1#!/usr/bin/python 2# 3# nodejs_http_server Basic example of node.js USDT tracing. 4# For Linux, uses BCC, BPF. Embedded C. 5# 6# USAGE: nodejs_http_server PID 7# 8# Copyright 2016 Netflix, Inc. 9# Licensed under the Apache License, Version 2.0 (the "License") 10 11from __future__ import print_function 12from bcc import BPF, USDT 13import sys 14 15if len(sys.argv) < 2: 16 print("USAGE: nodejs_http_server PID") 17 exit() 18pid = sys.argv[1] 19debug = 0 20 21# load BPF program 22bpf_text = """ 23#include <uapi/linux/ptrace.h> 24int do_trace(struct pt_regs *ctx) { 25 uint64_t addr; 26 char path[128]={0}; 27 bpf_usdt_readarg(6, ctx, &addr); 28 bpf_probe_read(&path, sizeof(path), (void *)addr); 29 bpf_trace_printk("path:%s\\n", path); 30 return 0; 31}; 32""" 33 34# enable USDT probe from given PID 35u = USDT(pid=int(pid)) 36u.enable_probe(probe="http__server__request", fn_name="do_trace") 37if debug: 38 print(u.get_text()) 39 print(bpf_text) 40 41# initialize BPF 42b = BPF(text=bpf_text, usdt_contexts=[u]) 43 44# header 45print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "ARGS")) 46 47# format output 48while 1: 49 try: 50 (task, pid, cpu, flags, ts, msg) = b.trace_fields() 51 except ValueError: 52 print("value error") 53 continue 54 print("%-18.9f %-16s %-6d %s" % (ts, task, pid, msg)) 55