Niels Lohmann b4fdf765e1 Fill the indentation buffer once instead of once per flush ...

@gregmarr's point on the fill-and-flush loop: flushing does not disturb what
the write buffer holds, so an indentation spanning several buffer-fulls only
has to be written into the buffer once and can then be handed to the adapter
as many times as needed. The loop re-filled it every time, doing work it
already knew was there.

put_indent() now fills the room left in the buffer, and if anything remains,
flushes, fills the buffer once, and re-flushes that same content. It also
returns early for a zero-width indentation, which is what the closing brace of
every outermost value asks for.

Measured over a dump(), counting memset calls and bytes inside put_indent:

    indent       before              after
         4       1 call /     4 B    1 call /     4 B
      2000       2 calls /  2000 B   2 calls /  2046 B
    100000      98 calls / 100000 B  2 calls /  2046 B

The wide case is now constant work rather than proportional to the indentation
width; ordinary widths are unchanged. Tests extended to cover several whole
buffer-fulls and an exact multiple of the buffer size.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

2026-08-19 23:03:15 +02:00

..

nlohmann

Fill the indentation buffer once instead of once per flush

2026-08-19 23:03:15 +02:00