/*
* Copyright © 2014 Cask Data, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package co.cask.cdap.data.stream.service;
import co.cask.cdap.api.data.stream.StreamSpecification;
import co.cask.cdap.api.dataset.DatasetDefinition;
import co.cask.cdap.api.dataset.DatasetProperties;
import co.cask.cdap.api.dataset.table.Table;
import co.cask.cdap.common.conf.CConfiguration;
import co.cask.cdap.data.Namespace;
import co.cask.cdap.data2.datafabric.DefaultDatasetNamespace;
import co.cask.cdap.data2.datafabric.dataset.DatasetsUtil;
import co.cask.cdap.data2.dataset2.DatasetFramework;
import co.cask.cdap.data2.dataset2.NamespacedDatasetFramework;
import co.cask.cdap.data2.dataset2.lib.table.MetadataStoreDataset;
import co.cask.cdap.data2.dataset2.tx.Transactional;
import co.cask.tephra.DefaultTransactionExecutor;
import co.cask.tephra.TransactionAware;
import co.cask.tephra.TransactionExecutor;
import co.cask.tephra.TransactionExecutorFactory;
import co.cask.tephra.TransactionSystemClient;
import com.google.common.base.Supplier;
import com.google.common.base.Throwables;
import com.google.common.collect.Iterators;
import com.google.inject.Inject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Iterator;
/**
* Implementation of {@link StreamMetaStore} that access MDS directly.
*/
public final class MDSStreamMetaStore implements StreamMetaStore {
private static final Logger LOG = LoggerFactory.getLogger(MDSStreamMetaStore.class);
// note: these constants should be same as in DefaultStore - this needs refactoring, but currently these pieces
// dependent
private static final String STREAM_META_TABLE = "app.meta";
private static final String TYPE_STREAM = "stream";
private Transactional<StreamMds, MetadataStoreDataset> txnl;
@Inject
public MDSStreamMetaStore(CConfiguration conf, final TransactionSystemClient txClient, DatasetFramework framework) {
final DatasetFramework dsFramework =
new NamespacedDatasetFramework(framework, new DefaultDatasetNamespace(conf, Namespace.SYSTEM));
txnl = Transactional.of(
new TransactionExecutorFactory() {
@Override
public TransactionExecutor createExecutor(Iterable<TransactionAware> transactionAwares) {
return new DefaultTransactionExecutor(txClient, transactionAwares);
}},
new Supplier<StreamMds>() {
@Override
public StreamMds get() {
try {
Table mdsTable = DatasetsUtil.getOrCreateDataset(dsFramework, STREAM_META_TABLE, "table",
DatasetProperties.EMPTY,
DatasetDefinition.NO_ARGUMENTS, null);
return new StreamMds(new MetadataStoreDataset(mdsTable));
} catch (Exception e) {
LOG.error("Failed to access app.meta table", e);
throw Throwables.propagate(e);
}
}
});
}
@Override
public void addStream(final String accountId, final String streamName) throws Exception {
txnl.executeUnchecked(new TransactionExecutor.Function<StreamMds, Void>() {
@Override
public Void apply(StreamMds mds) throws Exception {
mds.streams.write(getKey(accountId, streamName),
createStreamSpec(streamName));
return null;
}
});
}
@Override
public void removeStream(final String accountId, final String streamName) throws Exception {
txnl.executeUnchecked(new TransactionExecutor.Function<StreamMds, Void>() {
@Override
public Void apply(StreamMds mds) throws Exception {
mds.streams.deleteAll(getKey(accountId, streamName));
return null;
}
});
}
@Override
public boolean streamExists(final String accountId, final String streamName) throws Exception {
return txnl.executeUnchecked(new TransactionExecutor.Function<StreamMds, Boolean>() {
@Override
public Boolean apply(StreamMds mds) throws Exception {
return mds.streams.get(getKey(accountId, streamName), StreamSpecification.class) != null;
}
});
}
private MetadataStoreDataset.Key getKey(String accountId, String streamName) {
return new MetadataStoreDataset.Key.Builder().add(TYPE_STREAM, accountId, streamName).build();
}
private StreamSpecification createStreamSpec(String streamName) {
return new StreamSpecification.Builder().setName(streamName).create();
}
private static final class StreamMds implements Iterable<MetadataStoreDataset> {
private final MetadataStoreDataset streams;
private StreamMds(MetadataStoreDataset metaTable) {
this.streams = metaTable;
}
@Override
public Iterator<MetadataStoreDataset> iterator() {
return Iterators.singletonIterator(streams);
}
}
}