vy commented on code in PR #2249:
URL: https://github.com/apache/logging-log4j2/pull/2249#discussion_r1467428953
##########
log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java:
##########
@@ -16,311 +16,567 @@
*/
package org.apache.logging.log4j.status;
-import java.io.Closeable;
+import static java.util.Objects.requireNonNull;
+
+import edu.umd.cs.findbugs.annotations.Nullable;
import java.io.IOException;
+import java.io.InputStream;
+import java.io.PrintStream;
+import java.net.URL;
+import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
import java.util.List;
+import java.util.Properties;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
-import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.message.MessageFactory;
import org.apache.logging.log4j.message.ParameterizedNoReferenceMessageFactory;
-import org.apache.logging.log4j.simple.SimpleLogger;
-import org.apache.logging.log4j.simple.SimpleLoggerContext;
import org.apache.logging.log4j.spi.AbstractLogger;
import org.apache.logging.log4j.util.Constants;
-import org.apache.logging.log4j.util.PropertiesUtil;
/**
- * Records events that occur in the logging system. By default, only error
messages are logged to {@link System#err}.
- * Normally, the Log4j StatusLogger is configured via the root {@code
<Configuration status="LEVEL"/>} node in a Log4j
- * configuration file. However, this can be overridden via a system property
named
- * {@value #DEFAULT_STATUS_LISTENER_LEVEL} and will work with any Log4j
provider.
- *
- * @see SimpleLogger
- * @see SimpleLoggerContext
+ * Records events that occur in the logging system.
+ * {@link StatusLogger} is expected to be a standalone, self-sufficient
component that the logging system can rely on for low-level logging purposes.
+ * <h3>Listeners</h3>
+ * <p>
+ * Each recorded event will first get buffered and used to notify the
registered {@link StatusListener}s.
+ * Listener registry is always initialized with a <em>default listener</em>,
which is a {@link StatusConsoleListener}.
+ * </p>
+ * <p>
+ * You can programmatically register listeners using {@link
#registerListener(StatusListener)} method.
+ * </p>
+ * <h3>Configuration</h3>
+ * <p>
+ * The {@code StatusLogger} can be configured in following ways:
+ * </p>
+ * <ol>
+ * <li>Passing system properties to the Java process (e.g., {@code
-Dlog4j2.StatusLogger.level=INFO})</li>
+ * <li>Providing properties in a {@value StatusLogger#PROPERTIES_FILE_NAME}
file in the classpath</li>
+ * <li>Using Log4j configuration (i.e., {@code <Configuration status="WARN"
dest="out">} in a {@code log4j2.xml} in the classpath)</li>
+ * </ol>
+ * <p>
+ * It is crucial to understand that there is a time between the first {@code
StatusLogger} access and a configuration file (e.g., {@code log4j2.xml}) read.
+ * Consider the following example:
+ * </p>
+ * <ol>
+ * <li>The default level is {@code ERROR}</li>
+ * <li>You have <Configuration status="WARN">} in your {@code log4j2.xml}</li>
+ * <li>Until your {@code log4j2.xml} configuration is read, the effective
level will be {@code ERROR}</li>
+ * <li>Once your {@code log4j2.xml} configuration is read, the effective level
will be {@code WARN} as you configured</li>
+ * </ol>
+ * <p>
+ * Hence, unless you use either system properties or {@value
StatusLogger#PROPERTIES_FILE_NAME} file in the classpath, there is a time
window that only the defaults will be effective.
+ * </p>
+ * <p>
+ * {@code StatusLogger} is designed as a singleton class accessed statically.
+ * If you are running an application containing multiple Log4j configurations
(e.g., in a servlet environment with multiple containers) and you happen to
have differing {@code StatusLogger} configurations (e.g, one {@code log4j2.xml}
containing {@code <Configuration status="ERROR">} while the other {@code
<Configuration status="INFO">}), the last loaded configuration will be
effective one.
+ * </p>
+ * <h3>Debug mode</h3>
+ * <p>
+ * When the {@value Constants#LOG4J2_DEBUG} system property is present, any
level-related filtering will be skipped and all events will be notified to
listeners.
+ * </p>
*/
-public final class StatusLogger extends AbstractLogger {
+public class StatusLogger extends AbstractLogger {
+
+ private static final long serialVersionUID = 2L;
+
+ /**
+ * The name of the system property that enables debug mode in its presence.
+ * <p>
+ * This is a local clone of {@link Constants#LOG4J2_DEBUG}.
+ * The cloning is necessary to avoid cyclic initialization.
+ * </p>
+ */
+ public static final String DEBUG_PROPERTY_NAME = "log4j2.debug";
+
+ /**
+ * The name of the system property that can be configured with the maximum
number of events buffered.
+ * <p>
+ * Once the limit is reached, older entries will be removed as new entries
are added.
+ * </p>
+ *
+ * @since 2.23.0
+ */
+ public static final String BUFFER_CAPACITY_PROPERTY_NAME =
"log4j2.status.entries";
+
+ /**
+ * The default value of the {@link #BUFFER_CAPACITY_PROPERTY_NAME} system
property: {@code 0}.
+ *
+ * @since 2.23.0
+ */
+ public static final int BUFFER_CAPACITY_DEFAULT_VALUE = 0;
/**
- * System property that can be configured with the number of entries in
the queue. Once the limit is reached older
- * entries will be removed as new entries are added.
+ * The name of the system property that can be configured with the maximum
number of events buffered.
+ * <p>
+ * Once the limit is reached, older entries will be removed as new entries
are added.
+ * </p>
+ *
+ * @deprecated Use {@link #BUFFER_CAPACITY_PROPERTY_NAME} instead.
+ */
+ @Deprecated
+ public static final String MAX_STATUS_ENTRIES =
BUFFER_CAPACITY_PROPERTY_NAME;
Review Comment:
Trying to adhere to `*_PROPERTY_NAME` and `*_DEFAULT_VALUE` convention.
##########
log4j-api/src/main/java/org/apache/logging/log4j/status/StatusConsoleListener.java:
##########
@@ -56,50 +54,59 @@ public StatusConsoleListener(final Level level) {
* @throws NullPointerException on null {@code level} or {@code stream}
*/
public StatusConsoleListener(final Level level, final PrintStream stream) {
- this(level, stream, SimpleLoggerFactory.getInstance());
- }
-
- StatusConsoleListener(final Level level, final PrintStream stream, final
SimpleLoggerFactory loggerFactory) {
- this.level = Objects.requireNonNull(level, "level");
- this.stream = Objects.requireNonNull(stream, "stream");
- this.logger = Objects.requireNonNull(loggerFactory, "loggerFactory")
- .createSimpleLogger(
- "StatusConsoleListener", level,
ParameterizedNoReferenceMessageFactory.INSTANCE, stream);
+ this.level = requireNonNull(level, "level");
+ this.stream = requireNonNull(stream, "stream");
}
/**
* Sets the level to a new value.
- * @param level The new Level.
+ *
+ * @param level the new level
+ * @throws NullPointerException on null {@code level}
*/
public void setLevel(final Level level) {
- this.level = level;
+ this.level = requireNonNull(level, "level");
}
/**
- * Return the Log Level for which the Listener should receive events.
- * @return the Log Level.
+ * Sets the output stream to a new value.
+ *
+ * @param stream the new output stream
+ * @throws NullPointerException on null {@code stream}
+ * @since 2.23.0
+ */
+ public void setStream(final PrintStream stream) {
+ this.stream = requireNonNull(stream, "stream");
+ }
+
+ /**
+ * Returns the level for which the listener should receive events.
+ *
+ * @return the log level
*/
@Override
public Level getStatusLevel() {
- return this.level;
+ return level;
}
/**
* Writes status messages to the console.
- * @param data The StatusData.
+ *
+ * @param data a status data
+ * @throws NullPointerException on null {@code data}
*/
@Override
public void log(final StatusData data) {
- logger
- // Logging using _only_ the following 4 fields set by
`StatusLogger#logMessage()`:
- .atLevel(data.getLevel())
- .withThrowable(data.getThrowable())
- .withLocation(data.getStackTraceElement())
- .log(data.getMessage());
+ requireNonNull(data, "data");
+ if (data.getLevel().isMoreSpecificThan(level)) {
+ final String formattedStatus = data.getFormattedStatus();
+ stream.println(formattedStatus);
Review Comment:
Call me opinionated, but I (strongly?) prefer `var a = a(); var b = b(a);
c(b)` over `c(b(a))`, since
1. Variables give you documentation opportunity (e.g., `boolean
validUserName = userName.matches(userNamePattern)`)
2. One-statement-per-line is easier to read and understand
3. Variables allow you to track intermediate values while stepping through
code in a debugger. AFAIK, this is not possible in `c(b(a))` form.
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