public BackendTransaction beginTransaction() throws StorageException {
StoreTransaction tx = storeManager.beginTransaction(ConsistencyLevel.DEFAULT);
if (bufferSize > 1) {
assert storeManager.getFeatures().supportsBatchMutation();
if (isKeyColumnValueStore) {
assert storeManager instanceof KeyColumnValueStoreManager;
tx =
new BufferTransaction(
tx,
(KeyColumnValueStoreManager) storeManager,
bufferSize,
writeAttempts,
persistAttemptWaittime);
} else {
assert storeManager instanceof KeyValueStoreManager;
// TODO: support buffer mutations
}
}
if (!storeFeatures.supportsLocking()) {
if (storeFeatures.isTransactional()) {
// No transaction wrapping needed
} else if (storeFeatures.supportsConsistentKeyOperations()) {
tx =
new ConsistentKeyLockTransaction(
tx, storeManager.beginTransaction(ConsistencyLevel.KEY_CONSISTENT));
}
}
return new BackendTransaction(tx);
}
private KeyColumnValueStore getLockStore(KeyColumnValueStore store) throws StorageException {
if (!storeFeatures.supportsLocking()) {
if (storeFeatures.isTransactional()) {
store = new TransactionalLockStore(store);
} else if (storeFeatures.supportsConsistentKeyOperations()) {
store =
new ConsistentKeyLockStore(
store, getStore(store.getName() + LOCK_STORE_SUFFIX), lockConfiguration);
} else throw new IllegalArgumentException("Store needs to support some form of locking");
}
return store;
}
public void initialize(Configuration config) {
try {
// EdgeStore & VertexIndexStore
KeyColumnValueStore idStore = getStore(ID_STORE_NAME);
idAuthority = null;
if (storeFeatures.isTransactional()) {
idAuthority = new TransactionalIDManager(idStore, storeManager, config);
} else if (storeFeatures.supportsConsistentKeyOperations()) {
idAuthority = new ConsistentKeyIDManager(idStore, storeManager, config);
} else {
idAuthority = new TransactionalIDManager(idStore, storeManager, config);
log.error(
"Store needs to support consistent key or transactional operations for ID manager to guarantee proper id allocations");
}
edgeStore = getLockStore(getBufferStore(EDGESTORE_NAME));
vertexIndexStore = getLockStore(getBufferStore(VERTEXINDEX_STORE_NAME));
if (hashPrefixIndex)
vertexIndexStore = new HashPrefixKeyColumnValueStore(vertexIndexStore, 4);
} catch (StorageException e) {
throw new TitanException("Could not initialize backend", e);
}
}