253 lines
7.5 KiB
Nim
253 lines
7.5 KiB
Nim
# Nim-RocksDB
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# Copyright 2018 Status Research & Development GmbH
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# Licensed under either of
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#
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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# * GPL license, version 2.0, ([LICENSE-GPLv2](LICENSE-GPLv2) or https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html)
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#
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import cpuinfo, options, ranges
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const useCApi = true
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when useCApi:
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import rocksdb/librocksdb
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export librocksdb
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type
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RocksPtr[T] = object
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res: T
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import typetraits
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when false:
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# XXX: generic types cannot have destructors at the moment:
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# https://github.com/nim-lang/Nim/issues/5366
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template managedResource(name) =
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template freeResource(r: `rocksdb name t`) =
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`rocksdb name destroy`(r)
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managedResource(WriteOptions)
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managedResource(ReadOptions)
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template initResource(resourceName): auto =
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var p = toRocksPtr(`rocksdb resourceName create`())
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# XXX: work-around the destructor issue above:
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# XXX: work-around disabled - it frees the resource too early - need to
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# free resource manually!
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# defer: freeResource p.res
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p.res
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proc `=destroy`*[T](rocksPtr: var RocksPtr[T]) =
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freeResource rocksPtr.res
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proc toRocksPtr[T](res: T): RocksPtr[T] =
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result.res = res
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else:
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{.error: "The C++ API of RocksDB is not supported yet".}
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# The intention of this template is that it will hide the
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# difference between the C and C++ APIs for objects such
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# as Read/WriteOptions, which are allocated either on the
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# stack or the heap.
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template initResource(resourceName) =
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var res = resourceName()
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res
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type
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# TODO: Replace this with a converter concept that will
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# handle openarray[char] and openarray[byte] in the same way.
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KeyValueType = openarray[byte]
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RocksDBInstance* = object
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db: rocksdb_t
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backupEngine: rocksdb_backup_engine_t
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options: rocksdb_options_t
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readOptions: rocksdb_readoptions_t
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writeOptions: rocksdb_writeoptions_t
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RocksDBResult*[T] = object
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case ok*: bool
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of true:
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when T isnot void: value*: T
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else:
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error*: string
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proc `$`*[T](s: RocksDBResult[T]): string =
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if s.ok:
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when T isnot void:
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$s.value
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else:
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""
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else:
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"(error) " & s.error
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template returnOk() =
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result.ok = true
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return
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template returnVal(v: auto) =
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result.ok = true
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result.value = v
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return
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template bailOnErrors {.dirty.} =
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if not errors.isNil:
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result.ok = false
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result.error = $errors
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rocksdb_free(errors)
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return
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proc init*(rocks: var RocksDBInstance,
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dbPath, dbBackupPath: string,
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readOnly = false,
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cpus = countProcessors(),
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createIfMissing = true): RocksDBResult[void] =
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rocks.options = rocksdb_options_create()
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rocks.readOptions = rocksdb_readoptions_create()
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rocks.writeOptions = rocksdb_writeoptions_create()
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# Optimize RocksDB. This is the easiest way to get RocksDB to perform well:
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rocksdb_options_increase_parallelism(rocks.options, cpus.int32)
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# This requires snappy - disabled because rocksdb is not always compiled with
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# snappy support (for example Fedora 28, certain Ubuntu versions)
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# rocksdb_options_optimize_level_style_compaction(options, 0);
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rocksdb_options_set_create_if_missing(rocks.options, uint8(createIfMissing))
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var errors: cstring
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if readOnly:
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rocks.db = rocksdb_open_for_read_only(rocks.options, dbPath, 0'u8, errors.addr)
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else:
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rocks.db = rocksdb_open(rocks.options, dbPath, errors.addr)
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bailOnErrors()
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rocks.backupEngine = rocksdb_backup_engine_open(rocks.options,
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dbBackupPath, errors.addr)
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bailOnErrors()
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returnOk()
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template initRocksDB*(args: varargs[untyped]): Option[RocksDBInstance] =
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var db: RocksDBInstance
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if not init(db, args):
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none(RocksDBInstance)
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else:
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some(db)
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when false:
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# TODO: These should be in the standard lib somewhere.
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proc to*(chars: openarray[char], S: typedesc[string]): string =
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result = newString(chars.len)
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copyMem(addr result[0], unsafeAddr chars[0], chars.len * sizeof(char))
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proc to*(chars: openarray[char], S: typedesc[seq[byte]]): seq[byte] =
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result = newSeq[byte](chars.len)
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copyMem(addr result[0], unsafeAddr chars[0], chars.len * sizeof(char))
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template toOpenArray*[T](p: ptr T, sz: int): openarray[T] =
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# XXX: The `TT` type is a work-around the fact that the `T`
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# generic param is not resolved properly within the body of
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# the template: https://github.com/nim-lang/Nim/issues/7995
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type TT = type(p[])
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let arr = cast[ptr UncheckedArray[TT]](p)
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toOpenArray(arr[], 0, sz)
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else:
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proc copyFrom(v: var seq[byte], data: cstring, sz: int) =
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v = newSeq[byte](sz)
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if sz > 0:
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copyMem(addr v[0], unsafeAddr data[0], sz)
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proc copyFrom(v: var string, data: cstring, sz: int) =
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v = newString(sz)
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if sz > 0:
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copyMem(addr v[0], unsafeAddr data[0], sz)
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template getImpl {.dirty.} =
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doAssert key.len > 0
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var
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errors: cstring
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len: csize
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data = rocksdb_get(db.db, db.readOptions,
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cast[cstring](unsafeAddr key[0]), key.len,
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addr len, errors.addr)
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bailOnErrors()
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if not data.isNil:
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result.ok = true
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result.value.copyFrom(data, len)
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rocksdb_free(data)
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else:
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result.error = $errors
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proc get*(db: RocksDBInstance, key: KeyValueType): RocksDBResult[string] =
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## Get value for `key`. If no value exists, set `result.ok` to `false`,
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## and result.error to `""`.
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getImpl
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proc getBytes*(db: RocksDBInstance, key: KeyValueType): RocksDBResult[seq[byte]] =
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## Get value for `key`. If no value exists, set `result.ok` to `false`,
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## and result.error to `""`.
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getImpl
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proc put*(db: RocksDBInstance, key, val: KeyValueType): RocksDBResult[void] =
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doAssert key.len > 0
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var
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errors: cstring
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rocksdb_put(db.db, db.writeOptions,
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cast[cstring](unsafeAddr key[0]), key.len,
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cast[cstring](if val.len > 0: unsafeAddr val[0] else: nil), val.len,
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errors.addr)
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bailOnErrors()
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returnOk()
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proc del*(db: RocksDBInstance, key: KeyValueType): RocksDBResult[void] =
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var errors: cstring
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rocksdb_delete(db.db, db.writeOptions,
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cast[cstring](unsafeAddr key[0]), key.len,
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errors.addr)
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bailOnErrors()
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returnOk()
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proc contains*(db: RocksDBInstance, key: KeyValueType): RocksDBResult[bool] =
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doAssert key.len > 0
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var
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errors: cstring
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len: csize
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data = rocksdb_get(db.db, db.readOptions,
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cast[cstring](unsafeAddr key[0]), key.len,
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addr len, errors.addr)
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bailOnErrors()
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result.ok = true
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if not data.isNil:
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result.value = true
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rocksdb_free(data)
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proc backup*(db: RocksDBInstance): RocksDBResult[void] =
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var errors: cstring
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rocksdb_backup_engine_create_new_backup(db.backupEngine, db.db, errors.addr)
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bailOnErrors()
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returnOk()
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# XXX: destructors are just too buggy at the moment:
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# https://github.com/nim-lang/Nim/issues/8112
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# proc `=destroy`*(db: var RocksDBInstance) =
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proc close*(db: var RocksDBInstance) =
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template freeField(name) =
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if db.`name`.isNil:
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`rocksdb name destroy`(db.`name`)
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db.`name` = nil
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freeField(writeOptions)
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freeField(readOptions)
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freeField(options)
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if not db.backupEngine.isNil:
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rocksdb_backup_engine_close(db.backupEngine)
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db.backupEngine = nil
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if not db.db.isNil:
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rocksdb_close(db.db)
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db.db = nil
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