Package org.jgroups.protocols

Class PDC

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.PDC

All Implemented Interfaces:

Lifecycle

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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	PDC.Mapping

Field Summary

Fields

Modifier and Type	Field	Description
protected final ConcurrentMap<Address,PhysicalAddress>	cache
protected String	cache_dir
protected FilenameFilter	filter
protected File	root_dir
protected static final String	SUFFIX

Fields inherited from class org.jgroups.stack.Protocol

after_creation_hook, down_prot, ergonomics, id, local_addr, log, policies, stack, stats, up_prot

Constructor Summary

Constructors

Constructor	Description
PDC()

Method Summary

Modifier and Type	Method	Description
protected static String	addressAsString(Address address)
protected void	createDiskCacheFile()
protected boolean	deleteFile(File file)	Attempts to delete the provided file. Logging is performed on the result
Object	down(Event evt)	An event is to be sent down the stack.
void	init()	Called after a protocol has been created and before the protocol is started.
String	printCache()
private PDC.Mapping	readAddressMapping(File file)
protected void	readCacheFromDisk()	Reads all mappings from disk
protected void	removeNodeFromDisk(Address logical_addr)
protected void	writeNodeToDisk(Address logical_addr, PhysicalAddress physical_addr)
protected File	writeToTempFile(File dir, Address logical_addr, Address physical_addr, 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

accept, addPolicy, addr, addr, afterCreationHook, destroy, down, down, enableStats, getAddress, getComponents, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getPolicies, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, policies, providedDownServices, providedUpServices, removePolicy, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setAddress, setDownProtocol, setErgonomics, setId, setLevel, setPolicies, setProtocolStack, setSocketFactory, setUpProtocol, setValue, start, statsEnabled, stop, toString, up, up, up

Methods inherited from class java.lang.Object

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

Field Details

cache

protected final ConcurrentMap<Address,PhysicalAddress> cache

cache_dir

protected String cache_dir

SUFFIX

protected static final String SUFFIX

See Also:

• Constant Field Values

root_dir

protected File root_dir

filter

protected FilenameFilter filter

Constructor Details

PDC

public PDC()

Method Details

printCache

public String printCache()

init

public void init()
          throws Exception

Description copied from class: Protocol

Called after a protocol has been created and before the protocol is started. Attributes are already set. Other protocols are not yet connected and events cannot yet be sent.

Specified by:

init in interface Lifecycle

Overrides:

init in class Protocol

Throws:

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

down

public Object down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. A protocol 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 protocol may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down().

Overrides:

down in class Protocol

createDiskCacheFile

protected void createDiskCacheFile()
                            throws IOException

Throws:

IOException

readCacheFromDisk

protected void readCacheFromDisk()

Reads all mappings from disk

readAddressMapping

private PDC.Mapping readAddressMapping(File file)

writeNodeToDisk

protected void writeNodeToDisk(Address logical_addr,
 PhysicalAddress physical_addr)

writeToTempFile

protected File writeToTempFile(File dir,
 Address logical_addr,
 Address physical_addr,
 String logical_name)
                        throws 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:

Exception

removeNodeFromDisk

protected void removeNodeFromDisk(Address logical_addr)

addressAsString

protected static String addressAsString(Address address)

deleteFile

protected boolean deleteFile(File file)

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

Parameters:

file -

Returns: