Preparing development version 1.2.1-SNAPSHOT
[SPARK-4422][MLLIB]In some cases, Vectors.fromBreeze get wrong results.

cc mengxr

Author: GuoQiang Li <witgo@qq.com>

Closes #3281 from witgo/SPARK-4422 and squashes the following commits:

5f1fa5e [GuoQiang Li] import order
50783bd [GuoQiang Li] review commits
7a10123 [GuoQiang Li] In some cases, Vectors.fromBreeze get wrong results.

(cherry picked from commit 5168c6ca9f0008027d688661bae57c28cf386b54)
Signed-off-by: Xiangrui Meng <meng@databricks.com>
[SPARK-4410][SQL] Add support for external sort

Adds a new operator that uses Spark's `ExternalSort` class.  It is off by default now, but we might consider making it the default if benchmarks show that it does not regress performance.

Author: Michael Armbrust <michael@databricks.com>

Closes #3268 from marmbrus/externalSort and squashes the following commits:

48b9726 [Michael Armbrust] comments
b98799d [Michael Armbrust] Add test
afd7562 [Michael Armbrust] Add support for external sort.

(cherry picked from commit 64c6b9bad559c21f25cd9fbe37c8813cdab939f2)
Signed-off-by: Reynold Xin <rxin@databricks.com>
Revert "Preparing development version 1.2.1-SNAPSHOT"

This reverts commit 6c6fd218c83a049c874b8a0ea737333c1899c94a.
Revert "Preparing Spark release v1.2.0-snapshot0"

This reverts commit bc09875799aa373f4320d38b02618173ffa4c96f.
Preparing Spark release v1.2.0-snapshot1
Preparing development version 1.2.1-SNAPSHOT
SPARK-4445, Don't display storage level in toDebugString unless RDD is persisted.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #3310 from ScrapCodes/SPARK-4445/rddDebugStringFix and squashes the following commits:

4e57c52 [Prashant Sharma] SPARK-4445, Don't display storage level in toDebugString unless RDD is persisted

(cherry picked from commit 5c92d47ad2e3414f2ae089cb47f3c6daccba8d90)
Signed-off-by: Patrick Wendell <pwendell@gmail.com>
SPARK-2811 upgrade algebird to 0.8.1

Author: Adam Pingel <adam@axle-lang.org>

Closes #3282 from adampingel/master and squashes the following commits:

70c8d3c [Adam Pingel] relocate the algebird example back to example/src
7a9d8be [Adam Pingel] SPARK-2811 upgrade algebird to 0.8.1

(cherry picked from commit e7690ed20a2734b7ca88e78a60a8e75ba19e9d8b)
Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-4444] Drop VD type parameter from EdgeRDD

Due to vertex attribute caching, EdgeRDD previously took two type parameters: ED and VD. However, this is an implementation detail that should not be exposed in the interface, so this PR drops the VD type parameter.

This requires removing the `filter` method from the EdgeRDD interface, because it depends on vertex attribute caching.

Author: Ankur Dave <ankurdave@gmail.com>

Closes #3303 from ankurdave/edgerdd-drop-tparam and squashes the following commits:

38dca9b [Ankur Dave] Leave EdgeRDD.fromEdges public
fafeb51 [Ankur Dave] Drop VD type parameter from EdgeRDD

(cherry picked from commit 9ac2bb18ede2e9f73c255fa33445af89aaf8a000)
Signed-off-by: Reynold Xin <rxin@databricks.com>
Revert "[SPARK-4075] [Deploy] Jar url validation is not enough for Jar file"

This reverts commit 098f83c7ccd7dad9f9228596da69fe5f55711a52.
HOTFIX: Error in release script that updates wrong version
[DOCS][SQL] Fix broken link to Row class scaladoc

Author: Andy Konwinski <andykonwinski@gmail.com>

Closes #3323 from andyk/patch-2 and squashes the following commits:

4699fdc [Andy Konwinski] Fix broken link to Row class scaladoc

(cherry picked from commit cec1116b4b80c36b36a8a13338b948e4d6ade377)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-4180] [Core] Prevent creation of multiple active SparkContexts

This patch adds error-detection logic to throw an exception when attempting to create multiple active SparkContexts in the same JVM, since this is currently unsupported and has been known to cause confusing behavior (see SPARK-2243 for more details).

**The solution implemented here is only a partial fix.**  A complete fix would have the following properties:

1. Only one SparkContext may ever be under construction at any given time.
2. Once a SparkContext has been successfully constructed, any subsequent construction attempts should fail until the active SparkContext is stopped.
3. If the SparkContext constructor throws an exception, then all resources created in the constructor should be cleaned up (SPARK-4194).
4. If a user attempts to create a SparkContext but the creation fails, then the user should be able to create new SparkContexts.

This PR only provides 2) and 4); we should be able to provide all of these properties, but the correct fix will involve larger changes to SparkContext's construction / initialization, so we'll target it for a different Spark release.

### The correct solution:

I think that the correct way to do this would be to move the construction of SparkContext's dependencies into a static method in the SparkContext companion object.  Specifically, we could make the default SparkContext constructor `private` and change it to accept a `SparkContextDependencies` object that contains all of SparkContext's dependencies (e.g. DAGScheduler, ContextCleaner, etc.).  Secondary constructors could call a method on the SparkContext companion object to create the `SparkContextDependencies` and pass the result to the primary SparkContext constructor.  For example:

```scala
class SparkContext private (deps: SparkContextDependencies) {
  def this(conf: SparkConf) {
    this(SparkContext.getDeps(conf))
  }
}

object SparkContext(
  private[spark] def getDeps(conf: SparkConf): SparkContextDependencies = synchronized {
    if (anotherSparkContextIsActive) { throw Exception(...) }
    var dagScheduler: DAGScheduler = null
    try {
        dagScheduler = new DAGScheduler(...)
        [...]
    } catch {
      case e: Exception =>
         Option(dagScheduler).foreach(_.stop())
          [...]
    }
    SparkContextDependencies(dagScheduler, ....)
  }
}
```

This gives us mutual exclusion and ensures that any resources created during the failed SparkContext initialization are properly cleaned up.

This indirection is necessary to maintain binary compatibility.  In retrospect, it would have been nice if SparkContext had no private constructors and could only be created through builder / factory methods on its companion object, since this buys us lots of flexibility and makes dependency injection easier.

### Alternative solutions:

As an alternative solution, we could refactor SparkContext's primary constructor to perform all object creation in a giant `try-finally` block.  Unfortunately, this will require us to turn a bunch of `vals` into `vars` so that they can be assigned from the `try` block.  If we still want `vals`, we could wrap each `val` in its own `try` block (since the try block can return a value), but this will lead to extremely messy code and won't guard against the introduction of future code which doesn't properly handle failures.

The more complex approach outlined above gives us some nice dependency injection benefits, so I think that might be preferable to a `var`-ification.

### This PR's solution:

- At the start of the constructor, check whether some other SparkContext is active; if so, throw an exception.
- If another SparkContext might be under construction (or has thrown an exception during construction), allow the new SparkContext to begin construction but log a warning (since resources might have been leaked from a failed creation attempt).
- At the end of the SparkContext constructor, check whether some other SparkContext constructor has raced and successfully created an active context.  If so, throw an exception.

This guarantees that no two SparkContexts will ever be active and exposed to users (since we check at the very end of the constructor).  If two threads race to construct SparkContexts, then one of them will win and another will throw an exception.

This exception can be turned into a warning by setting `spark.driver.allowMultipleContexts = true`.  The exception is disabled in unit tests, since there are some suites (such as Hive) that may require more significant refactoring to clean up their SparkContexts.  I've made a few changes to other suites' test fixtures to properly clean up SparkContexts so that the unit test logs contain fewer warnings.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #3121 from JoshRosen/SPARK-4180 and squashes the following commits:

23c7123 [Josh Rosen] Merge remote-tracking branch 'origin/master' into SPARK-4180
d38251b [Josh Rosen] Address latest round of feedback.
c0987d3 [Josh Rosen] Accept boolean instead of SparkConf in methods.
85a424a [Josh Rosen] Incorporate more review feedback.
372d0d3 [Josh Rosen] Merge remote-tracking branch 'origin/master' into SPARK-4180
f5bb78c [Josh Rosen] Update mvn build, too.
d809cb4 [Josh Rosen] Improve handling of failed SparkContext creation attempts.
79a7e6f [Josh Rosen] Fix commented out test
a1cba65 [Josh Rosen] Merge remote-tracking branch 'origin/master' into SPARK-4180
7ba6db8 [Josh Rosen] Add utility to set system properties in tests.
4629d5c [Josh Rosen] Set spark.driver.allowMultipleContexts=true in tests.
ed17e14 [Josh Rosen] Address review feedback; expose hack workaround for existing unit tests.
1c66070 [Josh Rosen] Merge remote-tracking branch 'origin/master' into SPARK-4180
06c5c54 [Josh Rosen] Add / improve SparkContext cleanup in streaming BasicOperationsSuite
d0437eb [Josh Rosen] StreamingContext.stop() should stop SparkContext even if StreamingContext has not been started yet.
c4d35a2 [Josh Rosen] Log long form of creation site to aid debugging.
918e878 [Josh Rosen] Document "one SparkContext per JVM" limitation.
afaa7e3 [Josh Rosen] [SPARK-4180] Prevent creations of multiple active SparkContexts.

(cherry picked from commit 0f3ceb56c78e7260725a09fba0e10aa193cbda4b)
Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SQL] Makes conjunction pushdown more aggressive for in-memory table

This is inspired by the [Parquet record filter generation code](https://github.com/apache/spark/blob/64c6b9bad559c21f25cd9fbe37c8813cdab939f2/sql/core/src/main/scala/org/apache/spark/sql/parquet/ParquetFilters.scala#L387-L400).

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Author: Cheng Lian <lian@databricks.com>

Closes #3318 from liancheng/aggresive-conj-pushdown and squashes the following commits:

78b69d2 [Cheng Lian] Makes conjunction pushdown more aggressive

(cherry picked from commit 5ce7dae859dc273b0fc532c9456b5960b1eca399)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-4420][SQL] Change nullability of Cast from DoubleType/FloatType to DecimalType.

This is follow-up of [SPARK-4390](https://issues.apache.org/jira/browse/SPARK-4390) (#3256).

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #3278 from ueshin/issues/SPARK-4420 and squashes the following commits:

7fea558 [Takuya UESHIN] Add some tests.
cb2301a [Takuya UESHIN] Fix tests.
133bad5 [Takuya UESHIN] Change nullability of Cast from DoubleType/FloatType to DecimalType.

(cherry picked from commit 3a81a1c9e0963173534d96850f3c0b7a16350838)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-4425][SQL] Handle NaN or Infinity cast to Timestamp correctly.

`Cast` from `NaN` or `Infinity` of `Double` or `Float` to `TimestampType` throws `NumberFormatException`.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #3283 from ueshin/issues/SPARK-4425 and squashes the following commits:

14def0c [Takuya UESHIN] Fix Cast to be able to handle NaN or Infinity to TimestampType.

(cherry picked from commit 566c791931645bfaaaf57ee5a15b9ffad534f81e)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SQL] Construct the MutableRow from an Array

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

Closes #3217 from chenghao-intel/mutablerow and squashes the following commits:

e8a10bd [Cheng Hao] revert the change of Row object
4681aea [Cheng Hao] Add toMutableRow method in object Row
a751838 [Cheng Hao] Construct the MutableRow from an existed row

(cherry picked from commit 69e858cc7748b6babadd0cbe20e65f3982161cbf)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-4309][SPARK-4407][SQL] Date type support for Thrift server, and fixes for complex types

This PR is exactly the same as #3178 except it reverts the `FileStatus.isDir` to `FileStatus.isDirectory` change, since it doesn't compile with Hadoop 1.

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Author: Cheng Lian <lian@databricks.com>

Closes #3298 from liancheng/date-for-thriftserver and squashes the following commits:

866037e [Cheng Lian] Revers isDirectory to isDir (it breaks Hadoop 1 profile)
6f71d0b [Cheng Lian] Makes toHiveString static
26fa955 [Cheng Lian] Fixes complex type support in Hive 0.13.1 shim
a92882a [Cheng Lian] Updates HiveShim for 0.13.1
73f442b [Cheng Lian] Adds Date support for HiveThriftServer2 (Hive 0.12.0)

(cherry picked from commit 6b7f2f753d16ff038881772f1958e3f4fd5597a7)
Signed-off-by: Michael Armbrust <michael@databricks.com>
[SPARK-4443][SQL] Fix statistics for external table in spark sql hive

The `totalSize` of external table  is always zero, which will influence join strategy(always use broadcast join for external table).

Author: w00228970 <wangfei1@huawei.com>

Closes #3304 from scwf/statistics and squashes the following commits:

568f321 [w00228970] fix statistics for external table

(cherry picked from commit 42389b1780311d90499b4ce2315ceabf5b6ab384)
Signed-off-by: Michael Armbrust <michael@databricks.com>