vy commented on code in PR #2249:
URL: https://github.com/apache/logging-log4j2/pull/2249#discussion_r1513500994
##########
log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java:
##########
@@ -16,311 +16,590 @@
*/
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;
+
+ /**
+ * The name of the system property that can be configured with the {@link
Level} name to use as the default listener level.
+ * <p>
+ * The listener registry is initialized with a default listener.
+ * This default listener will accept entries filtered by the level
provided in this configuration.
+ * </p>
+ *
+ * @since 2.23.0
+ */
+ public static final String DEFAULT_LISTENER_LEVEL_PROPERTY_NAME =
"log4j2.StatusLogger.level";
+
+ /**
+ * The default value of the {@link #DEFAULT_LISTENER_LEVEL_PROPERTY_NAME}
system property: {@code ERROR}.
+ *
+ * @since 2.23.0
+ */
+ public static final Level DEFAULT_LISTENER_LEVEL_DEFAULT_VALUE =
Level.ERROR;
+
+ /**
+ * The name of the system property that can be configured with the {@link
Level} name to use as the default listener level.
+ * <p>
+ * The listener registry is initialized with a default listener.
+ * This default listener will accept entries filtered by the level
provided in this configuration.
+ * </p>
+ *
+ * @since 2.8
+ * @deprecated Use {@link #DEFAULT_LISTENER_LEVEL_PROPERTY_NAME} instead.
*/
- public static final String MAX_STATUS_ENTRIES = "log4j2.status.entries";
+ @Deprecated
+ public static final String DEFAULT_STATUS_LISTENER_LEVEL =
DEFAULT_LISTENER_LEVEL_PROPERTY_NAME;
/**
- * System property that can be configured with the {@link Level} name to
use as the default level for
- * {@link StatusListener}s.
+ * The name of the system property that can be configured with a {@link
java.time.format.DateTimeFormatter} pattern that will be passed to the default
listener.
+ *
+ * @since 2.23.0
*/
- public static final String DEFAULT_STATUS_LISTENER_LEVEL =
"log4j2.StatusLogger.level";
+ public static final String INSTANT_FORMAT_PROPERTY_NAME =
"log4j2.StatusLogger.DateFormat";
/**
- * System property that can be configured with a date-time format string
to use as the format for timestamps
- * in the status logger output. See {@link java.text.SimpleDateFormat} for
supported formats.
+ * The name of the system property that can be configured with a {@link
java.time.format.DateTimeFormatter} pattern that will be passed to the default
listener.
+ *
* @since 2.11.0
+ * @deprecated Use {@link #INSTANT_FORMAT_PROPERTY_NAME} instead.
*/
- public static final String STATUS_DATE_FORMAT =
"log4j2.StatusLogger.DateFormat";
+ @Deprecated
+ public static final String STATUS_DATE_FORMAT =
INSTANT_FORMAT_PROPERTY_NAME;
- private static final long serialVersionUID = 2L;
+ /**
+ * The name of the file to be searched in the classpath to read properties
from.
+ *
+ * @since 2.23.0
+ */
+ public static final String PROPERTIES_FILE_NAME =
"log4j2.StatusLogger.properties";
+
+ /**
+ * Holder for user-provided {@link StatusLogger} configurations.
+ *
+ * @since 2.23.0
+ */
+ public static final class Config {
+
+ private static final Config INSTANCE = new Config();
+
+ private final boolean debugEnabled;
+
+ private final int bufferCapacity;
+
+ private final Level defaultListenerLevel;
+
+ @Nullable
+ private final DateTimeFormatter instantFormatter;
+
+ /**
+ * Constructs an instance using the given properties.
+ * <b>Users should not create new instances, but use {@link
#getInstance()} instead</b>!
+ *
+ * @param debugEnabled the value of the {@value DEBUG_PROPERTY_NAME}
property
+ * @param bufferCapacity the value of the {@value
BUFFER_CAPACITY_PROPERTY_NAME} property
+ * @param defaultListenerLevel the value of the {@value
DEFAULT_LISTENER_LEVEL_PROPERTY_NAME} property
+ * @param instantFormatter the value of the {@value
INSTANT_FORMAT_PROPERTY_NAME} property
+ */
+ public Config(
+ boolean debugEnabled,
+ int bufferCapacity,
+ Level defaultListenerLevel,
+ @Nullable DateTimeFormatter instantFormatter) {
+ this.debugEnabled = debugEnabled;
+ if (bufferCapacity < 0) {
+ throw new IllegalArgumentException(
+ "was expecting a positive `bufferCapacity`, found: " +
bufferCapacity);
+ }
+ this.bufferCapacity = bufferCapacity;
+ this.defaultListenerLevel = requireNonNull(defaultListenerLevel,
"defaultListenerLevel");
+ this.instantFormatter = requireNonNull(instantFormatter,
"instantFormatter");
+ }
+
+ /**
+ * Constructs an instance using either system properties or a property
file (i.e., {@value Config#PROPERTIES_FILE_NAME}) in the classpath, if
available.
+ * <b>Users should not create new instances, but use {@link
#getInstance()} instead</b>!
+ */
+ public Config() {
+ final Properties fileProvidedProperties = readPropertiesFile();
+ this.debugEnabled = readDebugEnabled(fileProvidedProperties);
+ this.bufferCapacity = readBufferCapacity(fileProvidedProperties);
+ this.defaultListenerLevel =
readDefaultListenerLevel(fileProvidedProperties);
+ this.instantFormatter =
readInstantFormatter(fileProvidedProperties);
+ }
+
+ /**
+ * Gets the static instance.
+ *
+ * @return a singleton instance
+ */
+ public static Config getInstance() {
+ return INSTANCE;
+ }
+
+ private static boolean readDebugEnabled(final Properties
fileProvidedProperties) {
+ final String debug = readProperty(fileProvidedProperties,
DEBUG_PROPERTY_NAME);
+ return debug != null;
+ }
+
+ private static int readBufferCapacity(final Properties
fileProvidedProperties) {
+ final String capacityString = readProperty(fileProvidedProperties,
BUFFER_CAPACITY_PROPERTY_NAME);
+ return capacityString != null ? Integer.parseInt(capacityString) :
BUFFER_CAPACITY_DEFAULT_VALUE;
+ }
- private static final String NOT_AVAIL = "?";
+ private static Level readDefaultListenerLevel(final Properties
fileProvidedProperties) {
+ final String level = readProperty(fileProvidedProperties,
DEFAULT_LISTENER_LEVEL_PROPERTY_NAME);
+ return level != null ? Level.valueOf(level) :
DEFAULT_LISTENER_LEVEL_DEFAULT_VALUE;
+ }
- static final PropertiesUtil PROPS = new
PropertiesUtil("log4j2.StatusLogger.properties");
+ private static DateTimeFormatter readInstantFormatter(final Properties
fileProvidedProperties) {
+ final String format = readProperty(fileProvidedProperties,
INSTANT_FORMAT_PROPERTY_NAME);
+ return format != null ? DateTimeFormatter.ofPattern(format) : null;
+ }
- private static final int MAX_ENTRIES =
PROPS.getIntegerProperty(MAX_STATUS_ENTRIES, 200);
+ private static String readProperty(final Properties
fileProvidedProperties, final String propertyName) {
+ final String systemProvidedValue =
System.getProperty(propertyName);
+ return systemProvidedValue != null
+ ? systemProvidedValue
+ : (String) fileProvidedProperties.get(propertyName);
+ }
- private static final String DEFAULT_STATUS_LEVEL =
PROPS.getStringProperty(DEFAULT_STATUS_LISTENER_LEVEL);
+ // We need to roll out our own `.properties` reader.
+ // We could have used `PropertiesUtil`, `PropertyFilePropertySource`,
etc.
+ // Consequently, they would delegate to `LoaderUtil`, etc.
+ // All these mechanisms expect a working `StatusLogger`.
+ // Hence, in order to be self-sufficient, we cannot rely on them.
+ private static Properties readPropertiesFile() {
+ final Properties properties = new Properties();
+ final URL url =
StatusLogger.class.getResource(PROPERTIES_FILE_NAME);
Review Comment:
@carterkozak, doh! :facepalm: Thanks for the report. Could you review #2354,
please?
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