public Backend(Configuration storageConfig) {
this.storageConfig = storageConfig;
storeManager = getStorageManager(storageConfig);
indexes = getIndexes(storageConfig);
storeFeatures = storeManager.getFeatures();
basicMetrics = storageConfig.getBoolean(BASIC_METRICS, BASIC_METRICS_DEFAULT);
mergeBasicMetrics =
storageConfig.getBoolean(MERGE_BASIC_METRICS_KEY, MERGE_BASIC_METRICS_DEFAULT);
int bufferSizeTmp = storageConfig.getInt(BUFFER_SIZE_KEY, BUFFER_SIZE_DEFAULT);
Preconditions.checkArgument(
bufferSizeTmp >= 0, "Buffer size must be non-negative (use 0 to disable)");
if (!storeFeatures.supportsBatchMutation()) {
bufferSize = 0;
log.debug("Buffering disabled because backend does not support batch mutations");
} else bufferSize = bufferSizeTmp;
writeAttempts = storageConfig.getInt(WRITE_ATTEMPTS_KEY, WRITE_ATTEMPTS_DEFAULT);
Preconditions.checkArgument(writeAttempts > 0, "Write attempts must be positive");
readAttempts = storageConfig.getInt(READ_ATTEMPTS_KEY, READ_ATTEMPTS_DEFAULT);
Preconditions.checkArgument(readAttempts > 0, "Read attempts must be positive");
persistAttemptWaittime =
storageConfig.getInt(STORAGE_ATTEMPT_WAITTIME_KEY, STORAGE_ATTEMPT_WAITTIME_DEFAULT);
Preconditions.checkArgument(
persistAttemptWaittime > 0, "Persistence attempt retry wait time must be non-negative");
// If lock prefix is unspecified, specify it now
storageConfig.setProperty(
ExpectedValueCheckingStore.LOCAL_LOCK_MEDIATOR_PREFIX_KEY,
storageConfig.getString(
ExpectedValueCheckingStore.LOCAL_LOCK_MEDIATOR_PREFIX_KEY, storeManager.getName()));
final String lockBackendName =
storageConfig.getString(
GraphDatabaseConfiguration.LOCK_BACKEND,
GraphDatabaseConfiguration.LOCK_BACKEND_DEFAULT);
if (REGISTERED_LOCKERS.containsKey(lockBackendName)) {
lockerCreator = REGISTERED_LOCKERS.get(lockBackendName);
} else {
throw new TitanConfigurationException(
"Unknown lock backend \""
+ lockBackendName
+ "\". Known lock backends: "
+ Joiner.on(", ").join(REGISTERED_LOCKERS.keySet())
+ ".");
}
// Never used for backends that have innate transaction support, but we
// want to maintain the non-null invariant regardless; it will default
// to connsistentkey impl if none is specified
Preconditions.checkNotNull(lockerCreator);
if (storeFeatures.isDistributed() && storeFeatures.isKeyOrdered()) {
log.debug("Wrapping index store with HashPrefix");
hashPrefixIndex = true;
} else {
hashPrefixIndex = false;
}
}
private KeyColumnValueStore getBufferStore(String name) throws StorageException {
Preconditions.checkArgument(
bufferSize <= 1 || storeManager.getFeatures().supportsBatchMutation());
KeyColumnValueStore store = null;
store = storeManager.openDatabase(name);
if (bufferSize > 1) {
store = new BufferedKeyColumnValueStore(store, true);
}
// Enable cache
store = new CachedKeyColumnValueStore(store);
return store;
}
/**
* Opens a new transaction against all registered backend system wrapped in one {@link
* BackendTransaction}.
*
* @return
* @throws StorageException
*/
public BackendTransaction beginTransaction(TransactionConfiguration configuration)
throws StorageException {
StoreTxConfig txConfig = new StoreTxConfig(configuration.getMetricsPrefix());
if (configuration.hasTimestamp()) txConfig.setTimestamp(configuration.getTimestamp());
StoreTransaction tx = storeManager.beginTransaction(txConfig);
if (bufferSize > 1) {
Preconditions.checkArgument(storeManager.getFeatures().supportsBatchMutation());
tx =
new BufferTransaction(
tx, storeManager, bufferSize, writeAttempts, persistAttemptWaittime);
}
if (!storeFeatures.supportsLocking()) {
if (storeFeatures.supportsTransactions()) {
// No transaction wrapping needed
} else if (storeFeatures.supportsConsistentKeyOperations()) {
txConfig =
new StoreTxConfig(ConsistencyLevel.KEY_CONSISTENT, configuration.getMetricsPrefix());
if (configuration.hasTimestamp()) txConfig.setTimestamp(configuration.getTimestamp());
tx =
new ExpectedValueCheckingTransaction(
tx, storeManager.beginTransaction(txConfig), readAttempts);
}
}
// Index transactions
Map<String, IndexTransaction> indexTx = new HashMap<String, IndexTransaction>(indexes.size());
for (Map.Entry<String, IndexProvider> entry : indexes.entrySet()) {
indexTx.put(entry.getKey(), new IndexTransaction(entry.getValue()));
}
return new BackendTransaction(
tx,
storeManager.getFeatures(),
edgeStore,
vertexIndexStore,
edgeIndexStore,
readAttempts,
persistAttemptWaittime,
indexTx);
}
/**
* Returns the {@link StoreFeatures} of the configured backend storage engine.
*
* @return
*/
public StoreFeatures getStoreFeatures() {
return storeManager.getFeatures();
}