org.apache.hadoop.yarn.util

Class BoundedAppender

java.lang.Object

org.apache.hadoop.yarn.util.BoundedAppender

@InterfaceAudience.Public
 @InterfaceStability.Unstable
 @VisibleForTesting
public class BoundedAppender
extends Object

A CharSequence appender that considers its limit as upper bound.

When limit would be reached on append, past messages will be truncated from head, and a header telling the user about truncation will be prepended, with ellipses in between header and messages.

Note that header and ellipses are not counted against limit.

An example:

 
   // At the beginning it's an empty string
   final Appendable shortAppender = new BoundedAppender(80);
   // The whole message fits into limit
   shortAppender.append(
       "message1 this is a very long message but fitting into limit\n");
   // The first message is truncated, the second not
   shortAppender.append("message2 this is shorter than the previous one\n");
   // The first message is deleted, the second truncated, the third
   // preserved
   shortAppender.append("message3 this is even shorter message, maybe.\n");
   // The first two are deleted, the third one truncated, the last preserved
   shortAppender.append("message4 the shortest one, yet the greatest :)");
   // Current contents are like this:
   // Diagnostic messages truncated, showing last 80 chars out of 199:
   // ...s is even shorter message, maybe.
   // message4 the shortest one, yet the greatest :)
 
 

Note that null values are appended just like in original implementation.

Note that this class is not thread safe.

Field Summary

Fields

Modifier and Type	Field and Description
static String	TRUNCATED_MESSAGES_TEMPLATE

Constructor Summary

Constructors

Constructor and Description
BoundedAppender(int limit)

Method Summary

Modifier and Type	Method and Description
BoundedAppender	append(CharSequence csq) Append a CharSequence considering limit, truncating from the head of csq or messages when necessary.
int	getLimit()
int	length() Get current length of messages considering truncates without header and ellipses.
String	toString() Get a string representation of the actual contents, displaying also a header and ellipses when there was a truncate.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

TRUNCATED_MESSAGES_TEMPLATE

@VisibleForTesting
public static final String TRUNCATED_MESSAGES_TEMPLATE

See Also:

Constant Field Values

Constructor Detail

BoundedAppender

public BoundedAppender(int limit)

Method Detail

append

public BoundedAppender append(CharSequence csq)

Append a CharSequence considering limit, truncating from the head of csq or messages when necessary.

Parameters:

csq - the CharSequence to append

Returns:

this

length

public int length()

Get current length of messages considering truncates without header and ellipses.

Returns:

current length

getLimit

public int getLimit()

toString

public String toString()

Get a string representation of the actual contents, displaying also a header and ellipses when there was a truncate.

Overrides:

toString in class Object

Returns:

String representation of the messages