org.mpisws.p2p.transport.peerreview.history
Class SecureHistoryImpl

java.lang.Object
  org.mpisws.p2p.transport.peerreview.history.SecureHistoryImpl

All Implemented Interfaces:

SecureHistory

public class SecureHistoryImpl
extends java.lang.Object
implements SecureHistory

The following class implements PeerReview's log. A log entry consists of a sequence number, a type, and a string of bytes. On disk, the log is stored as two files: An index file and a data file.

Author:

Jeff Hoye, Andreas Haeberlen

Constructor Summary

SecureHistoryImpl(RandomAccessFileIOBuffer indexFile, RandomAccessFileIOBuffer dataFile, boolean readOnly, HashProvider hashProv, IndexEntryFactory indexFactory, Logger logger)

Method Summary

void	appendEntry(short type, boolean storeFullEntry, java.nio.ByteBuffer... entry) Appends a new entry to the log.
void	appendHash(short type, Hash hash) Append a new hashed entry to the log.
void	close() The destructor.
long	findLastEntry(short[] types, long maxSeq) Find the most recent entry whose type is in the specified set.
long	findSeqOrHigher(long seq, boolean allowHigher) Look up a given sequence number, or the first sequence number that is not lower than a given number.
long	getBaseSeq()
byte[]	getEntry(IndexEntry ie, int maxSizeToRead)
byte[]	getEntry(long idx, int maxSizeToRead) Get the content of a log entry, specified by its record number
long	getLastSeq()
long	getNumEntries()
HashSeq	getTopLevelEntry() Returns the node hash and the sequence number of the most recent log entry
boolean	serializeRange(int idxFrom, int idxTo, HashPolicy hashPolicy, RandomAccessFileIOBuffer outfile) Serialize a given range of entries, and write the result to the specified file.
boolean	setNextSeq(long nextSeq) Sets the next sequence number to be used.
IndexEntry	statEntry(long idx) Retrieve information about a given record
boolean	upgradeHashedEntry(int idx, java.nio.ByteBuffer entry) If the log already contains an entry in 'hashed' form and we learn the actual contents later, this function is called.

Methods inherited from class java.lang.Object

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

Constructor Detail

SecureHistoryImpl

public SecureHistoryImpl(RandomAccessFileIOBuffer indexFile,
                         RandomAccessFileIOBuffer dataFile,
                         boolean readOnly,
                         HashProvider hashProv,
                         IndexEntryFactory indexFactory,
                         Logger logger)
                  throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getBaseSeq

public long getBaseSeq()

Specified by:

getBaseSeq in interface SecureHistory

getLastSeq

public long getLastSeq()

Specified by:

getLastSeq in interface SecureHistory

getNumEntries

public long getNumEntries()

Specified by:

getNumEntries in interface SecureHistory

getTopLevelEntry

public HashSeq getTopLevelEntry()

Returns the node hash and the sequence number of the most recent log entry

Specified by:

getTopLevelEntry in interface SecureHistory

appendEntry

public void appendEntry(short type,
                        boolean storeFullEntry,
                        java.nio.ByteBuffer... entry)
                 throws java.io.IOException

Appends a new entry to the log. If 'storeFullEntry' is false, only the hash of the entry is stored. If 'header' is not NULL, the log entry is formed by concatenating 'header' and 'entry'; otherwise, only 'entry' is used.

Specified by:

appendEntry in interface SecureHistory

Throws:

java.io.IOException

appendHash

public void appendHash(short type,
                       Hash hash)
                throws java.io.IOException

Append a new hashed entry to the log. Unlike appendEntry(), this only keeps the content type, sequence number, and hash values. No entry is made in the data file.

Specified by:

appendHash in interface SecureHistory

Throws:

java.io.IOException

setNextSeq

public boolean setNextSeq(long nextSeq)

Sets the next sequence number to be used. The PeerReview library typically uses the format , where X is a timestamp in microseconds and Y a sequence number. The sequence numbers need not be contigious (and usually aren't)

Specified by:

setNextSeq in interface SecureHistory

close

public void close()
           throws java.io.IOException

The destructor. Closes the file handles.

Specified by:

close in interface SecureHistory

Throws:

java.io.IOException

findSeqOrHigher

public long findSeqOrHigher(long seq,
                            boolean allowHigher)
                     throws java.io.IOException

Look up a given sequence number, or the first sequence number that is not lower than a given number. The return value is the number of the corresponding record in the index file, or -1 if no matching record was found.

Specified by:

findSeqOrHigher in interface SecureHistory

Throws:

java.io.IOException

serializeRange

public boolean serializeRange(int idxFrom,
                              int idxTo,
                              HashPolicy hashPolicy,
                              RandomAccessFileIOBuffer outfile)
                       throws java.io.IOException

Serialize a given range of entries, and write the result to the specified file. This is used when we need to send a portion of our log to some other node, e.g. during an audit. The format of the serialized log segment is as follows: 1. base hash value (size depends on hash function) 2. entry type (1 byte) 3. entry size in bytes (1 byte); 0x00=entry is hashed; 0xFF=16-bit size follows 4. entry content (size as specified; omitted if entry is hashed) 5. difference to next sequence number (1 byte) 0x00: increment by one 0xFF: 64-bit sequence number follows Otherwise: Round down to nearest multiple of 1000, then add specified value times 1000 6. repeat 2-5 as often as necessary; 5 is omitted on last entry. Note that the idxFrom and idxTo arguments are record numbers, NOT sequence numbers. Use findSeqOrHigher() to get these if only sequence numbers are known.

Specified by:

serializeRange in interface SecureHistory

Throws:

java.io.IOException

statEntry

public IndexEntry statEntry(long idx)
                     throws java.io.IOException

Retrieve information about a given record

Specified by:

statEntry in interface SecureHistory

Parameters:

idx - the index you are interested in

Throws:

java.io.IOException

getEntry

public byte[] getEntry(long idx,
                       int maxSizeToRead)
                throws java.io.IOException

Get the content of a log entry, specified by its record number

Specified by:

getEntry in interface SecureHistory

Throws:

java.io.IOException

getEntry

public byte[] getEntry(IndexEntry ie,
                       int maxSizeToRead)
                throws java.io.IOException

Specified by:

getEntry in interface SecureHistory

Throws:

java.io.IOException

upgradeHashedEntry

public boolean upgradeHashedEntry(int idx,
                                  java.nio.ByteBuffer entry)
                           throws java.io.IOException

If the log already contains an entry in 'hashed' form and we learn the actual contents later, this function is called.

Specified by:

upgradeHashedEntry in interface SecureHistory

Throws:

java.io.IOException

findLastEntry

public long findLastEntry(short[] types,
                          long maxSeq)
                   throws java.io.IOException

Find the most recent entry whose type is in the specified set. Useful e.g. for locating the last CHECKPOINT or INIT entry.

Specified by:

findLastEntry in interface SecureHistory

Throws:

java.io.IOException