Algorithm 2 Adjust thread sleep time (ATST) algorithm, which is used to dynamically change the length of sleep time of a thread

Input: current data transmission interval transInterval, which is a double precision number time interval that the database storing sensor data transmission frequencies is queried

queryDBInterval, which is double precision number total time a thread has slept for sleptTime, which is a double precision number database connection string connectionString sensor identification sensorid

Output: void

Use: GetSqlConnection(connectionString) to get a database connection object using the given connection string

CloseSqlConnection(conn) to close the database connection that connection object conn holds to release database resource

GetTransIntervalBySensorID(conn, sensorID) to get sensor data transmission interval from database

GetQueryDBIntervalFromCfg() to get database query interval from external configuration file

ThreadSleep(timeInterval) to make a thread sleep for time timeInterval

Declare: None

Begin:

1:If (indicationInterval <= queryDBInterval) then

2:{ThreadSleep(transInterval);}

3:Else

4:{ThreadSleep(queryDBInterval);

5: conn = GetSqlConnection(connectionString);

6: double newTransInterval = 0.0;

7: If (conn! = null) then

8: {newTransInterval= GetTransIntervalBySensorID(conn, sensorid);

9: CloseSqlConnection(conn);}

10: End If

11: sleptTime = sleptTime + queryDBInterval;

12: If (newTransInterval > sleptTime) then

13: {newTransInterval = newTransInterval- sleptTime;

14: queryDBInterval = GetQueryDBIntervalFromCfg();

15: ATST(newTransInterval, queryDBInterval, sleptTime, connectionString, sensorid);}

16: End If}

17:End If

End