109 lines
3.2 KiB
Nim
109 lines
3.2 KiB
Nim
## Nim-Dagger
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## Copyright (c) 2022 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import std/options
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import pkg/upraises
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push: {.upraises: [].}
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import pkg/libp2p
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import pkg/chronos
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import pkg/chronicles
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import pkg/stew/ptrops
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import ../stores
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import ../manifest
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import ../blocktype
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import ./seekablestream
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export stores, blocktype, manifest, chronos
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logScope:
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topics = "dagger storestream"
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type
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# Make SeekableStream from a sequence of blocks stored in Manifest
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# (only original file data - see StoreStream.size)
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StoreStream* = ref object of SeekableStream
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store*: BlockStore # Store where to lookup block contents
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manifest*: Manifest # List of block CIDs
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pad*: bool # Pad last block to manifest.blockSize?
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proc new*(
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T: type StoreStream,
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store: BlockStore,
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manifest: Manifest,
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pad = true): T =
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result = T(
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store: store,
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manifest: manifest,
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pad: pad,
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offset: 0)
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result.initStream()
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method `size`*(self: StoreStream): int =
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bytes(self.manifest, self.pad)
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proc `size=`*(self: StoreStream, size: int)
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{.error: "Setting the size is forbidden".} =
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discard
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method atEof*(self: StoreStream): bool =
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self.offset >= self.size
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method readOnce*(
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self: StoreStream,
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pbytes: pointer,
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nbytes: int): Future[int] {.async.} =
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## Read `nbytes` from current position in the StoreStream into output buffer pointed by `pbytes`.
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## Return how many bytes were actually read before EOF was encountered.
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## Raise exception if we are already at EOF.
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trace "Reading from manifest", cid = $self.manifest.cid.get(), blocks = self.manifest.len
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if self.atEof:
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raise newLPStreamEOFError()
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# The loop iterates over blocks in the StoreStream,
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# reading them and copying their data into outbuf
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var read = 0 # Bytes read so far, and thus write offset in the outbuf
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while read < nbytes and not self.atEof:
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# Compute from the current stream position `self.offset` the block num/offset to read
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# Compute how many bytes to read from this block
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let
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blockNum = self.offset div self.manifest.blockSize
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blockOffset = self.offset mod self.manifest.blockSize
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readBytes = min([self.size - self.offset, nbytes - read, self.manifest.blockSize - blockOffset])
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# Read contents of block `blockNum`
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without blk =? await self.store.getBlock(self.manifest[blockNum]), error:
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raise newLPStreamReadError(error)
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trace "Reading bytes from store stream", blockNum, cid = blk.cid, bytes = readBytes, blockOffset
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# Copy `readBytes` bytes starting at `blockOffset` from the block into the outbuf
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if blk.isEmpty:
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zeroMem(pbytes.offset(read), readBytes)
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else:
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copyMem(pbytes.offset(read), blk.data[blockOffset].addr, readBytes)
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# Update current positions in the stream and outbuf
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self.offset += readBytes
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read += readBytes
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return read
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method closeImpl*(self: StoreStream) {.async.} =
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trace "Closing StoreStream"
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self.offset = self.size # set Eof
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await procCall LPStream(self).closeImpl()
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