3 ms·

It’s just two pointers the current place to write and the current place to read, escapes are always more characters than they represent so there’s no danger of

by _3u10 1y ago

It’s just two pointers the current place to write and the current place to read, escapes are always more characters than they represent so there’s no danger of overwriting the read pointer. If you support compression this can become somewhat of and issue but you simply support a max block size which is usually defined by the compression algorithm anyway.

Ygg2 1y ago
If you have a place to write, then it's not zero allocation. You did an allocation. And usually if you want maximum performance, buffered read is the way to go, which means you need a write slab allocation.
- lelanthran 1y ago
  > If you have a place to write, then it's not zero allocation. You did an allocation. Where did that allocation happen? You can write into the buffer you're reading from, because the replacement data is shorter than the original data.
  - Ygg2 1y ago
    You have a read buffer and somewhere where you have to write to. Even if we pretend that the read buffer is not allocating (plausible), you will have to allocate for the write source for the general case (think GiB or TiB of XML or JSON).
    - lelanthran 1y ago
      > You have a read buffer and somewhere where you have to write to. The "somewhere you have to write to" is the same buffer you are reading from.
      - Ygg2 1y ago
        Not if you are doing buffered reads, where you replace slow file access with fast memory access. This buffer is cleared every X bytes processed. Writing to it would be pointless because clears obliterate anything written; or inefficient because you are somehow offsetting clears, which would sabotage the buffered reading performance gains.
        lelanthran 1y ago
        Maybe I missed it, but ITT we were talking about C buffers, not buffered reads.
        Ygg2 1y ago
        I thought we were talking about high performance parsing. Of which buffered reads are one. Other is loading entire document into mutable memory, which also has limitations.

by _3u10 1y ago

Ygg2 1y ago

If you have a place to write, then it's not zero allocation. You did an allocation. And usually if you want maximum performance, buffered read is the way to go, which means you need a write slab allocation.

lelanthran 1y ago
> If you have a place to write, then it's not zero allocation. You did an allocation. Where did that allocation happen? You can write into the buffer you're reading from, because the replacement data is shorter than the original data.
- Ygg2 1y ago
  You have a read buffer and somewhere where you have to write to. Even if we pretend that the read buffer is not allocating (plausible), you will have to allocate for the write source for the general case (think GiB or TiB of XML or JSON).
  - lelanthran 1y ago
    > You have a read buffer and somewhere where you have to write to. The "somewhere you have to write to" is the same buffer you are reading from.
    - Ygg2 1y ago
      Not if you are doing buffered reads, where you replace slow file access with fast memory access. This buffer is cleared every X bytes processed. Writing to it would be pointless because clears obliterate anything written; or inefficient because you are somehow offsetting clears, which would sabotage the buffered reading performance gains.
      - lelanthran 1y ago
        Maybe I missed it, but ITT we were talking about C buffers, not buffered reads.
        Ygg2 1y ago
        I thought we were talking about high performance parsing. Of which buffered reads are one. Other is loading entire document into mutable memory, which also has limitations.