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# Class w3c.www.protocol.http.cache.CacheFilter

    java.lang.Object
       |
       +----w3c.www.protocol.http.cache.CacheFilter

public class CacheFilter
extends Object
implements PropRequestFilter, PropertyMonitoring

##

CACHE_CONNECTED_P
  Name of the property indicating wether the cache is connected or not.
CACHE_DIRECTORY_P
  Name of the property giving the cache's directory.
CACHE_SIZE_P
  The name of the properties indicating the size of the cache (in bytes).
connected
  Is this cache connected ?
debug
  The debug flag.
DEBUG_P
  Name of the property indicating if the cache is in debug mode.
directory
  The directory where the cache is stored.
expires_drift
  The expires drift.
FILE_SIZE_RATIO_P
  Name of the property indicating the max size for files to be cached.
fileSizeRatio
  The file size quota.
GARBAGE_COLLECTION_ENABLED_P
  Name of the property enabling garbage collection of the cache.
garbageCollectionEnabled
  Should we enable garbage collection of the cache ?
props
  The properties we initialized ourself from.
shared
  Is this cached shared ?
SHARED_P
  Name of the property indicating if this cache is shared.
size
  The current cache size.
STATE_CACHABLE
STATE_ORIGREQ
  Name of the request state used tokeep track of original request
STATE_RESOURCE
STATE_REVALIDATION
  Name of the request state that marks a request as being a revalidation.
STATE_WARNINGS
  Name of the request state used to collect warnings.
stats
  Our real time statistics.
WARN_DISCONNECTED
  The HTTP warning used to notify of a disconnected cache.
WARN_HEURISTIC
  The HTTP warning used to indicate a heuristic expiration time.
WARN_STALE
  The HTTP warning used to mark invalid entries

##

CacheFilter()

##

addWarning(Request, HttpWarning)
  Add a warning, to be emitted at reply time.
canCache(Request, Reply)
  Can the given reply to the given request be added to the cache.
canUseCache(Request)
  Can the given request be fullfilled by the cache filter ? This method distinguishes two situations.
exceptionFilter(Request, HttpException)
  This filter doesn't handle exceptions.
getCacheSize()
  Get the total size allocated to the cache.
getFile(URL)
getStatistics()
  Get the statistics repository associated with that filter.
hasResource(String)
  Does the cache knows about this resource ?
ingoingFilter(Request)
initialize(HttpManager)
  Initialize a new reuqest manager.
isConnected()
  Is this cache connected to the net ?
isGarbageCollectionEnabled()
  Are we allow to run garbage collections at all ?
isShared()
  Is this cache shared among multiple users ?
loadResource(String)
  Try to load from the cache the resource's whose URL is gievn.
markUsed(CachedResource)
markUsed(CachedResource, int)
markUsed(CachedResource, int, int)
  Mark the given cached resource as having been used recently.
outgoingFilter(Request, Reply)
propertyChanged(String)
  PropertyMonitoring implementation - Commit property changes.
removeResource(String)
  Remove a resource from the cache.
setWarnings(Request, Reply)
  Copy all warnings colllected into the given reply.
sync()
  Save all cache related infos to stable storage.
trace(Request, String)
updateCacheSpaceCounter(int)

##

STATE_WARNINGS

      public final static String STATE_WARNINGS

  Name of the request state used to collect warnings.

STATE_ORIGREQ

      public final static String STATE_ORIGREQ

  Name of the request state used tokeep track of original request

STATE_REVALIDATION

      public final static String STATE_REVALIDATION

  Name of the request state that marks a request as being a revalidation.

WARN_DISCONNECTED

      protected static HttpWarning WARN_DISCONNECTED

  The HTTP warning used to notify of a disconnected cache.

WARN_STALE

      protected static HttpWarning WARN_STALE

  The HTTP warning used to mark invalid entries

WARN_HEURISTIC

      protected static HttpWarning WARN_HEURISTIC

  The HTTP warning used to indicate a heuristic expiration time.

CACHE_SIZE_P

      public final static String CACHE_SIZE_P

  The name of the properties indicating the size of the cache (in bytes). This property will give the value of the disk-based cache size. This value only takes into account the size of the entities saved, not the size of the associated headers.

  This property defaults to 5000000 bytes.

DEBUG_P

      public final static String DEBUG_P

  Name of the property indicating if the cache is in debug mode.

  This property defaults to false.

SHARED_P

      public final static String SHARED_P

  Name of the property indicating if this cache is shared.

  This property defaults to true.

CACHE_DIRECTORY_P

      public final static String CACHE_DIRECTORY_P

  Name of the property giving the cache's directory. This property defaults to the current directory.

CACHE_CONNECTED_P

      public final static String CACHE_CONNECTED_P

  Name of the property indicating wether the cache is connected or not. This property defaults to true.

GARBAGE_COLLECTION_ENABLED_P

      public final static String GARBAGE_COLLECTION_ENABLED_P

  Name of the property enabling garbage collection of the cache. This property defaults to true.

FILE_SIZE_RATIO_P

      public final static String FILE_SIZE_RATIO_P

  Name of the property indicating the max size for files to be cached. This property gives the ratio (relative to the cache size) of the number of bytes a single entry is able to occupy.

  The ratio should be given as a floating point value between 0 and 1. If set to 0.1 and the cache size is 5000000, files larger then 500000 will not be cached (except if garbage collection is disbabled).

  This property defaults to 0.1.

STATE_CACHABLE

      public final static String STATE_CACHABLE

STATE_RESOURCE

      public final static String STATE_RESOURCE

props

      protected ObservableProperties props

  The properties we initialized ourself from.

directory

      protected File directory

  The directory where the cache is stored.

size

      protected int size

  The current cache size.

debug

      protected boolean debug

  The debug flag.

shared

      protected boolean shared

  Is this cached shared ?

connected

      protected boolean connected

  Is this cache connected ?

garbageCollectionEnabled

      protected boolean garbageCollectionEnabled

  Should we enable garbage collection of the cache ?

fileSizeRatio

      protected double fileSizeRatio

  The file size quota.

  Indicates the percentage of cache size allowed to be occupied by a single file. This is not taken into account when garbage collection is disabled.

expires_drift

      protected long expires_drift

  The expires drift.

  Control if we will cache already expires documents, in the hope that revalidation will be enough to refresh them, or also because the cache will be used in disconnected mode.

stats

      protected cacheStatistics stats

  Our real time statistics.

##

CacheFilter

      public CacheFilter()

##

addWarning

      protected void addWarning(Request request,
                                HttpWarning warning)

  Add a warning, to be emitted at reply time. The cache filter keeps track, through a specific piece of request state of the warnings to be emitted at reply time (if any).

  During request processing, cached resources can add any kind of warnings, which will be collected and forwarded back to the reply.

  Parameters:
    request - The request being process, and whose reply requires some warnings.
    warning - The warning to be emitted if ever we use the cache filter to answer the above request.

setWarnings

      protected final void setWarnings(Request request,
                                       Reply reply)

  Copy all warnings colllected into the given reply. This method collects all HTTP warnings saved during request processing and create (if needed) the approporiate warning header in the given reply.
  Parameters:
    request - The request that has been processed by the cache filter.
    reply - The reply that has been constructed from the cache.
  See Also:
    addWarning

trace

      protected final void trace(Request request,
                                 String msg)

updateCacheSpaceCounter

      protected final void updateCacheSpaceCounter(int delta)

isShared

      public final boolean isShared()

  Is this cache shared among multiple users ?
  Returns:
    A boolean true if shared, false otherwise.

isConnected

      public final boolean isConnected()

  Is this cache connected to the net ?
  Returns:
    A boolean, true if the cache is connected, false otherwise.

isGarbageCollectionEnabled

      public final boolean isGarbageCollectionEnabled()

  Are we allow to run garbage collections at all ?
  Returns:
    A boolean true if garbage collection is allowed , false otherwise.

getFile

      protected File getFile(URL url)

markUsed

      protected void markUsed(CachedResource resource,
                              int osize,
                              int nsize)

  Mark the given cached resource as having been used recently.
  Parameters:
    resource - The CachedResource instance that has been used.

markUsed

      protected void markUsed(CachedResource resource,
                              int nsize)

markUsed

      protected void markUsed(CachedResource resource)

propertyChanged

      public boolean propertyChanged(String name)

  PropertyMonitoring implementation - Commit property changes.
  Parameters:
    name - The name of the property that has changed.
  Returns:
    A boolean true if change was commited, false otherwise.

getCacheSize

      public final int getCacheSize()

  Get the total size allocated to the cache.
  Returns:
    The cache size as an integer.

initialize

      public void initialize(HttpManager manager) throws PropRequestFilterException

  Initialize a new reuqest manager. At this time, only one manager is allowed per application. This restriction will be removed either by using several managers, or by providing manager contexts.
  Parameters:
    manager - The manager to initialize.
  Throws: FilterInitException
    If the cache directory couldn't be created.

getStatistics

      public cacheStatistics getStatistics()

  Get the statistics repository associated with that filter.
  Returns:
    An instance of cacheStatistics.

loadResource

      public CachedResource loadResource(String url) throws InvalidResourceException

  Try to load from the cache the resource's whose URL is gievn.
  Parameters:
    url - The String version of the url of the resource to load.
  Returns:
    An instance of `CachedResource` (or one of its subclasses), or null if not found.

hasResource

      public boolean hasResource(String url)

  Does the cache knows about this resource ?
  Returns:
    A boolean true if this resource is known, false otherwise.

removeResource

      public void removeResource(String urlloc)

  Remove a resource from the cache.
  Parameters:
    urlloc - The URL of the resource to remove, encoded as a String.

canUseCache

      public boolean canUseCache(Request request)

  Can the given request be fullfilled by the cache filter ? This method distinguishes two situations. It first check if anything in the request makes it uncachable, if this is the case, processing continues normally. If the request can be answered by the cache, we mark it as such by setting the `w3c.www.protocol.http.cache` state of the request to Boolean.TRUE, ans we return true.
  Returns:
    A boolean, true if the request can be fullfilled by the cache, false otherwise.

canCache

      public boolean canCache(Request request,
                              Reply reply)

  Can the given reply to the given request be added to the cache. This method performs all checks to detect wether the given request, reply can be cached.

  We don't check for expires or maxage here, since we expect some sites to use negative expires, or zero max age, just for the sake of revalidation (that's fine).

  Returns:
    A boolean true if we can cache, false otherwise.

exceptionFilter

      public boolean exceptionFilter(Request request,
                                     HttpException ex)

  This filter doesn't handle exceptions.
  Parameters:
    request - The request that triggered the exception.
    ex - The triggered exception.
  Returns:
    Always false.

ingoingFilter

      public Reply ingoingFilter(Request request) throws HttpException

outgoingFilter

      public Reply outgoingFilter(Request request,
                                  Reply reply) throws HttpException

sync

      public void sync()

  Save all cache related infos to stable storage.

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