buildSCSTest fails on certain occassions

[diamog]

Error output for test:

6: Test timeout computed to be: 10000000
6: 
6: Beginning DefaultTest
6: Building SCS with C: 2 sigma: 2147483647 V: 2
6: 
6: Particle Structures Sell-C-Sigma C: 2 sigma: 2147483647 V: 2.
6: Number of Elements: 5.
6: Number of Particles: 20.
6: Number of Chunks: 3.
6: Number of Slices: 6.
6:   Chunk 0. Elements: 3 2
6:     Slice 0 | 1 1 | 1 1
6:     Slice 1 | 1 1 | 1 1
6:     Slice 2 | 1 1 | 1 1
6:     Slice 3 | 1 1 | 1 1
6:     Slice 4 | 1 1 | 1 0
6:     Slice 5 | 1 0
6: 
6: Beginning NoSort Test
6: Building SCS with C: 2 sigma: 1 V: 2
6: :0: : block: [1,0,0], thread: [0,0,0] Assertion `View bounds error of view particle_mask` failed.
6: :0: : block: [1,0,0], thread: [0,1,0] Assertion `View bounds error of view particle_mask` failed.
6: terminate called after throwing an instance of 'std::runtime_error'
6:   what():  cudaDeviceSynchronize() error( cudaErrorAssert): device-side assert triggered /home/diamog/Documents/scorec/kokkos/core/src/Cuda/Kokkos_Cuda_Instance.cpp:120
6: Traceback functionality not available
6: 
1/1 Test #6: buildSCS .........................Child aborted***Exception:   0.31 sec

First noticed on commit 61bc5cc0712ca3af9b8527a4c7da9344c76fa5f7

[MatthewChristoff]

I noticed this issue while I was doing my testing. I was able to track down the location of this bug to an out-of-bounds error on this reference to the active mask.

[diamog]

I've tracked the issue to occur when the first chunk of the SCS is empty. Working on a fix now

[cwsmith]

I assume full sorting must be disabled for that to happen?

[diamog]

Yes, the error in the test is only occurring in the no sort test when all particles are places in the later elements. This is why the error seemed like a race condition as it was dependent on the random assignment of particles.

[diamog]

The above commit fixes the issue when any number of the first chunks are empty.

We also have a new getFirstValue(view) function... Maybe I should have just made a getIndex function, but oh well.