@Test
public void useTransactionTest() throws Exception {
// Performing admin operations to create dataset instance
// keyValueTable is a system dataset module
Id.DatasetInstance myTableInstance = Id.DatasetInstance.from(namespace, "myTable");
dsFramework.addInstance("keyValueTable", myTableInstance, DatasetProperties.EMPTY);
Assert.assertTrue(feedManager.createFeed(FEED1));
try {
Cancellable cancellable =
notificationService.subscribe(
FEED1,
new NotificationHandler<String>() {
private int received = 0;
@Override
public Type getNotificationType() {
return String.class;
}
@Override
public void received(
final String notification, NotificationContext notificationContext) {
notificationContext.execute(
new TxRunnable() {
@Override
public void run(DatasetContext context) throws Exception {
KeyValueTable table = context.getDataset("myTable");
table.write("foo", String.format("%s-%d", notification, received++));
}
},
TxRetryPolicy.maxRetries(5));
}
});
TimeUnit.SECONDS.sleep(2);
try {
notificationService.publish(FEED1, "foobar");
// Waiting for the subscriber to receive that notification
TimeUnit.SECONDS.sleep(2);
KeyValueTable table =
dsFramework.getDataset(myTableInstance, DatasetDefinition.NO_ARGUMENTS, null);
Assert.assertNotNull(table);
Transaction tx1 = txManager.startShort(100);
table.startTx(tx1);
Assert.assertEquals("foobar-0", Bytes.toString(table.read("foo")));
Assert.assertTrue(table.commitTx());
txManager.canCommit(tx1, table.getTxChanges());
txManager.commit(tx1);
table.postTxCommit();
} finally {
cancellable.cancel();
}
} finally {
dsFramework.deleteInstance(myTableInstance);
feedManager.deleteFeed(FEED1);
}
}
/**
* Returns the top words associated with the specified word and the number of times the words have
* appeared together.
*
* @param word the word of interest
* @param limit the number of associations to return, at most
* @return a map of the top associated words to their co-occurrence count
*/
public Map<String, Long> readWordAssocs(String word, int limit) {
// Retrieve all columns of the word’s row
Row result = this.table.get(new Get(word));
TopKCollector collector = new TopKCollector(limit);
if (!result.isEmpty()) {
// Iterate over all columns
for (Map.Entry<byte[], byte[]> entry : result.getColumns().entrySet()) {
collector.add(Bytes.toLong(entry.getValue()), Bytes.toString(entry.getKey()));
}
}
return collector.getTopK();
}
public KeyValue.Value get(String key) throws Exception {
return GSON.fromJson(
Bytes.toString(table.get(Bytes.toBytes(key), COL)), KeyValue.Value.class);
}
@Override
public KeyValue makeRecord(byte[] key, Row row) {
return new KeyValue(
Bytes.toInt(key),
GSON.fromJson(Bytes.toString(row.get(KeyValueTable.COL)), String.class));
}
public String get(int key) throws Exception {
return Bytes.toString(table.get(Bytes.toBytes(key), COL));
}
