[SPARK-17731][SQL][STREAMING] Metrics for structured streaming

## What changes were proposed in this pull request?

Metrics are needed for monitoring structured streaming apps. Here is the design doc for implementing the necessary metrics.
https://docs.google.com/document/d/1NIdcGuR1B3WIe8t7VxLrt58TJB4DtipWEbj5I_mzJys/edit?usp=sharing

Specifically, this PR adds the following public APIs changes.

### New APIs
- `StreamingQuery.status` returns a `StreamingQueryStatus` object (renamed from `StreamingQueryInfo`, see later)

- `StreamingQueryStatus` has the following important fields
  - inputRate - Current rate (rows/sec) at which data is being generated by all the sources
  - processingRate - Current rate (rows/sec) at which the query is processing data from
                                  all the sources
  - ~~outputRate~~ - *Does not work with wholestage codegen*
  - latency - Current average latency between the data being available in source and the sink writing the corresponding output
  - sourceStatuses: Array[SourceStatus] - Current statuses of the sources
  - sinkStatus: SinkStatus - Current status of the sink
  - triggerStatus - Low-level detailed status of the last completed/currently active trigger
    - latencies - getOffset, getBatch, full trigger, wal writes
    - timestamps - trigger start, finish, after getOffset, after getBatch
    - numRows - input, output, state total/updated rows for aggregations

- `SourceStatus` has the following important fields
  - inputRate - Current rate (rows/sec) at which data is being generated by the source
  - processingRate - Current rate (rows/sec) at which the query is processing data from the source
  - triggerStatus - Low-level detailed status of the last completed/currently active trigger

- Python API for `StreamingQuery.status()`

### Breaking changes to existing APIs
**Existing direct public facing APIs**
- Deprecated direct public-facing APIs `StreamingQuery.sourceStatuses` and `StreamingQuery.sinkStatus` in favour of `StreamingQuery.status.sourceStatuses/sinkStatus`.
  - Branch 2.0 should have it deprecated, master should have it removed.

**Existing advanced listener APIs**
- `StreamingQueryInfo` renamed to `StreamingQueryStatus` for consistency with `SourceStatus`, `SinkStatus`
   - Earlier StreamingQueryInfo was used only in the advanced listener API, but now it is used in direct public-facing API (StreamingQuery.status)

- Field `queryInfo` in listener events `QueryStarted`, `QueryProgress`, `QueryTerminated` changed have name `queryStatus` and return type `StreamingQueryStatus`.

- Field `offsetDesc` in `SourceStatus` was Option[String], converted it to `String`.

- For `SourceStatus` and `SinkStatus` made constructor private instead of private[sql] to make them more java-safe. Instead added `private[sql] object SourceStatus/SinkStatus.apply()` which are harder to accidentally use in Java.

## How was this patch tested?

Old and new unit tests.
- Rate calculation and other internal logic of StreamMetrics tested by StreamMetricsSuite.
- New info in statuses returned through StreamingQueryListener is tested in StreamingQueryListenerSuite.
- New and old info returned through StreamingQuery.status is tested in StreamingQuerySuite.
- Source-specific tests for making sure input rows are counted are is source-specific test suites.
- Additional tests to test minor additions in LocalTableScanExec, StateStore, etc.

Metrics also manually tested using Ganglia sink

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #15307 from tdas/SPARK-17731.

1 files changed, 27 insertions, 0 deletions

diff --git a/external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaSourceSuite.scala b/external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaSourceSuite.scala
index c640b93b0a..8b5296ea13 100644
--- a/external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaSourceSuite.scala
+++ b/external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaSourceSuite.scala
@@ -264,6 +264,33 @@ class KafkaSourceSuite extends KafkaSourceTest {
     testUnsupportedConfig("kafka.auto.offset.reset", "latest")
   }
 
+  test("input row metrics") {
+    val topic = newTopic()
+    testUtils.createTopic(topic, partitions = 5)
+    testUtils.sendMessages(topic, Array("-1"))
+    require(testUtils.getLatestOffsets(Set(topic)).size === 5)
+
+    val kafka = spark
+      .readStream
+      .format("kafka")
+      .option("subscribe", topic)
+      .option("kafka.bootstrap.servers", testUtils.brokerAddress)
+      .load()
+      .selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
+      .as[(String, String)]
+
+    val mapped = kafka.map(kv => kv._2.toInt + 1)
+    testStream(mapped)(
+      makeSureGetOffsetCalled,
+      AddKafkaData(Set(topic), 1, 2, 3),
+      CheckAnswer(2, 3, 4),
+      AssertOnLastQueryStatus { status =>
+        assert(status.triggerDetails.get("numRows.input.total").toInt > 0)
+        assert(status.sourceStatuses(0).processingRate > 0.0)
+      }
+    )
+  }
+
   private def newTopic(): String = s"topic-${topicId.getAndIncrement()}"
 
   private def testFromLatestOffsets(topic: String, options: (String, String)*): Unit = {