org.opennms.netmgt.rrd
Class JniRrdStrategy

java.lang.Object
  org.opennms.netmgt.rrd.JniRrdStrategy

All Implemented Interfaces:

RrdStrategy

class JniRrdStrategy

extends java.lang.Object

implements RrdStrategy

Provides an rrdtool based implementation of RrdStrategy. It uses the existing JNI based single-threaded interface to write the rrdtool compatibile RRD files. The JNI interface takes command-like arguments and doesn't provide open files so the the Objects used to represent open files are really partial command strings See the individual methods for more details

Field Summary

(package private) boolean	graphicsInitialized
(package private) boolean	initialized

Constructor Summary

(package private)

JniRrdStrategy()

Method Summary

private void	checkState(java.lang.String methodName) Ensures that the initialize method has been called.
void	closeFile(java.lang.Object rrd) The 'closes' the rrd file.
java.lang.Object	createDefinition(java.lang.String creator, java.lang.String directory, java.lang.String dsName, int step, java.lang.String dsType, int dsHeartbeat, java.lang.String dsMin, java.lang.String dsMax, java.util.List rraList) Constructs an rrdtool create command string that can be used to create the rrd file and returns it as the rrdDefinition object.
void	createFile(java.lang.Object rrdDef) Creates a the rrd file from the rrdDefinition.
java.io.InputStream	createGraph(java.lang.String command, java.io.File workDir) Executes the given graph comnmand as process with workDir as the current directory.
java.lang.Double	fetchLastValue(java.lang.String rrdFile, int interval) Fetches the last value directly from the rrd file using the JNI Interface.
java.lang.String	getStats() No stats are kept for this implementation.
void	graphicsInitialize() This Initializes the graphics subsystem only.
void	initialize() Initialized the JNI Interface
java.lang.Object	openFile(java.lang.String fileName) The 'opens' the given rrd file.
void	updateFile(java.lang.Object rrd, java.lang.String data) This 'updates' the given rrd file by providing data.

Methods inherited from class java.lang.Object

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

Field Detail

initialized

boolean initialized

graphicsInitialized

boolean graphicsInitialized

Constructor Detail

JniRrdStrategy

JniRrdStrategy()

Method Detail

closeFile

public void closeFile(java.lang.Object rrd)
               throws java.lang.Exception

The 'closes' the rrd file. This is where the actual work of writing the RRD files takes place. The passed in rrd is actually an rrd command string containing updates. This method executes this command.

Specified by:

closeFile in interface RrdStrategy

Parameters:

rrd - an rrd object created using openFile

Throws:

java.lang.Exception - if an error occurs closing the file

checkState

private void checkState(java.lang.String methodName)

Ensures that the initialize method has been called.

Parameters:

methodName - the name of the method we are called from

Throws:

IllegalState - exception of intialize has not been called.

createDefinition

public java.lang.Object createDefinition(java.lang.String creator,
                                         java.lang.String directory,
                                         java.lang.String dsName,
                                         int step,
                                         java.lang.String dsType,
                                         int dsHeartbeat,
                                         java.lang.String dsMin,
                                         java.lang.String dsMax,
                                         java.util.List rraList)
                                  throws java.lang.Exception

Constructs an rrdtool create command string that can be used to create the rrd file and returns it as the rrdDefinition object.

Specified by:

createDefinition in interface RrdStrategy

Parameters:

creator - - A string representing who is creating this file for use in log msgs

directory - - The directory to create the file in

dsName - - The datasource name for use in the round robin database

step - - the step for the database

dsType - - the type for the datasource

dsHeartbeat - - the heartbeat for the datasouce

dsMin - - the minimum allowable value for the datasource

dsMax - - the maximum allowable value for the datasouce

rraList - - a List of the round robin archives to create in the database

Returns:

an object representing the definition of an round robin database

Throws:

java.lang.Exception - If an error occurs while creating the definition

createFile

public void createFile(java.lang.Object rrdDef)
                throws java.lang.Exception

Creates a the rrd file from the rrdDefinition. Since this definition is really just the create command string it just executes it.

Specified by:

createFile in interface RrdStrategy

Parameters:

rrdDef - an round robin database definition created using the createDefinition call.

Throws:

java.lang.Exception - if an error occurs create the file

openFile

public java.lang.Object openFile(java.lang.String fileName)
                          throws java.lang.Exception

The 'opens' the given rrd file. In actuality since the JNI interface does not provide files that may be open, this constructs the beginning portion of the rrd command to update the file.

Specified by:

openFile in interface RrdStrategy

Parameters:

fileName - the name of the associated rrd file

Returns:

an open rrd reference that can by used in calls to updateFile and closeFile

Throws:

java.lang.Exception - if an error occurs opening the file

updateFile

public void updateFile(java.lang.Object rrd,
                       java.lang.String data)
                throws java.lang.Exception

This 'updates' the given rrd file by providing data. Since the JNI interface does not provide files that can be open, this just appends the data to the command string constructed so far. The data is not immediately written to the file since this would eliminate the possibility of getting performance benefit by doing more than one write per open. The updates are all performed at once in the closeFile method.

Specified by:

updateFile in interface RrdStrategy

Parameters:

rrd - an rrd object created using openFile

data - a string of the form :

Throws:

java.lang.Exception - if an error occurs updating the file

initialize

public void initialize()
                throws java.lang.Exception

Initialized the JNI Interface

Specified by:

initialize in interface RrdStrategy

Throws:

java.lang.Exception - if an Error occurs

graphicsInitialize

public void graphicsInitialize()
                        throws java.lang.Exception

Description copied from interface: RrdStrategy

This Initializes the graphics subsystem only. This is used by the web application to avoid the need for the JNI infrastructure in the webapp.

Specified by:

graphicsInitialize in interface RrdStrategy

Throws:

java.lang.Exception

fetchLastValue

public java.lang.Double fetchLastValue(java.lang.String rrdFile,
                                       int interval)
                                throws java.lang.NumberFormatException,
                                       RrdException

Fetches the last value directly from the rrd file using the JNI Interface.

Specified by:

fetchLastValue in interface RrdStrategy

Parameters:

rrdFile - a name the represents a round robin database

interval - a step interval of the round robin database

Returns:

The last value as a Double (if the last value didn't exist returns a Double.NaN)

Throws:

java.lang.NumberFormatException

RrdException

createGraph

public java.io.InputStream createGraph(java.lang.String command,
                                       java.io.File workDir)
                                throws java.io.IOException,
                                       RrdException

Executes the given graph comnmand as process with workDir as the current directory. The output stream of the command (a PNG image) is copied to a the InputStream returned from the method.

Specified by:

createGraph in interface RrdStrategy

Parameters:

command - the command needed to create the graph

workDir - the directory that all referenced files are relative to

Returns:

an input stream representing the bytes of a graph image as a PNG file

Throws:

RrdException - if an RRD error occurs

java.io.IOException - if an IOError occurs

getStats

public java.lang.String getStats()

No stats are kept for this implementation.

Specified by:

getStats in interface RrdStrategy

Returns:

a non-null string representing any staticstics to be included in the logs