GitHub user okram opened a pull request:
https://github.com/apache/tinkerpop/pull/349
TINKERPOP-1349: RepeatUnrollStrategy should unroll loops while maintaining
equivalent semantics.
https://issues.apache.org/jira/browse/TINKERPOP-1349
`RepeatUnrollStrategy` is a Standard-only strategy that will unroll a
`repeat()` into a linear form if and only if it has a known loop amount (e.g.
`times(2)`). That is `repeat(out()).times(2)` becomes
`out().barrier().out().barrier()`. The `barrier()` insertions are necessary as
`repeat()` itself is a barrier step and also, the benefit of bulking is
leveraged. `RepeatUnrollStrategy` removes the need for `RepeatStep`,
`RepeatEndStep`, and `LoopTraversal`.
`RepeatUnrollStrategyTest` ensures that unrolling is faster than
not-unrolling. Here are some runtimes. The first item in the Pair is the
runtime and the second item is the amount of unique objects being processed.
With more unique objects, the faster it gets. Note that at 10 unique elements
(tiny traversal), sometimes rolled is faster than unrolled and vice versa (i.e.
they are equal).
```
rolled:[0.22843720299999998, 10] unrolled:[0.174451055, 10]
rolled:[0.514145509, 100] unrolled:[0.212532769, 100]
rolled:[1.4944357259999999, 1000] unrolled:[0.441714987, 1000]
rolled:[28.502658626, 10000] unrolled:[12.936112649999998,
10000]
```
Also in this ticket, I fixed a bug in `BranchStep` where children were not
being integrated and thus, susceptible to clone-problems. Moreover, I added a
timing test to `IdentityRemovalStrategyTest`. @spmallette, do you know how to
make a test run once and only once in a `Parameterized` test case? If so, can
you update `IdentityRemoveStrategyTest` and `RepeatUnrollStrategyTest`
accordingly?
---
```
CHANGELOG
* Added `RepeatUnrollStrategy` to linearize a `repeat()`-traversal if loop
amount is known at compile time.
* Fixed a bug in `BranchStep` around child integration during `clone()`.
```
VOTE +1.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/tinkerpop TINKERPOP-1349
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/tinkerpop/pull/349.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #349
----
commit 8753366a975101ba4edaa1888163abda3238f7ff
Author: Marko A. Rodriguez <okramma...@gmail.com>
Date: 2016-06-28T16:44:32Z
added RepeatUnrollStrategy for when the loop amount is known at compile
time. Fixed a bug in BranchStep around child integration.
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