org.dellroad.muxable.simple.LoggingSupport Maven / Gradle / Ivy
/*
* Copyright (C) 2021 Archie L. Cobbs. All rights reserved.
*/
package org.dellroad.muxable.simple;
import java.nio.ByteBuffer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Debug logging support class.
*/
public class LoggingSupport {
protected final Logger log;
protected final String logPrefix;
// Constructors
/**
* Default constructor.
*
*
* Uses the {@link Logger} returned by {@link LoggerFactory#getLogger(Class) LoggerFactory.getLogger()}
* and the log prefix returned by {@link #simpleLogPrefix LogginSupport.simpleLogPrefix()}, when given
* this instance.
*/
public LoggingSupport() {
this.log = LoggerFactory.getLogger(this.getClass());
this.logPrefix = LoggingSupport.simpleLogPrefix(this);
}
/**
* Constructor.
*
*
* Uses the {@link Logger} returned by {@link LoggerFactory#getLogger(Class) LoggerFactory.getLogger()}
* and the log prefix returned by {@link #simpleLogPrefix LogginSupport.simpleLogPrefix()}, when given
* the specified object.
*
* @param obj object about which to log
* @throws IllegalArgumentException if {@code obj} is null
*/
public LoggingSupport(Object obj) {
this.logPrefix = LoggingSupport.simpleLogPrefix(obj);
this.log = LoggerFactory.getLogger(obj.getClass());
}
/**
* Primary constructor.
*
* @param log {@link Logger} to use
* @param logPrefix prefix for all log messages, or null for empty string
* @throws IllegalArgumentException if {@code log} is null
*/
public LoggingSupport(Logger log, String logPrefix) {
if (log == null)
throw new IllegalArgumentException("null log");
if (logPrefix == null)
logPrefix = "";
this.log = log;
this.logPrefix = logPrefix;
}
// Setup stuff
/**
* Build a simple log message prefix based on the given object.
*
*
* The implementation in {@link LoggingSupport} returns a prefix containing the given
* instance's class' simple name and its {@link System#identityHashCode}.
*
* @param obj object about which to log
* @return default log prefix
* @throws IllegalArgumentException if {@code obj} is null
*/
public static String simpleLogPrefix(Object obj) {
if (obj == null)
throw new IllegalArgumentException("null obj");
return String.format("%s[%08x]: ", obj.getClass().getSimpleName(), System.identityHashCode(obj));
}
// Methods
/**
* Log at trace level (if enabled).
*
* @param format format string for {@link String#format(String, Object[]) String.format()}
* @param args format string arguments
*/
protected void trace(String format, Object... args) {
if (this.log.isTraceEnabled())
this.log.trace(this.formatLog(format, args));
}
/**
* Log at debug level (if enabled).
*
* @param format format string for {@link String#format(String, Object[]) String.format()}
* @param args format string arguments
*/
protected void debug(String format, Object... args) {
if (this.log.isDebugEnabled())
this.log.debug(this.formatLog(format, args));
}
/**
* Log at info level (if enabled).
*
* @param format format string for {@link String#format(String, Object[]) String.format()}
* @param args format string arguments
*/
protected void info(String format, Object... args) {
if (this.log.isInfoEnabled())
this.log.info(this.formatLog(format, args));
}
/**
* Log at warn level (if enabled).
*
* @param format format string for {@link String#format(String, Object[]) String.format()}
* @param args format string arguments
*/
protected void warn(String format, Object... args) {
if (this.log.isWarnEnabled())
this.log.warn(this.formatLog(format, args));
}
/**
* Log at error level (if enabled).
*
* @param format format string for {@link String#format(String, Object[]) String.format()}
* @param args format string arguments
*/
protected void error(String format, Object... args) {
if (this.log.isErrorEnabled())
this.log.error(this.formatLog(format, args));
}
/**
* Produce a debug-loggable {@link String} version of the given {@link ByteBuffer}.
*
*
* Examples: {@code "[0123456789abcdef0123456789abcdef]"}, {@code "[0123456789abcdef...8 more]"}
*
* @param data byte buffer
* @param maxBytes maximum number of bytes to decode
* @return initial bytes in {@code data}, or "null" of {@code data} is null
* @throws IllegalArgumentException if {@code maxBytes} is negative
*/
public static String toString(ByteBuffer data, int maxBytes) {
if (maxBytes < 0)
throw new IllegalArgumentException("maxBytes < 0");
if (data == null)
return "null";
maxBytes = Math.min(maxBytes, data.remaining());
final StringBuilder buf = new StringBuilder(1/*'['*/ + maxBytes * 2 + 3/*"..."*/ + 10/*remain*/ + 5/*" more"*/ + 1/*']'*/);
buf.append('[');
int pos = data.position();
while (maxBytes-- > 0) {
final int b = data.get(pos++) & 0xff;
buf.append(Character.forDigit((b >> 4) & 0xf, 16));
buf.append(Character.forDigit(b & 0xf, 16));
}
if (pos < data.limit())
buf.append("...").append(data.limit() - pos).append(" more");
buf.append(']');
return buf.toString();
}
/**
* Format a log message.
*
*
* The implementation in {@link LoggingSupport} delegates to {@link String#format(String, Object[]) String.format()}
* and adds {@link #logPrefix} as a prefix.
*
* @param format {@link String#format(String, Object[]) String.format()} format string
* @param args {@link String#format(String, Object[]) String.format()} format arguments
* @return formatted log message
*/
protected String formatLog(String format, Object... args) {
return this.logPrefix + String.format(format, args);
}
}