/**
* Checking the structure based on a long array denoting the path to a leaf (either data or
* revrootbucket) and their super-bucket.
*
* <p>The check is performed but no feedback is given because of the side-effects because of
* caching. This can easily be covered by flag, etc. but not in the scope of this prototype.
*
* @param pReader reader for getting the data from the backend
* @param pKeys long array denoting the path to the leaf starting from top to bottom
* @param mRootOfSubtree referencebucket representing the root
* @param pSeqBucketKey order key for getting the offsets on each level
* @throws TTIOException
*/
private static final void checkStructure(
final IBackendReader pReader,
final long[] pKeys,
final IReferenceBucket mRootOfSubtree,
final long pSeqBucketKey)
throws TTIOException {
// getting the offsets on each level, globally
final long[] orderNumbers = getOrderNumbers(pSeqBucketKey);
// starting from the bottong...
IBucket currentBucket = pReader.read(pKeys[pKeys.length - 1]);
// ...all data is reconstructed bottom up (meaning from behind to the begin of the path...
for (int i = orderNumbers.length - 1; i >= 0; i--) {
// ..for each element, compute the hash and..
// final byte[] currentHash = currentBucket.secureHash().asBytes();
// just for benchmarking, since the hash is atm not checked to to side-effekts in caching
// resolvable
// over flags within this retrieval
currentBucket.secureHash().asBytes();
// ..retrieve the parent and.
currentBucket = pReader.read(pKeys[i]);
// ..retrieve the hash form the storage.
final byte[] storedHash =
((IReferenceBucket) currentBucket).getReferenceHashs()[dataBucketOffset(orderNumbers[i])];
// if the hash was either bootstrapped or the bucket is currently in progress,
if (Arrays.equals(storedHash, IConstants.NON_HASHED)
|| Arrays.equals(storedHash, IConstants.BOOTSTRAP_HASHED)) {
// ..just return.
return;
} // ...otherwise compare and print the error.
// else {
// if (!Arrays.equals(currentHash, storedHash)) {
// System.err.println("Hashes differ!");
// }
// }
}
// for the last level, the top (either revrootbucket or uberbucket, do the same.
// final byte[] currentHash = currentBucket.secureHash().asBytes();
// just for benchmarking, since the hash is atm not checked to to side-effekts in caching
// resolvable
// over flags within this retrieval
currentBucket.secureHash().asBytes();
final byte[] storedHash =
mRootOfSubtree.getReferenceHashs()[IReferenceBucket.GUARANTEED_INDIRECT_OFFSET];
// since the revroot currently in progress is linked to former substructure but has no actual
// hash,
// ignore it in that case.
if (Arrays.equals(storedHash, IConstants.NON_HASHED)
|| Arrays.equals(storedHash, IConstants.BOOTSTRAP_HASHED)) {
return;
// } else {
// if (!Arrays.equals(currentHash, storedHash)) {
// System.err.println("Hashes differ!");
// }
}
}
/**
* Find reference pointing to leaf bucket of an indirect tree.
*
* @param pStartKey Start reference pointing to the indirect tree.
* @param pSeqBucketKey Key to look up in the indirect tree.
* @return Reference denoted by key pointing to the leaf bucket.
* @throws TTIOException if something odd happens within the creation process.
*/
protected static final long[] dereferenceLeafOfTree(
final IBackendReader pReader, final long pStartKey, final long pSeqBucketKey)
throws TTIOException {
final long[] orderNumber = getOrderNumbers(pSeqBucketKey);
// Initial state pointing to the indirect bucket of level 0.
final long[] keys = new long[IConstants.INDIRECT_BUCKET_COUNT.length + 1];
IndirectBucket bucket = null;
keys[0] = pStartKey;
// Iterate through all levels...
for (int level = 0; level < orderNumber.length; level++) {
// ..read the buckets and..
bucket = (IndirectBucket) pReader.read(keys[level]);
// ..compute the offsets out of the order-numbers pre-computed before and store it in the
// key-array.
keys[level + 1] = bucket.getReferenceKeys()[dataBucketOffset(orderNumber[level])];
// if the bucketKey is 0, return -1 to distinguish mark non-written buckets explicitly.
if (keys[level + 1] == 0) {
Arrays.fill(keys, -1);
return keys;
}
}
// Return reference to leaf of indirect tree.
return keys;
}
/**
* 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;
}
/**
* 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;
}
}