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 getBufferStore(String name) throws StorageException {
Preconditions.checkArgument(
bufferSize <= 1 || storeManager.getFeatures().supportsBatchMutation());
KeyColumnValueStore store = null;
if (isKeyColumnValueStore) {
assert storeManager instanceof KeyColumnValueStoreManager;
store = ((KeyColumnValueStoreManager) storeManager).openDatabase(name);
if (bufferSize > 1) {
store = new BufferedKeyColumnValueStore(store, true);
}
} else {
assert storeManager instanceof KeyValueStoreManager;
KeyValueStore kvstore = ((KeyValueStoreManager) storeManager).openDatabase(name);
if (bufferSize > 1) {
// TODO: support buffer mutations for KeyValueStores
}
store = KeyValueStoreManagerAdapter.wrapKeyValueStore(kvstore, staticKeyLengths);
}
return store;
}
public Backend(Configuration storageConfig) {
storeManager = getStorageManager(storageConfig);
isKeyColumnValueStore = storeManager instanceof KeyColumnValueStoreManager;
storeFeatures = storeManager.getFeatures();
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;
if (!storeFeatures.supportsLocking() && storeFeatures.supportsConsistentKeyOperations()) {
lockConfiguration =
new ConsistentKeyLockConfiguration(storageConfig, storeManager.toString());
} else {
lockConfiguration = null;
}
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 (storeFeatures.isDistributed() && storeFeatures.isKeyOrdered()) {
log.debug("Wrapping index store with HashPrefix");
hashPrefixIndex = true;
} else {
hashPrefixIndex = false;
}
}
public StoreFeatures getStoreFeatures() {
return storeManager.getFeatures();
}