This is an automated email from the ASF dual-hosted git repository.
vy pushed a commit to branch 2.x
in repository https://gitbox.apache.org/repos/asf/logging-log4j2.git
The following commit(s) were added to refs/heads/2.x by this push:
new 246fc76eea fix: `InstantPatternLegacyFormatter` precision for legacy
`n` patterns (#4220)
246fc76eea is described below
commit 246fc76eea147ea067e0924e92bb85580b90a336
Author: Sebastien Tardif <[email protected]>
AuthorDate: Thu Aug 13 03:33:41 2026 -0700
fix: `InstantPatternLegacyFormatter` precision for legacy `n` patterns
(#4220)
Signed-off-by: Sebastien Tardif <[email protected]>
Co-authored-by: Volkan Yazıcı <[email protected]>
---
.../core/pattern/NamedInstantPatternTest.java | 1 +
...InstantPatternLegacyFormatterPrecisionTest.java | 60 ++++++++++++++++++++++
.../instant/InstantPatternLegacyFormatter.java | 5 +-
.../3816_legacy_instant_pattern_precision.xml | 11 ++++
4 files changed, 76 insertions(+), 1 deletion(-)
diff --git
a/log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/NamedInstantPatternTest.java
b/log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/NamedInstantPatternTest.java
index e4065438cb..332613b13d 100644
---
a/log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/NamedInstantPatternTest.java
+++
b/log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/NamedInstantPatternTest.java
@@ -55,5 +55,6 @@ class NamedInstantPatternTest {
String legacy = legacyFormatter.format(instant);
String modern = formatter.format(instant);
assertThat(legacy).isEqualTo(modern);
+
assertThat(legacyFormatter.getPrecision()).isEqualTo(formatter.getPrecision());
}
}
diff --git
a/log4j-core-test/src/test/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatterPrecisionTest.java
b/log4j-core-test/src/test/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatterPrecisionTest.java
new file mode 100644
index 0000000000..f8b4a86e8a
--- /dev/null
+++
b/log4j-core-test/src/test/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatterPrecisionTest.java
@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.log4j.core.util.internal.instant;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.temporal.ChronoUnit;
+import java.util.Locale;
+import java.util.TimeZone;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Regression for issue #3816: legacy fractional-second letter {@code n} must
not be
+ * treated as always-nanosecond when computing cache precision.
+ */
+class InstantPatternLegacyFormatterPrecisionTest {
+
+ @Test
+ void microsPatternUsingLegacyNUsesMicroPrecision() {
+ final InstantPatternFormatter legacy =
InstantPatternFormatter.newBuilder()
+ .setLegacyFormattersEnabled(true)
+ .setPattern("yyyy-MM-dd HH:mm:ss,nnnnnn")
+ .setLocale(Locale.US)
+ .setTimeZone(TimeZone.getTimeZone("UTC"))
+ .build();
+ final InstantPatternFormatter modern =
InstantPatternFormatter.newBuilder()
+ .setLegacyFormattersEnabled(false)
+ .setPattern("yyyy-MM-dd HH:mm:ss,SSSSSS")
+ .setLocale(Locale.US)
+ .setTimeZone(TimeZone.getTimeZone("UTC"))
+ .build();
+ assertThat(legacy.getPrecision()).isEqualTo(ChronoUnit.MICROS);
+ assertThat(legacy.getPrecision()).isEqualTo(modern.getPrecision());
+ }
+
+ @Test
+ void millisPatternUsingLegacySssUsesMilliPrecision() {
+ final InstantPatternFormatter legacy =
InstantPatternFormatter.newBuilder()
+ .setLegacyFormattersEnabled(true)
+ .setPattern("yyyy-MM-dd HH:mm:ss,SSS")
+ .setLocale(Locale.US)
+ .setTimeZone(TimeZone.getTimeZone("UTC"))
+ .build();
+ assertThat(legacy.getPrecision()).isEqualTo(ChronoUnit.MILLIS);
+ }
+}
diff --git
a/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatter.java
b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatter.java
index aaf380c7f0..9d57493e5d 100644
---
a/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatter.java
+++
b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/instant/InstantPatternLegacyFormatter.java
@@ -46,7 +46,10 @@ final class InstantPatternLegacyFormatter implements
InstantPatternFormatter {
private final BiConsumer<StringBuilder, Instant> formatter;
InstantPatternLegacyFormatter(final String pattern, final Locale locale,
final TimeZone timeZone) {
- this.precision = new InstantPatternDynamicFormatter(pattern, locale,
timeZone).getPrecision();
+ // Replaces 'n' used in legacy patterns with 'S' to obtain the right
precision.
+ // In legacy patterns, the precision of 'n' depends on the pattern
length, but
+ // in `DateTimeFormatter`, it is always nanoseconds.
+ this.precision = new
InstantPatternDynamicFormatter(pattern.replace('n', 'S'), locale,
timeZone).getPrecision();
this.pattern = pattern;
this.locale = locale;
this.timeZone = timeZone;
diff --git a/src/changelog/.2.x.x/3816_legacy_instant_pattern_precision.xml
b/src/changelog/.2.x.x/3816_legacy_instant_pattern_precision.xml
new file mode 100644
index 0000000000..6fd2f4c120
--- /dev/null
+++ b/src/changelog/.2.x.x/3816_legacy_instant_pattern_precision.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+ xmlns="https://logging.apache.org/xml/ns";
+ xsi:schemaLocation="https://logging.apache.org/xml/ns
https://logging.apache.org/xml/ns/log4j-changelog-0.xsd";
+ type="fixed">
+ <issue id="3816"
link="https://github.com/apache/logging-log4j2/issues/3816"/>
+ <issue id="4220" link="https://github.com/apache/logging-log4j2/pull/4220"/>
+ <description format="asciidoc">
+ Fix precision detection in legacy date & time pattern formatting
+ </description>
+</entry>
