Example of a decorator that inserts "logs" into `dtruss` output to better help correlate code to syscalls

dtruss_python_example.py

"""
$ sudo dtruss -f -t open python main.py

18564/0xc29254:  open("function-main-start\0", 0x1000000, 0x1B6)                 = -1 Err#2
18564/0xc29254:  open("/anaconda3/lib/python3.6/__pycache__/random.cpython-36.pyc\0", 0x1000000, 0x1B6)          = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/math.cpython-36m-darwin.so\0", 0x0, 0x0)             = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/__pycache__/hashlib.cpython-36.pyc\0", 0x1000000, 0x1B6)                 = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/_hashlib.cpython-36m-darwin.so\0", 0x0, 0x0)                 = 3 0
18564/0xc29254:  open("/anaconda3/lib/libssl.1.0.0.dylib\0", 0x0, 0x0)           = 3 0
18564/0xc29254:  open("/anaconda3/lib/libcrypto.1.0.0.dylib\0", 0x0, 0x0)                = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/_blake2.cpython-36m-darwin.so\0", 0x0, 0x0)          = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/_sha3.cpython-36m-darwin.so\0", 0x0, 0x0)            = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/__pycache__/bisect.cpython-36.pyc\0", 0x1000000, 0x1B6)          = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/_bisect.cpython-36m-darwin.so\0", 0x0, 0x0)          = 3 0
18564/0xc29254:  open("/anaconda3/lib/python3.6/lib-dynload/_random.cpython-36m-darwin.so\0", 0x0, 0x0)          = 3 0
18564/0xc29254:  open("/dev/urandom\0", 0x1000000, 0x2C0EDDF)            = 3 0
18564/0xc29254:  open("function-main-end\0", 0x1000000, 0x1B6)           = -1 Err#2
"""


class strace_mark(object):
    def __init__(self, f, *args, **kwargs):
        self.f = f
        self.args = args
        self.kwargs = kwargs

    def __call__(self):
        try:
            open('function-%s-start' % self.f.__name__, 'r')
        except IOError:
            pass
        ret = self.f(*self.args, **self.kwargs)
        try:
            open('function-%s-end' % self.f.__name__, 'r')
        except IOError:
            pass
        return ret


@strace_mark
def main():
    from random import randint
    print(randint(0, 9))


main()