A Buffer together with the BufferRange of free bytes. The filled space starts at offset 0 and ends at the first free byte.

A range of bytes in a buffer represented by the pointer to the first byte of the range and the pointer to the first byte after the range.

Allocate a new buffer of the given size.

Combined size of the filled and free space in the buffer.

Convert the filled part of a Buffer to a strict ByteString .

A stream of chunks that are constructed in the IO monad.

This datatype serves as the common interface for the buffer-by-buffer execution of a BuildStep by buildStepToCIOS . Typical users of this interface are ciosToLazyByteString or iteratee-style libraries like enumerator .

Convert a BuildStep to a ChunkIOStream stream by executing it on Buffer s allocated according to the given AllocationStrategy .

Convert a ChunkIOStream () to a lazy ByteString using unsafeDupablePerformIO .

Convert a ChunkIOStream to a lazy tuple of the result and the written ByteString using unsafeDupablePerformIO .

BuildSignal s abstract signals to the caller of a BuildStep . There are three signals: done , bufferFull , or 'insertChunks signals

BuildStep s may be called *multiple times* and they must not rise an async. exception.

The final build step that returns the done signal.

Signal that the current BuildStep is done and has computed a value.

Signal that the current buffer is full.

Signal that a ByteString chunk should be inserted directly.

Fill a BufferRange using a BuildStep .

Builder s denote sequences of bytes. They are Monoid s where mempty is the zero-length sequence and mappend is concatenation, which runs in O(1) .

Construct a Builder . In contrast to BuildStep s, Builder s are referentially transparent.

Run a Builder with the finalBuildStep .

Run a Builder .

The Builder denoting a zero-length sequence of bytes. This function is only exported for use in rewriting rules. Use mempty otherwise.

Concatenate two Builder s. This function is only exported for use in rewriting rules. Use mappend otherwise.

Flush the current buffer. This introduces a chunk boundary.

ensureFree n ensures that there are at least n free bytes for the following Builder .

Construct a Builder that copies the strict ByteString .

Use this function to create Builder s from smallish ( <= 4kb ) ByteString s or if you need to guarantee that the ByteString is not shared with the chunks generated by the Builder .

Construct a Builder that always inserts the strict ByteString directly as a chunk.

This implies flushing the output buffer, even if it contains just a single byte. You should therefore use byteStringInsert only for large ( > 8kb ) ByteString s. Otherwise, the generated chunks are too fragmented to be processed efficiently afterwards.

Construct a Builder that copies the strict ByteString s, if it is smaller than the treshold, and inserts it directly otherwise.

For example, byteStringThreshold 1024 copies strict ByteString s whose size is less or equal to 1kb, and inserts them directly otherwise. This implies that the average chunk-size of the generated lazy ByteString may be as low as 513 bytes, as there could always be just a single byte between the directly inserted 1025 byte, strict ByteString s.

Construct a Builder that copies the lazy ByteString .

Construct a Builder that inserts all chunks of the lazy ByteString directly.

Construct a Builder that uses the thresholding strategy of byteStringThreshold for each chunk of the lazy ByteString .

Construct a Builder that copies the ShortByteString .

The maximal size of a ByteString that is copied. 2 * smallChunkSize to guarantee that on average a chunk is of smallChunkSize .

Create a Builder denoting the same sequence of bytes as a strict ByteString . The Builder inserts large ByteString s directly, but copies small ones to ensure that the generated chunks are large on average.

Create a Builder denoting the same sequence of bytes as a lazy ByteString . The Builder inserts large chunks of the lazy ByteString directly, but copies small ones to ensure that the generated chunks are large on average.

Heavy inlining. Execute a Builder with custom execution parameters.

This function is inlined despite its heavy code-size to allow fusing with the allocation strategy. For example, the default Builder execution function toLazyByteString is defined as follows.

{-# NOINLINE toLazyByteString #-}
toLazyByteString =
  toLazyByteStringWith (safeStrategy smallChunkSize defaultChunkSize) L.empty

where L.empty is the zero-length lazy ByteString .

In most cases, the parameters used by toLazyByteString give good performance. A sub-performing case of toLazyByteString is executing short (<128 bytes) Builder s. In this case, the allocation overhead for the first 4kb buffer and the trimming cost dominate the cost of executing the Builder . You can avoid this problem using

toLazyByteStringWith (safeStrategy 128 smallChunkSize) L.empty

This reduces the allocation and trimming overhead, as all generated ByteString s fit into the first buffer and there is no trimming required, if more than 64 bytes and less than 128 bytes are written.

A buffer allocation strategy for executing Builder s.

Use this strategy for generating lazy ByteString s whose chunks are likely to survive one garbage collection. This strategy trims buffers that are filled less than half in order to avoid spilling too much memory.

Use this strategy for generating lazy ByteString s whose chunks are discarded right after they are generated. For example, if you just generate them to write them to a network socket.

Create a custom allocation strategy. See the code for safeStrategy and untrimmedStrategy for examples.

The recommended chunk size. Currently set to 4k, less the memory management overhead

The chunk size used for I/O. Currently set to 32k, less the memory management overhead

The memory management overhead. Currently this is tuned for GHC only.

A Put action denotes a computation of a value that writes a stream of bytes as a side-effect. Put s are strict in their side-effect; i.e., the stream of bytes will always be written before the computed value is returned.

Put s are a generalization of Builder s. The typical use case is the implementation of an encoding that might fail (e.g., an interface to the zlib compression library or the conversion from Base64 encoded data to 8-bit data). For a Builder , the only way to handle and report such a failure is ignore it or call error . In contrast, Put actions are expressive enough to allow reportng and handling such a failure in a pure fashion.

Put () actions are isomorphic to Builder s. The functions putBuilder and fromPut convert between these two types. Where possible, you should use Builder s, as sequencing them is slightly cheaper than sequencing Put s because they do not carry around a computed value.

Construct a Put action. In contrast to BuildStep s, Put s are referentially transparent in the sense that sequencing the same Put multiple times yields every time the same value with the same side-effect.

Run a Put .

Execute a Put and return the computed result and the bytes written during the computation as a lazy ByteString .

This function is strict in the computed result and lazy in the writing of the bytes. For example, given

infinitePut = sequence_ (repeat (putBuilder (word8 1))) >> return 0
 

evaluating the expression

fst $ putToLazyByteString infinitePut
 

does not terminate, while evaluating the expression

L.head $ snd $ putToLazyByteString infinitePut
 

does terminate and yields the value 1 :: Word8 .

An illustrative example for these strictness properties is the implementation of Base64 decoding ( http://en.wikipedia.org/wiki/Base64 ).

type DecodingState = ...

decodeBase64 :: ByteString -> DecodingState -> Put (Maybe DecodingState)
decodeBase64 = ...
 

The above function takes a strict ByteString supposed to represent Base64 encoded data and the current decoding state. It writes the decoded bytes as the side-effect of the Put and returns the new decoding state, if the decoding of all data in the ByteString was successful. The checking if the strict ByteString represents Base64 encoded data and the actual decoding are fused. This makes the common case, where all data represents Base64 encoded data, more efficient. It also implies that all data must be decoded before the final decoding state can be returned. Put s are intended for implementing such fused checking and decoding/encoding, which is reflected in their strictness properties.

Execute a Put with a buffer-allocation strategy and a continuation. For example, putToLazyByteString is implemented as follows.

putToLazyByteString = putToLazyByteStringWith
    (safeStrategy smallChunkSize defaultChunkSize) (x -> (x, L.empty))
 

Run a Put action redirecting the produced output to a Handle .

The output is buffered using the Handle s associated buffer. If this buffer is too small to execute one step of the Put action, then it is replaced with a large enough buffer.

Run a Builder as a side-effect of a Put () action.

Convert a Put () action to a Builder .