Add time utils (#10849)

### What problem does this PR solve?

- Add time utilities and unit tests

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

common/time_utils.py

@@ -0,0 +1,126 @@
+#
+#  Copyright 2024 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import datetime
+import time
+
+def current_timestamp():
+    """
+    Get the current timestamp in milliseconds.
+
+    Returns:
+        int: Current Unix timestamp in milliseconds (13 digits)
+
+    Example:
+        >>> current_timestamp()
+        1704067200000
+    """
+    return int(time.time() * 1000)
+
+
+def timestamp_to_date(timestamp, format_string="%Y-%m-%d %H:%M:%S"):
+    """
+    Convert a timestamp to formatted date string.
+
+    Args:
+        timestamp: Unix timestamp in milliseconds. If None or empty, uses current time.
+        format_string: Format string for the output date (default: "%Y-%m-%d %H:%M:%S")
+
+    Returns:
+        str: Formatted date string
+
+    Example:
+        >>> timestamp_to_date(1704067200000)
+        '2024-01-01 08:00:00'
+    """
+    if not timestamp:
+        timestamp = time.time()
+    timestamp = int(timestamp) / 1000
+    time_array = time.localtime(timestamp)
+    str_date = time.strftime(format_string, time_array)
+    return str_date
+
+
+def date_string_to_timestamp(time_str, format_string="%Y-%m-%d %H:%M:%S"):
+    """
+    Convert a date string to timestamp in milliseconds.
+
+    Args:
+        time_str: Date string to convert
+        format_string: Format of the input date string (default: "%Y-%m-%d %H:%M:%S")
+
+    Returns:
+        int: Unix timestamp in milliseconds
+
+    Example:
+        >>> date_string_to_timestamp("2024-01-01 00:00:00")
+        1704067200000
+    """
+    time_array = time.strptime(time_str, format_string)
+    time_stamp = int(time.mktime(time_array) * 1000)
+    return time_stamp
+
+def datetime_format(date_time: datetime.datetime) -> datetime.datetime:
+    """
+    Normalize a datetime object by removing microsecond component.
+
+    Creates a new datetime object with only year, month, day, hour, minute, second.
+    Microseconds are set to 0.
+
+    Args:
+        date_time: datetime object to normalize
+
+    Returns:
+        datetime.datetime: New datetime object without microseconds
+
+    Example:
+        >>> dt = datetime.datetime(2024, 1, 1, 12, 30, 45, 123456)
+        >>> datetime_format(dt)
+        datetime.datetime(2024, 1, 1, 12, 30, 45)
+    """
+    return datetime.datetime(date_time.year, date_time.month, date_time.day,
+                             date_time.hour, date_time.minute, date_time.second)
+
+
+def get_format_time() -> datetime.datetime:
+    """
+    Get current datetime normalized without microseconds.
+
+    Returns:
+        datetime.datetime: Current datetime with microseconds set to 0
+
+    Example:
+        >>> get_format_time()
+        datetime.datetime(2024, 1, 1, 12, 30, 45)
+    """
+    return datetime_format(datetime.datetime.now())
+
+
+def delta_seconds(date_string: str):
+    """
+    Calculate seconds elapsed from a given date string to now.
+
+    Args:
+        date_string: Date string in "YYYY-MM-DD HH:MM:SS" format
+
+    Returns:
+        float: Number of seconds between the given date and current time
+
+    Example:
+        >>> delta_seconds("2024-01-01 12:00:00")
+        3600.0  # If current time is 2024-01-01 13:00:00
+    """
+    dt = datetime.datetime.strptime(date_string, "%Y-%m-%d %H:%M:%S")
+    return (datetime.datetime.now() - dt).total_seconds()