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author | sterni <sternenseemann@systemli.org> | 2023-05-15T21·36+0200 |
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committer | clbot <clbot@tvl.fyi> | 2023-05-18T16·14+0000 |
commit | 3d2e55ad535371d1152a221dc31a8773b3a09ddf (patch) | |
tree | 2c036f24436431882536615f3aa8d0176e4604cc /users/Profpatsch/ini/default.nix | |
parent | b379e44dfb871100546b3d60bd3c77fbeac61adc (diff) |
refactor(mime4cl): replace *-input-adapter-stream with flexi-streams r/6152
The input adapter streams were input streams yielding either binary or character data that could be constructed from a variable data source. The stream would take care not to destroy the underlying data source (i.e. not close it if it was a stream), so similar to with FILE-PORTIONs, but simpler. Unfortunately, the implementation was quite inefficient: They are ultimately defined in terms of a function that retrieves the next character in the source. This only allows for an implementation of READ-CHAR (and READ-BYTE). Thanks to cl/8559, READ-SEQUENCE can be used on e.g. FILE-PORTION, but this was still negated by a input adapter based on one—then, READ-SEQUENCE would need to fall back on READ-CHAR or READ-BYTE again. Luckily, we can replace BINARY-INPUT-ADAPTER-STREAM and CHARACTER-INPUT-ADAPTER-STREAM with a much simpler abstraction: Instead of extra stream classes, we have a function, MAKE-INPUT-ADAPTER, which returns an appropriate instance of FLEXI-STREAM based on a given source. This way, the need for a distinction between binary and character input adapter is eliminated, since FLEXI-STREAMS supports both binary and character reads (external format is not yet handled, though). Consequently, the :binary keyword argument to MIME-BODY-STREAM can be dropped. flexi-streams provides stream classes for everything except a stream that doesn't close the underlying one. Since we have already implemented this in POSITIONED-FLEXI-INPUT-STREAM, we can split this functionality into a new superclass ADAPTER-FLEXI-INPUT-STREAM. This change also allows addressing the performance regression encountered in cl/8559: It seems that flexi-streams performs worse when we are reading byte by byte or char by char. (After this change mblog is still two times slower than on r/6150.) By eliminating the adapter streams, we can start utilizing READ-SEQUENCE via decoding code that supports it (i.e. qbase64) and bring performance on par with r/6150 again. Surely there are also ways to gain back even more performance which has to be determined using profiling. Buffering more aggressively seems like a sure bet, though. Switching to flexi-streams still seems like a no-brainer, as it allows us to drop a lot of code that was quite hacky (e.g. DELIMITED-INPUT- STREAM) and implements en/decoding handling we did not support before, but would need for improved correctness. Change-Id: Ie2d1f4e42b47512a5660a1ccc0deeec2bff9788d Reviewed-on: https://cl.tvl.fyi/c/depot/+/8581 Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
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