/**
* Getting the data related to the given data key.
*
* @param pDataKey searched for
* @return the related data
* @throws TTIOException if the read to the persistent storage fails
*/
public IData getData(final long pDataKey) throws TTIOException {
checkArgument(pDataKey >= 0);
checkState(!mClose, "Transaction already closed");
// Calculate bucket and data part for given datakey.
final long seqBucketKey = pDataKey >> IConstants.INDIRECT_BUCKET_COUNT[3];
final int dataBucketOffset = dataBucketOffset(pDataKey);
DataBucket bucket = mCache.getIfPresent(seqBucketKey);
if (bucket == null) {
final List<DataBucket> listRevs = getSnapshotBuckets(seqBucketKey);
final DataBucket[] revs = listRevs.toArray(new DataBucket[listRevs.size()]);
checkState(revs.length > 0, "Number of Buckets to reconstruct must be larger than 0");
// Build up the complete bucket.
final IRevisioning revision = mSession.getConfig().mRevision;
bucket = revision.combineBuckets(revs);
mCache.put(seqBucketKey, bucket);
}
final IData returnVal = bucket.getData(dataBucketOffset);
// root-fsys is excluded from the checkagainst deletion based on the necesssity of the
// data-layer to
// reference against this data while creation of the transaction
if (pDataKey == 0) {
return returnVal;
} else {
return checkItemIfDeleted(returnVal);
}
}
/**
* Closing this Readtransaction.
*
* @throws TTIOException if the closing to the persistent storage fails.
*/
public boolean close() throws TTIOException {
if (!mClose) {
mSession.deregisterBucketTrx(this);
mBucketReader.close();
mClose = true;
return true;
} else {
return false;
}
}
/**
* Dereference data bucket reference.
*
* @param pSeqDataBucketKey Key of data bucket.
* @return Dereferenced bucket.
* @throws TTIOException if something odd happens within the creation process.
*/
protected final List<DataBucket> getSnapshotBuckets(final long pSeqDataBucketKey)
throws TTIOException {
// Return Value, since the revision iterates a flexible number of version, this has to be a list
// first.
final List<DataBucket> dataBuckets = new ArrayList<DataBucket>();
// Getting the keys for the revRoots
final long[] pathToRoot =
BucketReadTrx.dereferenceLeafOfTree(
mBucketReader,
mUberBucket.getReferenceKeys()[IReferenceBucket.GUARANTEED_INDIRECT_OFFSET],
mRootBucket.getRevision());
final RevisionRootBucket rootBucket =
(RevisionRootBucket)
mBucketReader.read(pathToRoot[IConstants.INDIRECT_BUCKET_COUNT.length]);
final int numbersToRestore =
Integer.parseInt(
mSession.getConfig().mProperties.getProperty(ConstructorProps.NUMBERTORESTORE));
// starting from the current databucket
final long[] pathToRecentBucket =
dereferenceLeafOfTree(
mBucketReader,
rootBucket.getReferenceKeys()[IReferenceBucket.GUARANTEED_INDIRECT_OFFSET],
pSeqDataBucketKey);
DataBucket bucket;
long bucketKey = pathToRecentBucket[IConstants.INDIRECT_BUCKET_COUNT.length];
// jumping through the databuckets based on the pointers
while (dataBuckets.size() < numbersToRestore && bucketKey > -1) {
bucket = (DataBucket) mBucketReader.read(bucketKey);
dataBuckets.add(bucket);
bucketKey = bucket.getLastBucketPointer();
}
// check if bucket was ever written before to perform check
if (bucketKey > -1) {
checkStructure(mBucketReader, pathToRecentBucket, rootBucket, pSeqDataBucketKey);
checkStructure(mBucketReader, pathToRoot, mUberBucket, mRootBucket.getRevision());
}
return dataBuckets;
}