add docs + fix tests

docs/content/DataSourceMetadataQuery.md

@@ -0,0 +1,31 @@
+---
+layout: doc_page
+---
+# Data Source Metadata Queries
+Data Source Metadata queries return ingestion related information for a dataSource. It returns the timestamp of latest ingested event for the datasource. The grammar is:
+
+```json
+{
+    "queryType" : "dataSourceMetadata",
+    "dataSource": "sample_datasource",
+}
+```
+
+There are 2 main parts to a Data Source Metadata query:
+
+|property|description|required?|
+|--------|-----------|---------|
+|queryType|This String should always be "dataSourceMetadata"; this is the first thing Druid looks at to figure out how to interpret the query|yes|
+|dataSource|A String defining the data source to query, very similar to a table in a relational database|yes|
+|context|An additional JSON Object which can be used to specify certain flags.|no|
+
+The format of the result is:
+
+```json
+[ {
+  "timestamp" : "2013-05-09T18:24:00.000Z",
+  "result" : {
+    "maxIngestedEventTime" : "2013-05-09T18:24:09.007Z",
+  }
+} ]
+```

docs/content/toc.textile

@@ -52,6 +52,7 @@ h2. Querying
 ** "Granularities":./Granularities.html
 ** "DimensionSpecs":./DimensionSpecs.html
 * Query Types
+** "DataSourceMetadataQuery":./DataSourceMetadataQuery.html
 ** "GroupBy":./GroupByQuery.html
 *** "LimitSpec":./LimitSpec.html
 *** "Having":./Having.html

processing/src/test/java/io/druid/query/datasourcemetadata/DataSourceMetadataQueryTest.java

@@ -28,6 +28,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.MapMaker;
 import com.metamx.common.guava.Sequences;
 import io.druid.data.input.MapBasedInputRow;
+import io.druid.granularity.QueryGranularity;
 import io.druid.jackson.DefaultObjectMapper;
 import io.druid.query.Druids;
 import io.druid.query.Query;
@@ -35,10 +36,13 @@ import io.druid.query.QueryRunner;
 import io.druid.query.QueryRunnerFactory;
 import io.druid.query.QueryRunnerTestHelper;
 import io.druid.query.Result;
+import io.druid.query.aggregation.AggregatorFactory;
+import io.druid.query.aggregation.CountAggregatorFactory;
 import io.druid.query.timeboundary.TimeBoundaryQueryQueryToolChest;
 import io.druid.segment.IncrementalIndexSegment;
 import io.druid.segment.TestIndex;
 import io.druid.segment.incremental.IncrementalIndex;
+import io.druid.segment.incremental.OnheapIncrementalIndex;
 import io.druid.timeline.LogicalSegment;
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
@@ -107,7 +111,9 @@ public class DataSourceMetadataQueryTest
   @Test
   public void testMaxIngestedEventTime() throws Exception
   {
-    final IncrementalIndex rtIndex = TestIndex.getIncrementalTestIndex(false);
+    final IncrementalIndex rtIndex = new OnheapIncrementalIndex(
+        0L, QueryGranularity.NONE, new AggregatorFactory[]{new CountAggregatorFactory("count")}, 1000
+    );;
     final QueryRunner runner = QueryRunnerTestHelper.makeQueryRunner(
         (QueryRunnerFactory) new DataSourceMetadataQueryRunnerFactory(
             QueryRunnerTestHelper.NOOP_QUERYWATCHER