7 releases
0.3.0 | Sep 19, 2023 |
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0.2.0 | Jul 9, 2023 |
0.1.4 | Jan 14, 2023 |
#727 in Encoding
153 downloads per month
Used in 2 crates
(via reductionml-core)
30KB
515 lines
Serde JSON Borrow
Up to 2x faster JSON parsing for ndjson type use cases.
serde_json_borrow
deserializes JSON from &'ctx str
into serde_json_borrow::Value<'ctx>
DOM, by trying to reference the original bytes, instead of copying them into Strings
.
In contrast the default serde_json parses into an owned serde_json::Value
. Every String
encountered is getting copied and
therefore allocated. That's great for ergnomonics, but not great for performance.
Especially in cases where the DOM representation is just an intermediate struct.
To get a little bit more performance, serde_json_borrow
pushes the (key,values) for JSON objects into a Vec
instead of using a BTreeMap
. Access works via
an iterator, which has the same API when iterating the BTreeMap
.
OwnedValue
You can take advantage of OwnedValue
to parse a String
containing unparsed JSON
into a Value
without having to worry about lifetimes,
as OwnedValue
will take ownership of the String
and reference slices of it, rather than making copies.
Limitations
Keys in objects are not allowed to have any JSON escaping characters. So if your keys contain any control characters (https://www.json.org/json-en.html), this crate will not work for you. List of unsupported characters in keys.
\" represents the quotation mark character (U+0022).
\\ represents the reverse solidus character (U+005C).
\/ represents the solidus character (U+002F).
\b represents the backspace character (U+0008).
\f represents the form feed character (U+000C).
\n represents the line feed character (U+000A).
\r represents the carriage return character (U+000D).
\t represents the character tabulation character (U+0009).
Benchmark
Running benches/crit_bench.rs (/home/pascal/cargo_target_dir/release/deps/crit_bench-fd2d661e0b4255c5)
flat-json-to-doc/serde-json-owned
time: [352.60 µs 353.40 µs 354.26 µs]
thrpt: [236.01 MiB/s 236.59 MiB/s 237.12 MiB/s]
flat-json-to-doc/serde-json-borrowed
time: [175.53 µs 175.72 µs 175.93 µs]
thrpt: [475.23 MiB/s 475.81 MiB/s 476.34 MiB/s]
TODO
Instead of parsing a JSON object into a Vec
, a BTreeMap
could be enabled via a feature flag.
Dependencies
~375–780KB
~17K SLoC