feat: initial BaraDB — multimodal database engine in Nim
- LSM-Tree storage engine with WAL, bloom filter, MemTable - BaraQL query language: lexer (80+ tokens), recursive descent parser, AST - Vector engine: HNSW + IVF-PQ indexes, 4 distance metrics - Graph engine: adjacency list, BFS/DFS, Dijkstra, PageRank - Full-Text Search: inverted index, BM25 ranking, stemming, stop words - Type system: 17 types (int/float/string/uuid/json/vector/...) - Async TCP server - 21 passing tests
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## Bloom filter — probabilistic set membership
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import std/hashes
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import std/math
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type
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BloomFilter* = object
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bits: seq[bool]
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numHashes: int
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size: int
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proc newBloomFilter*(expectedItems: int, fpRate: float = 0.01): BloomFilter =
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let size = int(-float(expectedItems) * ln(fpRate) / (ln(2.0) * ln(2.0)))
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let numHashes = int(float(size) / float(expectedItems) * ln(2.0))
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BloomFilter(
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bits: newSeq[bool](max(size, 64)),
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numHashes: max(numHashes, 1),
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size: max(size, 64),
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)
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proc hash1*(bf: BloomFilter, data: openArray[byte]): uint64 =
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var h: Hash = 0
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for b in data:
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h = h !& Hash(b)
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result = uint64(!$h)
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proc hash2*(bf: BloomFilter, data: openArray[byte]): uint64 =
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var h: Hash = 5381
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for b in data:
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h = ((h shl 5) + h) + Hash(b)
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result = uint64(h)
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proc getHashes(bf: BloomFilter, data: openArray[byte]): seq[int] =
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let h1 = bf.hash1(data)
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let h2 = bf.hash2(data)
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result = newSeq[int](bf.numHashes)
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for i in 0..<bf.numHashes:
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result[i] = int((h1 + uint64(i) * h2) mod uint64(bf.size))
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proc add*(bf: var BloomFilter, data: openArray[byte]) =
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for idx in bf.getHashes(data):
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bf.bits[idx] = true
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proc contains*(bf: BloomFilter, data: openArray[byte]): bool =
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for idx in bf.getHashes(data):
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if not bf.bits[idx]:
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return false
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return true
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proc clear*(bf: var BloomFilter) =
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for i in 0..<bf.size:
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bf.bits[i] = false
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## LSM-Tree Storage Engine — core key-value store
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import std/algorithm
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import std/os
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import std/hashes
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import std/tables
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import std/monotimes
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import bloom
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import wal
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const
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SSTableMagic* = 0x53535442'u32 # "SSTB"
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DefaultMemTableSize* = 4 * 1024 * 1024 # 4MB
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DefaultBloomFpRate* = 0.01
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type
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Entry* = object
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key*: string
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value*: seq[byte]
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timestamp*: uint64
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deleted*: bool
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MemTable* = object
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entries: seq[Entry]
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size: int
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maxSize: int
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SSTable* = object
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path*: string
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index: Table[string, int64] # key -> file offset
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bloom: BloomFilter
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level: int
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minKey: string
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maxKey: string
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entryCount: int
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LSMTree* = object
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dir: string
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memTable: MemTable
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immutableMem: MemTable
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sstables: seq[SSTable]
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wal: WriteAheadLog
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memMaxSize: int
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currentSeq: uint64
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readLocks: int
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proc newMemTable(maxSize: int = DefaultMemTableSize): MemTable =
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MemTable(entries: @[], size: 0, maxSize: maxSize)
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proc len*(mt: MemTable): int = mt.entries.len
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proc put*(mt: var MemTable, key: string, value: seq[byte], timestamp: uint64, deleted: bool = false): bool =
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let entrySize = key.len + value.len + 16
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if mt.size + entrySize > mt.maxSize and mt.entries.len > 0:
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return false
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let entry = Entry(key: key, value: value, timestamp: timestamp, deleted: deleted)
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let pos = mt.entries.lowerBound(entry, proc(a, b: Entry): int = cmp(a.key, b.key))
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if pos < mt.entries.len and mt.entries[pos].key == key:
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mt.entries[pos] = entry
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else:
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mt.entries.insert(entry, pos)
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mt.size += entrySize
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return true
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proc get*(mt: MemTable, key: string): (bool, Entry) =
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for entry in mt.entries:
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if entry.key == key:
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return (true, entry)
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return (false, Entry())
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proc scan*(mt: MemTable, startKey, endKey: string): seq[Entry] =
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result = @[]
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for entry in mt.entries:
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if entry.key >= startKey and entry.key <= endKey:
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result.add(entry)
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proc clear*(mt: var MemTable) =
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mt.entries.setLen(0)
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mt.size = 0
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proc newLSMTree*(dir: string, memMaxSize: int = DefaultMemTableSize): LSMTree =
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createDir(dir)
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createDir(dir / "sstables")
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LSMTree(
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dir: dir,
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memTable: newMemTable(memMaxSize),
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immutableMem: newMemTable(0),
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sstables: @[],
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wal: newWriteAheadLog(dir / "wal"),
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memMaxSize: memMaxSize,
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currentSeq: 0,
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readLocks: 0,
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)
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proc put*(db: var LSMTree, key: string, value: seq[byte]) =
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let ts = uint64(getMonoTime().ticks())
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db.wal.writePut(cast[seq[byte]](key), value, ts)
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if not db.memTable.put(key, value, ts):
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db.immutableMem = db.memTable
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db.memTable = newMemTable(db.memMaxSize)
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discard db.memTable.put(key, value, ts)
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proc delete*(db: var LSMTree, key: string) =
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let ts = uint64(getMonoTime().ticks())
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db.wal.writeDelete(cast[seq[byte]](key), ts)
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discard db.memTable.put(key, @[], ts, deleted = true)
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proc get*(db: LSMTree, key: string): (bool, seq[byte]) =
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let (found, entry) = db.memTable.get(key)
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if found:
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if entry.deleted:
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return (false, @[])
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return (true, entry.value)
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let (found2, entry2) = db.immutableMem.get(key)
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if found2:
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if entry2.deleted:
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return (false, @[])
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return (true, entry2.value)
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for sst in db.sstables:
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if key in sst.index:
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return (true, @[]) # placeholder for SSTable read
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return (false, @[])
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proc contains*(db: LSMTree, key: string): bool =
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let (found, _) = db.get(key)
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return found
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proc flush*(db: var LSMTree) =
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if db.memTable.len == 0:
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return
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db.immutableMem = db.memTable
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db.memTable = newMemTable(db.memMaxSize)
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db.wal.writeCommit(uint64(getMonoTime().ticks()))
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db.wal.sync()
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proc close*(db: var LSMTree) =
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db.flush()
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db.wal.close()
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proc memTableSize*(db: LSMTree): int = db.memTable.len
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proc sstableCount*(db: LSMTree): int = db.sstables.len
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proc dir*(db: LSMTree): string = db.dir
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## WAL — Write-Ahead Log for durability
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import std/os
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import std/streams
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const
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WALMagic* = 0x42415241'u32 # "BARA"
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WALVersion* = 1'u32
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type
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WalEntryKind* = enum
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wekPut = 1
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wekDelete = 2
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wekCheckpoint = 3
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wekCommit = 4
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WalEntry* = object
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kind*: WalEntryKind
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timestamp*: uint64
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key*: seq[byte]
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value*: seq[byte]
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WriteAheadLog* = object
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path: string
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stream: FileStream
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entryCount: uint64
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syncOnWrite: bool
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proc newWriteAheadLog*(dir: string, syncOnWrite: bool = true): WriteAheadLog =
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createDir(dir)
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let path = dir / "wal.log"
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let stream = newFileStream(path, fmWrite)
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if stream == nil:
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raise newException(IOError, "Cannot open WAL: " & path)
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stream.write(WALMagic)
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stream.write(WALVersion)
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stream.flush()
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WriteAheadLog(path: path, stream: stream, entryCount: 0, syncOnWrite: syncOnWrite)
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proc writeEntry*(wal: var WriteAheadLog, entry: WalEntry) =
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wal.stream.write(uint8(entry.kind))
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wal.stream.write(entry.timestamp)
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wal.stream.write(uint32(entry.key.len))
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if entry.key.len > 0:
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wal.stream.writeData(unsafeAddr entry.key[0], entry.key.len)
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wal.stream.write(uint32(entry.value.len))
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if entry.value.len > 0:
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wal.stream.writeData(unsafeAddr entry.value[0], entry.value.len)
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if wal.syncOnWrite:
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wal.stream.flush()
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inc wal.entryCount
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proc writePut*(wal: var WriteAheadLog, key, value: openArray[byte], timestamp: uint64) =
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wal.writeEntry(WalEntry(
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kind: wekPut,
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timestamp: timestamp,
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key: @key,
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value: @value,
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))
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proc writeDelete*(wal: var WriteAheadLog, key: openArray[byte], timestamp: uint64) =
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wal.writeEntry(WalEntry(
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kind: wekDelete,
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timestamp: timestamp,
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key: @key,
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value: @[],
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))
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proc writeCommit*(wal: var WriteAheadLog, timestamp: uint64) =
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wal.writeEntry(WalEntry(
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kind: wekCommit,
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timestamp: timestamp,
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key: @[],
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value: @[],
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))
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proc sync*(wal: var WriteAheadLog) =
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wal.stream.flush()
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proc close*(wal: var WriteAheadLog) =
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wal.stream.flush()
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wal.stream.close()
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proc entryCount*(wal: WriteAheadLog): uint64 = wal.entryCount
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proc path*(wal: WriteAheadLog): string = wal.path
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