⚠️ Work in progress. Expect bugs and/or missing features ⚠️

simdjzon

This is a port of simdjson, a high performance JSON parser developed by Daniel Lemire and Geoff Langdale to zig.

cpu support

Only 64 bit CPUs are supported so far.

x86_64

A CPU with AVX is required and CLMUL is preferred. the following usually have both

• Intel - Haswell from 2013 onwards
• AMD - Ryzen/EPYC CPU (Q1 2017)

These commands show how to test for specific target and cpu support

zig build test -Dtarget=x86_64-linux -Dcpu=x86_64+avx # uses clmulSoft - missing pclmul
zig build test -Dtarget=x86_64-linux -Dcpu=x86_64+avx+pclmul
# zig build test -Dtarget=x86_64-linux # doesn't work - missing avx
# zig build test -Dcpu=x86_64_v2 # doesn't work - missing avx

aarch64

A CPU with AES is preferred.

zig build test -Dtarget=aarch64-linux -Dcpu=apple_latest-aes -fqemu # uses clmulSoft
zig build test -Dtarget=aarch64-linux -fqemu

powerpc

Not supported yet

# zig build test -Dtarget=powerpc-linux -fqemu # doesn't work - no classify() + 32bit errors
# zig build test -Dtarget=powerpc64-linux -fqemu # doesn't work - no classify()

fallback

No fallback for unsupported CPUs is provided yet.

# zig build test -Dcpu=baseline # doesn't work - no classify()

zig compiler support

The main branch is meant to compile with zig's master branch. It is tested weekly on linux, windows and macos.

For older compiler versions, use a tagged version.

usage

# json validation
$ git clone https://github.com/travisstaloch/simdjzon
$ cd simdjzon
$ zig build -Drelease-fast # uses the dom api by default
$ zig-out/bin/simdjzon test/test.json
$ echo $? # 0 on success
0
$ zig build -Drelease-fast -Dondemand # use the ondemand api
$ zig-out/bin/simdjzon test/test.json
$ echo $? # 0 on success
0
$ zig build test
All 19 tests passed.

const dom = @import("dom.zig");
test "get with struct" {
    const S = struct { a: u8, b: []const u8, c: struct { d: u8 } };
    const input =
        \\{"a": 42, "b": "b-string", "c": {"d": 126}}
    ;
    var parser = try dom.Parser.initFixedBuffer(allr, input, .{});
    defer parser.deinit();
    try parser.parse();
    var s: S = undefined;
    try parser.element().get(&s);
    try testing.expectEqual(@as(u8, 42), s.a);
    try testing.expectEqualStrings("b-string", s.b);
    try testing.expectEqual(@as(u8, 126), s.c.d);
}

test "at_pointer" {
    const input =
        \\{"a": {"b": [1,2,3]}}
    ;
    var parser = try dom.Parser.initFixedBuffer(allr, input, .{});
    defer parser.deinit();
    try parser.parse();
    const b0 = try parser.element().at_pointer("/a/b/0");
    try testing.expectEqual(@as(i64, 1), try b0.get_int64());
}

const ondemand = @import("ondemand.zig");
// ondemand api users must specify `pub const read_buf_cap = N;` in their
// root source file.  In tests, this defaults to `std.mem.page_size`. 
test "ondemand get with struct" {
    const S = struct { a: struct { b: []const u8 } };
    const input =
        \\{"a": {"b": "b-string"}}
    ;
    var src = std.io.StreamSource{ .const_buffer = std.io.fixedBufferStream(input) };
    var parser = try ondemand.Parser.init(&src, allr, "<fba>", .{});
    defer parser.deinit();
    var doc = try parser.iterate();

    var s: S = undefined;
    try doc.get(&s, .{ .allocator = allr });
    defer allr.free(s.a.b);
    try testing.expectEqualStrings("b-string", s.a.b);
}

test "ondemand at_pointer" {
    const input =
        \\{"a": {"b": [1,2,3]}}
    ;
    var src = std.io.StreamSource{ .const_buffer = std.io.fixedBufferStream(input) };
    var parser = try ondemand.Parser.init(&src, allr, "<fba>", .{});
    defer parser.deinit();
    var doc = try parser.iterate();
    var b0 = try doc.at_pointer("/a/b/0");
    try testing.expectEqual(@as(u8, 1), try b0.get_int(u8));
}

performance

parsing/validating twitter.json (630Kb)

simdjson

$ wget https://raw.githubusercontent.com/simdjson/simdjson/master/singleheader/simdjson.h https://raw.githubusercontent.com/simdjson/simdjson/master/singleheader/simdjson.cpp https://raw.githubusercontent.com/simdjson/simdjson/master/jsonexamples/twitter.json

$ cat main.cpp
#include "simdjson.h"
using namespace simdjson;
int main(int argc, char** argv) {
    if(argc != 2) {
        std::cout << "USAGE: ./simdjson <file.json>" << std::endl;
        exit(1);
    }
    dom::parser parser; 
    try
    {
        const dom::element doc = parser.load(argv[1]);
    }
    catch(const std::exception& e)
    {
        std::cerr << e.what() << '\n';
        return 1;
    }
    return 0;
}

$ g++ main.cpp simdjson.cpp -o simdjson -O3 -march=native
$ time ./simdjson twitter.json

real	0m0.003s
user	0m0.002s
sys	0m0.001s

$ echo $?
0

simdjzon

$ time zig-out/bin/simdjzon twitter.json 

real	0m0.002s
user	0m0.000s
sys	0m0.002s

$ echo $?
0

timed against simdjson, go, nim, zig std lib

The simdjson binary was compiled as shown above. Go and nim binaries created with sources from JSONTestSuite. zig std lib driver. Validation times for several large json files. Created with benchmark_and_plot.jl

JSONTestSuite

Results of running simdjson and simdjzon through JSONTestSuite. Results are equal as of 8/7/21