Replace internal buffer in decoder with BufRead
#231
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The `DecoderReader` used an internal buffer for reading which came with a number of disadvantages, such as: * Needless copying from in-memory readers (slices) * Double-buffering already-buffered readers * The bytes are lost when dropping or calling `into_inner` * `BUF_SIZE` is not configurable * `std::io::BufReader` has access to some unstable optimizations which this crate cannot use * Reinvents the wheel; there already is `std::io::BufReader` This change removes it and requires `BufRead` instead. Decoding is implemented on top of `fill_buf` for larger chunks with fallback to small, stack-allocated buffer for tiny chunks that may appear at boundaries. To resolve borrowing problems `decode_to_buf` had to be removed which also enabled decoding bytes directly into internal buffer when the buffer to be filled is small rather than into a temporary buffer which is then copied. This improves performance of reading by around 7-22% on my machine.
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Thanks for the contribution. It will probably take me some time to review it, but I'll get to it when I can. |
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The
DecoderReaderused an internal buffer for reading which came with a number of disadvantages, such as:into_innerBUF_SIZEis not configurablestd::io::BufReaderhas access to some unstable optimizations which this crate cannot usestd::io::BufReaderThis change removes it and requires
BufReadinstead. Decoding is implemented on top offill_buffor larger chunks with fallback to small, stack-allocated buffer for tiny chunks that may appear at boundaries.To resolve borrowing problems
decode_to_bufhad to be removed which also enabled decoding bytes directly into internal buffer when the buffer to be filled is small rather than into a temporary buffer which is then copied.This improves performance of reading by around 7-22% on my machine.
Closes #230