mirror of
https://github.com/codex-storage/nim-codex.git
synced 2025-02-22 17:48:24 +00:00
130 lines
3.7 KiB
Nim
130 lines
3.7 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/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 ../utils
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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 = "codex storestream"
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const
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StoreStreamTrackerName* = "StoreStream"
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type
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StoreStream* = ref object of LPStream
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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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iter*: AsyncIter[?!Block]
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lastBlock: Block
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lastIndex: int
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offset: int
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method initStream*(s: StoreStream) =
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if s.objName.len == 0:
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s.objName = StoreStreamTrackerName
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procCall LPStream(s).initStream()
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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
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): StoreStream =
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## Create a new StoreStream instance for a given store and manifest
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##
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result = StoreStream(
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store: store,
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manifest: manifest,
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pad: pad,
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lastIndex: -1,
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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).int
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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
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): 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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##
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trace "Reading from manifest", cid = self.manifest.cid.get(), blocks = self.manifest.blocksCount
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if self.atEof:
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raise newLPStreamEOFError()
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# Initialize a block iterator
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if self.lastIndex < 0:
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without iter =? await self.store.getBlocks(self.manifest.treeCid, self.manifest.blocksCount, self.manifest.treeRoot), err:
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raise newLPStreamReadError(err)
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self.iter = iter
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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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if self.offset >= (self.lastIndex + 1) * self.manifest.blockSize.int:
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if not self.iter.finished:
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without lastBlock =? await self.iter.next(), err:
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raise newLPStreamReadError(err)
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self.lastBlock = lastBlock
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inc self.lastIndex
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else:
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raise newLPStreamReadError(newException(CodexError, "Block iterator finished prematurely"))
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# Compute how many bytes to read from this block
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let
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blockOffset = self.offset mod self.manifest.blockSize.int
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readBytes = min([self.size - self.offset,
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nbytes - read,
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self.manifest.blockSize.int - blockOffset])
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# Copy `readBytes` bytes starting at `blockOffset` from the block into the outbuf
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if self.lastBlock.isEmpty:
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zeroMem(pbytes.offset(read), readBytes)
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else:
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copyMem(pbytes.offset(read), self.lastBlock.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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