[SPARK-2179][SQL] A minor refactoring Java data type APIs (2179 follow-up).

It is a follow-up PR of SPARK-2179 (https://issues.apache.org/jira/browse/SPARK-2179). It makes package names of data type APIs more consistent across languages (Scala: `org.apache.spark.sql`, Java: `org.apache.spark.sql.api.java`, Python: `pyspark.sql`).

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #1712 from yhuai/javaDataType and squashes the following commits:

62eb705 [Yin Huai] Move package-info.
add4bcb [Yin Huai] Make the package names of data type classes consistent across languages by moving all Java data type classes to package sql.api.java.
[SQL][SPARK-2212]Hash Outer Join

This patch is to support the hash based outer join. Currently, outer join for big relations are resort to `BoradcastNestedLoopJoin`, which is super slow. This PR will create 2 hash tables for both relations in the same partition, which greatly reduce the table scans.

Here is the testing code that I used:
```
package org.apache.spark.sql.hive

import org.apache.spark.SparkContext
import org.apache.spark.SparkConf
import org.apache.spark.sql._

case class Record(key: String, value: String)

object JoinTablePrepare extends App {
  import TestHive2._

  val rdd = sparkContext.parallelize((1 to 3000000).map(i => Record(s"${i % 828193}", s"val_$i")))

  runSqlHive("SHOW TABLES")
  runSqlHive("DROP TABLE if exists a")
  runSqlHive("DROP TABLE if exists b")
  runSqlHive("DROP TABLE if exists result")
  rdd.registerAsTable("records")

  runSqlHive("""CREATE TABLE a (key STRING, value STRING)
                 | ROW FORMAT SERDE
                 | 'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe'
                 | STORED AS RCFILE
               """.stripMargin)
  runSqlHive("""CREATE TABLE b (key STRING, value STRING)
                 | ROW FORMAT SERDE
                 | 'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe'
                 | STORED AS RCFILE
               """.stripMargin)
  runSqlHive("""CREATE TABLE result (key STRING, value STRING)
                 | ROW FORMAT SERDE
                 | 'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe'
                 | STORED AS RCFILE
               """.stripMargin)

  hql(s"""from records
             | insert into table a
             | select key, value
           """.stripMargin)
  hql(s"""from records
             | insert into table b select key + 100000, value
           """.stripMargin)
}

object JoinTablePerformanceTest extends App {
  import TestHive2._

  hql("SHOW TABLES")
  hql("set spark.sql.shuffle.partitions=20")

  val leftOuterJoin = "insert overwrite table result select a.key, b.value from a left outer join b on a.key=b.key"
  val rightOuterJoin = "insert overwrite table result select a.key, b.value from a right outer join b on a.key=b.key"
  val fullOuterJoin = "insert overwrite table result select a.key, b.value from a full outer join b on a.key=b.key"

  val results = ("LeftOuterJoin", benchmark(leftOuterJoin)) :: ("LeftOuterJoin", benchmark(leftOuterJoin)) ::
                ("RightOuterJoin", benchmark(rightOuterJoin)) :: ("RightOuterJoin", benchmark(rightOuterJoin)) ::
                ("FullOuterJoin", benchmark(fullOuterJoin)) :: ("FullOuterJoin", benchmark(fullOuterJoin)) :: Nil
  val explains = hql(s"explain $leftOuterJoin").collect ++ hql(s"explain $rightOuterJoin").collect ++ hql(s"explain $fullOuterJoin").collect
  println(explains.mkString(",\n"))
  results.foreach { case (prompt, result) => {
      println(s"$prompt: took ${result._1} ms (${result._2} records)")
    }
  }

  def benchmark(cmd: String) = {
    val begin = System.currentTimeMillis()
    val result = hql(cmd)
    val end = System.currentTimeMillis()
    val count = hql("select count(1) from result").collect.mkString("")
    ((end - begin), count)
  }
}
```
And the result as shown below:
```
[Physical execution plan:],
[InsertIntoHiveTable (MetastoreRelation default, result, None), Map(), true],
[ Project [key#95,value#98]],
[  HashOuterJoin [key#95], [key#97], LeftOuter, None],
[   Exchange (HashPartitioning [key#95], 20)],
[    HiveTableScan [key#95], (MetastoreRelation default, a, None), None],
[   Exchange (HashPartitioning [key#97], 20)],
[    HiveTableScan [key#97,value#98], (MetastoreRelation default, b, None), None],
[Physical execution plan:],
[InsertIntoHiveTable (MetastoreRelation default, result, None), Map(), true],
[ Project [key#102,value#105]],
[  HashOuterJoin [key#102], [key#104], RightOuter, None],
[   Exchange (HashPartitioning [key#102], 20)],
[    HiveTableScan [key#102], (MetastoreRelation default, a, None), None],
[   Exchange (HashPartitioning [key#104], 20)],
[    HiveTableScan [key#104,value#105], (MetastoreRelation default, b, None), None],
[Physical execution plan:],
[InsertIntoHiveTable (MetastoreRelation default, result, None), Map(), true],
[ Project [key#109,value#112]],
[  HashOuterJoin [key#109], [key#111], FullOuter, None],
[   Exchange (HashPartitioning [key#109], 20)],
[    HiveTableScan [key#109], (MetastoreRelation default, a, None), None],
[   Exchange (HashPartitioning [key#111], 20)],
[    HiveTableScan [key#111,value#112], (MetastoreRelation default, b, None), None]
LeftOuterJoin: took 16072 ms ([3000000] records)
LeftOuterJoin: took 14394 ms ([3000000] records)
RightOuterJoin: took 14802 ms ([3000000] records)
RightOuterJoin: took 14747 ms ([3000000] records)
FullOuterJoin: took 17715 ms ([6000000] records)
FullOuterJoin: took 17629 ms ([6000000] records)
```

Without this PR, the benchmark will run seems never end.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #1147 from chenghao-intel/hash_based_outer_join and squashes the following commits:

65c599e [Cheng Hao] Fix issues with the community comments
72b1394 [Cheng Hao] Fix bug of stale value in joinedRow
55baef7 [Cheng Hao] Add HashOuterJoin
[SPARK-2729] [SQL] Forgot to match Timestamp type in ColumnBuilder

just a match forgot, found after SPARK-2710 , TimestampType can be used by a SchemaRDD generated from JDBC ResultSet

Author: chutium <teng.qiu@gmail.com>

Closes #1636 from chutium/SPARK-2729 and squashes the following commits:

71af77a [chutium] [SPARK-2729] [SQL] added Timestamp in NullableColumnAccessorSuite
39cf9f8 [chutium] [SPARK-2729] add Timestamp Type into ColumnBuilder TestSuite, ref. #1636
ab6ff97 [chutium] [SPARK-2729] Forgot to match Timestamp type in ColumnBuilder
[SPARK-2767] [SQL] SparkSQL CLI doens't output error message if query failed.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #1686 from chenghao-intel/spark_sql_cli and squashes the following commits:

eb664cc [Cheng Hao] Output detailed failure message in console
93b0382 [Cheng Hao] Fix Bug of no output in cli if exception thrown internally
[SQL] Documentation: Explain cacheTable command

add the `cacheTable` specification

Author: CrazyJvm <crazyjvm@gmail.com>

Closes #1681 from CrazyJvm/sql-programming-guide-cache and squashes the following commits:

0a231e0 [CrazyJvm] grammar fixes
a04020e [CrazyJvm] modify title to Cached tables
18b6594 [CrazyJvm] fix format
2cbbf58 [CrazyJvm] add cacheTable guide
[SPARK-695] In DAGScheduler's getPreferredLocs, track set of visited partitions.

getPreferredLocs traverses a dependency graph of partitions using depth first search.  Given a complex dependency graph, the old implementation may explore a set of paths in the graph that is exponential in the number of nodes.  By maintaining a set of visited nodes the new implementation avoids revisiting nodes, preventing exponential blowup.

Some comment and whitespace cleanups are also included.

Author: Aaron Staple <aaron.staple@gmail.com>

Closes #1362 from staple/SPARK-695 and squashes the following commits:

ecea0f3 [Aaron Staple] address review comments
751c661 [Aaron Staple] [SPARK-695] Add a unit test.
5adf326 [Aaron Staple] Replace getPreferredLocsInternal's HashMap argument with a simpler HashSet.
58e37d0 [Aaron Staple] Replace comment documenting NarrowDependency.
6751ced [Aaron Staple] Revert "Remove unused variable."
04c7097 [Aaron Staple] Fix indentation.
0030884 [Aaron Staple] Remove unused variable.
33f67c6 [Aaron Staple] Clarify comment.
4e42b46 [Aaron Staple] Remove apparently incorrect comment describing NarrowDependency.
65c2d3d [Aaron Staple] [SPARK-695] In DAGScheduler's getPreferredLocs, track set of visited partitions.
[SPARK-2490] Change recursive visiting on RDD dependencies to iterative approach

When performing some transformations on RDDs after many iterations, the dependencies of RDDs could be very long. It can easily cause StackOverflowError when recursively visiting these dependencies in Spark core. For example:

    var rdd = sc.makeRDD(Array(1))
    for (i <- 1 to 1000) {
      rdd = rdd.coalesce(1).cache()
      rdd.collect()
    }

This PR changes recursive visiting on rdd's dependencies to iterative approach to avoid StackOverflowError.

In addition to the recursive visiting, since the Java serializer has a known [bug](http://bugs.java.com/bugdatabase/view_bug.do?bug_id=4152790) that causes StackOverflowError too when serializing/deserializing a large graph of objects. So applying this PR only solves part of the problem. Using KryoSerializer to replace Java serializer might be helpful. However, since KryoSerializer is not supported for `spark.closure.serializer` now, I can not test if KryoSerializer can solve Java serializer's problem completely.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #1418 from viirya/remove_recursive_visit and squashes the following commits:

6b2c615 [Liang-Chi Hsieh] change function name; comply with code style.
5f072a7 [Liang-Chi Hsieh] add comments to explain Stack usage.
8742dbb [Liang-Chi Hsieh] comply with code style.
900538b [Liang-Chi Hsieh] change recursive visiting on rdd's dependencies to iterative approach to avoid stackoverflowerror.
SPARK-1612: Fix potential resource leaks

JIRA: https://issues.apache.org/jira/browse/SPARK-1612

Move the "close" statements into a "finally" block.

Author: zsxwing <zsxwing@gmail.com>

Closes #535 from zsxwing/SPARK-1612 and squashes the following commits:

ae52f50 [zsxwing] Update to follow the code style
549ba13 [zsxwing] SPARK-1612: Fix potential resource leaks
[SPARK-2379] Fix the bug that streaming's receiver may fall into a dead loop

Author: joyyoj <sunshch@gmail.com>

Closes #1694 from joyyoj/SPARK-2379 and squashes the following commits:

d73790d [joyyoj] SPARK-2379 Fix the bug that streaming's receiver may fall into a dead loop
22e7821 [joyyoj] Merge remote-tracking branch 'apache/master'
3f4a602 [joyyoj] Merge remote-tracking branch 'remotes/apache/master'
f4660c5 [joyyoj] [SPARK-1998] SparkFlumeEvent with body bigger than 1020 bytes are not read properly
SPARK-2791: Fix committing, reverting and state tracking in shuffle file consolidation

All changes from this PR are by mridulm and are drawn from his work in #1609. This patch is intended to fix all major issues related to shuffle file consolidation that mridulm found, while minimizing changes to the code, with the hope that it may be more easily merged into 1.1.

This patch is **not** intended as a replacement for #1609, which provides many additional benefits, including fixes to ExternalAppendOnlyMap, improvements to DiskBlockObjectWriter's API, and several new unit tests.

If it is feasible to merge #1609 for the 1.1 deadline, that is a preferable option.

Author: Aaron Davidson <aaron@databricks.com>

Closes #1678 from aarondav/consol and squashes the following commits:

53b3f6d [Aaron Davidson] Correct behavior when writing unopened file
701d045 [Aaron Davidson] Rebase with sort-based shuffle
9160149 [Aaron Davidson] SPARK-2532: Minimal shuffle consolidation fixes
getOrElse(null) -> orNull
reduce(_+_) -> sum
filter + size -> count
fold -> forall
exists + == -> contains
filter + headOption -> find
map + getOrElse -> exists
get + getOrElse -> getOrElse
! isEmpty -> nonEmpty
Revert change of Scala REPL class