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Uber-fast, ultra-lightweight Java classpath scanner. Scans the classpath by parsing the classfile binary format directly rather than by using reflection.
See https://github.com/lukehutch/fast-classpath-scanner
/*
* This file is part of FastClasspathScanner.
*
* Author: Luke Hutchison
*
* Hosted at: https://github.com/lukehutch/fast-classpath-scanner
*
* --
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Luke Hutchison
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including without
* limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
* LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
* EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
* OR OTHER DEALINGS IN THE SOFTWARE.
*/
package io.github.lukehutch.fastclasspathscanner.utils;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.atomic.AtomicInteger;
import io.github.lukehutch.fastclasspathscanner.FastClasspathScanner;
/**
* A tree-structured threadsafe log that allows you to add log entries in arbitrary order, and have the output
* retain a sane order. The order may also be made deterministic by specifying a sort key for log entries.
*/
public class LogNode {
/**
* The timestamp at which the log node was created (relative to some arbitrary system timepoint).
*/
private final long timeStampNano = System.nanoTime();
/** The timestamp at which the log node was created, in epoch millis. */
private final long timeStampMillis = System.currentTimeMillis();
/** The log message. */
private final String msg;
/** The stacktrace, if this log entry was due to an exception. */
private String stackTrace;
/** The time between when this log entry was created and addElapsedTime() was called. */
private long elapsedTimeNanos;
/** The child nodes of this log node. */
private final Map children = new ConcurrentSkipListMap<>();
/** The sort key prefix for deterministic ordering of log entries. */
private String sortKeyPrefix = "";
/** The sort key suffix for this log entry, used to make sort keys unique. */
private static AtomicInteger sortKeyUniqueSuffix = new AtomicInteger(0);
/** The date/time formatter (not threadsafe). */
private static final SimpleDateFormat dateTimeFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZZ");
/** The elapsed time formatter. */
private static final DecimalFormat nanoFormatter = new DecimalFormat("0.000000");
/**
* If this is set to true, log entries are output in realtime, as well as added to the LogNode tree. This can
* help debug situations where log info is never shown, e.g. deadlocks, or where you need to show the log info
* right up to the point where you hit a breakpoint.
*/
public static boolean LOG_IN_REALTIME = false;
/**
* Create a non-toplevel log node. The order may also be made deterministic by specifying a sort key for log
* entries.
*/
private LogNode(final String sortKey, final String msg, final long elapsedTimeNanos,
final Throwable exception) {
this.sortKeyPrefix = sortKey;
this.msg = msg;
this.elapsedTimeNanos = elapsedTimeNanos;
if (exception != null) {
final StringWriter writer = new StringWriter();
exception.printStackTrace(new PrintWriter(writer));
stackTrace = writer.toString();
} else {
stackTrace = null;
}
if (LOG_IN_REALTIME) {
System.err.println(toString());
}
}
/** Create a toplevel log node. */
public LogNode() {
this("", "", /* elapsedTimeNanos = */ -1L, /* exception = */ null);
this.log("FastClasspathScanner version " + FastClasspathScanner.getVersion());
JarUtils.logJavaInfo(this);
}
/** Append a line to the log output, indenting this log entry according to tree structure. */
private void appendLine(final String timeStampStr, final int indentLevel, final String line,
final StringBuilder buf) {
buf.append(timeStampStr);
buf.append('\t');
buf.append(FastClasspathScanner.class.getSimpleName());
buf.append('\t');
final int numDashes = 2 * (indentLevel - 1);
for (int i = 0; i < numDashes; i++) {
buf.append('-');
}
if (numDashes > 0) {
buf.append(' ');
}
buf.append(line);
buf.append('\n');
}
/** Recursively build the log output. */
private void toString(final int indentLevel, final StringBuilder buf) {
final Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(timeStampMillis);
final String timeStampStr = dateTimeFormatter.format(cal.getTime());
if (msg != null && !msg.isEmpty()) {
appendLine(timeStampStr, indentLevel,
elapsedTimeNanos > 0L
? msg + " (took " + nanoFormatter.format(elapsedTimeNanos * 1e-9) + " sec)" //
: msg,
buf);
}
if (stackTrace != null && !stackTrace.isEmpty()) {
final String[] parts = stackTrace.split("\n");
for (int i = 0; i < parts.length; i++) {
appendLine(timeStampStr, indentLevel, parts[i], buf);
}
}
for (final Entry ent : children.entrySet()) {
final LogNode child = ent.getValue();
child.toString(indentLevel + 1, buf);
}
}
/** Build the log output. Call this on the toplevel log node. */
@Override
public String toString() {
// DateTimeFormatter is not threadsafe
synchronized (dateTimeFormatter) {
final StringBuilder buf = new StringBuilder();
toString(0, buf);
return buf.toString();
}
}
/**
* Call this once the work corresponding with a given log entry has completed if you want to show the time taken
* after the log entry.
*/
public void addElapsedTime() {
elapsedTimeNanos = System.nanoTime() - timeStampNano;
}
/** Add a child log node. */
private LogNode addChild(final String sortKey, final String msg, final long elapsedTimeNanos,
final Throwable exception) {
final String newSortKey = sortKeyPrefix + "\t" + (sortKey == null ? "" : sortKey) + "\t"
+ String.format("%09d", sortKeyUniqueSuffix.getAndIncrement());
final LogNode newChild = new LogNode(newSortKey, msg, elapsedTimeNanos, exception);
// Make the sort key unique, so that log entries are not clobbered if keys are reused; increment unique
// suffix with each new log entry, so that ties are broken in chronological order.
children.put(newSortKey, newChild);
return newChild;
}
/** Add a child log node for a message. */
private LogNode addChild(final String sortKey, final String msg, final long elapsedTimeNanos) {
return addChild(sortKey, msg, elapsedTimeNanos, null);
}
/** Add a child log node for an exception. */
private LogNode addChild(final Throwable exception) {
return addChild("", "", -1L, exception);
}
/**
* Add a log entry with sort key for deterministic ordering.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String sortKey, final String msg, final long elapsedTimeNanos, final Throwable e) {
return addChild(sortKey, msg, elapsedTimeNanos).addChild(e);
}
/**
* Add a log entry with sort key for deterministic ordering.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String sortKey, final String msg, final long elapsedTimeNanos) {
return addChild(sortKey, msg, elapsedTimeNanos);
}
/**
* Add a log entry with sort key for deterministic ordering.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String sortKey, final String msg, final Throwable e) {
return addChild(sortKey, msg, -1L).addChild(e);
}
/**
* Add a log entry with sort key for deterministic ordering.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String sortKey, final String msg) {
return addChild(sortKey, msg, -1L);
}
/**
* Add a log entry.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String msg, final long elapsedTimeNanos, final Throwable e) {
return addChild("", msg, elapsedTimeNanos).addChild(e);
}
/**
* Add a log entry.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String msg, final long elapsedTimeNanos) {
return addChild("", msg, elapsedTimeNanos);
}
/**
* Add a log entry.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String msg, final Throwable e) {
return addChild("", msg, -1L).addChild(e);
}
/**
* Add a log entry.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final String msg) {
return addChild("", msg, -1L);
}
/**
* Add a series of log entries. Returns the last LogNode created.
*
* @return the last log node created, which can be used to add sub-entries.
*/
public LogNode log(final List msgs) {
LogNode last = null;
for (final String msg : msgs) {
last = log(msg);
}
return last;
}
/**
* Add a log entry.
*
* @return a child log node, which can be used to add sub-entries.
*/
public LogNode log(final Throwable e) {
return log("Exception thrown").addChild(e);
}
/**
* Flush out the log to stderr, and clear the log contents. Only call this on the toplevel log node, when
* threads do not have access to references of internal log nodes so that they cannot add more log entries
* inside the tree, otherwise log entries may be lost.
*/
public void flush() {
final String logOutput = this.toString();
this.children.clear();
System.out.flush();
System.err.print(logOutput);
System.err.flush();
}
}