src/sydra/log.zig

Purpose

Provides a small JSON logging helper that writes one JSON object per line (“JSONL”), intended for structured logs.

Public API

pub const Level = enum { debug, info, warn, err }

Serialized using @tagName(level) (e.g. "info").

pub fn logJson(level: Level, msg: []const u8, fields: ?[]const std.json.Value, writer: *std.io.Writer) !void

Writes a JSON object with at least:

• ts: std.time.milliTimestamp()
• level: string tag name
• msg: message string

Optional field merge behavior:

• When fields is provided, each entry is examined.
• If an entry is a JSON object (v == .object), its key/value pairs are written into the output object.
• Non-object values are ignored.

Note: if multiple field objects contain the same key, the output will contain duplicate keys (JSON parsers generally take the last occurrence).

The function appends a trailing newline ("\n").

src/sydra/log.zig (full file)

const std = @import("std");

pub const Level = enum { debug, info, warn, err };

pub fn logJson(level: Level, msg: []const u8, fields: ?[]const std.json.Value, writer: *std.io.Writer) !void {
    var jw = std.json.Stringify{ .writer = writer };
    try jw.beginObject();
    try jw.objectField("ts");
    try jw.write(std.time.milliTimestamp());
    try jw.objectField("level");
    try jw.write(@tagName(level));
    try jw.objectField("msg");
    try jw.write(msg);
    if (fields) |arr| {
        for (arr) |v| {
            // Best-effort merge of flat objects passed in.
            if (v == .object) {
                var it = v.object.iterator();
                while (it.next()) |entry| {
                    try jw.objectField(entry.key_ptr.*);
                    try jw.write(entry.value_ptr.*);
                }
            }
        }
    }
    try jw.endObject();
    try writer.writeAll("\n");
}