Parse composite patterns using ClassicFormat.parseObject (#40100)

Java-time fails parsing composite patterns when first pattern matches only the prefix of the input. It expects pattern in longest to shortest order. Because of this constructing just one DateTimeFormatter with appendOptional is not sufficient. Parsers have to be iterated and if the parsing fails, the next one in order should be used. In order to not degrade performance parsing should not be throw exceptions on failure. Format.parseObject was used as it only returns null when parsing failed and allows to check if full input was read.
 
closes #39916

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

@@ -1585,7 +1585,7 @@ public class DateFormatters {
             if (printer == null) {
                 printer = javaDateFormatter.getPrinter();
             }
-            dateTimeFormatters.add(javaDateFormatter.getParser());
+            dateTimeFormatters.addAll(javaDateFormatter.getParsers());
             roundupBuilder.appendOptional(javaDateFormatter.getRoundupParser());
         }
         DateTimeFormatter roundUpParser = roundupBuilder.toFormatter(Locale.ROOT);
@@ -1632,7 +1632,7 @@ public class DateFormatters {
         if (zoneId == null) {
             zoneId = ZoneOffset.UTC;
         }
-        
+
         LocalDate localDate = accessor.query(TemporalQueries.localDate());
         LocalTime localTime = accessor.query(TemporalQueries.localTime());
         boolean isLocalDateSet = localDate != null;

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

@@ -21,6 +21,7 @@ package org.elasticsearch.common.time;
 
 import org.elasticsearch.common.Strings;
 
+import java.text.ParsePosition;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeFormatterBuilder;
@@ -29,7 +30,10 @@ import java.time.temporal.ChronoField;
 import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalField;
 import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
@@ -39,6 +43,7 @@ class JavaDateFormatter implements DateFormatter {
 
     // base fields which should be used for default parsing, when we round up for date math
     private static final Map<TemporalField, Long> ROUND_UP_BASE_FIELDS = new HashMap<>(6);
+
     {
         ROUND_UP_BASE_FIELDS.put(ChronoField.MONTH_OF_YEAR, 1L);
         ROUND_UP_BASE_FIELDS.put(ChronoField.DAY_OF_MONTH, 1L);
@@ -50,22 +55,15 @@ class JavaDateFormatter implements DateFormatter {
 
     private final String format;
     private final DateTimeFormatter printer;
-    private final DateTimeFormatter parser;
+    private final List<DateTimeFormatter> parsers;
     private final DateTimeFormatter roundupParser;
 
-    private JavaDateFormatter(String format, DateTimeFormatter printer, DateTimeFormatter roundupParser, DateTimeFormatter parser) {
-        this.format = format;
-        this.printer = printer;
-        this.roundupParser = roundupParser;
-        this.parser = parser;
-    }
-
     JavaDateFormatter(String format, DateTimeFormatter printer, DateTimeFormatter... parsers) {
         this(format, printer, builder -> ROUND_UP_BASE_FIELDS.forEach(builder::parseDefaulting), parsers);
     }
 
     JavaDateFormatter(String format, DateTimeFormatter printer, Consumer<DateTimeFormatterBuilder> roundupParserConsumer,
-                              DateTimeFormatter... parsers) {
+                      DateTimeFormatter... parsers) {
         if (printer == null) {
             throw new IllegalArgumentException("printer may not be null");
         }
@@ -79,26 +77,21 @@ class JavaDateFormatter implements DateFormatter {
         }
         this.printer = printer;
         this.format = format;
+
         if (parsers.length == 0) {
-            this.parser = printer;
-        } else if (parsers.length == 1) {
-            this.parser = parsers[0];
+            this.parsers = Collections.singletonList(printer);
         } else {
-            DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder();
-            for (DateTimeFormatter parser : parsers) {
-                builder.appendOptional(parser);
-            }
-            this.parser = builder.toFormatter(Locale.ROOT);
+            this.parsers = Arrays.asList(parsers);
         }
 
         DateTimeFormatterBuilder builder = new DateTimeFormatterBuilder();
         if (format.contains("||") == false) {
-            builder.append(this.parser);
+            builder.append(this.parsers.get(0));
         }
         roundupParserConsumer.accept(builder);
-        DateTimeFormatter roundupFormatter = builder.toFormatter(parser.getLocale());
+        DateTimeFormatter roundupFormatter = builder.toFormatter(locale());
         if (printer.getZone() != null) {
-            roundupFormatter = roundupFormatter.withZone(printer.getZone());
+            roundupFormatter = roundupFormatter.withZone(zone());
         }
         this.roundupParser = roundupFormatter;
     }
@@ -107,10 +100,6 @@ class JavaDateFormatter implements DateFormatter {
         return roundupParser;
     }
 
-    DateTimeFormatter getParser() {
-        return parser;
-    }
-
     DateTimeFormatter getPrinter() {
         return printer;
     }
@@ -122,30 +111,64 @@ class JavaDateFormatter implements DateFormatter {
         }
 
         try {
-            return parser.parse(input);
+            return doParse(input);
         } catch (DateTimeParseException e) {
             throw new IllegalArgumentException("failed to parse date field [" + input + "] with format [" + format + "]", e);
         }
     }
 
+    /**
+     * Attempt parsing the input without throwing exception. If multiple parsers are provided,
+     * it will continue iterating if the previous parser failed. The pattern must fully match, meaning whole input was used.
+     * This also means that this method depends on <code>DateTimeFormatter.ClassicFormat.parseObject</code>
+     * which does not throw exceptions when parsing failed.
+     *
+     * The approach with collection of parsers was taken because java-time requires ordering on optional (composite)
+     * patterns. Joda does not suffer from this.
+     * https://bugs.openjdk.java.net/browse/JDK-8188771
+     *
+     * @param input An arbitrary string resembling the string representation of a date or time
+     * @return a TemporalAccessor if parsing was successful.
+     * @throws DateTimeParseException when unable to parse with any parsers
+     */
+    private TemporalAccessor doParse(String input) {
+        if (parsers.size() > 1) {
+            for (DateTimeFormatter formatter : parsers) {
+                ParsePosition pos = new ParsePosition(0);
+                Object object = formatter.toFormat().parseObject(input, pos);
+                if (parsingSucceeded(object, input, pos) == true) {
+                    return (TemporalAccessor) object;
+                }
+            }
+            throw new DateTimeParseException("Failed to parse with all enclosed parsers", input, 0);
+        }
+        return this.parsers.get(0).parse(input);
+    }
+
+    private boolean parsingSucceeded(Object object, String input, ParsePosition pos) {
+        return object != null && pos.getIndex() == input.length();
+    }
+
     @Override
     public DateFormatter withZone(ZoneId zoneId) {
         // shortcurt to not create new objects unnecessarily
-        if (zoneId.equals(parser.getZone())) {
+        if (zoneId.equals(zone())) {
             return this;
         }
 
-        return new JavaDateFormatter(format, printer.withZone(zoneId), roundupParser.withZone(zoneId), parser.withZone(zoneId));
+        return new JavaDateFormatter(format, printer.withZone(zoneId),
+            parsers.stream().map(p -> p.withZone(zoneId)).toArray(size -> new DateTimeFormatter[size]));
     }
 
     @Override
     public DateFormatter withLocale(Locale locale) {
         // shortcurt to not create new objects unnecessarily
-        if (locale.equals(parser.getLocale())) {
+        if (locale.equals(locale())) {
             return this;
         }
 
-        return new JavaDateFormatter(format, printer.withLocale(locale), roundupParser.withLocale(locale), parser.withLocale(locale));
+        return new JavaDateFormatter(format, printer.withLocale(locale),
+            parsers.stream().map(p -> p.withLocale(locale)).toArray(size -> new DateTimeFormatter[size]));
     }
 
     @Override
@@ -170,7 +193,7 @@ class JavaDateFormatter implements DateFormatter {
 
     @Override
     public DateMathParser toDateMathParser() {
-        return new JavaDateMathParser(format, parser, roundupParser);
+        return new JavaDateMathParser(format, this, getRoundupParser());
     }
 
     @Override
@@ -186,12 +209,16 @@ class JavaDateFormatter implements DateFormatter {
         JavaDateFormatter other = (JavaDateFormatter) obj;
 
         return Objects.equals(format, other.format) &&
-               Objects.equals(locale(), other.locale()) &&
-               Objects.equals(this.printer.getZone(), other.printer.getZone());
+            Objects.equals(locale(), other.locale()) &&
+            Objects.equals(this.printer.getZone(), other.printer.getZone());
     }
 
     @Override
     public String toString() {
         return String.format(Locale.ROOT, "format[%s] locale[%s]", format, locale());
     }
+
+    Collection<DateTimeFormatter> getParsers() {
+        return parsers;
+    }
 }

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

@@ -35,6 +35,7 @@ import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalAdjusters;
 import java.time.temporal.TemporalQueries;
 import java.util.Objects;
+import java.util.function.Function;
 import java.util.function.LongSupplier;
 
 /**
@@ -46,11 +47,11 @@ import java.util.function.LongSupplier;
  */
 public class JavaDateMathParser implements DateMathParser {
 
-    private final DateTimeFormatter formatter;
+    private final JavaDateFormatter formatter;
     private final DateTimeFormatter roundUpFormatter;
     private final String format;
 
-    JavaDateMathParser(String format, DateTimeFormatter formatter, DateTimeFormatter roundUpFormatter) {
+    JavaDateMathParser(String format, JavaDateFormatter formatter, DateTimeFormatter roundUpFormatter) {
         this.format = format;
         Objects.requireNonNull(formatter);
         this.formatter = formatter;
@@ -215,12 +216,12 @@ public class JavaDateMathParser implements DateMathParser {
             throw new ElasticsearchParseException("cannot parse empty date");
         }
 
-        DateTimeFormatter formatter = roundUpIfNoTime ? this.roundUpFormatter : this.formatter;
+        Function<String,TemporalAccessor> formatter = roundUpIfNoTime ? this.roundUpFormatter::parse : this.formatter::parse;
         try {
             if (timeZone == null) {
-                return DateFormatters.from(formatter.parse(value)).toInstant();
+                return DateFormatters.from(formatter.apply(value)).toInstant();
             } else {
-                TemporalAccessor accessor = formatter.parse(value);
+                TemporalAccessor accessor = formatter.apply(value);
                 ZoneId zoneId = TemporalQueries.zone().queryFrom(accessor);
                 if (zoneId != null) {
                     timeZone = zoneId;
@@ -228,7 +229,7 @@ public class JavaDateMathParser implements DateMathParser {
 
                 return DateFormatters.from(accessor).withZoneSameLocal(timeZone).toInstant();
             }
-        } catch (DateTimeParseException e) {
+        } catch (IllegalArgumentException | DateTimeParseException e) {
             throw new ElasticsearchParseException("failed to parse date field [{}] with format [{}]: [{}]",
                 e, value, format, e.getMessage());
         }

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

@@ -343,6 +343,17 @@ public class JavaJodaTimeDuellingTests extends ESTestCase {
         assertSameDate("2012-W1-1", "weekyear_week_day");
     }
 
+    public void testCompositeParsing(){
+        //in all these examples the second pattern will be used
+        assertSameDate("2014-06-06T12:01:02.123", "yyyy-MM-dd'T'HH:mm:ss||yyyy-MM-dd'T'HH:mm:ss.SSS");
+        assertSameDate("2014-06-06T12:01:02.123", "strictDateTimeNoMillis||yyyy-MM-dd'T'HH:mm:ss.SSS");
+        assertSameDate("2014-06-06T12:01:02.123", "yyyy-MM-dd'T'HH:mm:ss+HH:MM||yyyy-MM-dd'T'HH:mm:ss.SSS");
+    }
+
+    public void testExceptionWhenCompositeParsingFails(){
+        assertParseException("2014-06-06T12:01:02.123", "yyyy-MM-dd'T'HH:mm:ss||yyyy-MM-dd'T'HH:mm:ss.SS");
+    }
+
     public void testDuelingStrictParsing() {
         assertSameDate("2018W313", "strict_basic_week_date");
         assertParseException("18W313", "strict_basic_week_date");