crazalchemist / simdjson-rust

Rust bindings for the simdjson project.

simdjson-rust

This crate currently uses simdjson 3.2.3. You can have a try and give feedback.

If you

• find certain APIs are missing
• encounter memory errors
• experience performance degradation

Please submit an issue.

Benchmark

Check SunDoge/json-benchmark

                                DOM                  STRUCT
======= serde_json ======= parse|stringify ===== parse|stringify ====
data/canada.json         400 MB/s   460 MB/s   500 MB/s   390 MB/s
data/citm_catalog.json   540 MB/s   790 MB/s  1000 MB/s  1070 MB/s
data/twitter.json        390 MB/s  1020 MB/s   680 MB/s  1090 MB/s

======= simd-json ======== parse|stringify ===== parse|stringify ====
data/canada.json         400 MB/s   540 MB/s   530 MB/s
data/citm_catalog.json  1080 MB/s  1000 MB/s  1570 MB/s
data/twitter.json       1100 MB/s  1460 MB/s  1180 MB/s

===== simdjson-rust ====== parse|stringify ===== parse|stringify ====
data/canada.json         960 MB/s
data/citm_catalog.json  3110 MB/s
data/twitter.json       3160 MB/s

Usage

Add this to your Cargo.toml

# In the `[dependencies]` section
simdjson-rust = "0.3.0"

Then, get started.

use simdjson_rust::prelude::*;
use simdjson_rust::{dom, ondemand};

fn main() -> simdjson_rust::Result<()> {
    let ps = "[0,1,2,3]".to_padded_string();

    // ondemand api.
    {
        let mut parser = ondemand::Parser::default();
        let mut doc = parser.iterate(&ps)?;
        let mut array = doc.get_array()?;
        for (index, value) in array.iter()?.enumerate() {
            assert_eq!(index as u64, value?.get_uint64()?);
        }
    }

    // dom api.
    {
        let mut parser = dom::Parser::default();
        let elem = parser.parse(&ps)?;
        let arr = elem.get_array()?;
        for (index, value) in arr.iter().enumerate() {
            assert_eq!(index as u64, value.get_uint64()?);
        }
    }

    Ok(())
}

dom and ondemand

simdjson now offer two kinds of API, dom and ondemand. dom will parsed the whole string while ondemand only parse what you request. Due to ffi, the overhead of ondemand API is relatively high. I have tested lto but it only improves a little :(

Thus it is suggestted that

• use ondemand if you only want to access a specific part of a large json,
• use dom if you want to parse the whole json.

padded_string

simdjson requires the input string to be padded. We must provide a string with capacity = len + SIMDJSON_PADDING. We provide utils to do so.

use simdjson_rust::prelude::*;

fn main() -> simdjson_rust::Result<()> {
    let ps = make_padded_string("[0,1,2,3]");
    let ps = "[0,1,2,3]".to_padded_string();
    // or reuse a buffer.
    let unpadded = String::from("[1,2,3,4]");
    let ps = unpadded.into_padded_string();
    // or load from file.
    let ps = load_padded_string("test.json")?;
    Ok(())
}

Other interesting things

There are also pure Rust port of simdjson available here simd-json.