/// <summary>
/// Initializes a new instance of the <see cref="SnapshotElementIndexer" /> class.
/// </summary>
/// <param name="region">The parent region that contains this element.</param>
/// <param name="elementIndex">The index of the element to begin pointing to.</param>
public unsafe SnapshotElementIndexer(
SnapshotRegion region,
Int32 elementIndex = 0)
{
this.Region = region;
this.ElementIndex = elementIndex;
}
/// <summary>
/// Merges regions in the current list of memory regions using a fast stack based algorithm O(nlogn + n).
/// </summary>
private void MergeAndSortRegions()
{
if (this.SnapshotRegions.IsNullOrEmpty())
{
return;
}
// First, sort by start address
IEnumerable <SnapshotRegion> sortedRegions = this.SnapshotRegions.OrderBy(x => x.BaseAddress.ToUInt64());
// Create and initialize the stack with the first region
Stack <SnapshotRegion> combinedRegions = new Stack <SnapshotRegion>();
combinedRegions.Push(sortedRegions.First());
// Build the remaining regions
foreach (SnapshotRegion region in sortedRegions.Skip(1))
{
SnapshotRegion top = combinedRegions.Peek();
// If the regions do not overlap, the new region is the top region
if (top.EndAddress.ToUInt64() < region.BaseAddress.ToUInt64())
{
combinedRegions.Push(region);
}
// The regions are exactly adjacent; merge them
else if (top.EndAddress.ToUInt64() == region.BaseAddress.ToUInt64())
{
top.RegionSize = region.EndAddress.Subtract(top.BaseAddress).ToUInt64();
// Combine values and labels
top.SetElementLabels(top.ElementLabels?.Concat(region.ElementLabels));
top.SetCurrentValues(top.CurrentValues?.Concat(region.CurrentValues));
top.SetPreviousValues(top.PreviousValues?.Concat(region.PreviousValues));
}
// The regions overlap
else if (top.EndAddress.ToUInt64() <= region.EndAddress.ToUInt64())
{
top.RegionSize = region.EndAddress.Subtract(top.BaseAddress).ToUInt64();
Int32 overlapSize = unchecked ((Int32)(region.EndAddress.ToUInt64() - top.EndAddress.ToUInt64()));
// Overlap has conflicting values, so we prioritize the top region and trim the current region
region.SetElementLabels(region.ElementLabels?.SubArray(overlapSize, region.RegionSize.ToInt32() - overlapSize));
region.SetCurrentValues(region.CurrentValues?.SubArray(overlapSize, region.RegionSize.ToInt32() - overlapSize));
region.SetPreviousValues(region.PreviousValues?.SubArray(overlapSize, region.RegionSize.ToInt32() - overlapSize));
// Combine values and labels
top.SetElementLabels(top.ElementLabels?.Concat(region.ElementLabels));
top.SetCurrentValues(top.CurrentValues?.Concat(region.CurrentValues));
top.SetPreviousValues(top.PreviousValues?.Concat(region.PreviousValues));
}
}
this.SnapshotRegions = combinedRegions.ToList().OrderBy(x => x.BaseAddress.ToUInt64()).ToList();
}
/// <summary>
/// Indexer to allow the retrieval of the element at the specified index. Notes: This does NOT index into a region.
/// </summary>
/// <param name="elementIndex">The index of the snapshot element.</param>
/// <returns>Returns the snapshot element at the specified index.</returns>
public SnapshotElementIndexer this[UInt64 elementIndex]
{
get
{
SnapshotRegion region = this.BinaryRegionSearch(elementIndex);
if (region == null)
{
return(null);
}
return(region[(elementIndex - region.BaseElementIndex).ToInt32()]);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="SnapshotElementComparer" /> class.
/// </summary>
/// <param name="region">The parent region that contains this element.</param>
/// <param name="elementIndex">The index of the element to begin pointing to.</param>
/// <param name="compareActionConstraint">The constraint to use for the element quick action.</param>
/// <param name="compareActionValue">The value to use for the element quick action.</param>
/// <param name="pointerIncrementMode">The method by which to increment element pointers.</param>
public unsafe SnapshotElementComparer(
SnapshotRegion region,
PointerIncrementMode pointerIncrementMode,
ScanConstraintManager scanConstraintManager)
{
this.Region = region;
// The garbage collector can relocate variables at runtime. Since we use unsafe pointers, we need to keep these pinned
this.CurrentValuesHandle = GCHandle.Alloc(this.Region.ReadGroup.CurrentValues, GCHandleType.Pinned);
this.PreviousValuesHandle = GCHandle.Alloc(this.Region.ReadGroup.PreviousValues, GCHandleType.Pinned);
this.InitializePointers();
this.SetConstraintFunctions();
this.SetPointerFunction(pointerIncrementMode);
this.SetCompareAction(scanConstraintManager);
}
/// <summary>
/// Initializes a new instance of the <see cref="SnapshotElementVectorComparer" /> class.
/// </summary>
/// <param name="region">The parent region that contains this element.</param>
/// <param name="vectorSize">The size of vectors on the system.</param>
/// <param name="scanConstraints">The set of constraints to use for the element comparisons.</param>
public unsafe SnapshotElementVectorComparer(
SnapshotRegion region,
ScanConstraintManager scanConstraints)
{
this.Region = region;
this.VectorSize = EngineCore.GetInstance().Architecture.GetVectorSize();
this.VectorReadBase = this.Region.ReadGroupOffset - this.Region.ReadGroupOffset % this.VectorSize;
this.VectorReadIndex = 0;
this.DataTypeSize = Conversions.SizeOf(this.Region.ReadGroup.ElementDataType);
// Initialize capacity to 1/16 elements
this.ResultRegions = new List <SnapshotRegion>(unchecked ((Int32)(this.Region.ElementCount)) / 16);
this.SetConstraintFunctions();
this.SetCompareAction(scanConstraints);
}
/// <summary>
/// Gets the regions in this snapshot with a valid bit set.
/// </summary>
/// <returns>The regions in this snapshot with a valid bit set.</returns>
public IEnumerable <SnapshotRegion> GetValidRegions()
{
List <SnapshotRegion> validRegions = new List <SnapshotRegion>();
Int32 elementSize = this.GetElementSize();
if (this.ValidBits == null)
{
return(validRegions);
}
for (Int32 startIndex = 0; startIndex < this.ValidBits.Length; startIndex += this.Alignment)
{
if (!this.ValidBits[startIndex])
{
continue;
}
// Get the length of this valid segment
Int32 validRegionSize = 0;
do
{
// We only care if the aligned elements are valid
validRegionSize += elementSize;
}while (startIndex + validRegionSize < this.ValidBits.Length && this.ValidBits[startIndex + validRegionSize]);
// Create new subregion from this valid region
SnapshotRegion subRegion = new SnapshotRegion(this.BaseAddress + startIndex, validRegionSize.ToUInt64());
// Ensure region size is worth keeping. This can happen if we grab a misaligned segment
if (subRegion.RegionSize < Conversions.GetTypeSize(this.ElementType).ToUInt64())
{
continue;
}
// Copy the current values and labels.
subRegion.SetCurrentValues(this.CurrentValues.LargestSubArray(startIndex, subRegion.RegionSize.ToInt64()));
subRegion.SetPreviousValues(this.PreviousValues.LargestSubArray(startIndex, subRegion.RegionSize.ToInt64()));
subRegion.SetElementLabels(this.ElementLabels.LargestSubArray(startIndex, subRegion.RegionSize.ToInt64()));
validRegions.Add(subRegion);
startIndex += validRegionSize;
}
this.ValidBits = null;
return(validRegions);
}
/// <summary>
/// Initializes a new instance of the <see cref="SnapshotElementIterator" /> class.
/// </summary>
/// <param name="parent">The parent region that contains this element.</param>
/// <param name="elementIndex">The index of the element to begin pointing to.</param>
/// <param name="compareActionConstraint">The constraint to use for the element quick action.</param>
/// <param name="compareActionValue">The value to use for the element quick action.</param>
/// <param name="pointerIncrementMode">The method by which to increment element pointers.</param>
public unsafe SnapshotElementIterator(
SnapshotRegion parent,
Int32 elementIndex = 0,
PointerIncrementMode pointerIncrementMode = PointerIncrementMode.AllPointers,
ConstraintsEnum compareActionConstraint = ConstraintsEnum.Changed,
Object compareActionValue = null)
{
this.Parent = parent;
// The garbage collector can relocate variables at runtime. Since we use unsafe pointers, we need to keep these pinned
this.CurrentValuesHandle = GCHandle.Alloc(this.Parent.CurrentValues, GCHandleType.Pinned);
this.PreviousValuesHandle = GCHandle.Alloc(this.Parent.PreviousValues, GCHandleType.Pinned);
this.InitializePointers(elementIndex);
this.SetConstraintFunctions();
this.SetPointerFunction(pointerIncrementMode);
this.SetCompareAction(compareActionConstraint, compareActionValue);
}
/// <summary>
/// Combines the given memory regions with the given memory regions, only keeping the common elements of the two in O(nlogn + n).
/// </summary>
/// <param name="otherSnapshot">The snapshot regions to mask the target regions against.</param>
private void Intersect(Snapshot otherSnapshot)
{
List <SnapshotRegion> resultRegions = new List <SnapshotRegion>();
otherSnapshot.MergeAndSortRegions();
IEnumerable <NormalizedRegion> otherRegions = otherSnapshot.GetSnapshotRegions();
if (this.SnapshotRegions.IsNullOrEmpty() || otherRegions.IsNullOrEmpty())
{
this.SnapshotRegions = resultRegions;
return;
}
this.MergeAndSortRegions();
// Initialize stacks with regions and masking regions
Queue <SnapshotRegion> snapshotRegionQueue = new Queue <SnapshotRegion>();
Queue <NormalizedRegion> groundTruthQueue = new Queue <NormalizedRegion>();
// Build candidate region queue from snapshot region array
foreach (SnapshotRegion region in this.SnapshotRegions.OrderBy(x => x.BaseAddress.ToUInt64()))
{
snapshotRegionQueue.Enqueue(region);
}
// Build masking region queue from snapshot
foreach (NormalizedRegion maskRegion in otherRegions.OrderBy(x => x.BaseAddress.ToUInt64()))
{
groundTruthQueue.Enqueue(maskRegion);
}
if (snapshotRegionQueue.Count <= 0 || groundTruthQueue.Count <= 0)
{
this.SnapshotRegions = resultRegions;
return;
}
SnapshotRegion nextSnapshotRegion;
NormalizedRegion groundTruthMask = groundTruthQueue.Dequeue();
while (snapshotRegionQueue.Count > 0)
{
// Grab next region
nextSnapshotRegion = snapshotRegionQueue.Dequeue();
// Grab the next mask following the current region
while (groundTruthMask.EndAddress.ToUInt64() < nextSnapshotRegion.BaseAddress.ToUInt64() && groundTruthQueue.Count > 0)
{
groundTruthMask = groundTruthQueue.Dequeue();
}
// Check for mask completely removing this region
if (groundTruthMask.EndAddress.ToUInt64() < nextSnapshotRegion.BaseAddress.ToUInt64() || groundTruthMask.BaseAddress.ToUInt64() > nextSnapshotRegion.EndAddress.ToUInt64())
{
continue;
}
// Check for mask completely engulfing this region
else if (groundTruthMask.BaseAddress.ToUInt64() <= nextSnapshotRegion.BaseAddress.ToUInt64() && groundTruthMask.EndAddress.ToUInt64() >= nextSnapshotRegion.EndAddress.ToUInt64())
{
resultRegions.Add(nextSnapshotRegion);
continue;
}
// There are no edge cases, we must mask and copy the valid portion of this region
else
{
UInt64 baseAddress = Math.Max(groundTruthMask.BaseAddress.ToUInt64(), nextSnapshotRegion.BaseAddress.ToUInt64());
UInt64 endAddress = Math.Min(groundTruthMask.EndAddress.ToUInt64(), nextSnapshotRegion.EndAddress.ToUInt64());
Int64 baseOffset = unchecked ((Int64)(baseAddress - nextSnapshotRegion.BaseAddress.ToUInt64()));
SnapshotRegion newRegion = new SnapshotRegion(nextSnapshotRegion as NormalizedRegion);
newRegion.BaseAddress = baseAddress.ToIntPtr();
newRegion.EndAddress = endAddress.ToIntPtr();
newRegion.SetCurrentValues(nextSnapshotRegion.CurrentValues.LargestSubArray(baseOffset, newRegion.RegionSize.ToInt64()));
newRegion.SetPreviousValues(nextSnapshotRegion.PreviousValues.LargestSubArray(baseOffset, newRegion.RegionSize.ToInt64()));
newRegion.SetElementLabels(nextSnapshotRegion.ElementLabels.LargestSubArray(baseOffset, newRegion.RegionSize.ToInt64()));
newRegion.ElementType = nextSnapshotRegion.ElementType;
newRegion.Alignment = nextSnapshotRegion.Alignment;
resultRegions.Add(newRegion);
}
}
this.SnapshotRegions = resultRegions;
}
/// <summary>
/// Finalizes any leftover snapshot regions and returns them.
/// </summary>
public IList <SnapshotRegion> GatherCollectedRegions()
{
// Create the final region if we are still encoding
if (this.Encoding)
{
this.ResultRegions.Add(new SnapshotRegion(this.Region.ReadGroup, this.VectorReadBase + this.VectorReadIndex - this.RunLength, this.RunLength));
this.RunLength = 0;
this.Encoding = false;
}
// Remove vector misaligned leading regions
SnapshotRegion firstRegion = this.ResultRegions.FirstOrDefault();
Int32 adjustedIndex = 0;
while (firstRegion != null)
{
// Exit if not misaligned
if (firstRegion.ReadGroupOffset >= this.Region.ReadGroupOffset)
{
break;
}
Int32 misalignment = this.Region.ReadGroupOffset - firstRegion.ReadGroupOffset;
if (firstRegion.RegionSize <= misalignment)
{
// The region is totally eclipsed -- remove it
this.ResultRegions.Remove(firstRegion);
}
else
{
// The region is partially eclipsed -- adjust the size
firstRegion.ReadGroupOffset += misalignment;
firstRegion.RegionSize -= misalignment;
adjustedIndex++;
}
firstRegion = this.ResultRegions.Skip(adjustedIndex).FirstOrDefault();
}
// Remove vector overreading trailing regions
SnapshotRegion lastRegion = this.ResultRegions.LastOrDefault();
adjustedIndex = 0;
while (lastRegion != null)
{
// Exit if not overreading
if (lastRegion.EndAddress.ToUInt64() <= this.Region.EndAddress.ToUInt64())
{
break;
}
Int32 overread = (lastRegion.EndAddress.ToUInt64() - this.Region.EndAddress.ToUInt64()).ToInt32();
if (lastRegion.RegionSize <= overread)
{
// The region is totally eclipsed -- remove it
this.ResultRegions.Remove(lastRegion);
}
else
{
lastRegion.RegionSize -= overread;
adjustedIndex++;
}
lastRegion = this.ResultRegions.Reverse().Skip(adjustedIndex).FirstOrDefault();
}
return(this.ResultRegions);
}
