Class Job

java.lang.Object
  |
  +--Job

public class Job

extends java.lang.Object

A Job represents one customer of services. It records the job's current state as well as statistics about its lifetime. It generally spends its lifetime moving form Server to Server.

One Job is created from each line of the input trace file.

The resources required by a Job are characterized by an amount `cpuNeeded' of CPU time (all times are in milliseconds) and a number `ioNeeded' of I/O operations, each representing one disk transfer of Sim.BLOCKSIZE bytes of data. The CPU time is assumed to be distributed as evenly as possible into ioNeeded "bursts" of cpu time, each followed by an I/O operation (unless the job does no I/O at all).

Note the terminology: A "burst" is the amount of computing a Job wants to do before choosing to do I/O. Depending on the CPU scheduing algorithm in force, these bursts may be divided into "quanta" (plural of "quantum").

Field Summary

static int	BLOCKED State value indicating that the Job needs to do an I/O operation next
int	burstStart Time when current burst started (job "arrived" at the cpu queue)
static int	DONE State value indicating that the Job has completed
static int	READY State value indicating that the Job is ready to run
java.lang.Object	schedulerInfo A place for the scheduler to store arbitrary info about this Job.

Constructor Summary

Job(java.io.BufferedReader traceFile)
Creates a Job from a line of the trace file.

Method Summary

int	arrivalTime() Indicates when this Job first arrived in the system.
int	burstRemaining() Returns the amount of CPU time remaining for this job until it next blocks for I/O or completes.
int	burstUsed() Indicates the amount of CPU time has this job used since the start of the burst (not including overhead).
int	currentBurst() Indicates the total length of the current burst.
void	doIO() Called by the simulator when this Job does an I/O operation
JobStats	finish() This job is finished.
void	startJob() Called by the simulator when this Job is started running on the CPU
int	state() Indicates the current state of this Job.
void	stopJob() Called by the simulator when this Job is removed from the CPU
java.lang.String	toString() For debugging, information about this Job.
void	updateRemaining() Called when an accurate value of the remaining time for this job is needed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DONE

public static final int DONE

State value indicating that the Job has completed

BLOCKED

public static final int BLOCKED

State value indicating that the Job needs to do an I/O operation next

READY

public static final int READY

State value indicating that the Job is ready to run

burstStart

public int burstStart

Time when current burst started (job "arrived" at the cpu queue)

schedulerInfo

public java.lang.Object schedulerInfo

A place for the scheduler to store arbitrary info about this Job.

Constructor Detail

Job

public Job(java.io.BufferedReader traceFile)
    throws java.io.EOFException

Creates a Job from a line of the trace file.

Parameters:

traceFile - the file to read from.

Method Detail

toString

public java.lang.String toString()

For debugging, information about this Job.

Overrides:

toString in class java.lang.Object

Returns:

information about the Job: If Sim.debugLevel() >= 2,

      job jobnumber[arrival-time; cpu; io]
      where cpu = total/remaining/burst-remaining
      and io = total/remaining
 

otherwise, just the serial number.

state

public int state()

Indicates the current state of this Job.

Returns:

READY, BLOCKED, or DONE

arrivalTime

public int arrivalTime()

Indicates when this Job first arrived in the system.

Returns:

arrival time (in ms since startup)

currentBurst

public int currentBurst()

Indicates the total length of the current burst. Note: This is "cheating". In a real system, this information is only available at the end of the burst.

Returns:

the length of the current burst.

burstRemaining

public int burstRemaining()

Returns the amount of CPU time remaining for this job until it next blocks for I/O or completes. Note: This is "cheating". In a real system, there would be no way to figure this out.

Returns:

the remaining time (in milliseconds)

burstUsed

public int burstUsed()

Indicates the amount of CPU time has this job used since the start of the burst (not including overhead). Note: Unlike currentBurst and burstRemaining, this is not cheating.

Returns:

the amount of CPU used since burst start.

startJob

public void startJob()

Called by the simulator when this Job is started running on the CPU

stopJob

public void stopJob()

Called by the simulator when this Job is removed from the CPU

updateRemaining

public void updateRemaining()

Called when an accurate value of the remaining time for this job is needed.

doIO

public void doIO()

Called by the simulator when this Job does an I/O operation

finish

public JobStats finish()

This job is finished. Return some summary statistics.

Returns:

summary statistics.