Of course! Here’s a comprehensive guide to using gettimeofday in Python, covering the standard library, the best practice for modern applications, and the underlying system call.

TL;DR: The Modern Pythonic Way

For most applications, you should use time.time_ns(). It's the most accurate, portable, and Pythonic way to get high-resolution timestamps.

import time
# Get the current time in nanoseconds since the Unix epoch
# This is the recommended way for modern Python (3.7+)
timestamp_ns = time.time_ns()
print(f"Current time in nanoseconds: {timestamp_ns}")
# You can easily convert it to seconds or other units
timestamp_seconds = timestamp_ns / 1_000_000_000
print(f"Current time in seconds: {timestamp_seconds}")

The time Module: The Standard Library Solution

Python's built-in time module provides high-level functions for time-related operations. While it doesn't have a function explicitly named gettimeofday, it provides equivalent or better functionality.

time.time(): The Classic Choice

This is the most common way to get the current time. It returns a floating-point number representing seconds since the "epoch" (January 1, 1970, 00:00:00 UTC).

• Resolution: Typically microsecond (µs) on Windows and nanosecond (ns) on Linux/macOS.
• Use Case: General-purpose timing, measuring durations, logging events.

import time
# Get the current time in seconds since the epoch
current_time_seconds = time.time()
print(f"Current time (seconds since epoch): {current_time_seconds}")
# Example output: 1678886400.123456

time.time_ns(): The High-Resolution Choice (Recommended)

Available since Python 3.7, this is the best choice for applications needing the highest possible precision.

• Resolution: Nanosecond (ns).
• Use Case: Performance benchmarking, scientific computing, any situation where you need to avoid floating-point inaccuracies and want maximum precision.

import time
# Get the current time in nanoseconds since the epoch
current_time_ns = time.time_ns()
print(f"Current time (nanoseconds since epoch): {current_time_ns}")
# Example output: 1678886400123456789

time.perf_counter(): For Measuring Short Durations

This function returns a high-resolution monotonic clock. It's not tied to the system wall-clock time, so it's perfect for measuring elapsed time (e.g., benchmarking a function). It will not go backward, even if the system time is changed.

• Resolution: Highest available resolution on the system.
• Use Case: Benchmarking, timing how long a piece of code takes to run.

import time
start_time = time.perf_counter()
# --- Do something you want to measure ---
sum = 0
for i in range(1_000_000):
    sum += i
# -----------------------------------------
end_time = time.perf_counter()
elapsed_time = end_time - start_time
print(f"Elapsed time: {elapsed_time:.6f} seconds")

The gettimeofday System Call (Low-Level)

If you specifically need the structure returned by the gettimeofday C function (which includes both seconds and microseconds), you'll need to use a C extension or a library that wraps system calls. The best way to do this in Python is with the ctypes module, which lets you call functions in shared libraries.

gettimeofday in C

The C function signature is:

#include <sys/time.h>
int gettimeofday(struct timeval *tv, struct timezone *tz);

The timeval struct looks like this:

struct timeval {
    long tv_sec;  // seconds
    long tv_usec; // microseconds
};

Python Implementation with ctypes

Here's how you can replicate this functionality in Python.

import ctypes
import ctypes.util
# Define the C timeval structure
class timeval(ctypes.Structure):
    _fields_ = [
        ("tv_sec", ctypes.c_long),      # seconds
        ("tv_usec", ctypes.c_long)      # microseconds
    ]
# Define the timezone structure (often ignored on modern systems)
class timezone(ctypes.Structure):
    _fields_ = [
        ("tz_minuteswest", ctypes.c_int),
        ("tz_dsttime", ctypes.c_int)
    ]
# Find the C library
lib_name = ctypes.util.find_library("c") or ctypes.util.find_library("libc")
if not lib_name:
    raise OSError("Could not find C library")
libc = ctypes.CDLL(lib_name)
# Set the argument types and return type for the gettimeofday function
libc.gettimeofday.argtypes = [ctypes.POINTER(timeval), ctypes.POINTER(timezone)]
libc.gettimeofday.restype = ctypes.c_int
def get_time_of_day():
    """
    Returns a tuple of (seconds, microseconds) since the epoch,
    similar to the C gettimeofday() function.
    """
    tv = timeval()
    tz = timezone()
    # Call the C function
    if libc.gettimeofday(ctypes.byref(tv), ctypes.byref(tz)) != 0:
        # An error occurred
        raise OSError("gettimeofday() failed")
    return tv.tv_sec, tv.tv_usec
# --- Usage ---
seconds, microseconds = get_time_of_day()
print(f"Seconds: {seconds}")
print(f"Microseconds: {microseconds}")
# Combine them into a float, similar to time.time()
time_float = seconds + (microseconds / 1_000_000.0)
print(f"Combined float: {time_float}")

Summary and Comparison

Final Recommendation

• For 99% of use cases: Use time.time_ns() if you need a high-precision integer timestamp, or time.time() if a float is sufficient.
• For benchmarking code: Use time.perf_counter().
• Only use ctypes: If you have a very specific requirement to interact with a C library or application that strictly expects the (seconds, microseconds) tuple format.