Niels Lohmann ceb3c92709 Reserve at least 64 bytes for the result of a binary serialization ...

The result of to_cbor() and its siblings reserved the lower bound of
binary_reserve_hint(), for a small object a few bytes, and the first write of
the sink replaced it by an allocation of 64 bytes, as an empty or too small
vector is grown to at least that. A small document therefore cost two
allocations and a free.

The result now reserves at least min_vector_sink_capacity (64) characters at
once. binary_reserve_hint() itself, a lower bound that is tested as such, is
unchanged.

Instructions to serialize a small object (six members, a nested array and object), Linux, GCC 13: to_cbor 1700 -> 1500, to_msgpack 1800 -> 1600, to_ubjson 1800 -> 1700, to_bson 2700 -> 2500. Documents larger than 64 bytes of hint are unchanged.

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

2026-10-22 09:29:11 +02:00

..

json_fwd.hpp

Scan strings with SSE2, SSSE3, or NEON (#5853)

2026-10-21 20:00:50 +02:00

json_literals.hpp

Move the user-defined string literals to <nlohmann/json_literals.hpp> and add JSON_NO_AUTOMATIC_UDLS (#5610)

2026-09-30 20:08:17 +02:00

json_view.hpp

Use standard library helpers where available, with C++11 fallbacks (#5876)

2026-10-21 20:14:59 +02:00

json.hpp

Reserve at least 64 bytes for the result of a binary serialization

2026-10-22 09:29:11 +02:00