ucar.nc2.util
Class DiskCache2

java.lang.Object
  ucar.nc2.util.DiskCache2

public class DiskCache2
extends java.lang.Object

Manages a place on disk to persistently cache files, which are deleted when the last modified date exceeds a certain time. This starts up a thread to periodically scour itself; be sure to call exit() to terminate the thread.

Each DiskCache has a "root directory", which may be set as an absolute path, or reletive to the DiskCache "home directory". The root directory must be writeable. The DiskCache home directory is set in the following order:

1. through the system property "nj22.cachePersistRoot" if it exists
2. through the system property "user.home" if it exists
3. through the system property "user.dir" if it exists
4. to the current working directory

Version:

$Revision:63 $ $Date:2006-07-12 21:50:51Z $

Author:

jcaron

Field Summary

static int	CACHEPATH_POLICY_NESTED_DIRECTORY
static int	CACHEPATH_POLICY_NESTED_TRUNCATE
static int	CACHEPATH_POLICY_ONE_DIRECTORY

Constructor Summary

DiskCache2(java.lang.String root, boolean reletiveToHome, int persistMinutes, int scourEveryMinutes)
Create a cache on disk.

Method Summary

void	cleanCache(java.io.File dir, java.lang.StringBuffer sbuff, boolean isRoot) Remove any files or directories whose last modified time greater than persistMinutes
void	exit() Be sure to call this when your application exits, otherwise the scour thread may not die.
java.io.File	getCacheFile(java.lang.String fileLocation) Get a File in the cache, corresponding to the fileLocation.
java.lang.String	getRootDirectory() Get the cache root directory.
static void	main(java.lang.String[] args) debug
void	setCachePathPolicy(int cachePathPolicy, java.lang.String cachePathPolicyParam) CACHEPATH_POLICY_ONE_DIRECTORY (default) : replace "/" with "-", so all files are in one directory.
void	setLogger(org.slf4j.Logger cacheLog) Optionally set a logger.
void	setRootDirectory(java.lang.String cacheDir)
void	showCache(java.io.PrintStream pw) Show cache contents.

Methods inherited from class java.lang.Object

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

Field Detail

CACHEPATH_POLICY_ONE_DIRECTORY

public static int CACHEPATH_POLICY_ONE_DIRECTORY

CACHEPATH_POLICY_NESTED_DIRECTORY

public static int CACHEPATH_POLICY_NESTED_DIRECTORY

CACHEPATH_POLICY_NESTED_TRUNCATE

public static int CACHEPATH_POLICY_NESTED_TRUNCATE

Constructor Detail

DiskCache2

public DiskCache2(java.lang.String root,
                  boolean reletiveToHome,
                  int persistMinutes,
                  int scourEveryMinutes)

Create a cache on disk.

Parameters:

root - the root directory of the cache. Must be writeable.

reletiveToHome - if the root directory is reletive to the cache home directory.

persistMinutes - how old a file should be before deleting.

scourEveryMinutes - how often to run the scour process. If <= 0, dont scour.

Method Detail

exit

public void exit()

Be sure to call this when your application exits, otherwise the scour thread may not die.

setLogger

public void setLogger(org.slf4j.Logger cacheLog)

Optionally set a logger. Each time a scour is done, a messsage is written to it.

setRootDirectory

public void setRootDirectory(java.lang.String cacheDir)

getRootDirectory

public java.lang.String getRootDirectory()

Get the cache root directory.

getCacheFile

public java.io.File getCacheFile(java.lang.String fileLocation)

Get a File in the cache, corresponding to the fileLocation. File may or may not exist. If fileLocation has "/" in it, and cachePathPolicy == CACHEPATH_POLICY_NESTED_DIRECTORY, the nested directories will be created.

Parameters:

fileLocation - logical file location

Returns:

physical File in the cache.

setCachePathPolicy

public void setCachePathPolicy(int cachePathPolicy,
                               java.lang.String cachePathPolicyParam)

CACHEPATH_POLICY_ONE_DIRECTORY (default) : replace "/" with "-", so all files are in one directory. CACHEPATH_POLICY_NESTED_DIRECTORY: cache files are in nested directories under the root.

showCache

public void showCache(java.io.PrintStream pw)

Show cache contents.

Parameters:

pw - write to this PrintStream.

cleanCache

public void cleanCache(java.io.File dir,
                       java.lang.StringBuffer sbuff,
                       boolean isRoot)

Remove any files or directories whose last modified time greater than persistMinutes

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

debug

Throws:

java.io.IOException