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sqlite: support read-only kvstores (#563) 

in a read-only database, we cannot create the table but we can still
reason about elements in it - they simply don't exist
This commit is contained in:
Jacek Sieka 2022-11-28 21:15:53 +01:00 committed by GitHub
parent 6499ee2bc5
commit 8f4ef19fc9
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 64 additions and 29 deletions
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67
eth/db/kvstore_sqlite3.nim
View File

@ -3,11 +3,11 @@
{.push raises: [Defect].}
import
std/[os, options, strformat],
std/[os, options, strformat, typetraits],
sqlite3_abi,
./kvstore
export kvstore
export kvstore, typetraits
type
RawStmtPtr = ptr sqlite3_stmt
@ -37,6 +37,7 @@ type
SqKeyspace* = object of RootObj
# A Keyspace is a single key-value table - it is generally efficient to
# create separate keyspaces for each type of data stored
open: bool
getStmt, putStmt, delStmt, containsStmt,
findStmt0, findStmt1, findStmt2: RawStmtPtr
@ -115,6 +116,7 @@ proc bindParam(s: RawStmtPtr, n: int, val: auto): cint =
template bindParams(s: RawStmtPtr, params: auto) =
when params is tuple:
when params.type.arity > 0:
var i = 1
for param in fields(params):
checkErr bindParam(s, i, param)
@ -208,6 +210,7 @@ proc exec*[Params, Res](s: SqliteStmt[Params, Res],
let v = sqlite3_step(s)
case v
of SQLITE_ROW:
if onData != nil:
onData(readResult(s, Res))
gotResults = true
of SQLITE_DONE:
@ -294,8 +297,9 @@ template exec*(db: SqStoreRef, stmt: string): KvResult[void] =
proc get*(db: SqKeyspaceRef,
key: openArray[byte],
onData: DataProc): KvResult[bool] =
if db.getStmt == nil: return err("sqlite: database closed")
if not db.open: return err("sqlite: database closed")
let getStmt = db.getStmt
if getStmt == nil: return ok(false) # no such table
checkErr bindParam(getStmt, 1, key)
let
@ -339,23 +343,26 @@ proc find*(
db: SqKeyspaceRef,
prefix: openArray[byte],
onFind: KeyValueProc): KvResult[int] =
if not db.open: return err("sqlite: database closed")
var next: seq[byte] # extended lifetime of bound param
let findStmt =
if prefix.len == 0:
if db.findStmt0 == nil: return ok(0) # no such table
db.findStmt0 # all rows
else:
if not nextPrefix(prefix, next):
# For example when looking for the prefix [byte 255], there are no
# prefixes that lexicographically are greater, thus we use the
# query that only does the >= comparison
if db.findStmt1 == nil: return ok(0) # no such table
checkErr bindParam(db.findStmt1, 1, prefix)
db.findStmt1
else:
if db.findStmt2 == nil: return ok(0) # no such table
checkErr bindParam(db.findStmt2, 1, prefix)
checkErr bindParam(db.findStmt2, 2, next)
db.findStmt2
if findStmt == nil: return err("sqlite: database closed")
var
total = 0
@ -369,6 +376,7 @@ proc find*(
kl = sqlite3_column_bytes(findStmt, 0)
vp = cast[ptr UncheckedArray[byte]](sqlite3_column_blob(findStmt, 1))
vl = sqlite3_column_bytes(findStmt, 1)
if onFind != nil:
onFind(kp.toOpenArray(0, kl - 1), vp.toOpenArray(0, vl - 1))
total += 1
of SQLITE_DONE:
@ -387,8 +395,9 @@ proc find*(
ok(total)
proc put*(db: SqKeyspaceRef, key, value: openArray[byte]): KvResult[void] =
if not db.open: return err("sqlite: database closed")
let putStmt = db.putStmt
if putStmt == nil: return err("sqlite: database closed")
if putStmt == nil: return err("sqlite: cannot write to read-only database")
checkErr bindParam(putStmt, 1, key)
checkErr bindParam(putStmt, 2, value)
@ -405,8 +414,10 @@ proc put*(db: SqKeyspaceRef, key, value: openArray[byte]): KvResult[void] =
res
proc contains*(db: SqKeyspaceRef, key: openArray[byte]): KvResult[bool] =
if not db.open: return err("sqlite: database closed")
let containsStmt = db.containsStmt
if containsStmt == nil: return err("sqlite: database closed")
if containsStmt == nil: return ok(false) # no such table
checkErr bindParam(containsStmt, 1, key)
let
@ -423,8 +434,9 @@ proc contains*(db: SqKeyspaceRef, key: openArray[byte]): KvResult[bool] =
res
proc del*(db: SqKeyspaceRef, key: openArray[byte]): KvResult[void] =
if not db.open: return err("sqlite: database closed")
let delStmt = db.delStmt
if delStmt == nil: return err("sqlite: database closed")
if delStmt == nil: return ok() # no such table
checkErr bindParam(delStmt, 1, key)
let res =
@ -473,14 +485,14 @@ proc checkpoint*(db: SqStoreRef, kind = SqStoreCheckpointKind.passive) =
template prepare(env: ptr sqlite3, q: string): ptr sqlite3_stmt =
block:
var s: ptr sqlite3_stmt
checkErr sqlite3_prepare_v2(env, q, q.len.cint, addr s, nil):
checkErr sqlite3_prepare_v2(env, cstring(q), q.len.cint, addr s, nil):
discard
s
template prepare(env: ptr sqlite3, q: string, cleanup: untyped): ptr sqlite3_stmt =
block:
var s: ptr sqlite3_stmt
checkErr sqlite3_prepare_v2(env, q, q.len.cint, addr s, nil)
checkErr sqlite3_prepare_v2(env, cstring(q), q.len.cint, addr s, nil)
s
template checkExec(s: ptr sqlite3_stmt) =
@ -564,7 +576,15 @@ proc init*(
readOnly: readOnly
))
proc openKvStore*(db: SqStoreRef, name = "kvstore", withoutRowid = false): KvResult[SqKeyspaceRef] =
proc hasTable*(db: SqStoreRef, name: string): KvResult[bool] =
let
sql = "SELECT name FROM sqlite_master WHERE type='table' AND name='" &
name & "';"
db.exec(sql, (), proc(_: openArray[byte]) = discard)
proc openKvStore*(
db: SqStoreRef, name = "kvstore", withoutRowid = false,
readOnly = false): KvResult[SqKeyspaceRef] =
## Open a new Key-Value store in the SQLite database
##
## withoutRowid: Create the table without rowid - this is more efficient when
@ -572,30 +592,33 @@ proc openKvStore*(db: SqStoreRef, name = "kvstore", withoutRowid = false): KvRes
## rows (the row being the sum of key and value) - see
## https://www.sqlite.org/withoutrowid.html
##
if not db.readOnly:
let hasTable = if db.readOnly or readOnly:
? db.hasTable(name)
else:
let createSql = """
CREATE TABLE IF NOT EXISTS """ & name & """ (
CREATE TABLE IF NOT EXISTS '""" & name & """' (
key BLOB PRIMARY KEY,
value BLOB
)"""
checkExec db.env,
if withoutRowid: createSql & " WITHOUT ROWID;" else: createSql & ";"
true
var
tmp: SqKeyspace
defer:
# We'll "move" ownership to the return value, effectively disabling "close"
close(tmp)
tmp.getStmt = prepare(db.env, "SELECT value FROM " & name & " WHERE key = ?;")
tmp.open = true
if hasTable:
tmp.getStmt =
prepare(db.env, "SELECT value FROM '" & name & "' WHERE key = ?;")
tmp.putStmt =
prepare(db.env, "INSERT OR REPLACE INTO " & name & "(key, value) VALUES (?, ?);")
tmp.delStmt = prepare(db.env, "DELETE FROM " & name & " WHERE key = ?;")
tmp.containsStmt = prepare(db.env, "SELECT 1 FROM " & name & " WHERE key = ?;")
tmp.findStmt0 = prepare(db.env, "SELECT key, value FROM " & name & ";")
tmp.findStmt1 = prepare(db.env, "SELECT key, value FROM " & name & " WHERE key >= ?;")
tmp.findStmt2 = prepare(db.env, "SELECT key, value FROM " & name & " WHERE key >= ? and key < ?;")
prepare(db.env, "INSERT OR REPLACE INTO '" & name & "'(key, value) VALUES (?, ?);")
tmp.delStmt = prepare(db.env, "DELETE FROM '" & name & "' WHERE key = ?;")
tmp.containsStmt = prepare(db.env, "SELECT 1 FROM '" & name & "' WHERE key = ?;")
tmp.findStmt0 = prepare(db.env, "SELECT key, value FROM '" & name & "';")
tmp.findStmt1 = prepare(db.env, "SELECT key, value FROM '" & name & "' WHERE key >= ?;")
tmp.findStmt2 = prepare(db.env, "SELECT key, value FROM '" & name & "' WHERE key >= ? and key < ?;")
var res = SqKeyspaceRef()
res[] = tmp

12
tests/db/test_kvstore_sqlite3.nim
View File

@ -16,6 +16,18 @@ procSuite "SqStoreRef":
testKvStore(kvStore kv.get(), true)
test "Readonly kvstore with no table":
let db = SqStoreRef.init("", "test", inMemory = true, readOnly = true)[]
defer: db.close()
let kv = db.openKvStore().expect("working db")
check:
not kv.get([byte 0, 1, 2], nil).expect("ok to query data")
kv.find([byte 0, 1, 2], nil).expect("ok") == 0
kv.put([byte 0, 1, 2], []).isErr
kv.del([byte 0, 1, 2]).isOk
defer: kv[].close()
test "Prepare and execute statements":
let db = SqStoreRef.init("", "test", inMemory = true)[]
defer: db.close()