/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="index">The zero-based index of the worker.</param>
/// <param name="context">The context the model is traversed in.</param>
/// <param name="stateStack">The state stack that should be used by the worker.</param>
/// <param name="model">The model that the worker should analyze.</param>
public Worker(int index, TraversalContext context, StateStack stateStack, AnalysisModel model)
{
Requires.NotNull(context, nameof(context));
Requires.NotNull(stateStack, nameof(stateStack));
Requires.NotNull(model, nameof(model));
_index = index;
_context = context;
_stateStack = stateStack;
Model = model;
}
/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="stacks"></param>
public LoadBalancer(StateStack[] stacks)
{
_stacks = stacks;
Reset();
}
/// <summary>
/// Splits the work between this instance and the <paramref name="other" /> instance. Returns <c>true</c> to indicate that
/// work has been split; <c>false</c>, otherwise.
/// </summary>
/// <param name="other">The other instance the work should be split with.</param>
public bool SplitWork(StateStack other)
{
Assert.That(CanSplit, "Cannot split the state stack.");
Assert.That(other.FrameCount == 0, "Expected an empty state stack.");
// We go through each frame and split the first frame with more than two states in half
for (var i = 0; i < FrameCount; ++i)
{
other.PushFrame();
switch (_frames[i].Count)
{
// The stack is in an invalid state; clear the other worker's stack and let this worker
// continue; it will clean up its stack and try to split work later
case 0:
other.Clear();
return false;
// We can't split work here, so just push the state to the other worker's stack
case 1:
other.PushState(_states[_frames[i].Offset]);
break;
// We've encountered a frame where we can actually split work; we always split work as early as possible,
// that is, as low on the stack as possible, to hopefully maximize the amount of work passed to the other worker
default:
// Split the states of the frame
var otherCount = _frames[i].Count / 2;
var thisCount = _frames[i].Count - otherCount;
// Add the first otherCount states to the other stack
for (var j = 0; j < otherCount; ++j)
other.PushState(_states[_frames[i].Offset + j]);
// Adjust the count and offset of the frame
_frames[i].Offset += otherCount;
_frames[i].Count = thisCount;
// Find the next splittable frame if this one no longer is
if (thisCount == 1)
UpdateLowestSplittableFrame();
return true;
}
}
// This stack could not be split, so we clear the other's stack and let some other worker try again
other.Clear();
return false;
}