139 lines
2.1 KiB
Markdown
139 lines
2.1 KiB
Markdown
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```c
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/*
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Finish the specification of this reservation concept,
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including its events, scenarios, and operational principles.
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*/
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sig Resource {}
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sig User {
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var reservations : set Resource
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}
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var sig Available in Resource {}
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pred reserve[u : User, r : Resource] {
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r in Available
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Available ' = Available - r
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u.reservations ' = u.reservations + r
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all x:User-u | x.reservations' = x.reservations
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}
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pred cancel[u : User, r : Resource] {
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// Cancel a reservation
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}
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pred use[u : User, r : Resource] {
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// Use a reserved resource
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}
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pred cleanup {
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// Make all used resources available again
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}
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pred stutter {
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Available' = Available
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reservations' = reservations
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}
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fact {
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Available = Resource
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no reservations
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always {
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stutter
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or
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cleanup
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or
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(some u : User , r : Resource| reserve[u,r] or cancel[u,r] or use[u,r])
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}
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}
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// Validation
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run Example {
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// Empty run to be used for simulation
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}
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run Scenario1 {
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// An user reserves a resource, uses it, and finally a cleanup occurs
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} expect 1
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run Scenario2 {
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// An user reserves a resource, cancels the reservation, and reserves again
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} expect 1
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run Scenario3 {
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// An user reserves two resources, cancels one, uses the other, and finally a cleanup occurs
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} expect 1
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run Scenario4 {
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// Two users try to reserve the same resource
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} expect 0
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run Scenario5 {
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// Eventually a cleanup is performed twice in a row
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} expect 0
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// Verification
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check OP1 {
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// Reserved resources aren't available
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}
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check OP2 {
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// Used resources were reserved before
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}
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check OP3 {
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// Used resourcse can only be reserved again after a cleanup
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}
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check OP4 {
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// After a cleanup all unreserved resources are available
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}
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check OP5 {
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// Cancel undoes reserve
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}
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check OP6 {
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// If a cleanup occurs some resource was used before
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}
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check OP7 {
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// Used resource were not canceled since being reserved
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}
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check OP8 {
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// Reserved resources can be used while not used or cenceled
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}
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check OP9 {
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// The first event to occur will be a reservation
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}
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check OP10 {
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// If cleanups and cancels never occur the available resources keep diminishing
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}
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```
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