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HADOOP-18653. LogLevel servlet to determine log impl before using setLevel #5456

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Merged
merged 4 commits into from
Mar 13, 2023
Merged

HADOOP-18653. LogLevel servlet to determine log impl before using setLevel #5456

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b4714dc
HADOOP-18653. LogLevel servlet to determine log impl before using set…
virajjasani Mar 6, 2023
5ff719c
addendum
virajjasani Mar 8, 2023
c74b7a0
addendum
virajjasani Mar 10, 2023
cfd3e93
addendum
virajjasani Mar 10, 2023
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11 changes: 9 additions & 2 deletions hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/log/LogLevel.java
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,8 @@

import org.apache.hadoop.classification.VisibleForTesting;
import org.apache.hadoop.thirdparty.com.google.common.base.Charsets;
import org.slf4j.LoggerFactory;

import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
Expand All @@ -44,6 +46,7 @@
import org.apache.hadoop.security.authentication.client.KerberosAuthenticator;
import org.apache.hadoop.security.ssl.SSLFactory;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.GenericsUtil;
import org.apache.hadoop.util.ServletUtil;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
Expand Down Expand Up @@ -338,14 +341,18 @@ public void doGet(HttpServletRequest request, HttpServletResponse response
out.println(MARKER
+ "Submitted Class Name: <b>" + logName + "</b><br />");

Logger log = Logger.getLogger(logName);
org.slf4j.Logger log = LoggerFactory.getLogger(logName);
out.println(MARKER
+ "Log Class: <b>" + log.getClass().getName() +"</b><br />");
if (level != null) {
out.println(MARKER + "Submitted Level: <b>" + level + "</b><br />");
}

process(log, level, out);
if (GenericsUtil.isLog4jLogger(logName)) {
process(Logger.getLogger(logName), level, out);
} else {
out.println("Sorry, setting log level is only supported for log4j loggers.<br />");
}
}

out.println(FORMS);
Expand Down
28 changes: 26 additions & 2 deletions hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/GenericsUtil.java
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Expand Up @@ -20,6 +20,7 @@

import java.lang.reflect.Array;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
Expand All @@ -33,6 +34,14 @@
@InterfaceStability.Unstable
public class GenericsUtil {

private static final String SLF4J_LOG4J_ADAPTER_CLASS = "org.slf4j.impl.Log4jLoggerAdapter";

/**
* Set to false only if log4j adapter class is not found in the classpath. Once set to false,
* the utility method should not bother re-loading class again.
*/
private static final AtomicBoolean IS_LOG4J_LOGGER = new AtomicBoolean(true);

/**
* Returns the Class object (of type <code>Class&lt;T&gt;</code>) of the
* argument of type <code>T</code>.
Expand Down Expand Up @@ -87,12 +96,27 @@ public static boolean isLog4jLogger(Class<?> clazz) {
if (clazz == null) {
return false;
}
Logger log = LoggerFactory.getLogger(clazz);
return isLog4jLogger(clazz.getName());
}

/**
* Determine whether the log of the given logger is of Log4J implementation.
*
* @param logger the logger name, usually class name as string.
* @return true if the logger uses Log4J implementation.
*/
public static boolean isLog4jLogger(String logger) {
if (logger == null || !IS_LOG4J_LOGGER.get()) {
return false;
}
Logger log = LoggerFactory.getLogger(logger);
try {
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this try/catch is a duplicate of isLog4jLogger(class).
why not do isLog4jLogger(LoggerFactory.getLogger(logger))

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I think the other way around would be more appropriate?
For instance, in slf4j implementation, they have:

    public static Logger getLogger(Class<?> clazz) {
        Logger logger = getLogger(clazz.getName());
...
...

Hence, we can also call clazz.getName() here.

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@virajjasani virajjasani Mar 10, 2023 •
edited
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How about this latest commit? c74b7a0 and cfd3e93

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Refactored to keep the logic in only one utility method. The other method will just call this one. Simplified (exactly as slf4j library methods).

Class log4jClass = Class.forName("org.slf4j.impl.Log4jLoggerAdapter");
Class<?> log4jClass = Class.forName(SLF4J_LOG4J_ADAPTER_CLASS);
return log4jClass.isInstance(log);
} catch (ClassNotFoundException e) {
IS_LOG4J_LOGGER.set(false);
return false;
}
}

}
2 changes: 1 addition & 1 deletion ...p-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestGenericsUtil.java
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Expand Up @@ -140,7 +140,7 @@ public void testGetClass() {

@Test
public void testIsLog4jLogger() throws Exception {
assertFalse("False if clazz is null", GenericsUtil.isLog4jLogger(null));
assertFalse("False if clazz is null", GenericsUtil.isLog4jLogger((Class<?>) null));
assertTrue("The implementation is Log4j",
GenericsUtil.isLog4jLogger(TestGenericsUtil.class));
}
Expand Down