Only init OpenCL once per Initialization

[fasmat]

This changes the API of internal/postrs to preserve an instance of post-rs's Initializer until explicitly freed.

• ScryPositions has been removed and replaced by a new struct Scrypt that has to be Instantiated with NewScrypt. This instance holds a reference to the rust exposed initializer that has to be explicitly freed by calling Scrypt::Close. The change has been propagated up different layers of abstructions into the initialization.Initializer.
• All code related to gpu-post has been removed due to becoming incompatible with the recent changes.

Do not merge before spacemeshos/post-rs#59

Closes #138

[pigmej]

Now the speed is as expected but it still crashed with

2023/05/15 10:52:28     DEBUG   initialization: file #2 current position: 38797312, remaining: 28311552
2023/05/15 10:52:30     DEBUG   initialization: file #2 current position: 39845888, remaining: 27262976
2023/05/15 10:52:32     DEBUG   initialization: file #2 current position: 40894464, remaining: 26214400
2023/05/15 10:52:34     DEBUG   initialization: file #2 current position: 41943040, remaining: 25165824
2023/05/15 10:52:36     DEBUG   initialization: file #2 current position: 42991616, remaining: 24117248
2023/05/15 10:52:39     DEBUG   initialization: file #2 current position: 44040192, remaining: 23068672
2023/05/15 10:52:41     DEBUG   initialization: file #2 current position: 45088768, remaining: 22020096
2023/05/15 10:52:43     DEBUG   initialization: file #2 current position: 46137344, remaining: 20971520
2023/05/15 10:52:45     DEBUG   initialization: file #2 current position: 47185920, remaining: 19922944
2023/05/15 10:52:47     DEBUG   initialization: file #2 current position: 48234496, remaining: 18874368
2023/05/15 10:52:50     DEBUG   initialization: file #2 current position: 49283072, remaining: 17825792
2023/05/15 10:52:52     DEBUG   initialization: file #2 current position: 50331648, remaining: 16777216
2023/05/15 10:52:54     DEBUG   initialization: file #2 current position: 51380224, remaining: 15728640
2023/05/15 10:52:56     DEBUG   initialization: file #2 current position: 52428800, remaining: 14680064
2023/05/15 10:52:58     DEBUG   initialization: file #2 current position: 53477376, remaining: 13631488
2023/05/15 10:53:01     DEBUG   initialization: file #2 current position: 54525952, remaining: 12582912
2023/05/15 10:53:03     DEBUG   initialization: file #2 current position: 55574528, remaining: 11534336
2023/05/15 10:53:05     DEBUG   initialization: file #2 current position: 56623104, remaining: 10485760
2023/05/15 10:53:07     DEBUG   initialization: file #2 current position: 57671680, remaining: 9437184
2023/05/15 10:53:09     DEBUG   initialization: file #2 current position: 58720256, remaining: 8388608
2023/05/15 10:53:12     DEBUG   initialization: file #2 current position: 59768832, remaining: 7340032
2023/05/15 10:53:14     DEBUG   initialization: file #2 current position: 60817408, remaining: 6291456
2023/05/15 10:53:16     DEBUG   initialization: file #2 current position: 61865984, remaining: 5242880
2023/05/15 10:53:18     DEBUG   initialization: file #2 current position: 62914560, remaining: 4194304
2023/05/15 10:53:21     DEBUG   initialization: file #2 current position: 63963136, remaining: 3145728
Found new smallest nonce: Some(VrfNonce { index: 199214068, label: [0, 0, 0, 1, 10, 251, 93, 246, 161, 28, 201, 140, 231, 38, 180, 178, 27, 93, 64, 199, 96, 105, 160, 107, 8, 151, 1
54, 192, 67, 170, 150, 173] })
2023/05/15 10:53:23     INFO    initialization: file #2, found nonce: 199214068, value: 000000010afb5df6a11cc98ce726b4b2
2023/05/15 10:53:23     INFO    initialization: file #2, found new best nonce
2023/05/15 10:53:23     DEBUG   initialization: file #2 current position: 65011712, remaining: 2097152
2023/05/15 10:53:25     DEBUG   initialization: file #2 current position: 66060288, remaining: 1048576
2023/05/15 10:53:27     INFO    initialization: file #2 completed; number of labels written: 67108864
2023/05/15 10:53:27     INFO    initialization: starting to write file #3; target number of labels: 67108864, start position: 201326592
Using provider: [GPU] NVIDIA CUDA/NVIDIA GeForce RTX 3090
device memory: 24259 MB, max_mem_alloc_size: 6064 MB, max_compute_units: 82, max_wg_size: 1024
preferred_wg_size_multiple: 32, kernel_wg_size: 256
Using: global_work_size: 12128, local_work_size: 32
Allocating buffer for input: 32 bytes
Allocating buffer for output: 388096 bytes
Allocating buffer for lookup: 6358564864 bytes
2023/05/15 10:53:27     DEBUG   initialization: file #3 current position: 0, remaining: 67108864
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: OclError(OclCore(Api(

################################ OPENCL ERROR ###############################

Error executing function: clEnqueueNDRangeKernel("scrypt")

Status error code: CL_MEM_OBJECT_ALLOCATION_FAILURE (-4)

Please visit the following url for more information:

https://www.khronos.org/registry/cl/sdk/1.2/docs/man/xhtml/clEnqueueNDRangeKernel.html#errors

#############################################################################
)))', ffi/src/initialization.rs:146:10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5
SIGABRT: abort
PC=0x7fd345a2fa7c m=9 sigcode=18446744073709551610
signal arrived during cgo execution

goroutine 1 [syscall]:
runtime.cgocall(0x523d16, 0xc0001495f8)
        /root/go/src/runtime/cgocall.go:158 +0x5c fp=0xc0001495d0 sp=0xc000149598 pc=0x40595c
github.com/spacemeshos/post/internal/postrs._Cfunc_initialize(0x7fd13cdcf8a0, 0xc000000, 0xc0fffff, 0x7fd13d0020d0, 0xc0002820b0)
        _cgo_gotypes.go:307 +0x4c fp=0xc0001495f8 sp=0xc0001495d0 pc=0x4f562c
github.com/spacemeshos/post/internal/postrs.cScryptPositions.func2(0x7fd13cdcf8a0, 0x1?, 0x7fd13d0020d0?, 0x657be0?, 0x0?)
        /root/post/internal/postrs/initializer.go:109 +0x7f fp=0xc000149658 sp=0xc0001495f8 pc=0x4f6bdf
github.com/spacemeshos/post/internal/postrs.cScryptPositions(0xc00013a000?, 0xc000149700?, 0xc000000, 0xc0fffff)
        /root/post/internal/postrs/initializer.go:109 +0xf1 fp=0xc000149708 sp=0xc000149658 pc=0x4f6831
github.com/spacemeshos/post/internal/postrs.(*Scrypt).Positions(0xc000280030, 0xc000000, 0xc0fffff)
        /root/post/internal/postrs/api.go:159 +0x7e fp=0xc000149760 sp=0xc000149708 pc=0x4f60fe
github.com/spacemeshos/post/oracle.(*WorkOracle).Positions(0x4000000?, 0x55dbd9?, 0x20?)
        /root/post/oracle/oracle.go:164 +0x33 fp=0xc0001497b8 sp=0xc000149760 pc=0x506513
github.com/spacemeshos/post/initialization.(*Initializer).initFile(0xc000176000, {0x588b18, 0xc00016c340}, 0xc000175a30?, 0x100000, 0xc000000, 0x4000000, {0xc00001a1a0, 0x20, 0x20})
        /root/post/initialization/initialization.go:479 +0xab0 fp=0xc0001499d8 sp=0xc0001497b8 pc=0x51f450
github.com/spacemeshos/post/initialization.(*Initializer).Initialize(0xc000176000, {0x588b18, 0xc00016c340})
        /root/post/initialization/initialization.go:266 +0x58a fp=0xc000149cb8 sp=0xc0001499d8 pc=0x51d9ea
main.main()
        /root/post/cmd/postcli/main.go:133 +0x3e5 fp=0xc000149f80 sp=0xc000149cb8 pc=0x522c85
runtime.main()
        /root/go/src/runtime/proc.go:250 +0x212 fp=0xc000149fe0 sp=0xc000149f80 pc=0x439052
runtime.goexit()
        /root/go/src/runtime/asm_amd64.s:1594 +0x1 fp=0xc000149fe8 sp=0xc000149fe0 pc=0x465e41

goroutine 2 [force gc (idle), 6 minutes]:

[pigmej]

That's probably caused by RUST side though.