urbit/pkg/king/lib/Vere/LMDB.hs
2019-08-30 01:43:22 -07:00

326 lines
10 KiB
Haskell

module Vere.LMDB where
import UrbitPrelude hiding (init)
import Data.RAcquire
-- import Data.Conduit
import Database.LMDB.Raw
import Foreign.Marshal.Alloc
import Foreign.Ptr
import Vere.Pier.Types
import Foreign.Storable (peek, poke, sizeOf)
import qualified Data.ByteString.Unsafe as BU
-- import qualified Data.Vector as V
-- Types -----------------------------------------------------------------------
type Env = MDB_env
type Val = MDB_val
type Txn = MDB_txn
type Dbi = MDB_dbi
type Cur = MDB_cursor
data VereLMDBExn
= NoLogIdentity
| MissingEvent EventId
| BadNounInLogIdentity ByteString DecodeErr ByteString
| BadKeyInEventLog
| BadWriteLogIdentity LogIdentity
| BadWriteEvent EventId
| BadWriteEffect EventId
deriving Show
instance Exception VereLMDBExn where
-- Transactions ----------------------------------------------------------------
{-
A read-only transaction that commits at the end.
Use this when opening database handles.
-}
openTxn :: Env -> RAcquire e Txn
openTxn env = mkRAcquire begin commit
where
begin = io $ mdb_txn_begin env Nothing True
commit = io . mdb_txn_commit
{-
A read-only transaction that aborts at the end.
Use this when reading data from already-opened databases.
-}
readTxn :: Env -> RAcquire e Txn
readTxn env = mkRAcquire begin abort
where
begin = io $ mdb_txn_begin env Nothing True
abort = io . mdb_txn_abort
{-
A read-write transaction that commits upon sucessful completion and
aborts on exception.
Use this when reading data from already-opened databases.
-}
writeTxn :: Env -> RAcquire e Txn
writeTxn env = mkRAcquireType begin finalize
where
begin = io $ mdb_txn_begin env Nothing False
finalize txn = io . \case
ReleaseNormal -> mdb_txn_commit txn
ReleaseEarly -> mdb_txn_commit txn
ReleaseException -> mdb_txn_abort txn
-- Cursors ---------------------------------------------------------------------
cursor :: Txn -> Dbi -> RAcquire e Cur
cursor txn dbi = mkRAcquire open close
where
open = io $ mdb_cursor_open txn dbi
close = io . mdb_cursor_close
-- Last Key In Dbi -------------------------------------------------------------
lastKeyWord64 :: Env -> Dbi -> Txn -> RIO e Word64
lastKeyWord64 env dbi txn =
rwith (cursor txn dbi) $ \cur ->
withKVPtrs' nullVal nullVal $ \pKey pVal ->
io $ mdb_cursor_get MDB_LAST cur pKey pVal >>= \case
False -> pure 0
True -> peek pKey >>= mdbValToWord64
-- Delete Rows -----------------------------------------------------------------
deleteAllRows :: Env -> Dbi -> RIO e ()
deleteAllRows env dbi =
rwith (writeTxn env) $ \txn ->
rwith (cursor txn dbi) $ \cur ->
withKVPtrs' nullVal nullVal $ \pKey pVal -> do
let loop = io (mdb_cursor_get MDB_LAST cur pKey pVal) >>= \case
False -> pure ()
True -> do io $ mdb_cursor_del (compileWriteFlags []) cur
loop
loop
deleteRowsFrom :: HasLogFunc e => Env -> Dbi -> Word64 -> RIO e ()
deleteRowsFrom env dbi start = do
rwith (writeTxn env) $ \txn -> do
last <- lastKeyWord64 env dbi txn
for_ [start..last] $ \eId -> do
withWordPtr eId $ \pKey -> do
let key = MDB_val 8 (castPtr pKey)
found <- io $ mdb_del txn dbi key Nothing
unless found $
throwIO (MissingEvent eId)
-- Append Rows to Sequence -----------------------------------------------------
{-
appendToSequence :: Env -> Dbi -> Vector ByteString -> RIO e ()
appendToSequence env dbi events = do
numEvs <- readIORef (numEvents log)
next <- pure (numEvs + 1)
doAppend $ zip [next..] $ toList events
writeIORef (numEvents log) (numEvs + word (length events))
where
flags = compileWriteFlags [MDB_NOOVERWRITE]
doAppend = \kvs ->
rwith (writeTxn env) $ \txn ->
for_ kvs $ \(k,v) -> do
putBytes flags txn dbi k v >>= \case
True -> pure ()
False -> throwIO (BadWriteEvent k)
-}
-- Insert ----------------------------------------------------------------------
insertWord64 :: Env -> Dbi -> Word64 -> ByteString -> RIO e ()
insertWord64 env dbi k v = do
rwith (writeTxn env) $ \txn ->
putBytes flags txn dbi k v >>= \case
True -> pure ()
False -> throwIO (BadWriteEffect k)
where
flags = compileWriteFlags []
{-
--------------------------------------------------------------------------------
-- Read Events -----------------------------------------------------------------
streamEvents :: HasLogFunc e
=> EventLog -> Word64
-> ConduitT () ByteString (RIO e) ()
streamEvents log first = do
last <- lift $ lastEv log
batch <- lift $ readBatch log first
unless (null batch) $ do
for_ batch yield
streamEvents log (first + word (length batch))
streamEffectsRows :: ∀e. HasLogFunc e
=> EventLog -> EventId
-> ConduitT () (Word64, ByteString) (RIO e) ()
streamEffectsRows log = go
where
go :: EventId -> ConduitT () (Word64, ByteString) (RIO e) ()
go next = do
batch <- lift $ readRowsBatch (env log) (effectsTbl log) next
unless (null batch) $ do
for_ batch yield
go (next + fromIntegral (length batch))
{-
Read 1000 rows from the events table, starting from event `first`.
Throws `MissingEvent` if an event was missing from the log.
-}
readBatch :: EventLog -> Word64 -> RIO e (V.Vector ByteString)
readBatch log first = start
where
start = do
last <- lastEv log
if (first > last)
then pure mempty
else readRows $ fromIntegral $ min 1000 $ ((last+1) - first)
assertFound :: EventId -> Bool -> RIO e ()
assertFound id found = do
unless found $ throwIO $ MissingEvent id
readRows count =
withWordPtr first $ \pIdx ->
withKVPtrs' (MDB_val 8 (castPtr pIdx)) nullVal $ \pKey pVal ->
rwith (readTxn $ env log) $ \txn ->
rwith (cursor txn $ eventsTbl log) $ \cur -> do
assertFound first =<< io (mdb_cursor_get MDB_SET_KEY cur pKey pVal)
fetchRows count cur pKey pVal
fetchRows count cur pKey pVal = do
env <- ask
V.generateM count $ \i -> runRIO env $ do
key <- io $ peek pKey >>= mdbValToWord64
val <- io $ peek pVal >>= mdbValToBytes
idx <- pure (first + word i)
unless (key == idx) $ throwIO $ MissingEvent idx
when (count /= succ i) $ do
assertFound idx =<< io (mdb_cursor_get MDB_NEXT cur pKey pVal)
pure val
{-
Read 1000 rows from the database, starting from key `first`.
-}
readRowsBatch :: ∀e. HasLogFunc e
=> Env -> Dbi -> Word64 -> RIO e (V.Vector (Word64, ByteString))
readRowsBatch env dbi first = readRows
where
readRows = do
logDebug $ display ("(readRowsBatch) From: " <> tshow first)
withWordPtr first $ \pIdx ->
withKVPtrs' (MDB_val 8 (castPtr pIdx)) nullVal $ \pKey pVal ->
rwith (readTxn env) $ \txn ->
rwith (cursor txn dbi) $ \cur ->
io (mdb_cursor_get MDB_SET_RANGE cur pKey pVal) >>= \case
False -> pure mempty
True -> V.unfoldrM (fetchBatch cur pKey pVal) 1000
fetchBatch :: Cur -> Ptr Val -> Ptr Val -> Word
-> RIO e (Maybe ((Word64, ByteString), Word))
fetchBatch cur pKey pVal 0 = pure Nothing
fetchBatch cur pKey pVal n = do
key <- io $ peek pKey >>= mdbValToWord64
val <- io $ peek pVal >>= mdbValToBytes
io $ mdb_cursor_get MDB_NEXT cur pKey pVal >>= \case
False -> pure $ Just ((key, val), 0)
True -> pure $ Just ((key, val), pred n)
-}
-- Utils -----------------------------------------------------------------------
withKVPtrs' :: (MonadIO m, MonadUnliftIO m)
=> Val -> Val -> (Ptr Val -> Ptr Val -> m a) -> m a
withKVPtrs' k v cb =
withRunInIO $ \run ->
withKVPtrs k v $ \x y -> run (cb x y)
nullVal :: MDB_val
nullVal = MDB_val 0 nullPtr
word :: Int -> Word64
word = fromIntegral
assertExn :: Exception e => Bool -> e -> IO ()
assertExn True _ = pure ()
assertExn False e = throwIO e
eitherExn :: Exception e => Either a b -> (a -> e) -> IO b
eitherExn eat exn = either (throwIO . exn) pure eat
byteStringAsMdbVal :: ByteString -> (MDB_val -> IO a) -> IO a
byteStringAsMdbVal bs k =
BU.unsafeUseAsCStringLen bs $ \(ptr,sz) ->
k (MDB_val (fromIntegral sz) (castPtr ptr))
mdbValToWord64 :: MDB_val -> IO Word64
mdbValToWord64 (MDB_val sz ptr) = do
assertExn (sz == 8) BadKeyInEventLog
peek (castPtr ptr)
withWord64AsMDBval :: (MonadIO m, MonadUnliftIO m)
=> Word64 -> (MDB_val -> m a) -> m a
withWord64AsMDBval w cb = do
withWordPtr w $ \p ->
cb (MDB_val (fromIntegral (sizeOf w)) (castPtr p))
withWordPtr :: (MonadIO m, MonadUnliftIO m)
=> Word64 -> (Ptr Word64 -> m a) -> m a
withWordPtr w cb =
withRunInIO $ \run ->
allocaBytes (sizeOf w) (\p -> poke p w >> run (cb p))
-- Lower-Level Operations ------------------------------------------------------
getMb :: MonadIO m => Txn -> Dbi -> ByteString -> m (Maybe Noun)
getMb txn db key =
io $
byteStringAsMdbVal key $ \mKey ->
mdb_get txn db mKey >>= traverse (mdbValToNoun key)
mdbValToBytes :: MDB_val -> IO ByteString
mdbValToBytes (MDB_val sz ptr) = do
BU.unsafePackCStringLen (castPtr ptr, fromIntegral sz)
mdbValToNoun :: ByteString -> MDB_val -> IO Noun
mdbValToNoun key (MDB_val sz ptr) = do
bs <- BU.unsafePackCStringLen (castPtr ptr, fromIntegral sz)
let res = cueBS bs
eitherExn res (\err -> BadNounInLogIdentity key err bs)
putNoun :: MonadIO m
=> MDB_WriteFlags -> Txn -> Dbi -> ByteString -> Noun -> m Bool
putNoun flags txn db key val =
io $
byteStringAsMdbVal key $ \mKey ->
byteStringAsMdbVal (jamBS val) $ \mVal ->
mdb_put flags txn db mKey mVal
putBytes :: MonadIO m
=> MDB_WriteFlags -> Txn -> Dbi -> Word64 -> ByteString -> m Bool
putBytes flags txn db id bs =
io $
withWord64AsMDBval id $ \idVal ->
byteStringAsMdbVal bs $ \mVal ->
mdb_put flags txn db idVal mVal