org.apache.hadoop.log
Class Log4Json

java.lang.Object
  org.apache.log4j.Layout
      org.apache.hadoop.log.Log4Json

All Implemented Interfaces:

org.apache.log4j.spi.OptionHandler

public class Log4Json
extends org.apache.log4j.Layout

This offers a log layout for JSON, with some test entry points. It's purpose is to allow Log4J to generate events that are easy for other programs to parse, but which are somewhat human-readable. Some features.

1. Every event is a standalone JSON clause
2. Time is published as a time_t event since 1/1/1970 -this is the fastest to generate.
3. An ISO date is generated, but this is cached and will only be accurate to within a second
4. the stack trace is included as an array

A simple log event will resemble the following

     {"name":"test","time":1318429136789,"date":"2011-10-12 15:18:56,789","level":"INFO","thread":"main","message":"test message"}
 

An event with an error will contain data similar to that below (which has been reformatted to be multi-line).

     {
     "name":"testException",
     "time":1318429136789,
     "date":"2011-10-12 15:18:56,789",
     "level":"INFO",
     "thread":"quoted\"",
     "message":"new line\n and {}",
     "exceptionclass":"java.net.NoRouteToHostException",
     "stack":[
         "java.net.NoRouteToHostException: that box caught fire 3 years ago",
         "\tat org.apache.hadoop.log.TestLog4Json.testException(TestLog4Json.java:49)",
         "\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
         "\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)",
         "\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)",
         "\tat java.lang.reflect.Method.invoke(Method.java:597)",
         "\tat junit.framework.TestCase.runTest(TestCase.java:168)",
         "\tat junit.framework.TestCase.runBare(TestCase.java:134)",
         "\tat junit.framework.TestResult$1.protect(TestResult.java:110)",
         "\tat junit.framework.TestResult.runProtected(TestResult.java:128)",
         "\tat junit.framework.TestResult.run(TestResult.java:113)",
         "\tat junit.framework.TestCase.run(TestCase.java:124)",
         "\tat junit.framework.TestSuite.runTest(TestSuite.java:232)",
         "\tat junit.framework.TestSuite.run(TestSuite.java:227)",
         "\tat org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)",
         "\tat org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:59)",
         "\tat org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:120)",
         "\tat org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:145)",
         "\tat org.apache.maven.surefire.Surefire.run(Surefire.java:104)",
         "\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
         "\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)",
         "\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)",
         "\tat java.lang.reflect.Method.invoke(Method.java:597)",
         "\tat org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:290)",
         "\tat org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:1017)"
         ]
     }
 

Field Summary

static String	DATE
static String	EXCEPTION_CLASS
static String	JSON_TYPE
static String	LEVEL
static String	MESSAGE
static String	NAME
static String	STACK
static String	THREAD
static String	TIME

Fields inherited from class org.apache.log4j.Layout

LINE_SEP, LINE_SEP_LEN

Constructor Summary

Log4Json()

Method Summary

void	activateOptions() Do nothing
String	format(org.apache.log4j.spi.LoggingEvent event)
String	getContentType()
boolean	ignoresThrowable() This appender does not ignore throwables
static org.codehaus.jackson.node.ContainerNode	parse(String json) For use in tests
String	toJson(org.apache.log4j.spi.LoggingEvent event) Convert an event to JSON
Writer	toJson(Writer writer, org.apache.log4j.spi.LoggingEvent event) Convert an event to JSON
Writer	toJson(Writer writer, String loggerName, long timeStamp, String level, String threadName, String message, org.apache.log4j.spi.ThrowableInformation ti) Build a JSON entry from the parameters.

Methods inherited from class org.apache.log4j.Layout

getFooter, getHeader

Methods inherited from class java.lang.Object

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

Field Detail

DATE

public static final String DATE

See Also:

Constant Field Values

EXCEPTION_CLASS

public static final String EXCEPTION_CLASS

See Also:

Constant Field Values

LEVEL

public static final String LEVEL

See Also:

Constant Field Values

MESSAGE

public static final String MESSAGE

See Also:

Constant Field Values

NAME

public static final String NAME

See Also:

Constant Field Values

STACK

public static final String STACK

See Also:

Constant Field Values

THREAD

public static final String THREAD

See Also:

Constant Field Values

TIME

public static final String TIME

See Also:

Constant Field Values

JSON_TYPE

public static final String JSON_TYPE

See Also:

Constant Field Values

Constructor Detail

Log4Json

public Log4Json()

Method Detail

getContentType

public String getContentType()

Overrides:

getContentType in class org.apache.log4j.Layout

Returns:

the mime type of JSON

format

public String format(org.apache.log4j.spi.LoggingEvent event)

Specified by:

format in class org.apache.log4j.Layout

toJson

public String toJson(org.apache.log4j.spi.LoggingEvent event)
              throws IOException

Convert an event to JSON

Parameters:

event - the event -must not be null

Returns:

a string value

Throws:

IOException - on problems generating the JSON

toJson

public Writer toJson(Writer writer,
                     org.apache.log4j.spi.LoggingEvent event)
              throws IOException

Convert an event to JSON

Parameters:

writer - the destination writer

event - the event -must not be null

Returns:

the writer

Throws:

IOException - on problems generating the JSON

toJson

public Writer toJson(Writer writer,
                     String loggerName,
                     long timeStamp,
                     String level,
                     String threadName,
                     String message,
                     org.apache.log4j.spi.ThrowableInformation ti)
              throws IOException

Build a JSON entry from the parameters. This is public for testing.

Parameters:

writer - destination

loggerName - logger name

timeStamp - time_t value

level - level string

threadName - name of the thread

message - rendered message

ti - nullable thrown information

Returns:

the writer

Throws:

IOException - on any problem

ignoresThrowable

public boolean ignoresThrowable()

This appender does not ignore throwables

Specified by:

ignoresThrowable in class org.apache.log4j.Layout

Returns:

false, always

activateOptions

public void activateOptions()

Do nothing

parse

public static org.codehaus.jackson.node.ContainerNode parse(String json)
                                                     throws IOException

For use in tests

Parameters:

json - incoming JSON to parse

Returns:

a node tree

Throws:

IOException - on any parsing problems