Erasure coding dataset (#72)

* add erasure coding support

* add leopard support

* erasure coding tests
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Dmitriy Ryajov 2022-04-05 13:12:59 -06:00 committed by GitHub
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## Nim-Dagger
## Copyright (c) 2022 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import ./erasure/erasure
import ./erasure/backends/leopard
export erasure
func leoEncoderProvider*(size, buffers, parity: int): EncoderBackend {.raises: [Defect].} =
LeoEncoderBackend.new(size, buffers, parity)
func leoDecoderProvider*(size, buffers, parity: int): DecoderBackend {.raises: [Defect].} =
LeoDecoderBackend.new(size, buffers, parity)

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## Nim-Dagger
## Copyright (c) 2022 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import pkg/upraises
push: {.upraises: [].}
import ../manifest
import ../stores
type
Backend* = ref object of RootObj
blockSize*: int # block size in bytes
buffers*: int # number of original pieces
parity*: int # number of redundancy pieces
EncoderBackend* = ref object of Backend
DecoderBackend* = ref object of Backend
method release*(self: Backend) {.base.} =
raiseAssert("not implemented!")
method encode*(
self: EncoderBackend,
buffers,
parity: var openArray[seq[byte]]): Result[void, cstring] {.base.} =
raiseAssert("not implemented!")
method decode*(
self: DecoderBackend,
buffers,
parity,
recovered: var openArray[seq[byte]]): Result[void, cstring] {.base.} =
raiseAssert("not implemented!")

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## Nim-Dagger
## Copyright (c) 2022 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import std/options
import pkg/leopard
import pkg/stew/results
import ../backend
type
LeoEncoderBackend* = ref object of EncoderBackend
encoder*: Option[LeoEncoder]
LeoDecoderBackend* = ref object of DecoderBackend
decoder*: Option[LeoDecoder]
method encode*(
self: LeoEncoderBackend,
data,
parity: var openArray[seq[byte]]): Result[void, cstring] =
var encoder = if self.encoder.isNone:
self.encoder = (? LeoEncoder.init(
self.blockSize,
self.buffers,
self.parity)).some
self.encoder.get()
else:
self.encoder.get()
encoder.encode(data, parity)
method decode*(
self: LeoDecoderBackend,
data,
parity,
recovered: var openArray[seq[byte]]): Result[void, cstring] =
var decoder = if self.decoder.isNone:
self.decoder = (? LeoDecoder.init(
self.blockSize,
self.buffers,
self.parity)).some
self.decoder.get()
else:
self.decoder.get()
decoder.decode(data, parity, recovered)
method release*(self: LeoEncoderBackend) =
if self.encoder.isSome:
self.encoder.get().free()
method release*(self: LeoDecoderBackend) =
if self.decoder.isSome:
self.decoder.get().free()
func new*(
T: type LeoEncoderBackend,
blockSize,
buffers,
parity: int): T =
T(
blockSize: blockSize,
buffers: buffers,
parity: parity)
func new*(
T: type LeoDecoderBackend,
blockSize,
buffers,
parity: int): T =
T(
blockSize: blockSize,
buffers: buffers,
parity: parity)

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## Nim-Dagger
## Copyright (c) 2022 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import pkg/upraises
push: {.upraises: [].}
import std/sequtils
import pkg/chronos
import pkg/chronicles
import ../manifest
import ../stores
import ../errors
import ../blocktype
import ./backend
export backend
logScope:
topics = "dagger erasure"
type
## Encode a manifest into one that is erasure protected.
##
## The new manifest has K `blocks` that are encoded into
## additional M `parity` blocks. The resulting dataset
## is padded with empty blocks if it doesn't have a square
## shape.
##
## NOTE: The padding blocks could be excluded
## from transmission, but they aren't for now.
##
## The resulting dataset is logically divided into rows
## where a row is made up of B blocks. There are then,
## K + M = N rows in total, each of length B blocks. Rows
## are assumed to be of the same number of (B) blocks.
##
## The encoding is systematic and the rows can be
## read sequentially by any node without decoding.
##
## Decoding is possible with any K rows or partial K
## columns (with up to M blocks missing per column),
## or any combination there of.
##
EncoderProvider* = proc(size, blocks, parity: int): EncoderBackend
{.raises: [Defect], noSideEffect.}
DecoderProvider* = proc(size, blocks, parity: int): DecoderBackend
{.raises: [Defect], noSideEffect.}
Erasure* = ref object
encoderProvider*: EncoderProvider
decoderProvider*: DecoderProvider
store*: BlockStore
proc encode*(
self: Erasure,
manifest: Manifest,
blocks: int,
parity: int): Future[?!Manifest] {.async.} =
## Encode a manifest into one that is erasure protected.
##
## `manifest` - the original manifest to be encoded
## `blocks` - the number of blocks to be encoded - K
## `parity` - the number of parity blocks to generate - M
##
logScope:
original_cid = manifest.cid.get()
original_len = manifest.len
blocks = blocks
parity = parity
trace "Erasure coding manifest", blocks, parity
without var encoded =? Manifest.new(manifest, blocks, parity), error:
trace "Unable to create manifest", msg = error.msg
return error.failure
logScope:
steps = encoded.steps
rounded_blocks = encoded.rounded
new_manifest = encoded.len
var
encoder = self.encoderProvider(manifest.blockSize, blocks, parity)
try:
for i in 0..<encoded.steps:
# TODO: Don't allocate a new seq everytime, allocate once and zero out
var
data = newSeq[seq[byte]](blocks) # number of blocks to encode
parityData = newSeqWith[seq[byte]](parity, newSeq[byte](manifest.blockSize))
# calculate block indexes to retrieve
blockIdx = toSeq(countup(i, encoded.rounded - 1, encoded.steps))
# request all blocks from the store
dataBlocks = await allFinished(
blockIdx.mapIt( self.store.getBlock(encoded[it]) ))
for j in 0..<blocks:
let idx = blockIdx[j]
if idx < manifest.len:
without var blk =? await dataBlocks[j], error:
trace "Unable to retrieve block", msg = error.msg
return error.failure
trace "Encoding block", cid = blk.cid, pos = idx
shallowCopy(data[j], blk.data)
else:
trace "Padding with empty block", pos = idx
data[j] = newSeq[byte](manifest.blockSize)
trace "Erasure coding data", data = data.len, parity = parityData.len
if (
let err = encoder.encode(data, parityData);
err.isErr):
trace "Unable to encode manifest!", err = $err.error
return failure($err.error)
for j in 0..<parity:
let idx = encoded.rounded + blockIdx[j]
without blk =? Block.new(parityData[j]), error:
trace "Unable to create parity block", err = error.msg
return failure(error)
trace "Adding parity block", cid = blk.cid, pos = idx
encoded[idx] = blk.cid
if not (await self.store.putBlock(blk)):
trace "Unable to store block!", cid = blk.cid
return failure("Unable to store block!")
except CancelledError as exc:
trace "Erasure coding encoding cancelled"
raise exc # cancellation needs to be propagated
except CatchableError as exc:
trace "Erasure coding encoding error", exc = exc.msg
return failure(exc)
finally:
encoder.release()
return encoded.success
proc decode*(
self: Erasure,
encoded: Manifest): Future[?!Manifest] {.async.} =
## Decode a protected manifest into it's original
## manifest
##
## `encoded` - the encoded (protected) manifest to
## be recovered
##
logScope:
steps = encoded.steps
rounded_blocks = encoded.rounded
new_manifest = encoded.len
var
decoder = self.decoderProvider(encoded.blockSize, encoded.K, encoded.M)
try:
for i in 0..<encoded.steps:
# TODO: Don't allocate a new seq everytime, allocate once and zero out
let
# calculate block indexes to retrieve
blockIdx = toSeq(countup(i, encoded.len - 1, encoded.steps))
# request all blocks from the store
pendingBlocks = blockIdx.mapIt(
self.store.getBlock(encoded[it]) # Get the data blocks (first K)
)
var
data = newSeq[seq[byte]](encoded.K) # number of blocks to encode
parityData = newSeq[seq[byte]](encoded.M)
recovered = newSeqWith[seq[byte]](encoded.K, newSeq[byte](encoded.blockSize))
idxPendingBlocks = pendingBlocks # copy futures to make using with `one` easier
emptyBlock = newSeq[byte](encoded.blockSize)
resolved = 0
while true:
if resolved >= (encoded.K + encoded.M) or idxPendingBlocks.len <= 0:
break
let
done = await one(idxPendingBlocks)
idx = pendingBlocks.find(done)
idxPendingBlocks.del(idxPendingBlocks.find(done))
without blk =? (await done), error:
trace "Failed retrieving block", exc = error.msg
if blk.isNil:
continue
if idx >= encoded.K:
trace "Retrieved parity block", cid = blk.cid, idx
shallowCopy(parityData[idx - encoded.K], if blk.isEmpty: emptyBlock else: blk.data)
else:
trace "Retrieved data block", cid = blk.cid, idx
shallowCopy(data[idx], if blk.isEmpty: emptyBlock else: blk.data)
resolved.inc
let
dataPieces = data.filterIt( it.len > 0 ).len
parityPieces = parityData.filterIt( it.len > 0 ).len
if dataPieces >= encoded.K:
trace "Retrieved all the required data blocks", data = dataPieces, parity = parityPieces
continue
trace "Erasure decoding data", data = dataPieces, parity = parityPieces
if (
let err = decoder.decode(data, parityData, recovered);
err.isErr):
trace "Unable to decode manifest!", err = $err.error
return failure($err.error)
for i in 0..<encoded.K:
if data[i].len <= 0:
without blk =? Block.new(recovered[i]), error:
trace "Unable to create block!", exc = error.msg
return failure(error)
trace "Recovered block", cid = blk.cid
if not (await self.store.putBlock(blk)):
trace "Unable to store block!", cid = blk.cid
return failure("Unable to store block!")
except CancelledError as exc:
trace "Erasure coding decoding cancelled"
raise exc # cancellation needs to be propagated
except CatchableError as exc:
trace "Erasure coding decoding error", exc = exc.msg
return failure(exc)
finally:
decoder.release()
without decoded =? Manifest.new(blocks = encoded.blocks[0..<encoded.originalLen]), error:
return error.failure
return decoded.success
proc start*(self: Erasure) {.async.} =
return
proc stop*(self: Erasure) {.async.} =
return
proc new*(
T: type Erasure,
store: BlockStore,
encoderProvider: EncoderProvider,
decoderProvider: DecoderProvider): Erasure =
Erasure(
store: store,
encoderProvider: encoderProvider,
decoderProvider: decoderProvider)

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import std/sequtils
import pkg/asynctest
import pkg/chronos
import pkg/libp2p
import pkg/questionable
import pkg/questionable/results
import pkg/dagger/erasure
import pkg/dagger/manifest
import pkg/dagger/stores
import pkg/dagger/blocktype
import pkg/dagger/rng
import ./helpers
suite "Erasure encode/decode":
test "Should tolerate loosing M data blocks in a single random column":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 2), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
var
column = rng.rand(encoded.len div encoded.steps) # random column
dropped: seq[Cid]
for _ in 0..<encoded.M:
dropped.add(encoded[column])
check (await store.delBlock(encoded[column]))
column.inc(encoded.steps)
var
decoded = (await erasure.decode(encoded)).tryGet()
check:
decoded.cid.tryGet() == manifest.cid.tryGet()
decoded.cid.tryGet() == encoded.originalCid
decoded.len == encoded.originalLen
for d in dropped:
check d in store
test "Should not tolerate loosing more than M data blocks in a single random column":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 2), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
var
column = rng.rand(encoded.len div encoded.steps) # random column
dropped: seq[Cid]
for _ in 0..<encoded.M + 1:
dropped.add(encoded[column])
check (await store.delBlock(encoded[column]))
column.inc(encoded.steps)
var
decoded: Manifest
expect ResultFailure:
decoded = (await erasure.decode(encoded)).tryGet()
for d in dropped:
check d notin store
test "Should tolerate loosing M data blocks in M random columns":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 5), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
var
blocks: seq[int]
offset = 0
while offset < encoded.steps - 1:
let
blockIdx = toSeq(countup(offset, encoded.len - 1, encoded.steps))
for _ in 0..<encoded.M:
blocks.add(rng.sample(blockIdx, blocks))
offset.inc
for idx in blocks:
check (await store.delBlock(encoded[idx]))
var
decoded = (await erasure.decode(encoded)).tryGet()
for d in manifest:
check d in store
test "Should not tolerate loosing more than M data blocks in M random columns":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 5), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
var
blocks: seq[int]
offset = 0
while offset < encoded.steps - 1:
let
blockIdx = toSeq(countup(offset, encoded.len - 1, encoded.steps))
for _ in 0..<encoded.M + 1: # NOTE: the +1
blocks.add(rng.sample(blockIdx, blocks))
offset.inc
for idx in blocks:
check (await store.delBlock(encoded[idx]))
var
decoded: Manifest
expect ResultFailure:
decoded = (await erasure.decode(encoded)).tryGet()
test "Should tolerate loosing M (a.k.a row) contiguous data blocks":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 5), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
for b in encoded.blocks[0..<encoded.steps * encoded.M]:
check (await store.delBlock(b))
var
decoded = (await erasure.decode(encoded)).tryGet()
for d in manifest:
check d in store
test "Should tolerate loosing M (a.k.a row) contiguous parity blocks":
const
buffers = 20
parity = 10
dataSetSize = BlockSize * 123 # weird geometry
var
chunker = RandomChunker.new(Rng.instance(), size = dataSetSize, chunkSize = BlockSize)
manifest = Manifest.new(blockSize = BlockSize).tryGet()
store = CacheStore.new(cacheSize = (dataSetSize * 5), chunkSize = BlockSize)
erasure = Erasure.new(store, leoEncoderProvider, leoDecoderProvider)
rng = Rng.instance
while (
let chunk = await chunker.getBytes();
chunk.len > 0):
let blk = Block.new(chunk).tryGet()
manifest.add(blk.cid)
check (await store.putBlock(blk))
let
encoded = (await erasure.encode(
manifest,
buffers,
parity)).tryGet()
check:
encoded.len mod (buffers + parity) == 0
encoded.rounded == (manifest.len + (buffers - (manifest.len mod buffers)))
encoded.steps == encoded.rounded div buffers
for b in encoded.blocks[^(encoded.steps * encoded.M)..^1]:
check (await store.delBlock(b))
var
decoded = (await erasure.decode(encoded)).tryGet()
for d in manifest:
check d in store

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@ -7,5 +7,6 @@ import ./dagger/testnode
import ./dagger/teststorestream
import ./dagger/testpurchasing
import ./dagger/testsales
import ./dagger/testerasure
{.warning[UnusedImport]: off.}