Safe Haskell	None
Language	Haskell2010

Data.ByteString.FastBuilder.Internal

Contents

Builder and related types
Internally used exceptions
Builder building blocks
Running builders
Basic builders
Performance tuning

Description

This is an internal module; its interface is unstable.

Synopsis

newtype Builder = Builder {
- unBuilder :: DataSink -> BuilderState -> BuilderState
}
type BuilderState = (# Addr#, Addr#, State# RealWorld #)
data DataSink
- = DynamicSink !(IORef DynamicSink)
- | GrowingBuffer !(IORef (ForeignPtr Word8))
- | HandleSink !Handle !Int !(IORef Queue)
data DynamicSink
- = ThreadedSink !(MVar Request) !(MVar Response)
- | BoundedGrowingBuffer !(ForeignPtr Word8) !Int
data Queue = Queue {
- queueBuffer :: !(ForeignPtr Word8)
- queueStart :: !Int
- queueTotal :: !Int
}
data Request = Request !(Ptr Word8) !(Ptr Word8)
data Response
- = Error SomeException
- | Done !(Ptr Word8)
- | MoreBuffer !(Ptr Word8) !Int
- | InsertByteString !(Ptr Word8) !ByteString
data SuspendBuilderException = SuspendBuilderException !(MVar ())
data ChunkOverflowException = ChunkOverflowException !ByteString !(MVar Request) !(MVar Response) !Int
newtype BuildM a = BuildM {
- runBuildM :: (a -> Builder) -> Builder
}
mkBuilder :: BuildM () -> Builder
useBuilder :: Builder -> BuildM ()
getSink :: BuildM DataSink
getCur :: BuildM (Ptr Word8)
getEnd :: BuildM (Ptr Word8)
setCur :: Ptr Word8 -> BuildM ()
setEnd :: Ptr Word8 -> BuildM ()
runBuilder :: Builder -> DataSink -> Ptr Word8 -> Ptr Word8 -> IO (Ptr Word8)
toLazyByteString :: Builder -> ByteString
toLazyByteStringWith :: Int -> Int -> Builder -> ByteString
toStrictByteString :: Builder -> ByteString
hPutBuilder :: Handle -> Builder -> IO ()
hPutBuilderLen :: Handle -> Builder -> IO Int
hPutBuilderWith :: Handle -> Int -> Int -> Builder -> IO Int
primBounded :: BoundedPrim a -> a -> Builder
primFixed :: FixedPrim a -> a -> Builder
primMapListBounded :: BoundedPrim a -> [a] -> Builder
primMapListFixed :: FixedPrim a -> [a] -> Builder
byteString :: ByteString -> Builder
byteStringThreshold :: Int -> ByteString -> Builder
byteStringCopy :: ByteString -> Builder
byteStringCopyNoCheck :: ByteString -> Builder
byteStringInsert :: ByteString -> Builder
unsafeCString :: CString -> Builder
unsafeCStringLen :: CStringLen -> Builder
ensureBytes :: Int -> Builder
getBytes :: Int -> Builder
rebuild :: Builder -> Builder

Builder and related types

newtype Builder Source #

Builder is an auxiliary type for efficiently generating a long ByteString. It is isomorphic to lazy ByteString, but offers constant-time concatanation via <>.

Use toLazyByteString to turn a Builder into a ByteString

Constructors

Builder
Fields unBuilder :: DataSink -> BuilderState -> BuilderState

Instances

Instances details

IsString Builder Source #	`fromString` = `stringUtf8`
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods fromString :: String -> Builder #
Semigroup Builder Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods (<>) :: Builder -> Builder -> Builder # sconcat :: NonEmpty Builder -> Builder # stimes :: Integral b => b -> Builder -> Builder #
Monoid Builder Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods mempty :: Builder # mappend :: Builder -> Builder -> Builder # mconcat :: [Builder] -> Builder #

type BuilderState = (# Addr#, Addr#, State# RealWorld #) Source #

The state of a builder. The components are:

The "cur" pointer
The "end" pointer
The state token

data DataSink Source #

Specifies where bytes generated by a builder go.

Constructors

DynamicSink !(IORef DynamicSink)	The destination of data changes while the builder is running.
GrowingBuffer !(IORef (ForeignPtr Word8))	Bytes are accumulated in a contiguous buffer.
HandleSink !Handle !Int !(IORef Queue)	Bytes are first accumulated in the `Queue`, then flushed to the `Handle`.

data DynamicSink Source #

Variable-destination cases.

Constructors

ThreadedSink !(MVar Request) !(MVar Response)	Bytes are sent to another thread.
BoundedGrowingBuffer !(ForeignPtr Word8) !Int	Bytes are accumulated in a contiguous buffer until the size limit is reached. After that, the destination switches to a `ThreadedSink`.

data Queue Source #

A mutable buffer.

Constructors

Queue
Fields queueBuffer :: !(ForeignPtr Word8) queueStart :: !Int Starting position. queueTotal :: !Int Bytes written to the handle so far.

data Request Source #

A request from the driver thread to the builder thread.

Constructors

Request !(Ptr Word8) !(Ptr Word8)

data Response Source #

A response from the builder thread to the driver thread.

Constructors

Error SomeException	A synchronous exception was thrown by the builder
Done !(Ptr Word8)	The builder thread has completed.
MoreBuffer !(Ptr Word8) !Int	The builder thread has finished generating one chunk, and waits for another request with the specified minimum size.
InsertByteString !(Ptr Word8) !ByteString	The builder thread has partially filled the current chunk, and wants to emit the bytestring to be included in the final output.

Instances

Instances details

Show Response Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods showsPrec :: Int -> Response -> ShowS # show :: Response -> String # showList :: [Response] -> ShowS #

Internally used exceptions

data SuspendBuilderException Source #

Used in the implementation of toLazyByteString. This is a message sent from the consumer thread to the builder thread, requesting the builder thread to temporarily pause execution. Later, the consumer thread may request resumption by filling the MVar.

Constructors

SuspendBuilderException !(MVar ())

Instances

Instances details

Show SuspendBuilderException Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods showsPrec :: Int -> SuspendBuilderException -> ShowS # show :: SuspendBuilderException -> String # showList :: [SuspendBuilderException] -> ShowS #
Exception SuspendBuilderException Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods toException :: SuspendBuilderException -> SomeException # fromException :: SomeException -> Maybe SuspendBuilderException # displayException :: SuspendBuilderException -> String #

data ChunkOverflowException Source #

Used in the implementation of toLazyByteString. This is an exception thrown by the consumer thread to itself when it has finished filling the first chunk of the output. After this, a thread will be forked, and the execution of the builder will be resumed in the new thread, using ThreadedSink.

Constructors

ChunkOverflowException !ByteString !(MVar Request) !(MVar Response) !Int

Instances

Instances details

Show ChunkOverflowException Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods showsPrec :: Int -> ChunkOverflowException -> ShowS # show :: ChunkOverflowException -> String # showList :: [ChunkOverflowException] -> ShowS #
Exception ChunkOverflowException Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods toException :: ChunkOverflowException -> SomeException # fromException :: SomeException -> Maybe ChunkOverflowException # displayException :: ChunkOverflowException -> String #

Builder building blocks

newtype BuildM a Source #

An internal type for making it easier to define builders. A value of BuildM a can do everything a Builder can do, and in addition, returns a value of type a upon completion.

Constructors

BuildM
Fields runBuildM :: (a -> Builder) -> Builder

Instances

Instances details

Monad BuildM Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods (>>=) :: BuildM a -> (a -> BuildM b) -> BuildM b # (>>) :: BuildM a -> BuildM b -> BuildM b # return :: a -> BuildM a #
Functor BuildM Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods fmap :: (a -> b) -> BuildM a -> BuildM b # (<$) :: a -> BuildM b -> BuildM a #
Applicative BuildM Source #
Instance details Defined in Data.ByteString.FastBuilder.Internal Methods pure :: a -> BuildM a # (<>) :: BuildM (a -> b) -> BuildM a -> BuildM b # liftA2 :: (a -> b -> c) -> BuildM a -> BuildM b -> BuildM c # (>) :: BuildM a -> BuildM b -> BuildM b # (<*) :: BuildM a -> BuildM b -> BuildM a #

mkBuilder :: BuildM () -> Builder Source #

Create a builder from a BuildM.

useBuilder :: Builder -> BuildM () Source #

Embed a builder in the BuildM context.

getSink :: BuildM DataSink Source #

Get the DataSink.

getCur :: BuildM (Ptr Word8) Source #

Get the current pointer.

getEnd :: BuildM (Ptr Word8) Source #

Get the end-of-buffer pointer.

setCur :: Ptr Word8 -> BuildM () Source #

Set the current pointer.

setEnd :: Ptr Word8 -> BuildM () Source #

Set the end-of-buffer pointer.

Running builders

runBuilder :: Builder -> DataSink -> Ptr Word8 -> Ptr Word8 -> IO (Ptr Word8) Source #

Run a builder.

toLazyByteString :: Builder -> ByteString Source #

Turn a Builder into a lazy ByteString.

Performance hint: when the resulting ByteString does not fit in one chunk, this function forks a thread. Due to this, the performance degrades sharply if you use this function from a bound thread. Note in particular that the main thread is a bound thread when you use ghc -threaded.

To avoid this problem, do one of these:

Make sure the resulting ByteString is consumed in an unbound thread. Consider using runInUnboundThread for this.
Use other function to run the Builder instead. Functions that don't return a lazy ByteString do not have this issue.
Link your program without -threaded.

toLazyByteStringWith :: Int -> Int -> Builder -> ByteString Source #

Like toLazyByteString, but allows the user to specify the initial and the subsequent desired buffer sizes.

toStrictByteString :: Builder -> ByteString Source #

Turn a Builder into a strict ByteString.

hPutBuilder :: Handle -> Builder -> IO () Source #

Output a Builder to a Handle.

hPutBuilderLen :: Handle -> Builder -> IO Int Source #

Output a Builder to a Handle. Returns the number of bytes written.

hPutBuilderWith :: Handle -> Int -> Int -> Builder -> IO Int Source #

Like hPutBuffer, but allows the user to specify the initial and the subsequent desired buffer sizes. This function may be useful for setting large buffer when high throughput I/O is needed.

Basic builders

primBounded :: BoundedPrim a -> a -> Builder Source #

Turn a value of type a into a Builder, using the given BoundedPrim.

primFixed :: FixedPrim a -> a -> Builder Source #

Turn a value of type a into a Builder, using the given FixedPrim.

primMapListBounded :: BoundedPrim a -> [a] -> Builder Source #

Turn a list of values of type a into a Builder, using the given BoundedPrim.

primMapListFixed :: FixedPrim a -> [a] -> Builder Source #

Turn a list of values of type a into a Builder, using the given FixedPrim.

byteString :: ByteString -> Builder Source #

Turn a ByteString to a Builder.

byteStringThreshold :: Int -> ByteString -> Builder Source #

Turn a ByteString to a Builder. If the size of the ByteString is larger than the given threshold, avoid copying it as much as possible.

byteStringCopy :: ByteString -> Builder Source #

Turn a ByteString to a Builder. The ByteString will be copied to the buffer, regardless of the size.

byteStringCopyNoCheck :: ByteString -> Builder Source #

Like byteStringCopy, but assumes that the current buffer is large enough.

byteStringInsert :: ByteString -> Builder Source #

Turn a ByteString to a Builder. When possible, the given ByteString will not be copied, and inserted directly into the output instead.

unsafeCString :: CString -> Builder Source #

Turn a C String into a Builder. The behavior is undefined if the given CString does not point to a constant null-terminated string.

unsafeCStringLen :: CStringLen -> Builder Source #

Turn a CStringLen into a Builder. The behavior is undefined if the given CStringLen does not point to a constant memory block.

ensureBytes :: Int -> Builder Source #

ensureBytes n ensures that at least n bytes of free space is available in the current buffer, by allocating a new buffer when necessary.

getBytes :: Int -> Builder Source #

getBytes n allocates a new buffer, containing at least n bytes.

Performance tuning

rebuild :: Builder -> Builder Source #

rebuild b is equivalent to b, but it allows GHC to assume that b will be run at most once. This can enable various optimizations that greately improve performance.

There are two types of typical situations where a use of rebuild is often a win:

When constructing a builder using a recursive function. e.g. rebuild $ foldr ....
When constructing a builder using a conditional expression. e.g. rebuild $ case x of ...