/// <summary>
/// Classifies how the transition set must be updated.
/// </summary>
private void ClassifyActivatedFaults(FaultSet activatedFaults, int faultIndex, out bool addTransition, out bool addFaults,
out bool cleanupTransitions)
{
addFaults = false;
cleanupTransitions = false;
// Basic invariant of the fault list: it contains only sets of activation-minimal faults
while (faultIndex != -1)
{
var faultSet = &_faults[faultIndex];
faultIndex = faultSet->NextSet;
// If the fault set is a subset of the activated faults, the current transition is not activation-minimal;
// we can therefore safely ignore the transition; due to the list invariant, none of the remaining
// fault sets in the list can be a superset of the activated faults because then the current fault set
// would also be a subset of that other fault set, violating the invariant
if (faultSet->ActivatedFaults.IsSubsetOf(activatedFaults))
{
addTransition = faultSet->ActivatedFaults == activatedFaults;
return;
}
// If at least one of the previously added transitions that we assumed to be activation-minimal is
// in fact not activation-minimal, we have to clean up the transition set
if (activatedFaults.IsSubsetOf(faultSet->ActivatedFaults))
{
cleanupTransitions = true;
}
}
// If we get here, we must add the faults and the transition
addTransition = true;
addFaults = true;
}
/// <summary>
/// Adds the <paramref name="successorState" /> to the transition set if neccessary, reached using the
/// <paramref name="activatedFaults" />.
/// </summary>
/// <param name="successorState">The successor state that should be added.</param>
/// <param name="activatedFaults">The faults activated by the transition to reach the state.</param>
private bool Add(byte *successorState, FaultSet activatedFaults)
{
var hash = MemoryBuffer.Hash(successorState, _stateVectorSize, 0);
for (var i = 1; i < ProbeThreshold; ++i)
{
var stateHash = MemoryBuffer.Hash((byte *)&hash, sizeof(int), i * 8345723) % _capacity;
var faultIndex = _lookup[stateHash];
// If we don't know the state yet, set everything up and add the transition
if (faultIndex == -1)
{
_successors.Add((uint)stateHash);
AddFaultMetadata(stateHash, activatedFaults, -1);
MemoryBuffer.Copy(successorState, _hashedStateMemory + stateHash * _stateVectorSize, _stateVectorSize);
return(true);
}
// If there is a hash conflict, try again
if (!MemoryBuffer.AreEqual(successorState, _hashedStateMemory + stateHash * _stateVectorSize, _stateVectorSize))
{
continue;
}
// The transition has an already-known target state; it might have to be added or invalidate previously found transitions
return(UpdateTransitions(stateHash, activatedFaults, faultIndex));
}
throw new OutOfMemoryException(
"Failed to find an empty hash table slot within a reasonable amount of time. Try increasing the successor state capacity.");
}
/// <summary>
/// Adds a transition to the <paramref name="model" />'s current state.
/// </summary>
/// <param name="model">The model the transition should be added for.</param>
public void Add(RuntimeModel model)
{
++ComputedTransitionCount;
// 1. Serialize the model's computed state; that is the successor state of the transition's source state
// modulo any changes resulting from notifications of fault activations
var successorState = _targetStateMemory + _stateVectorSize * Count;
var activatedFaults = FaultSet.FromActivatedFaults(model.Faults);
model.Serialize(successorState);
// 2. Make sure the transition we're about to add is activation-minimal
if (!Add(successorState, activatedFaults))
{
return;
}
// 3. Execute fault activation notifications and serialize the updated state if necessary
if (model.NotifyFaultActivations())
{
model.Serialize(successorState);
}
// 4. Store the transition
_transitions[Count] = new Transition
{
TargetState = successorState,
Formulas = new StateFormulaSet(_formulas),
IsValid = true,
};
++Count;
}
/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="serializedData">The serialized data describing the model.</param>
/// <param name="stateHeaderBytes">
/// The number of bytes that should be reserved at the beginning of each state vector for the model checker tool.
/// </param>
internal RuntimeModel(SerializedRuntimeModel serializedData, int stateHeaderBytes = 0)
{
Requires.That(serializedData.Model != null, "Expected a valid model instance.");
var buffer = serializedData.Buffer;
var rootComponents = serializedData.Model.Roots;
var objectTable = serializedData.ObjectTable;
var formulas = serializedData.Formulas;
Requires.NotNull(buffer, nameof(buffer));
Requires.NotNull(rootComponents, nameof(rootComponents));
Requires.NotNull(objectTable, nameof(objectTable));
Requires.NotNull(formulas, nameof(formulas));
Requires.That(stateHeaderBytes % 4 == 0, nameof(stateHeaderBytes), "Expected a multiple of 4.");
Model = serializedData.Model;
SerializedModel = buffer;
RootComponents = rootComponents.Cast <Component>().ToArray();
Faults = objectTable.OfType <Fault>().Where(fault => fault.Activation == Activation.Nondeterministic && fault.IsUsed).ToArray();
ActivationSensitiveFaults = Faults.Where(fault => fault.RequiresActivationNotification).ToArray();
StateFormulas = objectTable.OfType <StateFormula>().ToArray();
Formulas = formulas;
// Create a local object table just for the objects referenced by the model; only these objects
// have to be serialized and deserialized. The local object table does not contain, for instance,
// the closure types of the state formulas
var objects = Model.ReferencedObjects;
var deterministicFaults = objectTable.OfType <Fault>().Where(fault => fault.Activation != Activation.Nondeterministic);
_serializedObjects = new ObjectTable(objects.Except(deterministicFaults, ReferenceEqualityComparer <object> .Default));
Objects = objectTable;
StateVectorLayout = SerializationRegistry.Default.GetStateVectorLayout(Model, _serializedObjects, SerializationMode.Optimized);
_deserialize = StateVectorLayout.CreateDeserializer(_serializedObjects);
_serialize = StateVectorLayout.CreateSerializer(_serializedObjects);
_restrictRanges = StateVectorLayout.CreateRangeRestrictor(_serializedObjects);
_stateHeaderBytes = stateHeaderBytes;
PortBinding.BindAll(objectTable);
_choiceResolver = new ChoiceResolver(objectTable);
ConstructionState = new byte[StateVectorSize];
fixed(byte *state = ConstructionState)
{
Serialize(state);
_restrictRanges();
}
FaultSet.CheckFaultCount(Faults.Length);
StateFormulaSet.CheckFormulaCount(StateFormulas.Length);
}
/// <summary>
/// Adds the fault metadata of the current transition.
/// </summary>
private void AddFaultMetadata(long stateHash, FaultSet activatedFaults, int nextSet)
{
if (_nextFaultIndex >= _capacity)
{
throw new OutOfMemoryException("Out of memory. Try increasing the successor state capacity.");
}
_faults[_nextFaultIndex] = new FaultSetInfo
{
ActivatedFaults = activatedFaults,
NextSet = nextSet,
Transition = &_transitions[Count]
};
_lookup[stateHash] = _nextFaultIndex;
_nextFaultIndex++;
}
/// <summary>
/// Adds the current transition if it is activation-minimal. Previously found transition might have to be removed if they are
/// no longer activation-minimal.
/// </summary>
private bool UpdateTransitions(long stateHash, FaultSet activatedFaults, int faultIndex)
{
bool addTransition;
bool addFaults;
bool cleanupTransitions;
ClassifyActivatedFaults(activatedFaults, faultIndex, out addTransition, out addFaults, out cleanupTransitions);
if (cleanupTransitions)
{
CleanupTransitions(activatedFaults, faultIndex, stateHash);
}
if (addFaults)
{
AddFaultMetadata(stateHash, activatedFaults, _lookup[stateHash]);
}
return(addTransition);
}
/// <summary>
/// Removes all transitions that are no longer activation minimal due to the current transition.
/// </summary>
private void CleanupTransitions(FaultSet activatedFaults, int faultIndex, long stateHash)
{
var current = faultIndex;
var nextPointer = &_lookup[stateHash];
while (current != -1)
{
var faultSet = &_faults[current];
// Remove the fault set and the corresponding transition if it is a proper subset of the activated faults
if (activatedFaults.IsSubsetOf(faultSet->ActivatedFaults) && activatedFaults != faultSet->ActivatedFaults)
{
faultSet->Transition->IsValid = false;
*nextPointer = faultSet->NextSet;
}
if (nextPointer != &_lookup[stateHash])
{
nextPointer = &faultSet->NextSet;
}
current = faultSet->NextSet;
}
}
