private Task <MethodBody> OptimizeBodyOrWaitAsync(
IMethod requestedDef,
MethodBodyHolder requestedHolder)
{
lock (graphLock)
{
if (IsActive(requestedDef) || IsComplete(requestedDef))
{
// If the method is already being optimized then we can just
// wait for it to finish. If the method has already been optimized,
// then we're already done.
return(Start(requestedDef));
}
else
{
// The method's not being optimized yet. Claim it by starting its
// optimization process. We'll actually optimize the method once
// we get out of the lock.
Start(requestedDef);
}
}
// Actually optimize the method's body.
return(OptimizeBodyAsync(requestedDef, requestedHolder));
}
private async Task <MethodBody> OptimizeBodyAsync(
IMethod requestedDef,
MethodBodyHolder requestedHolder)
{
// Get the method's initial body.
var body = requestedHolder.Body;
// Create optimization state.
var state = new OptimizationState(requestedDef, this);
// Apply passes from the pipeline until we're done.
foreach (var pass in pipeline)
{
body = await pass.ApplyAsync(body, state);
if (pass.IsCheckpoint)
{
// Update the method body for the method if we've
// reached a checkpoint.
requestedHolder.Body = body;
}
}
requestedHolder.Body = body;
return(body);
}
private Task <MethodBody> OptimizeBodyOrWaitAsync(
IMethod requestedDef,
IMethod requestingDef,
MethodBodyHolder requestedHolder)
{
lock (graphLock)
{
// Make sure that the method that's requesting the dependency
// is marked as started.
Start(requestingDef);
// Get the dependency set for the requesting method.
var requestingDependencies = dependencies[requestingDef];
if (requestingDependencies.Contains(requestedDef) ||
IsComplete(requestedDef))
{
// If the requesting method is already dependent on the
// requested method, then we can just proceed. Ditto for
// methods that are fully optimized already.
return(Start(requestedDef));
}
else if (!IsActive(requestedDef))
{
// Looks like the method simply isn't being optimized yet.
// This will work to our advantage.
requestingDependencies.Add(requestedDef);
// "Start" the requested method's optimization to avoid
// race conditions where two threads try to optimize the
// same method.
Start(requestedDef);
}
else
{
// Okay, so both methods are currently being optimized and the
// requesting method is not yet dependent on the requesting
// method. What we need to figure out now is whether introducing
// a dependency on the requested method would introduce a cycle
// in the dependency graph. Such a cycle means a deadlock, so we
// absolutely cannot let that happen.
if (IsDependentOn(requestingDef, requestedDef))
{
// Introducing a dependency would create a cycle. Return
// the latest version of the requested method's body and
// call it a day.
return(Task.FromResult(requestedHolder.Body));
}
else
{
// Introducing a dependency would not create a cycle. Add the
// dependency and wait for the other method to finish.
requestingDependencies.Add(requestedDef);
return(Start(requestedDef));
}
}
}
// The requested method isn't active yet. We'll just optimize it ourselves.
return(OptimizeBodyAsync(requestedDef, requestedHolder));
}