/// <summary>
/// Enumerates GCRoots of a given object. Similar to !gcroot.
/// </summary>
/// <param name="target">The target object to search for GC rooting.</param>
/// <param name="unique">Whether to only return fully unique paths.</param>
/// <param name="cancelToken">A cancellation token to stop enumeration.</param>
/// <returns>An enumeration of all GC roots found for target.</returns>
public IEnumerable <RootPath> EnumerateGCRoots(ulong target, bool unique, CancellationToken cancelToken)
{
_heap.BuildDependentHandleMap(cancelToken);
long totalObjects = _heap.TotalObjects;
long lastObjectReported = 0;
bool parallel = AllowParallelSearch && IsFullyCached && _maxTasks > 0;
Task <Tuple <LinkedList <ClrObject>, ClrRoot> >[] tasks;
ObjectSet processedObjects;
Dictionary <ulong, LinkedListNode <ClrObject> > knownEndPoints = new Dictionary <ulong, LinkedListNode <ClrObject> >();
if (parallel)
{
processedObjects = new ParallelObjectSet(_heap);
}
else
{
processedObjects = new ObjectSet(_heap);
}
int initial = 0;
tasks = new Task <Tuple <LinkedList <ClrObject>, ClrRoot> > [_maxTasks];
foreach (ClrHandle handle in _heap.EnumerateStrongHandles())
{
Debug.Assert(handle.HandleType != HandleType.Dependent);
Debug.Assert(handle.Object != 0);
if (processedObjects.Contains(handle.Object))
{
continue;
}
Debug.Assert(_heap.GetObjectType(handle.Object) == handle.Type);
if (parallel)
{
var task = PathToParallel(processedObjects, knownEndPoints, handle, target, unique, cancelToken);
if (initial < tasks.Length)
{
tasks[initial++] = task;
}
else
{
int i = Task.WaitAny(tasks);
var completed = tasks[i];
tasks[i] = task;
if (completed.Result.Item1 != null)
{
yield return new RootPath()
{
Root = completed.Result.Item2, Path = completed.Result.Item1.ToArray()
}
}
;
}
}
else
{
var path = PathTo(processedObjects, knownEndPoints, new ClrObject(handle.Object, handle.Type), target, unique, false, cancelToken).FirstOrDefault();
if (path != null)
{
yield return new RootPath()
{
Root = GetHandleRoot(handle), Path = path.ToArray()
}
}
;
}
ReportObjectCount(processedObjects.Count, ref lastObjectReported, totalObjects);
}
foreach (ClrRoot root in _heap.EnumerateStackRoots())
{
if (!processedObjects.Contains(root.Object))
{
Debug.Assert(_heap.GetObjectType(root.Object) == root.Type);
if (parallel)
{
var task = PathToParallel(processedObjects, knownEndPoints, root, target, unique, cancelToken);
if (initial < tasks.Length)
{
tasks[initial++] = task;
}
else
{
int i = Task.WaitAny(tasks);
var completed = tasks[i];
tasks[i] = task;
if (completed.Result.Item1 != null)
{
yield return new RootPath()
{
Root = completed.Result.Item2, Path = completed.Result.Item1.ToArray()
}
}
;
}
}
else
{
var path = PathTo(processedObjects, knownEndPoints, new ClrObject(root.Object, root.Type), target, unique, false, cancelToken).FirstOrDefault();
if (path != null)
{
yield return new RootPath()
{
Root = root, Path = path.ToArray()
}
}
;
}
ReportObjectCount(processedObjects.Count, ref lastObjectReported, totalObjects);
}
}
foreach (Tuple <LinkedList <ClrObject>, ClrRoot> result in WhenEach(tasks))
{
ReportObjectCount(processedObjects.Count, ref lastObjectReported, totalObjects);
yield return(new RootPath()
{
Root = result.Item2, Path = result.Item1.ToArray()
});
}
ReportObjectCount(totalObjects, ref lastObjectReported, totalObjects);
}
/// <summary>
/// Enumerates GCRoots of a given object. Similar to !gcroot.
/// </summary>
/// <param name="target">The target object to search for GC rooting.</param>
/// <param name="unique">Whether to only return fully unique paths.</param>
/// <param name="maxDegreeOfParallelism">The number of threads this class is allowed to use to calculate the result.
/// Setting this to 1 will cause the algorithm to run on the current thread.</param>
/// <param name="roots">The roots to consider. You can pass ClrMD.</param>
/// <param name="cancellationToken">A cancellation token to stop enumeration.</param>
/// <returns>An enumeration of all GC roots found for target.</returns>
public IEnumerable <GCRootPath> EnumerateGCRoots(ulong target, bool unique, int maxDegreeOfParallelism, IEnumerable <IClrRoot> roots, CancellationToken cancellationToken = default)
{
if (roots is null)
{
throw new ArgumentNullException(nameof(roots));
}
bool parallel = Heap.Runtime.IsThreadSafe && maxDegreeOfParallelism > 1;
Dictionary <ulong, LinkedListNode <ClrObject> > knownEndPoints = new Dictionary <ulong, LinkedListNode <ClrObject> >()
{
{ target, new LinkedListNode <ClrObject>(Heap.GetObject(target)) }
};
if (!parallel)
{
int count = 0;
ObjectSet processedObjects = new ObjectSet(Heap);
foreach (IClrRoot root in roots)
{
LinkedList <ClrObject> path = PathsTo(processedObjects, knownEndPoints, root.Object, target, unique, cancellationToken).FirstOrDefault();
if (path != null)
{
yield return(new GCRootPath(root, path.ToImmutableArray()));
}
if (count != processedObjects.Count)
{
count = processedObjects.Count;
ProgressUpdated?.Invoke(this, count);
}
}
}
else
{
ParallelObjectSet processedObjects = new ParallelObjectSet(Heap);
ConcurrentQueue <GCRootPath> results = new ConcurrentQueue <GCRootPath>();
using BlockingCollection <IClrRoot?> queue = new BlockingCollection <IClrRoot?>();
Thread[] threads = new Thread[Math.Min(maxDegreeOfParallelism, Environment.ProcessorCount)];
for (int i = 0; i < threads.Length; i++)
{
threads[i] = new Thread(() => WorkerThread(queue, results, processedObjects, knownEndPoints, target, all: true, unique, cancellationToken))
{
Name = "GCRoot Worker Thread"
};
threads[i].Start();
}
foreach (IClrRoot root in roots)
{
queue.Add(root);
}
// Add one sentinal value for every thread
for (int i = 0; i < threads.Length; i++)
{
queue.Add(null);
}
int count = 0;
// Worker threads end when they have run out of roots to process. While we are waiting for them to exit, yield return
// any results they've found. We'll use a 100 msec timeout because processing roots is slooooow and finding a root is
// rare. There's no reason to check these results super quickly and starve worker threads.
for (int i = 0; i < threads.Length; i++)
{
while (!threads[i].Join(100))
{
while (results.TryDequeue(out GCRootPath result))
{
yield return(result);
}
}
if (count != processedObjects.Count)
{
count = processedObjects.Count;
ProgressUpdated?.Invoke(this, count);
}
}
// We could have raced to put an object in the results queue while joining the last thread, so we need to drain the
// results queue one last time.
while (results.TryDequeue(out GCRootPath result))
{
yield return(result);
}
if (count != processedObjects.Count)
{
count = processedObjects.Count;
ProgressUpdated?.Invoke(this, count);
}
}
}
