org.jgroups.protocols
Class PDC

java.lang.Object
  org.jgroups.stack.Protocol
      org.jgroups.protocols.PDC

public class PDC
extends Protocol

Persistent Discovery Cache. Caches mapping between logical and physical addresses on disk, merges them with the results of the get physical address(es) events. This is done by intercepting the get and set physical address(es) event. Needs to be placed between the transport and the discovery protocol. The disk cache stores each mapping in a separate file, named by the logical address.

Since:

3.3

Author:

Bela Ban

Nested Class Summary

protected static class

PDC.Mapping

Field Summary

protected java.util.concurrent.ConcurrentMap<Address,PhysicalAddress>	cache
protected java.lang.String	cache_dir
protected java.io.FilenameFilter	filter
protected Address	local_addr
protected java.io.File	root_dir
protected static java.lang.String	SUFFIX

Fields inherited from class org.jgroups.stack.Protocol

down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

PDC()

Method Summary

protected static java.lang.String	addressAsString(Address address)
protected void	createDiskCacheFile()
protected boolean	deleteFile(java.io.File file) Attempts to delete the provided file. Logging is performed on the result
java.lang.Object	down(Event evt) An event is to be sent down the stack.
void	init() Called after instance has been created (null constructor) and before protocol is started.
java.lang.String	printCache()
protected void	readCacheFromDisk() Reads all mappings from disk
protected void	removeNodeFromDisk(Address logical_addr)
protected void	writeNodeToDisk(Address logical_addr, PhysicalAddress physical_addr)
protected java.io.File	writeToTempFile(java.io.File dir, Address logical_addr, Address physical_addr, java.lang.String logical_name) Writes the data to a temporary file. The file is stored in the same directory as the other cluster files but is given the .tmp suffix

Methods inherited from class org.jgroups.stack.Protocol

destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, stop, up

Methods inherited from class java.lang.Object

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

Field Detail

cache

protected final java.util.concurrent.ConcurrentMap<Address,PhysicalAddress> cache

cache_dir

protected java.lang.String cache_dir

SUFFIX

protected static final java.lang.String SUFFIX

See Also:

Constant Field Values

root_dir

protected java.io.File root_dir

filter

protected java.io.FilenameFilter filter

local_addr

protected Address local_addr

Constructor Detail

PDC

public PDC()

Method Detail

printCache

public java.lang.String printCache()

init

public void init()
          throws java.lang.Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Protocol

Throws:

java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

down

public java.lang.Object down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().

Overrides:

down in class Protocol

createDiskCacheFile

protected void createDiskCacheFile()
                            throws java.io.IOException

Throws:

java.io.IOException

readCacheFromDisk

protected void readCacheFromDisk()

Reads all mappings from disk

writeNodeToDisk

protected void writeNodeToDisk(Address logical_addr,
                               PhysicalAddress physical_addr)

writeToTempFile

protected java.io.File writeToTempFile(java.io.File dir,
                                       Address logical_addr,
                                       Address physical_addr,
                                       java.lang.String logical_name)
                                throws java.lang.Exception

Writes the data to a temporary file.
The file is stored in the same directory as the other cluster files but is given the .tmp suffix

Parameters:

dir - The disk cache root dir

logical_addr - The logical address

physical_addr - The physical address

Returns:

Throws:

java.lang.Exception

removeNodeFromDisk

protected void removeNodeFromDisk(Address logical_addr)

addressAsString

protected static java.lang.String addressAsString(Address address)

deleteFile

protected boolean deleteFile(java.io.File file)

Attempts to delete the provided file.
Logging is performed on the result

Parameters:

file -

Returns: