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Optimize InstantDeserializer method replaceZeroOffsetAsZIfNecessary() #266

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merged 3 commits into from
Feb 16, 2023
Merged

Optimize InstantDeserializer method replaceZeroOffsetAsZIfNecessary() #266

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e6a483f
Optimize InstantDeserializer replaceZeroOffsetAsZIfNecessary
schlosna Feb 8, 2023
7c02954
Add test cases for alternate zero zone offsets
schlosna Feb 8, 2023
e6ddb31
replaceZeroOffsetAsZIfNecessary uses text.regionMatches
schlosna Feb 9, 2023
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30 changes: 21 additions & 9 deletions datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/deser/InstantDeserializer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -54,13 +54,6 @@ public class InstantDeserializer<T extends Temporal>
{
private static final long serialVersionUID = 1L;

/**
* Constants used to check if the time offset is zero. See [jackson-modules-java8#18]
*
* @since 2.9.0
*/
private static final Pattern ISO8601_UTC_ZERO_OFFSET_SUFFIX_REGEX = Pattern.compile("\\+00:?(00)?$");

/**
* Constants used to check if ISO 8601 time string is colonless. See [jackson-modules-java8#131]
*
Expand Down Expand Up @@ -226,7 +219,7 @@ public T deserialize(JsonParser parser, DeserializationContext context) throws I
return (T) parser.getEmbeddedObject();

case JsonTokenId.ID_START_ARRAY:
return _deserializeFromArray(parser, context);
return _deserializeFromArray(parser, context);
}
return _handleUnexpectedToken(context, parser, JsonToken.VALUE_STRING,
JsonToken.VALUE_NUMBER_INT, JsonToken.VALUE_NUMBER_FLOAT);
Expand Down Expand Up @@ -337,12 +330,31 @@ private ZoneId getZone(DeserializationContext context)
private String replaceZeroOffsetAsZIfNecessary(String text)
{
if (replaceZeroOffsetAsZ) {
return ISO8601_UTC_ZERO_OFFSET_SUFFIX_REGEX.matcher(text).replaceFirst("Z");
return replaceZeroOffsetAsZ(text);
}

return text;
}

private static String replaceZeroOffsetAsZ(String text)
{
int plusIndex = text.lastIndexOf('+');
if (plusIndex < 0) {
return text;
}
int maybeOffsetIndex = plusIndex + 1;
int remaining = text.length() - maybeOffsetIndex;
if (remaining < 2 || remaining == 3 || remaining > 5) {
return text;
}

String maybeOffset = text.substring(maybeOffsetIndex);
if ("00".equals(maybeOffset) || "0000".equals(maybeOffset) || "00:00".equals(maybeOffset)) {
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@carterkozak carterkozak Feb 9, 2023 •
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Can we optimize this using String.regionMatches?
perhaps using something along the lines of

switch (remaining) {
    case 2:
       return text.regionmatches..."00" ? text.substring(0, plusIndex) + 'Z' : text;
     case 4:
        ..etc
     case 5:
       ..etc
 }
 return text;

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Seems reasonable to avoid the substring allocation, updated to use regionMatches & switch and reran JMH and tested locally with JDKs 8, 11, 17.

Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz
JDK 17.0.5, OpenJDK 64-Bit Server VM, 17.0.5+8-LTS
Benchmark                           Mode  Cnt    Score   Error  Units
InstantDeserializerBenchmark.index  avgt    5   20.003 ± 0.486  ns/op
InstantDeserializerBenchmark.regex  avgt    5  156.174 ± 7.654  ns/op

Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz
JDK 11.0.16.1, OpenJDK 64-Bit Server VM, 11.0.16.1+9-LTS
Benchmark                           Mode  Cnt    Score   Error  Units
InstantDeserializerBenchmark.index  avgt    5   20.818 ± 1.267  ns/op
InstantDeserializerBenchmark.regex  avgt    5  192.248 ± 7.341  ns/op

Apple M1 Pro aarch64
JDK 17.0.6, OpenJDK 64-Bit Server VM, 17.0.6+10-LTS
Benchmark                           Mode  Cnt   Score   Error  Units
InstantDeserializerBenchmark.index  avgt    5  17.498 ± 0.677  ns/op
InstantDeserializerBenchmark.regex  avgt    5  58.096 ± 1.330  ns/op

Apple M1 Pro aarch64
Benchmark                           Mode  Cnt   Score   Error  Units
InstantDeserializerBenchmark.index  avgt    5  16.176 ± 7.842  ns/op
InstantDeserializerBenchmark.regex  avgt    5  63.201 ± 5.668  ns/op

return text.substring(0, plusIndex) + 'Z';
}
return text;
}

// @since 2.13
private String addInColonToOffsetIfMissing(String text)
{
Expand Down
34 changes: 34 additions & 0 deletions datetime/src/test/java/com/fasterxml/jackson/datatype/jsr310/deser/InstantDeserTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
import static com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer.ISO8601_COLONLESS_OFFSET_REGEX;
import static org.junit.Assert.*;
import static org.junit.Assert.assertNull;
import static org.junit.Assume.assumeTrue;

public class InstantDeserTest extends ModuleTestBase
{
Expand Down Expand Up @@ -434,10 +435,43 @@ public void testDeserializationFromStringWithZeroZoneOffset03() throws Exception
assertEquals("The value is not correct.", date, result);
}

@Test
public void testDeserializationFromStringWithZeroZoneOffset04() throws Exception {
assumeInstantCanParseOffsets();
Instant date = Instant.now();
String json = formatWithZeroZoneOffset(date, "+00:30");
Instant result = READER.readValue(json);
assertNotEquals("The value is not correct.", date, result);
}

@Test
public void testDeserializationFromStringWithZeroZoneOffset05() throws Exception {
assumeInstantCanParseOffsets();
Instant date = Instant.now();
String json = formatWithZeroZoneOffset(date, "+01:30");
Instant result = READER.readValue(json);
assertNotEquals("The value is not correct.", date, result);
}

@Test
public void testDeserializationFromStringWithZeroZoneOffset06() throws Exception {
assumeInstantCanParseOffsets();
Instant date = Instant.now();
String json = formatWithZeroZoneOffset(date, "-00:00");
Instant result = READER.readValue(json);
assertEquals("The value is not correct.", date, result);
}

private String formatWithZeroZoneOffset(Instant date, String offset){
return '"' + FORMATTER.format(date).replaceFirst("Z$", offset) + '"';
}

private static void assumeInstantCanParseOffsets() {
// DateTimeFormatter.ISO_INSTANT didn't handle offsets until JDK 12+.
// This was added by https://bugs.openjdk.org/browse/JDK-8166138
assumeTrue(System.getProperty("java.specification.version").compareTo("12") > 0);
}

/*
/**********************************************************************
/* Deserialization, misc other
Expand Down