Relative timestamp when real time clock is unavailable

Patent metadata

Field	Value
Publication number	US-9544374-B2
Application number	US-201514609698-A
Country	US
Kind code	B2
Filing date	Jan 30, 2015
Priority date	Mar 31, 2011
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

An operating system or other software resident on an electronic processing device employs aggregated timestamps. In this way timestamps can be generated and compared to one another without the need for a real-time clock with a power backup. Aggregated time includes the last known time that the device synchronized its clock with a reference time available over a network. Aggregated time also includes a relative time value which in part accumulates using a session clock whenever the device is powered-up. When network time becomes available the operating system or other software will use this information to fix up the already generated aggregated timestamps. A comparison of timestamps will most of the time be resolved for stamps generated on the same device and will generally be resolved by comparing time frames when the timestamps being compared are generated by different devices.

First claim

The invention claimed is:

1. An electronic processing device comprising:
a processor;
a network interface configured to communicate with at least one external device;
a system bus communicatively coupling the network interface and the processor;
a session clock operably coupled to the processor, the session clock having circuitry that maintains chronological time when the electronic processing device is powered;
computer readable media communicatively coupled to the processor, the computer readable media storing computer-executable instructions that include an operating system, which when executed by the processor, control operation of the electronic processing device;
persistent memory operably coupled to the processor, the persistent memory storing at least one timestamp generated when a reference time was not available;
timestamp logic coupled to the processor and configured to convert timestamps, generated when a reference time was not available, to time of day timestamps once a reference time is acquired via the network interface.

2. The electronic processing device of claim 1 , wherein the persistent memory is included in the computer readable media.

3. The electronic processing device of claim 1 , wherein the timestamp logic is adapted to generate a timestamp and store the timestamp in the persistent memory.

4. The electronic processing device of claim 3 , wherein the timestamp includes:
information indicative of a most recent time when a reference time was acquired by the electronic processing device via the network interface;
an amount of time that begins with a session following a most recent session in which the reference time was acquired;
a time at which the reference time was acquired after a timestamp was generated when the reference time was not available; and
a system identifier.

5. The electronic processing device of claim 1 , wherein the timestamp logic is adapted to compare a plurality of timestamps stored in the persistent memory.

6. The electronic processing device of claim 1 , wherein the processor is configured by the computer-executable instructions stored in the computer readable media to trigger a timestamp maintenance operation that updates at least one timestamp stored in the persistent memory once a reference time becomes available.

7. The electronic processing device of claim 1 , wherein the session clock includes resettable battery-less clock circuitry for maintaining non-persistent time records.

8. The electronic processing device of claim 7 , wherein the session clock is implemented in a timer of the processor.

9. The electronic processing device of claim 1 , wherein the session clock is implemented in software.

10. The electronic processing device of claim 1 , wherein the timestamp logic is configured to calculate time of day timestamps based on the reference time and an amount of time that has elapsed since each respective timestamp was generated while the reference time was not available.

11. The electronic processing device of claim 1 , wherein the at least one timestamp is a file creation timestamp.

12. The electronic processing device of claim 1 , wherein the reference time is acquired via the network interface using communication in accordance with network time protocol.

13. The electronic processing device of claim 2 , wherein the reference time is acquired via the network interface using communication in accordance with simple network time protocol.

14. A computer-implemented method of storing timestamp information, the method comprising:
booting a device having a session clock at a time when the device does not have a network connection;
generating and storing a time record for an event while the device does not have a network connection, the time record including a value generated from the session clock;
establishing a network connection with the device and causing the device to obtain a reference time; and
after obtaining the reference time, using the reference time to update the stored time record to generate a real time value for the time record to indicate a real time of the event.

15. The computer-implemented method of claim 14 , wherein the session clock is a resettable battery-less clock.

16. The computer-implemented method of claim 14 , wherein the event is a file creation event.

17. The computer-implemented method of claim 14 , and further comprising comparing a plurality of time records stored while the device does not have a network connection.

18. The computer-implemented method of claim 14 , wherein the updated time record is stored in persistent memory of the device.

19. The computer-implemented method of claim 14 , wherein causing the device to obtain a reference time includes communicating with a remote device through the network connection.

20. The computer-implemented method of claim 19 , wherein the communication with the remote device is in accordance with the network time protocol.

21. The computer-implemented method of claim 19 , wherein the communication with the remote device is in accordance with the simple network time protocol.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Callaghan David
• Karamov Sergey

Classifications

• G06F1/14

  Time supervision arrangements, e.g. real time clock · CPC title

• H04L41/0686 Primary

  Additional information in the notification, e.g. enhancement of specific meta-data · CPC title

• H04L67/142 Primary

  Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms · CPC title

• H04L67/1095

  Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes · CPC title