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

      • getServerTypes

         List<ServerType> getServerTypes()

        Gets the list of server types configured for this queue.

        Returns:

        a new list containing the server types

      • setHeteroSchedPolicy

         void setHeteroSchedPolicy(HeteroSchedPolicy policy)

        Sets the scheduling policy for heterogeneous servers.

        This policy determines how jobs are assigned to server types when a job's class is compatible with multiple server types.

        Parameters:
        policy - the heterogeneous scheduling policy

      • getImmediateFeedbackClasses

         Set<Integer> getImmediateFeedbackClasses()

        Gets the set of class indices with immediate feedback enabled.

        Returns:

        set of class indices, or null if none are set

      • 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

      • setJointDependence

         void setJointDependence(Matrix scalingTable, Matrix cutoffs)

        Sets joint class-dependent scaling for service rates using a lookup table.

        The scaling table is indexed by the per-class population vector (n1, n2, ..., nR) and returns the service rate scaling factor for that state. The table is stored in linearized form with index = n1 + n2*(N1+1) + n3*(N1+1)*(N2+1) + ...

        Parameters:
        scalingTable - Linearized lookup table for (n1, n2, ...
        cutoffs - Per-class cutoffs [N1, N2, ...

      • setJointDependence

         void setJointDependence(Matrix scalingTable)

        Sets joint class-dependent scaling with auto-computed cutoffs.

        Cutoffs are automatically computed using the formula: ceil(6000^(1/(M*K))) where M is the number of stations and K is the number of classes.

        Parameters:
        scalingTable - Linearized lookup table for (n1, n2, ...

      • setJointClassDependence

         void setJointClassDependence(Map<JobClass, Matrix> scalingTables, Matrix cutoffs)

        Sets per-class joint class-dependent scaling for service rates.

        Unlike setJointDependence which uses a single scaling factor for all classes, this method allows each class to have its own scaling table indexed by the per-class population vector (n1, n2, ..., nK).

        This is essential for Flow-Equivalent Server (FES) aggregation where the service rate for class c in state (n1,...,nK) equals the throughput of class c in an isolated subnetwork.

        Parameters:
        scalingTables - Map from JobClass to linearized scaling table
        cutoffs - Per-class cutoffs [N1, N2, ...

      • 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.

      • setLimit

         void setLimit(int limit)

        Sets the maximum number of jobs for LPS scheduling. For LPS: limit is the max number of jobs that can execute in PS mode.

        Parameters:
        limit - the maximum number of concurrent jobs in PS mode

      • 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

      • isDelayOffEnabled

         boolean isDelayOffEnabled()

        Checks if this queue has delay-off times enabled. Delay-off is considered enabled if any job class has both a setup time and a delay-off time distribution configured.

        Returns:

        true if delay-off is enabled, false otherwise

      • addServerType

         void addServerType(ServerType serverType)

        Adds a server type to this queue for heterogeneous multiserver configuration.

        When server types are added, the queue becomes a heterogeneous multiserver queue where different server types can have different service rates and serve different subsets of job classes.

        The total number of servers at this queue becomes the sum of all server type counts.

        Parameters:
        serverType - the server type to add

      • getNumServerTypes

         int getNumServerTypes()

        Gets the number of server types configured for this queue.

        Returns:

        the number of server types, or 0 if homogeneous

      • isHeterogeneous

         boolean isHeterogeneous()

        Checks if this queue is configured as a heterogeneous multiserver queue.

        Returns:

        true if server types are defined, false for homogeneous queue

      • setService

         void setService(JobClass jobClass, ServerType serverType, Distribution distribution)

        Sets the service time distribution for a specific job class and server type.

        This method is used for heterogeneous multiserver queues where different server types may have different service rates for the same job class.

        Parameters:
        jobClass - the job class
        serverType - the server type
        distribution - the service time distribution

      • getService

         Distribution getService(JobClass jobClass, ServerType serverType)

        Gets the service time distribution for a specific job class and server type.

        Parameters:
        jobClass - the job class
        serverType - the server type
        Returns:

        the service time distribution, or null if not set

      • getServerType

         ServerType getServerType(int id)

        Gets a server type by its ID.

        Parameters:
        id - the server type ID
        Returns:

        the server type, or null if not found

      • getServerType

         ServerType getServerType(String name)

        Gets a server type by its name.

        Parameters:
        name - the server type name
        Returns:

        the server type, or null if not found

      • validateCompatibility

         boolean validateCompatibility()

        Checks if all job classes have at least one compatible server type.

        This validation is important because in heterogeneous queues, every job class must be able to be served by at least one server type.

        Returns:

        true if all job classes have at least one compatible server type

      • setImmediateFeedback

         void setImmediateFeedback(boolean enabled)

        Enables or disables immediate feedback for all job classes at this queue. When enabled, jobs that self-loop at this station stay in service instead of rejoining the queue.

        Parameters:
        enabled - true to enable immediate feedback for all classes, false to disable

      • setImmediateFeedback

         void setImmediateFeedback(JobClass jobClass)

        Enables immediate feedback for a specific job class at this queue.

        Parameters:
        jobClass - the job class to enable immediate feedback for

      • setImmediateFeedbackForClasses

         void setImmediateFeedbackForClasses(List<JobClass> jobClasses)

        Enables immediate feedback for multiple job classes at this queue.

        Parameters:
        jobClasses - list of job classes to enable immediate feedback for

      • hasImmediateFeedback

         boolean hasImmediateFeedback()

        Checks if immediate feedback is enabled for any class at this queue.

        Returns:

        true if immediate feedback is enabled for at least one class

      • hasImmediateFeedback

         boolean hasImmediateFeedback(int classId)

        Checks if immediate feedback is enabled for a specific class at this queue.

        Parameters:
        classId - the class index (0-based)
        Returns:

        true if immediate feedback is enabled for the specified class

      • isImmediateFeedbackAll

         boolean isImmediateFeedbackAll()

        Checks if immediate feedback is enabled for all classes.

        Returns:

        true if immediate feedback is enabled for all classes