systime(8)

Usage

kysdk-systime

Overview

kysdk-systime is a system time monitoring service in the KYLIN SDK system. This service provides real-time system time broadcasting and monitoring capabilities, detecting system time changes and timezone changes, and broadcasting time information through D-Bus signals.

The service runs as a system daemon that continuously monitors the system clock for changes and broadcasts time updates every minute. It also monitors for system time adjustments and timezone changes, ensuring accurate time information is available to all subscribed applications.

Features

`Real-time Time Broadcasting`	Broadcasts current system time every minute through D-Bus signals
`System Time Change Detection`	Monitors and detects system time adjustments using timerfd
`Timezone Change Monitoring`	Monitors changes to system timezone settings using inotify
`D-Bus Signal Broadcasting`	Provides time information through D-Bus signals for inter-process communication
`Precise Timing`	Uses high-precision timers for accurate time synchronization

D-Bus INTERFACE

The service implements the following D-Bus interface `com.kylin.kysdk.TimeInterface` with these signals:

TimeSignal: Emitted every minute with current time information in format: "YYYY/MM/DD HH:MM:SS"

TimeChangeSignal: Emitted when system time or timezone changes, providing updated time information

Monitored events

System Time Changes: Detects manual time adjustments, NTP synchronization, and other time modifications

Timezone Changes: Monitors changes to /etc/localtime for timezone updates

Clock Drift: Handles clock synchronization and drift correction

Threading model

The service uses a multi-threaded architecture:

`Main Thread`	Handles D-Bus communication and main event loop
`Time Change Monitor Thread`	Monitors system time changes using timerfd
`Timezone Monitor Thread`	Monitors timezone changes using inotify
`Time Broadcast Thread`	Manages periodic time broadcasting

Timer system

`Periodic Timer`	Runs every 60 seconds for regular time broadcasting
`Single-shot Timer`	Used for immediate time change notifications
`Timer Synchronization`	Automatically resynchronizes when time changes are detected

Files

/usr/bin/systime: Main executable file

/etc/systemd/system/kysdk-systime.service: Systemd service configuration file

/etc/localtime: Monitored file for timezone changes

Service

The service runs as a systemd service with: - Service name: kysdk-systime.service - D-Bus name: com.kylin.kysdk.TimeServer - Object path: /com/kylin/kysdk/Timer - Interface: com.kylin.kysdk.TimeInterface - Type: D-Bus activated service

Dependencies

`D-Bus`	For inter-process communication
`GLib`	For main loop integration
`libkytimer`	For timer management functionality
`systemd`	For service management

Signal handling

`SIGTERM, SIGINT`	Graceful shutdown signals
`TFD_TIMER_CANCEL_ON_SET`	Special timer flag for detecting time changes

Time formats

All time information is broadcast in the following format: YYYY/MM/DD HH:MM:SS - 4-digit year - 2-digit month (01-12) - 2-digit day (01-31) - 2-digit hour (00-23) - 2-digit minute (00-59) - 2-digit second (00-59)

Synchronization

`Automatic Resync`	Automatically resynchronizes timers when time changes are detected
`Mis-sync Handling`	Detects and corrects timing drift or missed notifications
`Timer Management`	Intelligently manages periodic and single-shot timers