ramanathan1504 commented on code in PR #4419:
URL: https://github.com/apache/logging-log4j2/pull/4419#discussion_r4409326636
##########
log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java:
##########
@@ -959,17 +959,30 @@ public synchronized void addLoggerAppender(
return;
}
final String loggerName = logger.getName();
- appenders.putIfAbsent(appender.getName(), appender);
+ final Appender registered = appenders.putIfAbsent(appender.getName(),
appender);
+ // The configuration owns a single appender per name: when another
instance is already registered under
+ // this name, attach that one instead of an instance the configuration
would never start or stop.
+ final Appender effective = registered == null ? appender : registered;
+ if (effective != appender) {
+ LOGGER.warn(
+ "An appender named '{}' is already registered; attaching
the registered instance to logger '{}' instead of the given one",
+ appender.getName(),
+ loggerName);
+ }
final LoggerConfig lc = getLoggerConfig(loggerName);
if (lc.getName().equals(loggerName)) {
- lc.addAppender(appender, null, null);
+ lc.addAppender(effective, null, null);
} else {
final LoggerConfig nlc = new LoggerConfig(loggerName,
lc.getLevel(), lc.isAdditive());
- nlc.addAppender(appender, null, null);
+ nlc.addAppender(effective, null, null);
nlc.setParent(lc);
- loggerConfigs.putIfAbsent(loggerName, nlc);
- setParents();
- logger.getContext().updateLoggers();
+ final LoggerConfig existing =
loggerConfigs.putIfAbsent(loggerName, nlc);
+ if (existing == null) {
+ setParents();
+ logger.getContext().updateLoggers();
+ } else {
+ existing.addAppender(effective, null, null);
Review Comment:
This branch and the `existing.addFilter(filter)` and
`existing.setAdditive(additive)` branches below have no test. Removing any of
them keeps every test green. A `LoggerConfig` added with `addLogger` under a
key that differs from its name reaches them, for example:
```java
final LoggerConfig other = new LoggerConfig("other", Level.INFO, true);
config.addLogger("mismatch", other);
config.addLoggerFilter(context.getLogger("mismatch"), filter);
assertThat(other.hasFilter()).isTrue();
```
##########
src/changelog/.2.x.x/3155_AbstractConfiguration_logger_mutators.xml:
##########
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns="https://logging.apache.org/xml/ns";
+ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+ xsi:schemaLocation="
+ https://logging.apache.org/xml/ns
+ https://logging.apache.org/xml/ns/log4j-changelog-0.xsd";
+ type="fixed">
+ <issue id="3155"
link="https://github.com/apache/logging-log4j2/issues/3155"/>
+ <description format="asciidoc">
+ Fix `addLoggerAppender()` attaching an unregistered appender when its
name is already registered, and `addLoggerFilter()`/`setLoggerAdditive()`
failing on `null` arguments.
Review Comment:
Can the entry be one short line with what the user sees?
```suggestion
Fix `Logger.addAppender()` attaching an unregistered appender.
```
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