[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
[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.
[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
[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.
[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.
[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
[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)
[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
[SPARK-4448] [SQL] unwrap for the ConstantObjectInspector

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

Closes #3308 from chenghao-intel/unwrap_constant_oi and squashes the following commits:

156b500 [Cheng Hao] rebase the master
c5b20ab [Cheng Hao] unwrap for the ConstantObjectInspector
[SPARK-4453][SPARK-4213][SQL] Simplifies Parquet filter generation code

While reviewing PR #3083 and #3161, I noticed that Parquet record filter generation code can be simplified significantly according to the clue stated in [SPARK-4453](https://issues.apache.org/jira/browse/SPARK-4213). This PR addresses both SPARK-4453 and SPARK-4213 with this simplification.

While generating `ParquetTableScan` operator, we need to remove all Catalyst predicates that have already been pushed down to Parquet. Originally, we first generate the record filter, and then call `findExpression` to traverse the generated filter to find out all pushed down predicates [[1](https://github.com/apache/spark/blob/64c6b9bad559c21f25cd9fbe37c8813cdab939f2/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala#L213-L228)]. In this way, we have to introduce the `CatalystFilter` class hierarchy to bind the Catalyst predicates together with their generated Parquet filter, and complicate the code base a lot.

The basic idea of this PR is that, we don't need `findExpression` after filter generation, because we already know a predicate can be pushed down if we can successfully generate its corresponding Parquet filter. SPARK-4213 is fixed by returning `None` for any unsupported predicate type.

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Author: Cheng Lian <lian@databricks.com>

Closes #3317 from liancheng/simplify-parquet-filters and squashes the following commits:

d6a9499 [Cheng Lian] Fixes import styling issue
43760e8 [Cheng Lian] Simplifies Parquet filter generation logic
SPARK-4466: Provide support for publishing Scala 2.11 artifacts to Maven

The maven release plug-in does not have support for publishing two separate sets of artifacts for a single release. Because of the way that Scala 2.11 support in Spark works, we have to write some customized code to do this. The good news is that the Maven release API is just a thin wrapper on doing git commits and pushing artifacts to the HTTP API of Apache's Sonatype server and this might overall make our deployment easier to understand.

This was already used for the 1.2 snapshot, so I think it is working well. One other nice thing is this could be pretty easily extended to publish nightly snapshots.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #3332 from pwendell/releases and squashes the following commits:

2fedaed [Patrick Wendell] Automate the opening and closing of Sonatype repos
e2a24bb [Patrick Wendell] Fixing issue where we overrode non-spark version numbers
9df3a50 [Patrick Wendell] Adding TODO
1cc1749 [Patrick Wendell] Don't build the thriftserver for 2.11
933201a [Patrick Wendell] Make tagging of release commit eager
d0388a6 [Patrick Wendell] Support Scala 2.11 build
4f4dc62 [Patrick Wendell] Change to 2.11 should not be included when committing new patch
bf742e1 [Patrick Wendell] Minor fixes
ffa1df2 [Patrick Wendell] Adding a Scala 2.11 package to test it
9ac4381 [Patrick Wendell] Addressing TODO
b3105ff [Patrick Wendell] Removing commented out code
d906803 [Patrick Wendell] Small fix
3f4d985 [Patrick Wendell] More work
fcd54c2 [Patrick Wendell] Consolidating use of keys
df2af30 [Patrick Wendell] Changes to release stuff
ALS implicit: added missing parameter alpha in doc string

Author: Felix Maximilian Möller <felixmaximilian.moeller@immobilienscout24.de>

Closes #3343 from felixmaximilian/fix-documentation and squashes the following commits:

43dcdfb [Felix Maximilian Möller] Removed the information about the switch implicitPrefs. The parameter implicitPrefs cannot be set in this context because it is inherent true when calling the trainImplicit method.
7d172ba [Felix Maximilian Möller] added missing parameter alpha in doc string.
[SPARK-4435] [MLlib] [PySpark] improve classification

This PR add setThrehold() and clearThreshold() for LogisticRegressionModel and SVMModel, also support RDD of vector in LogisticRegressionModel.predict(), SVNModel.predict() and NaiveBayes.predict()

Author: Davies Liu <davies@databricks.com>

Closes #3305 from davies/setThreshold and squashes the following commits:

d0b835f [Davies Liu] Merge branch 'master' of github.com:apache/spark into setThreshold
e4acd76 [Davies Liu] address comments
2231a5f [Davies Liu] bugfix
7bd9009 [Davies Liu] address comments
0b0a8a7 [Davies Liu] address comments
c1e5573 [Davies Liu] improve classification
[SPARK-4396] allow lookup by index in Python's Rating

In PySpark, ALS can take an RDD of (user, product, rating) tuples as input. However, model.predict outputs an RDD of Rating. So on the input side, users can use r[0], r[1], r[2], while on the output side, users have to use r.user, r.product, r.rating. We should allow lookup by index in Rating by making Rating a namedtuple.

davies

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Author: Xiangrui Meng <meng@databricks.com>

Closes #3261 from mengxr/SPARK-4396 and squashes the following commits:

543aef0 [Xiangrui Meng] use named tuple to implement ALS
0b61bae [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-4396
d3bd7d4 [Xiangrui Meng] allow lookup by index in Python's Rating
[SQL] Support partitioned parquet tables that have the key in both the directory and the file

Author: Michael Armbrust <michael@databricks.com>

Closes #3272 from marmbrus/keyInPartitionedTable and squashes the following commits:

447f08c [Michael Armbrust] Support partitioned parquet tables that have the key in both the directory and the file
[SPARK-4075][SPARK-4434] Fix the URI validation logic for Application Jar name.

This PR adds a regression test for SPARK-4434.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #3326 from sarutak/add-triple-slash-testcase and squashes the following commits:

82bc9cc [Kousuke Saruta] Fixed wrong grammar in comment
9149027 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into add-triple-slash-testcase
c1c80ca [Kousuke Saruta] Fixed style
4f30210 [Kousuke Saruta] Modified comments
9e09da2 [Kousuke Saruta] Fixed URI validation for jar file
d4b99ef [Kousuke Saruta] [SPARK-4075] [Deploy] Jar url validation is not enough for Jar file
ac79906 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into add-triple-slash-testcase
6d4f47e [Kousuke Saruta] Added a test case as a regression check for SPARK-4434
[SPARK-4404] remove sys.exit() in shutdown hook

If SparkSubmit die first, then bootstrapper will be blocked by shutdown hook. sys.exit() in a shutdown hook will cause some kind of dead lock.

cc andrewor14

Author: Davies Liu <davies@databricks.com>

Closes #3289 from davies/fix_bootstraper and squashes the following commits:

ea5cdd1 [Davies Liu] Merge branch 'master' of github.com:apache/spark into fix_bootstraper
e04b690 [Davies Liu] remove sys.exit in hook
4d11366 [Davies Liu] remove shutdown hook if subprocess die fist
[SPARK-4017] show progress bar in console

The progress bar will look like this:

![1___spark_job__85_250_finished__4_are_running___java_](https://cloud.githubusercontent.com/assets/40902/4854813/a02f44ac-6099-11e4-9060-7c73a73151d6.png)

In the right corner, the numbers are: finished tasks, running tasks, total tasks.

After the stage has finished, it will disappear.

The progress bar is only showed if logging level is WARN or higher (but progress in title is still showed), it can be turned off by spark.driver.showConsoleProgress.

Author: Davies Liu <davies@databricks.com>

Closes #3029 from davies/progress and squashes the following commits:

95336d5 [Davies Liu] Merge branch 'master' of github.com:apache/spark into progress
fc49ac8 [Davies Liu] address commentse
2e90f75 [Davies Liu] show multiple stages in same time
0081bcc [Davies Liu] address comments
38c42f1 [Davies Liu] fix tests
ab87958 [Davies Liu] disable progress bar during tests
30ac852 [Davies Liu] re-implement progress bar
b3f34e5 [Davies Liu] Merge branch 'master' of github.com:apache/spark into progress
6fd30ff [Davies Liu] show progress bar if no task finished in 500ms
e4e7344 [Davies Liu] refactor
e1f524d [Davies Liu] revert unnecessary change
a60477c [Davies Liu] Merge branch 'master' of github.com:apache/spark into progress
5cae3f2 [Davies Liu] fix style
ea49fe0 [Davies Liu] address comments
bc53d99 [Davies Liu] refactor
e6bb189 [Davies Liu] fix logging in sparkshell
7e7d4e7 [Davies Liu] address commments
5df26bb [Davies Liu] fix style
9e42208 [Davies Liu] show progress bar in console and title
[SPARK-4463] Add (de)select all button for add'l metrics.

This commit removes the behavior where when a user clicks
"Show additional metrics" on the stage page, all of the additional
metrics are automatically selected; now, collapsing and expanding
the additional metrics has no effect on which options are selected.
Instead, there's a "(De)select All" box at the top; checking this box
checks all additional metrics (and similarly, unchecking it unchecks
all additional metrics).

This commit is intended to be backported to 1.2, so that the additional
metrics behavior is not confusing to users.

Now when a user clicks the "Show additional metrics" menu, this is what
it looks like:
![image](https://cloud.githubusercontent.com/assets/1108612/5094347/1541ead6-6f15-11e4-8e8c-25a65ddbdfb2.png)

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #3331 from kayousterhout/SPARK-4463 and squashes the following commits:

9e17cea [Kay Ousterhout] Added italics
b731230 [Kay Ousterhout] [SPARK-4463] Add (de)select all button for add'l metrics.
[SPARK-4306] [MLlib] Python API for LogisticRegressionWithLBFGS

```
class LogisticRegressionWithLBFGS
 |  train(cls, data, iterations=100, initialWeights=None, corrections=10, tolerance=0.0001, regParam=0.01, intercept=False)
 |      Train a logistic regression model on the given data.
 |
 |      :param data:           The training data, an RDD of LabeledPoint.
 |      :param iterations:     The number of iterations (default: 100).
 |      :param initialWeights: The initial weights (default: None).
 |      :param regParam:       The regularizer parameter (default: 0.01).
 |      :param regType:        The type of regularizer used for training
 |                             our model.
 |                             :Allowed values:
 |                               - "l1" for using L1 regularization
 |                               - "l2" for using L2 regularization
 |                               - None for no regularization
 |                               (default: "l2")
 |      :param intercept:      Boolean parameter which indicates the use
 |                             or not of the augmented representation for
 |                             training data (i.e. whether bias features
 |                             are activated or not).
 |      :param corrections:    The number of corrections used in the LBFGS update (default: 10).
 |      :param tolerance:      The convergence tolerance of iterations for L-BFGS (default: 1e-4).
 |
 |      >>> data = [
 |      ...     LabeledPoint(0.0, [0.0, 1.0]),
 |      ...     LabeledPoint(1.0, [1.0, 0.0]),
 |      ... ]
 |      >>> lrm = LogisticRegressionWithLBFGS.train(sc.parallelize(data))
 |      >>> lrm.predict([1.0, 0.0])
 |      1
 |      >>> lrm.predict([0.0, 1.0])
 |      0
 |      >>> lrm.predict(sc.parallelize([[1.0, 0.0], [0.0, 1.0]])).collect()
 |      [1, 0]
```

Author: Davies Liu <davies@databricks.com>

Closes #3307 from davies/lbfgs and squashes the following commits:

34bd986 [Davies Liu] Merge branch 'master' of http://git-wip-us.apache.org/repos/asf/spark into lbfgs
5a945a6 [Davies Liu] address comments
941061b [Davies Liu] Merge branch 'master' of github.com:apache/spark into lbfgs
03e5543 [Davies Liu] add it to docs
ed2f9a8 [Davies Liu] add regType
76cd1b6 [Davies Liu] reorder arguments
4429a74 [Davies Liu] Update classification.py
9252783 [Davies Liu] python api for LogisticRegressionWithLBFGS