Implement racket/trace Like Observability Using eBPF https://hemslo.io/implement-racket-trace-like-observability-using-ebpf/

bpftrace2trace.py

#!/usr/bin/env python3

import sys
import json

def main():
    result = []
    for line in sys.stdin:
        if line:
            data = json.loads(line.strip())
            if data['type'] == 'printf':
                type, value, timestamp, pid, tid = data['data'].strip().split(',')
                args = { 'arg0': int(value) } if type == '>' else { 'ret': int(value) }
                result.append({
                    'ph': 'B' if type == '>' else 'E',
                    'name': f'fib({value})' if type == '>' else '',
                    'ts': int(timestamp),
                    'pid': int(pid),
                    'tid': int(tid),
                    'args': args,
                })
    print(json.dumps(result))

if __name__ == '__main__':
    main()

fib.bt

#!/usr/bin/env bpftrace

uprobe:./fib:fib {
    printf(">,%d,%d,%d,%d\n", arg0, elapsed / 1000, pid, tid);
}

uretprobe:./fib:fib {
    printf("<,%d,%d,%d,%d\n", retval, elapsed / 1000, pid, tid);
}

fib.c

#include <stdio.h>

int fib(int n)
{
    return n < 2 ? n : fib(n - 1) + fib(n - 2);
}

void main(void)
{
    int n = 4;
    int res = fib(n);
    printf("fib(%d) = %d\n", n, res);
}

fib.go

package main

import (
    "fmt"
)

func fib(n int) int {
    if n < 2 {
        return n
    }
    return fib(n - 1) + fib(n - 2)
}

func main() {
    n := 4
    res := fib(n)
    fmt.Printf("fib(%d) = %d\n", n, res)
}

trace.json

[{"ph": "B", "name": "fib(4)", "ts": 4292644, "pid": 3837, "tid": 3837, "args": {"arg0": 4}}, {"ph": "B", "name": "fib(3)", "ts": 4292918, "pid": 3837, "tid": 3837, "args": {"arg0": 3}}, {"ph": "B", "name": "fib(2)", "ts": 4294835, "pid": 3837, "tid": 3837, "args": {"arg0": 2}}, {"ph": "B", "name": "fib(1)", "ts": 4295346, "pid": 3837, "tid": 3837, "args": {"arg0": 1}}, {"ph": "E", "name": "", "ts": 4295570, "pid": 3837, "tid": 3837, "args": {"ret": 1}}, {"ph": "B", "name": "fib(0)", "ts": 4295779, "pid": 3837, "tid": 3837, "args": {"arg0": 0}}, {"ph": "E", "name": "", "ts": 4295998, "pid": 3837, "tid": 3837, "args": {"ret": 0}}, {"ph": "E", "name": "", "ts": 4296198, "pid": 3837, "tid": 3837, "args": {"ret": 1}}, {"ph": "B", "name": "fib(1)", "ts": 4296381, "pid": 3837, "tid": 3837, "args": {"arg0": 1}}, {"ph": "E", "name": "", "ts": 4296637, "pid": 3837, "tid": 3837, "args": {"ret": 1}}, {"ph": "E", "name": "", "ts": 4296835, "pid": 3837, "tid": 3837, "args": {"ret": 2}}, {"ph": "B", "name": "fib(2)", "ts": 4296996, "pid": 3837, "tid": 3837, "args": {"arg0": 2}}, {"ph": "B", "name": "fib(1)", "ts": 4297213, "pid": 3837, "tid": 3837, "args": {"arg0": 1}}, {"ph": "E", "name": "", "ts": 4297470, "pid": 3837, "tid": 3837, "args": {"ret": 1}}, {"ph": "B", "name": "fib(0)", "ts": 4297632, "pid": 3837, "tid": 3837, "args": {"arg0": 0}}, {"ph": "E", "name": "", "ts": 4297887, "pid": 3837, "tid": 3837, "args": {"ret": 0}}, {"ph": "E", "name": "", "ts": 4298044, "pid": 3837, "tid": 3837, "args": {"ret": 1}}, {"ph": "E", "name": "", "ts": 4298331, "pid": 3837, "tid": 3837, "args": {"ret": 3}}]

trace.jsonl

{"type": "attached_probes", "data": {"probes": 2}}
{"type": "printf", "data": ">,4,4292644,3837,3837\n"}
{"type": "printf", "data": ">,3,4292918,3837,3837\n"}
{"type": "printf", "data": ">,2,4294835,3837,3837\n"}
{"type": "printf", "data": ">,1,4295346,3837,3837\n"}
{"type": "printf", "data": "<,1,4295570,3837,3837\n"}
{"type": "printf", "data": ">,0,4295779,3837,3837\n"}
{"type": "printf", "data": "<,0,4295998,3837,3837\n"}
{"type": "printf", "data": "<,1,4296198,3837,3837\n"}
{"type": "printf", "data": ">,1,4296381,3837,3837\n"}
{"type": "printf", "data": "<,1,4296637,3837,3837\n"}
{"type": "printf", "data": "<,2,4296835,3837,3837\n"}
{"type": "printf", "data": ">,2,4296996,3837,3837\n"}
{"type": "printf", "data": ">,1,4297213,3837,3837\n"}
{"type": "printf", "data": "<,1,4297470,3837,3837\n"}
{"type": "printf", "data": ">,0,4297632,3837,3837\n"}
{"type": "printf", "data": "<,0,4297887,3837,3837\n"}
{"type": "printf", "data": "<,1,4298044,3837,3837\n"}
{"type": "printf", "data": "<,3,4298331,3837,3837\n"}