[SPARK-9192][SQL] add initialization phase for nondeterministic expression

Currently nondeterministic expression is broken without a explicit initialization phase.

Let me take `MonotonicallyIncreasingID` as an example. This expression need a mutable state to remember how many times it has been evaluated, so we use `transient var count: Long` there. By being transient, the `count` will be reset to 0 and **only** to 0 when serialize and deserialize it, as deserialize transient variable will result to default value. There is *no way* to use another initial value for `count`, until we add the explicit initialization phase.

Another use case is local execution for `LocalRelation`, there is no serialize and deserialize phase and thus we can't reset mutable states for it.

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #7535 from cloud-fan/init and squashes the following commits:

6c6f332 [Wenchen Fan] add test
ef68ff4 [Wenchen Fan] fix comments
9eac85e [Wenchen Fan] move init code to interpreted class
bb7d838 [Wenchen Fan] pulls out nondeterministic expressions into a project
b4a4fc7 [Wenchen Fan] revert a refactor
86fee36 [Wenchen Fan] add initialization phase for nondeterministic expression

0 files changed, 0 insertions, 0 deletions