weka.core

Class WekaPackageLibIsolatingClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

java.net.URLClassLoader

weka.core.WekaPackageLibIsolatingClassLoader

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class WekaPackageLibIsolatingClassLoader
extends java.net.URLClassLoader

A ClassLoader that loads/finds classes from one Weka plugin package. This includes the top-level jar file(s) and third-party libraries in the package's lib directory. First checks the parent classloader (typically application classloader) - covers general stuff and weka core classes. Next tries the package jar files and third-party libs covered by this classloader/package. Next tries packages this one depends on and their third-party libs - this is transitive. Finally tries all top-level package jar files over all packages.

The basic assumption for Weka packages is that classes present in top-level jar package jar files contain Weka-related code (schemes, filters, GUI panels, tools, etc.), that is visible to all other packages via Weka's dynamic class discovery mechanism. A top-level jar file should not contain any third-party library code. If package A needs to compile against (and explicitly reference) classes provided by package B (either top-level jar or third-party library), then it should declare a dependency on package B.

Field Summary

Fields

Modifier and Type	Field and Description
protected WekaPackageClassLoaderManager	m_classloaderRepo A reference to the classloader manager
protected boolean	m_debug True to output debugging info
protected java.util.Set<java.lang.String>	m_libJarEntries Classes in the lib jar file(s)
protected java.util.Set<java.lang.String>	m_packageDependencies Which packages this one depends on
protected java.util.Set<java.lang.String>	m_packageJarEntries Classes in the top-level jar file(s)
protected java.util.Set<java.lang.String>	m_packageJarResources Resources in the top-level jar file(s)
protected java.lang.String	m_packageName The name of the package that this classloader loads classes from

Constructor Summary

Constructors

Constructor and Description
WekaPackageLibIsolatingClassLoader(WekaPackageClassLoaderManager repo, java.io.File packageDir) Constructor

Method Summary

Modifier and Type	Method and Description
protected void	addPackageDependency(java.lang.String packageName) Add a package dependency to this classloader
protected boolean	checkForMissingClasses(Package toCheck, java.io.PrintStream... progress) Checks to see if there are any classes that we should try to instantiate before allowing this package to be loaded.
static boolean	checkForMissingFiles(Package toLoad, java.io.File packageRoot, java.io.PrintStream... progress) Checks to see if there are any missing files/directories for a given package.
protected java.util.List<java.lang.String>	checkForNativeLibs(Package toLoad, java.io.File packageDir) Checks for native libraries and any native library loader classes, as specified by the presence of "NativeLibs" and "InjectLoader" entries in the package's Description.props file respectively.
protected static boolean	checkForUnsetEnvVar(Package toLoad) Checks to see if there are any environment variables or properties that should be set at startup before allowing this package to be loaded.
protected void	closeClassLoader() Try to clear classloader file locks under Windows
protected java.lang.Class<?>	findClass(java.lang.String name) Find a class using this package classloader.
protected java.lang.Class<?>	findGloballyVisiblePackageClass(java.lang.String name) Returns a Class object if this classloader covers the named globally visible class (i.e. its top-level jar(s) contain the class), or null otherwise.
protected java.net.URL	findGloballyVisiblePackageResource(java.lang.String name) Returns a URL a resource if this classloader covers the named globally visible resource (i.e. its top-level jar(s) contain the resource), or null otherwise
protected java.util.Enumeration<java.net.URL>	findGloballyVisiblePackageResources(java.lang.String name) return an enumeration of URLS if this classloader covers the named globally visible resource, or null otherwise.
java.util.List<WekaPackageLibIsolatingClassLoader>	getPackageClassLoadersForDependencies() Gets a list of class loaders for the packages that this one depends on
java.util.Set<java.lang.String>	getPackageJarEntries() Get a Set of the names of all classes contained within top-level jar files in this package
java.lang.String	getPackageName() Return the name of the package that this classloader loads classes for
java.net.URL	getResource(java.lang.String name) Find a named resource.
java.util.Enumeration<java.net.URL>	getResources(java.lang.String name) Find an enumeration of resources matching the supplied name.
boolean	hasThirdPartyClass(java.lang.String className) Returns true if this classloader is covering the named third-party class
protected void	init(java.io.File packageDir) Initializes the classloader from the package directory.
protected void	installNativeLibs(java.io.File packageDir, java.lang.String libJar, java.util.List<java.lang.String> libJarPaths) Installs any native libraries in the specified jar to $WEKA_HOME/native, if not already present therein.
protected boolean	integrityCheck() Check the integrity of this classloader (typically done for each classloader after all packages have been loaded by the package manager).
protected boolean	nativeLibInstalled(java.lang.String libName) Returns true if a named native library is already present in $WEKA_HOME/native
protected void	processDir(java.io.File dir, java.util.List<java.lang.String> jarsToIgnore, boolean topLevel) Process jar files in a directory of this package.
protected void	setSystemProperties(Package toLoad, java.io.PrintStream... progress) Set any system properties specified in the metadata for this package
protected void	storeJarContents(java.io.File jarFile, java.util.Set<java.lang.String> repo, boolean isTopLevelPackageJar) Stores all the names of all classes in the supplied jar file in the supplied set.
java.lang.String	toString() String representation of this classloader

Methods inherited from class java.net.URLClassLoader

addURL, close, definePackage, findResource, findResources, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Field Detail

m_packageName

protected java.lang.String m_packageName

The name of the package that this classloader loads classes from

m_classloaderRepo

protected WekaPackageClassLoaderManager m_classloaderRepo

A reference to the classloader manager

m_packageJarEntries

protected java.util.Set<java.lang.String> m_packageJarEntries

Classes in the top-level jar file(s)

m_packageJarResources

protected java.util.Set<java.lang.String> m_packageJarResources

Resources in the top-level jar file(s)

m_libJarEntries

protected java.util.Set<java.lang.String> m_libJarEntries

Classes in the lib jar file(s)

m_debug

protected boolean m_debug

True to output debugging info

m_packageDependencies

protected java.util.Set<java.lang.String> m_packageDependencies

Which packages this one depends on

Constructor Detail

WekaPackageLibIsolatingClassLoader

public WekaPackageLibIsolatingClassLoader(WekaPackageClassLoaderManager repo,
                                          java.io.File packageDir)
                                   throws java.lang.Exception

Constructor

Parameters:

repo - a reference to the classloader manager

packageDir - the package directory for the package covered by this classloader

Throws:

java.lang.Exception - if a problem occurs

Method Detail

init

protected void init(java.io.File packageDir)
             throws java.lang.Exception

Initializes the classloader from the package directory. Checks for, and processes, any native libraries and loaders specified in the Description.props file; Assembles a list of packages that this one depends on; processes top-level jar files and third party libraries in the lib directory.

Parameters:

packageDir - the home directory for the package

Throws:

java.lang.Exception - if a problem occurs

addPackageDependency

protected void addPackageDependency(java.lang.String packageName)

Add a package dependency to this classloader

Parameters:

packageName - the name of the package to add as a dependency

getPackageClassLoadersForDependencies

public java.util.List<WekaPackageLibIsolatingClassLoader> getPackageClassLoadersForDependencies()

Gets a list of class loaders for the packages that this one depends on

Returns:

a list of class loaders for the packages that this one depends on

checkForNativeLibs

protected java.util.List<java.lang.String> checkForNativeLibs(Package toLoad,
                                                              java.io.File packageDir)

Checks for native libraries and any native library loader classes, as specified by the presence of "NativeLibs" and "InjectLoader" entries in the package's Description.props file respectively. Native libraries are copied to $WEKA_HOME/native (if not already present therein). Classes specified by "InjectLoader" are injected into the root classloader.

Parameters:

toLoad - the package object for the this package

packageDir - the home directory of the package

Returns:

a list of jar files that should be ignored by this classloader when loading classes (i.e. all jar files specified in the "InjectLoader" entry)

installNativeLibs

protected void installNativeLibs(java.io.File packageDir,
                                 java.lang.String libJar,
                                 java.util.List<java.lang.String> libJarPaths)
                          throws java.io.IOException

Installs any native libraries in the specified jar to $WEKA_HOME/native, if not already present therein.

Parameters:

packageDir - the home directory of this package

libJar - the path to the jar that contains the libs (relative to the package home directory)

libJarPaths - paths to libraries to install within the jar

Throws:

java.io.IOException - if a problem occurs

nativeLibInstalled

protected boolean nativeLibInstalled(java.lang.String libName)

Returns true if a named native library is already present in $WEKA_HOME/native

Parameters:

libName - the name of the library to check

Returns:

true if the library is already present in $WEKA_HOME/native

processDir

protected void processDir(java.io.File dir,
                          java.util.List<java.lang.String> jarsToIgnore,
                          boolean topLevel)
                   throws java.net.MalformedURLException

Process jar files in a directory of this package. Jar files at the top-level and those in the lib directory are added to this URLClassLoader's list, unless specified in the list of jars to ignore.

Parameters:

dir - the directory to process

jarsToIgnore - a list of jar files to ignore

topLevel - true if this is the top-level (home) directory of the package

Throws:

java.net.MalformedURLException - if a problem occurs

storeJarContents

protected void storeJarContents(java.io.File jarFile,
                                java.util.Set<java.lang.String> repo,
                                boolean isTopLevelPackageJar)

Stores all the names of all classes in the supplied jar file in the supplied set. Non-class, non-directory entries in jar files at the top-level of the package are stored as resources in a separate lookup set.

Parameters:

jarFile - jar file to process

repo - a set to store class names in

isTopLevelPackageJar - true if this jar file is at the top-level of the package.

findClass

protected java.lang.Class<?> findClass(java.lang.String name)
                                throws java.lang.ClassNotFoundException

Find a class using this package classloader. First checks the parent classloader (typically application classloader) - covers general stuff and weka core classes. Next tries the package jar files and third-party libs covered by this classloader. Next tries packages this one depends on and their third-party libs - this is transitive. Finally tries all top-level package jar files over all packages.

Overrides:

findClass in class java.net.URLClassLoader

Parameters:

name - the name of the class to find

Returns:

the class

Throws:

java.lang.ClassNotFoundException - if the class cannot be found

getResource

public java.net.URL getResource(java.lang.String name)

Find a named resource. First checks parent classloader and stuff covered by this classloader. Next tries packages that this one depends on.

Overrides:

getResource in class java.lang.ClassLoader

Parameters:

name - the name of the resource to look for

Returns:

the URL of the resource, or null if the resource is not found

getResources

public java.util.Enumeration<java.net.URL> getResources(java.lang.String name)
                                                 throws java.io.IOException

Find an enumeration of resources matching the supplied name. First checks parent classloader and stuff covered by this classloader. Next tries packages that this one depends on.

Overrides:

getResources in class java.lang.ClassLoader

Parameters:

name - the name to look for

Returns:

an enumeration of URLs

Throws:

java.io.IOException - if a problem occurs

hasThirdPartyClass

public boolean hasThirdPartyClass(java.lang.String className)

Returns true if this classloader is covering the named third-party class

Parameters:

className - the third-party classname to check for

Returns:

true if this classloader is covering the named third-party class

findGloballyVisiblePackageClass

protected java.lang.Class<?> findGloballyVisiblePackageClass(java.lang.String name)

Returns a Class object if this classloader covers the named globally visible class (i.e. its top-level jar(s) contain the class), or null otherwise.

Parameters:

name - the name of the class to check for

Returns:

the Class or null.

findGloballyVisiblePackageResource

protected java.net.URL findGloballyVisiblePackageResource(java.lang.String name)

Returns a URL a resource if this classloader covers the named globally visible resource (i.e. its top-level jar(s) contain the resource), or null otherwise

Parameters:

name - the path to the resource

Returns:

a URL to the resource, or null if not covered by this package.

findGloballyVisiblePackageResources

protected java.util.Enumeration<java.net.URL> findGloballyVisiblePackageResources(java.lang.String name)
                                                                           throws java.io.IOException

return an enumeration of URLS if this classloader covers the named globally visible resource, or null otherwise.

Parameters:

name - the path of the resource to check for

Returns:

an enumeration of URLs, or null

Throws:

java.io.IOException - if a problem occurs

closeClassLoader

protected void closeClassLoader()

Try to clear classloader file locks under Windows

toString

public java.lang.String toString()

String representation of this classloader

Overrides:

toString in class java.lang.Object

Returns:

the string representation of this classloader

getPackageName

public java.lang.String getPackageName()

Return the name of the package that this classloader loads classes for

Returns:

return the name of the package that this classloader loads classes for

getPackageJarEntries

public java.util.Set<java.lang.String> getPackageJarEntries()

Get a Set of the names of all classes contained within top-level jar files in this package

Returns:

a Set of the names of classes contained in top-level jar files in this package

integrityCheck

protected boolean integrityCheck()
                          throws java.lang.Exception

Check the integrity of this classloader (typically done for each classloader after all packages have been loaded by the package manager). Checks to see that a classloader for each dependency is available

Returns:

true if a classloader for each dependency is available

Throws:

java.lang.Exception

setSystemProperties

protected void setSystemProperties(Package toLoad,
                                   java.io.PrintStream... progress)

Set any system properties specified in the metadata for this package

Parameters:

toLoad - the package in question

progress - for printing progress/debug info

checkForMissingClasses

protected boolean checkForMissingClasses(Package toCheck,
                                         java.io.PrintStream... progress)
                                  throws java.lang.Exception

Checks to see if there are any classes that we should try to instantiate before allowing this package to be loaded. This is useful for checking to see if third-party classes are accessible. An example would be Java3D, which has an installer that installs into the JRE/JDK.

Parameters:

toCheck - the package in question

progress - for printing progress/error info

Returns:

true if good to go

Throws:

java.lang.Exception - if there is a problem

checkForMissingFiles

public static boolean checkForMissingFiles(Package toLoad,
                                           java.io.File packageRoot,
                                           java.io.PrintStream... progress)

Checks to see if there are any missing files/directories for a given package. If there are missing files, then the package can't be loaded. An example would be a connector package that, for whatever reason, can't include a necessary third-party jar file in its lib folder, and requires the user to download and install this jar file manually.

Parameters:

toLoad - the package to check

packageRoot - the root directory of the package

progress - for printing progress/error info

Returns:

true if good to go

checkForUnsetEnvVar

protected static boolean checkForUnsetEnvVar(Package toLoad)

Checks to see if there are any environment variables or properties that should be set at startup before allowing this package to be loaded. This is useful for packages that might not be able to function correctly if certain variables are not set correctly.

Parameters:

toLoad - the package to check

Returns:

true if good to go