assertThat(instant.getNano(), is(345_000_000));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("12345."));
+            assertThat(instant.getEpochSecond(), is(12L));
+            assertThat(instant.getNano(), is(345_000_000));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("-12345.6789"));
+            assertThat(instant.getEpochSecond(), is(-13L));
+            assertThat(instant.getNano(), is(1_000_000_000 - 345_678_900));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("-436134.241272"));
+            assertThat(instant.getEpochSecond(), is(-437L));
+            assertThat(instant.getNano(), is(1_000_000_000 - 134_241_272));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("-12345"));
+            assertThat(instant.getEpochSecond(), is(-13L));
+            assertThat(instant.getNano(), is(1_000_000_000 - 345_000_000));
+        }
+        {
+            Instant instant = Instant.from(formatter.parse("0"));
+            assertThat(instant.getEpochSecond(), is(0L));
+            assertThat(instant.getNano(), is(0));
+        }
+    }
+
     public void testEpochMilliParser() {
         DateFormatter formatter = DateFormatters.forPattern("epoch_millis");
         DateTimeParseException e = expectThrows(DateTimeParseException.class, () -> formatter.parse("invalid"));
         assertThat(e.getMessage(), containsString("invalid number"));
+
+        e = expectThrows(DateTimeParseException.class, () -> formatter.parse("123.1234567"));
+        assertThat(e.getMessage(), containsString("too much granularity after dot [123.1234567]"));
     }
 
     // this is not in the duelling tests, because the epoch second parser in joda time drops the milliseconds after the comma
@@ -61,6 +106,10 @@ public class DateFormattersTests extends ESTestCase {
         assertThat(Instant.from(formatter.parse("1234.1234567")).getNano(), is(123_456_700));
         assertThat(Instant.from(formatter.parse("1234.12345678")).getNano(), is(123_456_780));
         assertThat(Instant.from(formatter.parse("1234.123456789")).getNano(), is(123_456_789));
+
+        assertThat(Instant.from(formatter.parse("-1234.567")).toEpochMilli(), is(-1234567L));
+        assertThat(Instant.from(formatter.parse("-1234")).getNano(), is(0));
+
         DateTimeParseException e = expectThrows(DateTimeParseException.class, () -> formatter.parse("1234.1234567890"));
         assertThat(e.getMessage(), is("too much granularity after dot [1234.1234567890]"));
         e = expectThrows(DateTimeParseException.class, () -> formatter.parse("1234.123456789013221"));