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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.messagebus;
/**
* A Trace object contains ad-hoc string notes organized in a strict-loose tree. A Trace object consists of a trace
* level indicating which trace notes should be included and a TraceTree object containing the tree structure and
* collecting the trace information. Tracing is used to collect debug information about a Routable traveling through the
* system. The trace level is in the range [0,9]. 0 means no tracing, and 9 means all tracing is enabled. A client that
* has the ability to trace information will have a predefined level attached to that information. If the level on the
* information is lower or equal to the level set in the Trace object, the information will be traced.
*
* @author Simon Thoresen Hult
*/
public class Trace {
private int level = 0;
private TraceNode root = new TraceNode();
/**
* Create an empty trace with level set to 0 (no tracing)
*/
public Trace() {
// empty
}
/**
* Create an empty trace with given level.
*
* @param level Level to set.
*/
public Trace(int level) {
this.level = level;
}
/**
* Remove all trace information and set the trace level to 0.
*
* @return This, to allow chaining.
*/
public Trace clear() {
level = 0;
root = new TraceNode();
return this;
}
/**
* Swap the internals of this with another.
*
* @param other The trace to swap internals with.
* @return This, to allow chaining.
*/
public Trace swap(Trace other) {
int level = this.level;
this.level = other.level;
other.level = level;
TraceNode root = this.root;
this.root = other.root;
other.root = root;
return this;
}
/**
* Set the trace level. 0 means no tracing, 9 means enable all tracing.
*
* @param level The level to set.
* @return This, to allow chaining.
*/
public Trace setLevel(int level) {
this.level = Math.min(Math.max(level, 0), 9);
return this;
}
/**
* Returns the trace level.
*
* @return The trace level.
*/
public int getLevel() {
return level;
}
/**
* Check if information with the given level should be traced. This method is added to allow clients to check if
* something should be traced before spending time building up the trace information itself.
*
* @param level The trace level to test.
* @return True if tracing is enabled for the given level, false otherwise.
*/
public boolean shouldTrace(int level) {
return level <= this.level;
}
/**
* Add the given note to the trace information if tracing is enabled for the given level.
*
* @param level The trace level of the note.
* @param note The note to add.
* @return True if the note was added to the trace information, false otherwise.
*/
public boolean trace(int level, String note) {
return trace(level, note, true);
}
/**
* Add the given note to the trace information if tracing is enabled for the given level. If the addTime parameter
* is true, then the note is prefixed with the current time. This is the default behaviour when ommiting this
* parameter.
*
* @param level The trace level of the note.
* @param note The note to add.
* @param addTime Whether or not to prefix note with a timestamp.
* @return True if the note was added to the trace information, false otherwise.
*/
public boolean trace(int level, String note, boolean addTime) {
if (!shouldTrace(level)) {
return false;
}
if (addTime) {
String timeString = Long.toString(System.currentTimeMillis());
StringBuilder buf = new StringBuilder();
buf.append("[");
int len = timeString.length();
// something wrong. handle it by using the input long as a string.
if (len < 3) {
buf.append(timeString);
} else {
buf.append(timeString.substring(0, len - 3));
buf.append('.');
buf.append(timeString.substring(len - 3));
}
buf.append("] ");
buf.append(note);
root.addChild(buf.toString());
} else {
root.addChild(note);
}
return true;
}
/**
* Returns the root of the trace tree.
*
* @return The root.
*/
public TraceNode getRoot() {
return root;
}
// Overrides Object.
@Override
public String toString() {
return root.toString(31337);
}
}
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