Ilia Denisov
90 lines
2.6 KiB
Go
90 lines
2.6 KiB
Go
// Package sessionlimit defines the domain decision shape used for active
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// device-session limit evaluation.
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package sessionlimit
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import (
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"errors"
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"fmt"
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)
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// Kind identifies the coarse outcome of evaluating the active-session limit.
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type Kind string
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const (
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// KindDisabled reports that no configured limit is currently active.
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KindDisabled Kind = "disabled"
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// KindAllowed reports that creating the next session is allowed.
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KindAllowed Kind = "allowed"
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// KindExceeded reports that creating the next session would exceed the
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// configured limit.
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KindExceeded Kind = "exceeded"
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)
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// IsKnown reports whether Kind is one of the session-limit outcomes supported
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// by the current domain model.
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func (k Kind) IsKnown() bool {
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switch k {
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case KindDisabled, KindAllowed, KindExceeded:
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return true
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default:
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return false
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}
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}
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// Decision stores the result of evaluating one possible next session creation.
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type Decision struct {
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// Kind reports the coarse decision outcome.
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Kind Kind
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// ConfiguredLimit stores the active configured limit when one exists.
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ConfiguredLimit *int
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// ActiveSessionCount stores the current active-session count before create.
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ActiveSessionCount int
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// NextSessionCount stores the count that would exist after creating the next
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// session.
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NextSessionCount int
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}
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// Validate reports whether Decision satisfies the Stage-2 structural
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// invariants.
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func (d Decision) Validate() error {
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if !d.Kind.IsKnown() {
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return fmt.Errorf("session-limit decision kind %q is unsupported", d.Kind)
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}
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if d.ActiveSessionCount < 0 {
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return errors.New("session-limit active session count must not be negative")
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}
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if d.NextSessionCount < 0 {
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return errors.New("session-limit next session count must not be negative")
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}
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if d.NextSessionCount != d.ActiveSessionCount+1 {
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return errors.New("session-limit next session count must equal active session count plus one")
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}
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switch d.Kind {
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case KindDisabled:
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if d.ConfiguredLimit != nil {
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return errors.New("disabled session-limit decision must not contain configured limit")
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}
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case KindAllowed, KindExceeded:
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if d.ConfiguredLimit == nil {
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return errors.New("limited session-limit decision must contain configured limit")
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}
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if *d.ConfiguredLimit <= 0 {
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return errors.New("session-limit configured limit must be positive")
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}
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if d.Kind == KindAllowed && d.NextSessionCount > *d.ConfiguredLimit {
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return errors.New("allowed session-limit decision must not exceed configured limit")
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}
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if d.Kind == KindExceeded && d.NextSessionCount <= *d.ConfiguredLimit {
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return errors.New("exceeded session-limit decision must be above configured limit")
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}
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}
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return nil
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}
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