blaze-builder-0.2.1.0: benchmarks/FastPut.hs
{-# LANGUAGE CPP, BangPatterns, Rank2Types #-}
-- |
-- Module : FastPut
-- Copyright : (c) 2010 Simon Meier
-- License : BSD3-style (see LICENSE)
--
-- Maintainer : Simon Meier <iridcode@gmail.com>
-- Stability : experimental
-- Portability : tested on GHC only
--
-- Implementation of a 'Put' monad with similar performance characteristics
-- like the 'Builder' monoid.
--
module FastPut where
import Foreign
import Data.Monoid
import Control.Monad (unless)
import qualified Data.ByteString as S
import qualified Data.ByteString.Lazy as L
#ifdef BYTESTRING_IN_BASE
import Data.ByteString.Base (inlinePerformIO)
import qualified Data.ByteString.Base as S
import qualified Data.ByteString.Lazy.Base as L -- FIXME: is this the right module for access to 'Chunks'?
#else
import Data.ByteString.Internal (inlinePerformIO)
import qualified Data.ByteString.Internal as S
import qualified Data.ByteString.Lazy.Internal as L
#endif
import qualified Blaze.ByteString.Builder.Internal as B
import qualified Blaze.ByteString.Builder.Write as B
import Blaze.ByteString.Builder.Write (Write(..))
import qualified Blaze.ByteString.Builder.Word as B
import Blaze.ByteString.Builder.Word (writeWord8)
import Criterion.Main
------------------------------------------------------------------------------
-- Benchmarks
------------------------------------------------------------------------------
main :: IO ()
main = defaultMain $ concat
[ return $ bench "cost of putBuilder" $ whnf
(L.length . toLazyByteString2 . mapM_ (fromBuilder . fromWord8))
word8s
, benchmark "putBuilder"
(fromBuilder . mconcat . map fromWord8)
(mconcat . map B.fromWord8)
word8s
, benchmark "fromWriteSingleton"
(mapM_ putWord8)
(mconcat . map B.fromWord8)
word8s
, benchmark "fromWrite"
(mapM_ (putWrite . writeWord8))
(mconcat . map (B.fromWrite . writeWord8))
word8s
]
where
benchmark name putF builderF x =
[ bench (name ++ " Put") $
whnf (L.length . toLazyByteString2 . putF) x
, bench (name ++ " Builder") $
whnf (L.length . B.toLazyByteString . builderF) x
]
word8s :: [Word8]
word8s = take 100000 $ cycle [0..]
{-# NOINLINE word8s #-}
------------------------------------------------------------------------------
-- The Put type
------------------------------------------------------------------------------
data BufRange = BufRange {-# UNPACK #-} !(Ptr Word8) {-# UNPACK #-} !(Ptr Word8)
newtype Put a = Put {
unPut :: forall r. (a -> PutStep r) -> PutStep r
}
data PutSignal a =
Done {-# UNPACK #-} !(Ptr Word8) a
| BufferFull
{-# UNPACK #-} !Int
{-# UNPACK #-} !(Ptr Word8)
!(PutStep a)
| InsertByteString
{-# UNPACK #-} !(Ptr Word8)
!S.ByteString
!(PutStep a)
type PutStep a = BufRange -> IO (PutSignal a)
instance Monad Put where
return x = Put $ \k -> k x
{-# INLINE return #-}
m >>= f = Put $ \k -> unPut m (\x -> unPut (f x) k)
{-# INLINE (>>=) #-}
m >> n = Put $ \k -> unPut m (\_ -> unPut n k)
{-# INLINE (>>) #-}
------------------------------------------------------------------------------
-- The Builder type with equal signals as the Put type
------------------------------------------------------------------------------
newtype Builder = Builder (forall r. PutStep r -> PutStep r)
instance Monoid Builder where
mempty = Builder id
{-# INLINE mempty #-}
(Builder b1) `mappend` (Builder b2) = Builder $ b1 . b2
{-# INLINE mappend #-}
mconcat = foldr mappend mempty
{-# INLINE mconcat #-}
fromBuilder :: Builder -> Put ()
fromBuilder (Builder build) = Put $ \k -> build (k ())
toBuilder :: Put () -> Builder
toBuilder (Put put) = Builder $ \k -> put (\_ -> k)
fromWrite :: Write -> Builder
fromWrite (Write size io) =
Builder step
where
step k (BufRange pf pe)
| pf `plusPtr` size <= pe = do
io pf
let !br' = BufRange (pf `plusPtr` size) pe
k br'
| otherwise = return $ BufferFull size pf (step k)
{-# INLINE fromWrite #-}
fromWriteSingleton :: (a -> Write) -> a -> Builder
fromWriteSingleton write =
mkPut
where
mkPut x = Builder step
where
step k (BufRange pf pe)
| pf `plusPtr` size <= pe = do
io pf
let !br' = BufRange (pf `plusPtr` size) pe
k br'
| otherwise = return $ BufferFull size pf (step k)
where
Write size io = write x
{-# INLINE fromWriteSingleton #-}
fromWord8 :: Word8 -> Builder
fromWord8 = fromWriteSingleton writeWord8
------------------------------------------------------------------------------
-- Implementations
------------------------------------------------------------------------------
putWord8 :: Word8 -> Put ()
putWord8 = putWriteSingleton writeWord8
putWrite :: Write -> Put ()
putWrite (Write size io) =
Put step
where
step k (BufRange pf pe)
| pf `plusPtr` size <= pe = do
io pf
let !br' = BufRange (pf `plusPtr` size) pe
k () br'
| otherwise = return $ BufferFull size pf (step k)
{-# INLINE putWrite #-}
putWriteSingleton :: (a -> Write) -> a -> Put ()
putWriteSingleton write =
mkPut
where
mkPut x = Put step
where
step k (BufRange pf pe)
| pf `plusPtr` size <= pe = do
io pf
let !br' = BufRange (pf `plusPtr` size) pe
k () br'
| otherwise = return $ BufferFull size pf (step k)
where
Write size io = write x
{-# INLINE putWriteSingleton #-}
putBuilder :: B.Builder -> Put ()
putBuilder (B.Builder b) =
Put step
where
finalStep _ pf = return $ B.Done pf
step k = go (b finalStep)
where
go buildStep (BufRange pf pe) = do
signal <- buildStep pf pe
case signal of
B.Done pf' -> do
let !br' = BufRange pf' pe
k () br'
B.BufferFull minSize pf' nextBuildStep ->
return $ BufferFull minSize pf' (go nextBuildStep)
B.ModifyChunks _ _ _ ->
error "putBuilder: ModifyChunks not implemented"
{-
m >>= f = GetC $ \done empty pe ->
runGetC m (\pr' x -> runGetC (f x) done empty pe pr')
(\m' -> empty (m' >>= f))
pe
newtype GetC r a = GetC {
runGetC ::
(Ptr Word8 -> a -> IO r) -> -- done
(GetC r a -> IO r ) -> -- empty buffer
Ptr Word8 -> -- end of buffer
Ptr Word8 -> -- next byte to read
IO r
}
instance Functor (GetC r) where
fmap f g = GetC $ \done empty ->
runGetC g (\pr' x -> done pr' (f x))
(\g' -> empty (fmap f g'))
instance Monad (GetC r) where
return x = GetC $ \done _ _ pr -> done pr x
m >>= f = GetC $ \done empty pe ->
runGetC m (\pr' x -> runGetC (f x) done empty pe pr')
(\m' -> empty (m' >>= f))
pe
-}
------------------------------------------------------------------------------
-- Internal global constants.
------------------------------------------------------------------------------
-- | Default size (~32kb) for the buffer that becomes a chunk of the output
-- stream once it is filled.
--
defaultBufferSize :: Int
defaultBufferSize = 32 * 1024 - overhead -- Copied from Data.ByteString.Lazy.
where overhead = 2 * sizeOf (undefined :: Int)
-- | The minimal length (~4kb) a buffer must have before filling it and
-- outputting it as a chunk of the output stream.
--
-- This size determines when a buffer is spilled after a 'flush' or a direct
-- bytestring insertion. It is also the size of the first chunk generated by
-- 'toLazyByteString'.
defaultMinimalBufferSize :: Int
defaultMinimalBufferSize = 4 * 1024 - overhead
where overhead = 2 * sizeOf (undefined :: Int)
-- | The default length (64) for the first buffer to be allocated when
-- converting a 'Builder' to a lazy bytestring.
--
-- See 'toLazyByteStringWith' for further explanation.
defaultFirstBufferSize :: Int
defaultFirstBufferSize = 64
-- | The maximal number of bytes for that copying is cheaper than direct
-- insertion into the output stream. This takes into account the fragmentation
-- that may occur in the output buffer due to the early 'flush' implied by the
-- direct bytestring insertion.
--
-- @'defaultMaximalCopySize' = 2 * 'defaultMinimalBufferSize'@
--
defaultMaximalCopySize :: Int
defaultMaximalCopySize = 2 * defaultMinimalBufferSize
------------------------------------------------------------------------------
-- Flushing and running a Builder
------------------------------------------------------------------------------
-- | Output all data written in the current buffer and start a new chunk.
--
-- The use uf this function depends on how the resulting bytestrings are
-- consumed. 'flush' is possibly not very useful in non-interactive scenarios.
-- However, it is kept for compatibility with the builder provided by
-- Data.Binary.Builder.
--
-- When using 'toLazyByteString' to extract a lazy 'L.ByteString' from a
-- 'Builder', this means that a new chunk will be started in the resulting lazy
-- 'L.ByteString'. The remaining part of the buffer is spilled, if the
-- reamining free space is smaller than the minimal desired buffer size.
--
{-
flush :: Builder
flush = Builder $ \k pf _ -> return $ ModifyChunks pf id k
-}
-- | Run a 'Builder' with the given buffer sizes.
--
-- Use this function for integrating the 'Builder' type with other libraries
-- that generate lazy bytestrings.
--
-- Note that the builders should guarantee that on average the desired chunk
-- size is attained. Builders may decide to start a new buffer and not
-- completely fill the existing buffer, if this is faster. However, they should
-- not spill too much of the buffer, if they cannot compensate for it.
--
-- A call @toLazyByteStringWith bufSize minBufSize firstBufSize@ will generate
-- a lazy bytestring according to the following strategy. First, we allocate
-- a buffer of size @firstBufSize@ and start filling it. If it overflows, we
-- allocate a buffer of size @minBufSize@ and copy the first buffer to it in
-- order to avoid generating a too small chunk. Finally, every next buffer will
-- be of size @bufSize@. This, slow startup strategy is required to achieve
-- good speed for short (<200 bytes) resulting bytestrings, as for them the
-- allocation cost is of a large buffer cannot be compensated. Moreover, this
-- strategy also allows us to avoid spilling too much memory for short
-- resulting bytestrings.
--
-- Note that setting @firstBufSize >= minBufSize@ implies that the first buffer
-- is no longer copied but allocated and filled directly. Hence, setting
-- @firstBufSize = bufSize@ means that all chunks will use an underlying buffer
-- of size @bufSize@. This is recommended, if you know that you always output
-- more than @minBufSize@ bytes.
toLazyByteStringWith
:: Int -- ^ Buffer size (upper-bounds the resulting chunk size).
-> Int -- ^ Minimal free buffer space for continuing filling
-- the same buffer after a 'flush' or a direct bytestring
-- insertion. This corresponds to the minimal desired
-- chunk size.
-> Int -- ^ Size of the first buffer to be used and copied for
-- larger resulting sequences
-> Put a -- ^ Builder to run.
-> L.ByteString -- ^ Lazy bytestring to output after the builder is
-- finished.
-> L.ByteString -- ^ Resulting lazy bytestring
toLazyByteStringWith bufSize minBufSize firstBufSize (Put b) k =
inlinePerformIO $ fillFirstBuffer (b finalStep)
where
finalStep _ (BufRange pf _) = return $ Done pf undefined
-- fill a first very small buffer, if we need more space then copy it
-- to the new buffer of size 'minBufSize'. This way we don't pay the
-- allocation cost of the big 'bufSize' buffer, when outputting only
-- small sequences.
fillFirstBuffer !step0
| minBufSize <= firstBufSize = fillNewBuffer firstBufSize step0
| otherwise = do
fpbuf <- S.mallocByteString firstBufSize
withForeignPtr fpbuf $ \pf -> do
let !br = BufRange pf (pf `plusPtr` firstBufSize)
mkbs pf' = S.PS fpbuf 0 (pf' `minusPtr` pf)
{-# INLINE mkbs #-}
next <- step0 br
case next of
Done pf' _
| pf' == pf -> return k
| otherwise -> return $ L.Chunk (mkbs pf') k
BufferFull newSize pf' nextStep -> do
let !l = pf' `minusPtr` pf
fillNewBuffer (max (l + newSize) minBufSize) $
\(BufRange pfNew peNew) -> do
copyBytes pfNew pf l
let !brNew = BufRange (pfNew `plusPtr` l) peNew
nextStep brNew
InsertByteString _ _ _ -> error "not yet implemented"
{-
ModifyChunks pf' bsk nextStep(
| pf' == pf ->
return $ bsk (inlinePerformIO $ fillNewBuffer bufSize nextStep)
| otherwise ->
return $ L.Chunk (mkbs pf')
(bsk (inlinePerformIO $ fillNewBuffer bufSize nextStep))
-}
-- allocate and fill a new buffer
fillNewBuffer !size !step0 = do
fpbuf <- S.mallocByteString size
withForeignPtr fpbuf $ fillBuffer fpbuf
where
fillBuffer fpbuf !pbuf = fill pbuf step0
where
!pe = pbuf `plusPtr` size
fill !pf !step = do
let !br = BufRange pf pe
next <- step br
let mkbs pf' = S.PS fpbuf (pf `minusPtr` pbuf) (pf' `minusPtr` pf)
{-# INLINE mkbs #-}
case next of
Done pf' _
| pf' == pf -> return k
| otherwise -> return $ L.Chunk (mkbs pf') k
BufferFull newSize pf' nextStep ->
return $ L.Chunk (mkbs pf')
(inlinePerformIO $
fillNewBuffer (max newSize bufSize) nextStep)
InsertByteString _ _ _ -> error "not yet implemented2"
{-
ModifyChunks pf' bsk nextStep
| pf' == pf ->
return $ bsk (inlinePerformIO $ fill pf' nextStep)
| minBufSize < pe `minusPtr` pf' ->
return $ L.Chunk (mkbs pf')
(bsk (inlinePerformIO $ fill pf' nextStep))
| otherwise ->
return $ L.Chunk (mkbs pf')
(bsk (inlinePerformIO $ fillNewBuffer bufSize nextStep))
-}
-- | Extract the lazy 'L.ByteString' from the builder by running it with default
-- buffer sizes. Use this function, if you do not have any special
-- considerations with respect to buffer sizes.
--
-- @ 'toLazyByteString' b = 'toLazyByteStringWith' 'defaultBufferSize' 'defaultMinimalBufferSize' 'defaultFirstBufferSize' b L.empty@
--
-- Note that @'toLazyByteString'@ is a 'Monoid' homomorphism.
--
-- > toLazyByteString mempty == mempty
-- > toLazyByteString (x `mappend` y) == toLazyByteString x `mappend` toLazyByteString y
--
-- However, in the second equation, the left-hand-side is generally faster to
-- execute.
--
toLazyByteString :: Put a -> L.ByteString
toLazyByteString b = toLazyByteStringWith
defaultBufferSize defaultMinimalBufferSize defaultFirstBufferSize b L.empty
{-# INLINE toLazyByteString #-}
------------------------------------------------------------------------------
-- Builder Enumeration
------------------------------------------------------------------------------
data BuildStream a =
BuildChunk S.ByteString (IO (BuildStream a))
| BuildYield
a
(forall b. Bool ->
Either (Maybe S.ByteString) (Put b -> IO (BuildStream b)))
enumPut :: Int -> Put a -> IO (BuildStream a)
enumPut bufSize (Put put0) =
fillBuffer bufSize (put0 finalStep)
where
finalStep :: forall b. b -> PutStep b
finalStep x (BufRange op _) = return $ Done op x
fillBuffer :: forall b. Int -> PutStep b -> IO (BuildStream b)
fillBuffer size step = do
fpbuf <- S.mallocByteString bufSize
let !pbuf = unsafeForeignPtrToPtr fpbuf
-- safe due to later reference of fpbuf
-- BETTER than withForeignPtr, as we lose a tail call otherwise
!br = BufRange pbuf (pbuf `plusPtr` size)
fillStep fpbuf br step
fillPut :: ForeignPtr Word8 -> BufRange ->
Bool -> Either (Maybe S.ByteString) (Put b -> IO (BuildStream b))
fillPut !fpbuf !(BufRange op _) False
| pbuf == op = Left Nothing
| otherwise = Left $ Just $
S.PS fpbuf 0 (op `minusPtr` pbuf)
where
pbuf = unsafeForeignPtrToPtr fpbuf
{-# INLINE pbuf #-}
fillPut !fpbuf !br True =
Right $ \(Put put) -> fillStep fpbuf br (put finalStep)
fillStep :: forall b. ForeignPtr Word8 -> BufRange -> PutStep b -> IO (BuildStream b)
fillStep !fpbuf !br@(BufRange _ ope) step = do
let pbuf = unsafeForeignPtrToPtr fpbuf
{-# INLINE pbuf #-}
signal <- step br
case signal of
Done op' x -> do -- builder completed, buffer partially filled
let !br' = BufRange op' ope
return $ BuildYield x (fillPut fpbuf br')
BufferFull minSize op' nextStep
| pbuf == op' -> do -- nothing written, larger buffer required
fillBuffer (max bufSize minSize) nextStep
| otherwise -> do -- some bytes written, new buffer required
return $ BuildChunk
(S.PS fpbuf 0 (op' `minusPtr` pbuf))
(fillBuffer (max bufSize minSize) nextStep)
InsertByteString op' bs nextStep
| S.null bs -> do -- empty bytestrings are ignored
let !br' = BufRange op' ope
fillStep fpbuf br' nextStep
| pbuf == op' -> do -- no bytes written: just insert bytestring
return $ BuildChunk bs (fillBuffer bufSize nextStep)
| otherwise -> do -- bytes written, insert buffer and bytestring
return $ BuildChunk (S.PS fpbuf 0 (op' `minusPtr` pbuf))
(return $ BuildChunk bs (fillBuffer bufSize nextStep))
toLazyByteString' :: Put () -> L.ByteString
toLazyByteString' put =
inlinePerformIO (consume `fmap` enumPut defaultBufferSize put)
where
consume :: BuildStream () -> L.ByteString
consume (BuildYield _ f) =
case f False of
Left Nothing -> L.Empty
Left (Just bs) -> L.Chunk bs L.Empty
Right _ -> error "toLazyByteString': enumPut violated postcondition"
consume (BuildChunk bs ioStream) =
L.Chunk bs $ inlinePerformIO (consume `fmap` ioStream)
{-
BufferFull minSize pf' nextStep -> do
io $ S.PS fpbuf 0 (pf' `minusPtr` pf)
fillBuffer (max bufSize minSize) nextStep
ModifyChunks pf' bsk nextStep -> do
io $ S.PS fpbuf 0 (pf' `minusPtr` pf)
L.foldrChunks (\bs -> (io bs >>)) (return ()) (bsk L.empty)
fillBuffer bufSize nextStep
-}
------------------------------------------------------------------------------
-- More explicit implementation of running builders
------------------------------------------------------------------------------
data Buffer = Buffer {-# UNPACK #-} !(ForeignPtr Word8) -- underlying pinned array
{-# UNPACK #-} !(Ptr Word8) -- beginning of slice
{-# UNPACK #-} !(Ptr Word8) -- next free byte
{-# UNPACK #-} !(Ptr Word8) -- first byte after buffer
allocBuffer :: Int -> IO Buffer
allocBuffer size = do
fpbuf <- S.mallocByteString size
let !pbuf = unsafeForeignPtrToPtr fpbuf
return $! Buffer fpbuf pbuf pbuf (pbuf `plusPtr` size)
unsafeFreezeBuffer :: Buffer -> S.ByteString
unsafeFreezeBuffer (Buffer fpbuf p0 op _) =
S.PS fpbuf 0 (op `minusPtr` p0)
unsafeFreezeNonEmptyBuffer :: Buffer -> Maybe S.ByteString
unsafeFreezeNonEmptyBuffer (Buffer fpbuf p0 op _)
| p0 == op = Nothing
| otherwise = Just $ S.PS fpbuf 0 (op `minusPtr` p0)
nextSlice :: Int -> Buffer -> Maybe Buffer
nextSlice minSize (Buffer fpbuf _ op ope)
| ope `minusPtr` op <= minSize = Nothing
| otherwise = Just (Buffer fpbuf op op ope)
runPut :: Monad m
=> (IO (PutSignal a) -> m (PutSignal a)) -- lifting of buildsteps
-> (Int -> Buffer -> m Buffer) -- output function for a guaranteedly non-empty buffer, the returned buffer will be filled next
-> (S.ByteString -> m ()) -- output function for guaranteedly non-empty bytestrings, that are inserted directly into the stream
-> Put a -- put to execute
-> Buffer -- initial buffer to be used
-> m (a, Buffer) -- result of put and remaining buffer
runPut liftIO outputBuf outputBS (Put put) =
runStep (put finalStep)
where
finalStep x !(BufRange op _) = return $ Done op x
runStep step buf@(Buffer fpbuf p0 op ope) = do
let !br = BufRange op ope
signal <- liftIO $ step br
case signal of
Done op' x -> -- put completed, buffer partially runSteped
return (x, Buffer fpbuf p0 op' ope)
BufferFull minSize op' nextStep -> do
buf' <- outputBuf minSize (Buffer fpbuf p0 op' ope)
runStep nextStep buf'
InsertByteString op' bs nextStep
| S.null bs -> -- flushing of buffer required
outputBuf 1 (Buffer fpbuf p0 op' ope) >>= runStep nextStep
| p0 == op' -> do -- no bytes written: just insert bytestring
outputBS bs
runStep nextStep buf
| otherwise -> do -- bytes written, insert buffer and bytestring
buf' <- outputBuf 1 (Buffer fpbuf p0 op' ope)
outputBS bs
runStep nextStep buf'
{-# INLINE runPut #-}
-- | A monad for lazily composing lazy bytestrings using continuations.
newtype LBSM a = LBSM { unLBSM :: (a, L.ByteString -> L.ByteString) }
instance Monad LBSM where
return x = LBSM (x, id)
(LBSM (x,k)) >>= f = let LBSM (x',k') = f x in LBSM (x', k . k')
(LBSM (_,k)) >> (LBSM (x',k')) = LBSM (x', k . k')
-- | Execute a put and return the written buffers as the chunks of a lazy
-- bytestring.
toLazyByteString2 :: Put a -> L.ByteString
toLazyByteString2 put =
k (bufToLBSCont (snd result) L.empty)
where
-- initial buffer
buf0 = inlinePerformIO $ allocBuffer defaultBufferSize
-- run put, but don't force result => we're lazy enough
LBSM (result, k) = runPut liftIO outputBuf outputBS put buf0
-- convert a buffer to a lazy bytestring continuation
bufToLBSCont = maybe id L.Chunk . unsafeFreezeNonEmptyBuffer
-- lifting an io putsignal to a lazy bytestring monad
liftIO io = LBSM (inlinePerformIO io, id)
-- add buffer as a chunk prepare allocation of new one
outputBuf minSize buf = LBSM
( inlinePerformIO $ allocBuffer (max minSize defaultBufferSize)
, bufToLBSCont buf )
-- add bytestring directly as a chunk; exploits postcondition of runPut
-- that bytestrings are non-empty
outputBS bs = LBSM ((), L.Chunk bs)
-- | A Builder that traces a message
traceBuilder :: String -> Builder
traceBuilder msg = Builder $ \k br@(BufRange op ope) -> do
putStrLn $ "traceBuilder " ++ show (op, ope) ++ ": " ++ msg
k br
flushBuilder :: Builder
flushBuilder = Builder $ \k (BufRange op _) -> do
return $ InsertByteString op S.empty k
test2 :: Word8 -> [S.ByteString]
test2 x = L.toChunks $ toLazyByteString2 $ fromBuilder $ mconcat
[ traceBuilder "before flush"
, fromWord8 48
, flushBuilder
, flushBuilder
, traceBuilder "after flush"
, fromWord8 x
]