InvariantChecker.scala 3.51 KB
Newer Older
Christian Müller's avatar
Christian Müller committed
1
2
3
4
5
6
7
8
9
package de.tum.workflows.toz3

import de.tum.workflows.blocks._
import de.tum.workflows.foltl.FOLTL._
import de.tum.workflows.ltl.LTL
import de.tum.workflows.Implicits._
import de.tum.workflows.WorkflowParser
import de.tum.workflows.Encoding
import de.tum.workflows.Preconditions
Christian Müller's avatar
Christian Müller committed
10
11
import de.tum.workflows.foltl.Properties.T1
import de.tum.workflows.foltl.Properties.T2
Christian Müller's avatar
Christian Müller committed
12
13
14
15
16
17
18

import scalax.collection.edge.LDiEdge // labeled directed edge
import com.microsoft.z3.Context
import java.util.HashMap
import org.omg.CORBA.TIMEOUT
import com.microsoft.z3.Status
import com.typesafe.scalalogging.LazyLogging
Christian Müller's avatar
Christian Müller committed
19
import de.tum.workflows.foltl.Properties
Christian Müller's avatar
Christian Müller committed
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

object InvariantChecker extends LazyLogging {
  
  val TIMEOUT = 60000 // in milliseconds
  
  def checkOnZ3(f:Formula) = {
      // Set up Z3
      val cfg = new HashMap[String, String]()
      cfg.put("timeout", TIMEOUT.toString())
      val ctx = new Context(cfg)
//      val t = ctx.andThen(ctx.mkTactic("qe"), ctx.mkTactic("smt"))
      val s = ctx.mkSolver()

      s.add(toZ3.translate(f, ctx))
      
      // Send to z3
      val c = s.check()
      if (c == Status.UNKNOWN) {
        logger.info(s"Z3 status unknown: ${s.getReasonUnknown()}")
      }
      if (c == Status.SATISFIABLE) {
        logger.info(s"Z3 model:\n${s.getModel()}")
      }
Christian Müller's avatar
Christian Müller committed
43
      (c, s)
Christian Müller's avatar
Christian Müller committed
44
45
46
47
48
49
50
  }
  
  def checkStubborn(w:Workflow, inv:Formula) = {
    
    // Build graph
    val graph = Encoding.toGraph(w)
    
Christian Müller's avatar
Christian Müller committed
51
    val msg = new StringBuilder()
52
    msg ++= s"Trying to prove safe with invariant:\n\n${inv.pretty()}\n\n"
Christian Müller's avatar
Christian Müller committed
53
    
Christian Müller's avatar
Christian Müller committed
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
    // Check all edges 
    val list = for (e <- graph.edges) yield {
      
      // Check I -> WP[w](inv)
      val b:SimpleBlock = e
      val precond = Preconditions.weakestPrecondition(inv, b)
      
      // Stubborn agents -> remove trace variable from choice predicate
      val stubprecond = precond.everywhere {
        case Fun(f, i, p) if b.may && f == b.pred.get => Fun(f, p)
      }
      
      val f = Implies(inv, stubprecond)
      
      logger.info(s"Checking invariant implication for ${e.label}")
      val tocheck = Neg(f).simplify()
      
Christian Müller's avatar
Christian Müller committed
71
      val (res, solver) = checkOnZ3(tocheck)
Christian Müller's avatar
Christian Müller committed
72
      if (res != Status.UNSATISFIABLE) {
Christian Müller's avatar
Christian Müller committed
73
74
75
76
77
78
79
80
        msg ++= s"Possibly unsafe: Block may not uphold invariant:\n\n${e.label}\n\n"
        if (res == Status.SATISFIABLE) {
          msg ++= "Satisfying model:\n"
          msg ++= toZ3.printModel(solver.getModel())
        } else {
          msg ++= s"Z3 result: $res\n"
        }
        msg ++= "\n"
Christian Müller's avatar
Christian Müller committed
81
82
83
84
85
86
87
88
89
        logger.info(s"Could not prove invariant $inv")
        logger.info(s"Z3 status $res")
        logger.info(s"Block ${e.label} may not uphold it")
      }
      res == Status.UNSATISFIABLE
    }
    
    val safe = list.reduceLeft(_ && _)
    if (safe) {
90
      msg ++= s"Proven safe.\n"
Christian Müller's avatar
Christian Müller committed
91
      logger.info(s"Workflow $w\n proven safe for invariant:\n${inv.pretty()}")
Christian Müller's avatar
Christian Müller committed
92
    }
Christian Müller's avatar
Christian Müller committed
93
    (safe, msg)
Christian Müller's avatar
Christian Müller committed
94
  }
Christian Müller's avatar
Christian Müller committed
95
96
97
98
99
100
101
102
103
104
  
  def genEq(f:Fun, p:List[Var]) = {
    val newf = f.parallelRename(f.params, p)
    Eq(newf.in(T1), newf.in(T2))
  }
  
  def invariantNoninterStubborn(spec:Spec) = {
    val agent = spec.target.params(0)
    
    val premise = And.make(for ((o,t) <- spec.declass) yield {
Christian Müller's avatar
Christian Müller committed
105
106
      // Forall fv(o). (t_T1 or t_t2) -> G (o_T1 <-> o_T2) 
      Forall(o.freeVars().toList, Implies(Or(t.in(T1), t.in(T2)), Eq(o.in(T1), o.in(T2))))
Christian Müller's avatar
Christian Müller committed
107
108
109
110
111
112
113
    })
    
    val conclusion = And.make(for (r <- spec.w.sig.preds.toList if r.params.head.typ == agent.typ) yield {
      val quant = r.params.drop(1)
      Forall(quant, genEq(r, agent::quant))
    })
    
114
    Forall(agent, Implies(premise, conclusion)).simplify()
Christian Müller's avatar
Christian Müller committed
115
  }
Christian Müller's avatar
Christian Müller committed
116
}