Package jline.lang.nodes

Class Queue

  • All Implemented Interfaces:
    java.io.Serializable , jline.lang.Copyable 
    
public class Queue
extends ServiceStation implements Serializable

    A queueing station that processes jobs according to various scheduling strategies.

    The Queue node is the fundamental service station in queueing networks. It models a system where jobs wait in a buffer and are processed by one or more servers according to a scheduling strategy. Common examples include CPU schedulers, disk I/O queues, network routers, and service desks.

    Key features:

    • Multiple scheduling strategies: FCFS, PS, LCFS, priority-based, etc.
    • Single or multi-server configurations
    • Load-dependent and class-dependent service rates
    • Support for preemptive and non-preemptive policies
    • Polling server capabilities with various polling types
    • Switchover times between job classes
    Since:

    1.0

    • Constructor Detail

      • Queue

        Queue(Network model, String name, SchedStrategy schedStrategy)
        Creates a new queueing station with the specified scheduling strategy.
        Parameters:
        model - the network model to add this queue to
        name - the name for this queueing station
        schedStrategy - the scheduling strategy to use (e.g.

      • Queue

        Queue(Network model, String name)
        Creates a new queueing station with default processor sharing (PS) scheduling.
        Parameters:
        model - The network model to add this queue to
        name - The name for this queueing station

    • Method Detail

      • containsJobClass

         boolean containsJobClass(JobClass jobClass)

        Checks whether this queue has a service process configured for the specified job class.

        Parameters:
        jobClass - The job class to check
        Returns:

        true if a service process exists for this job class, false otherwise

      • getSchedPolicy

         SchedStrategyType getSchedPolicy()

        Gets the scheduling policy type (preemptive or non-preemptive).

        Returns:

        The scheduling policy type (PR for preemptive, NP for non-preemptive)

      • getSchedStrategy

         SchedStrategy getSchedStrategy()

        Gets the scheduling strategy used by this queue.

        Returns:

        The scheduling strategy (e.g., FCFS, PS, LCFS, etc.)

      • getSchedStrategyPar

         double getSchedStrategyPar(JobClass jobClass)

        Gets the scheduling strategy parameter for a specific job class.

        For strategies like DPS (Discriminatory Processor Sharing) and GPS (Generalized Processor Sharing), this returns the weight or priority parameter for the job class.

        Parameters:
        jobClass - The job class to get the parameter for
        Returns:

        The scheduling parameter value, or 0.0 if not set

      • getService

         Distribution getService(JobClass jobClass)

        Gets the service time distribution for a specific job class.

        Parameters:
        jobClass - The job class to get the service distribution for
        Returns:

        The service time distribution for this job class

      • printSummary

         void printSummary()

        Prints a summary of this queue's configuration to standard output.

        The summary includes the queue name, service processes for each job class, their mean service times and squared coefficients of variation, number of servers, and output routing configuration.

      • setClassDependence

         void setClassDependence(SerializableFunction<Matrix, Double> beta)

        Sets a class-dependent scaling function for service rates.

        The function takes a matrix representing the number of jobs of each class at the station and returns a scaling factor for the service rate. This enables modeling of systems where service rates depend on the job mix.

        Parameters:
        beta - A function that maps job class populations to a service rate scaling factor

      • setLoadDependence

         void setLoadDependence(Matrix alpha)

        Sets load-dependent service rate scaling factors.

        Each element alpha[n] specifies the service rate scaling when there are n jobs at the station. This enables modeling of systems where performance degrades under load.

        Parameters:
        alpha - A matrix of scaling factors indexed by the number of jobs

      • setNumberOfServers

         void setNumberOfServers(int numberOfServers)

        Sets the number of servers at this queueing station.

        For infinite server (IS) queues, this method has no effect as they always have unlimited servers.

        Parameters:
        numberOfServers - The number of parallel servers (must be positive)

      • setSchedStrategyPar

         void setSchedStrategyPar(JobClass jobClass, double weight)

        Sets the scheduling strategy parameter for a specific job class.

        For weighted scheduling strategies (DPS, GPS, etc.), this sets the weight or priority parameter that determines the job class's share of the service capacity.

        Parameters:
        jobClass - The job class to set the parameter for
        weight - The scheduling parameter value (e.g.

      • setPollingType

         void setPollingType(PollingType pollingType)

        Sets the polling type for this queue (only valid for POLLING scheduling strategy).

        Parameters:
        pollingType - the polling type (GATED, EXHAUSTIVE, or KLIMITED)

      • setPollingType

         void setPollingType(PollingType pollingType, int k)

        Sets the polling type for this queue with K value for K-LIMITED (only valid for POLLING scheduling strategy).

        Parameters:
        pollingType - the polling type (GATED, EXHAUSTIVE, or KLIMITED)
        k - the K value for K-LIMITED polling (ignored for other types)

      • setPollingK

         void setPollingK(int k)

        Sets the K value for K-LIMITED polling (only valid for POLLING scheduling strategy with K-LIMITED type).

        Parameters:
        k - the K value (must be greater than 0)

      • setSwitchover

         void setSwitchover(JobClass jobClass, Distribution switchoverTime)

        Sets the switchover time for a job class (only valid for POLLING scheduling strategy).

        Parameters:
        jobClass - the job class
        switchoverTime - the switchover time distribution

      • setSwitchover

         void setSwitchover(JobClass fromClass, JobClass toClass, Distribution switchoverTime)

        Sets the switchover time from one job class to another (for general scheduling strategies).

        Parameters:
        fromClass - the job class to switch from
        toClass - the job class to switch to
        switchoverTime - the switchover time distribution

      • getSwitchover

         Distribution getSwitchover(JobClass fromClass, JobClass toClass)

        Gets the switchover time from one job class to another.

        Parameters:
        fromClass - the job class to switch from
        toClass - the job class to switch to
        Returns:

        the switchover time distribution, or null if not set

      • getSwitchover

         Distribution getSwitchover(JobClass jobClass)

        Gets the switchover time for a job class (POLLING scheduling strategy).

        Parameters:
        jobClass - the job class
        Returns:

        the switchover time distribution, or null if not set

      • setDelayOff

         void setDelayOff(JobClass jobClass, Distribution setupTime, Distribution delayoffTime)

        Sets the setup time and delay off time for a job class. This is typically used for function-based tasks that have initialization overhead.

        Parameters:
        jobClass - the job class
        setupTime - the setup time distribution
        delayoffTime - the delay off time distribution

      • getSetupTime

         Distribution getSetupTime(JobClass jobClass)

        Gets the setup time distribution for a job class.

        Parameters:
        jobClass - the job class
        Returns:

        the setup time distribution, or null if not set

      • getDelayOffTime

         Distribution getDelayOffTime(JobClass jobClass)

        Gets the delay-off time distribution for a job class.

        Parameters:
        jobClass - the job class
        Returns:

        the delay-off time distribution, or null if not set