timer.py

```python
import time
from functools import wraps

# with 写法
class Timer(object):

def __init__(self, name=""):
        self.name = name
        self.start_time = 0

def __enter__(self):
        self.start_time = time.time()

def __exit__(self, exc_type, exc_val, exc_tb):
        t = round(time.time() - self.start_time, 3)
        print(f"[{self.name}]耗时：{t}s")

# 装饰器写法
def timer(name):
    def wrapper01(func):

@wraps(func)
        def wrapper02(*args, **kwargs):
            t1 = time.time()
            r = func(*args, **kwargs)
            t = round(time.time() - t1, 3)
            print(f"[{name}]耗时：{t}s")
            return r
        return wrapper02
    return wrapper01

# 装饰器写法(二)
class Timer02(object):
    def __init__(self, name):
        self.name = name

def __call__(self, func):
        def wrapper(*args, **kwargs):
            t1 = time.time()
            r = func(*args, **kwargs)
            t = round(time.time() - t1, 3)
            print(f"[{self.name}]耗时：{t}s")
            return r
        return wrapper
```

使用方法：
```
with Timer(name="数据集转换"):
	vaex.open(csv_file_path, convert=dst_file_path)
```

打印结果：
```
[数据集转换]耗时：12.205s
```