Ryujinx/Ryujinx.Memory/Tracking/RegionHandle.cs
riperiperi 54adc5f9fb
Ensure that all threads wait for a read tracking action to complete. (#2597)
* Lock around tracking action consume + execute. Not particularly fast.

* Lock around preaction registration and use

* Create a lock object

* Nit
2021-08-29 16:03:41 -03:00

315 lines
10 KiB
C#

using Ryujinx.Memory.Range;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
namespace Ryujinx.Memory.Tracking
{
/// <summary>
/// A tracking handle for a given region of virtual memory. The Dirty flag is updated whenever any changes are made,
/// and an action can be performed when the region is read to or written from.
/// </summary>
public class RegionHandle : IRegionHandle, IRange
{
/// <summary>
/// If more than this number of checks have been performed on a dirty flag since its last reprotect,
/// then it is dirtied infrequently.
/// </summary>
private static int CheckCountForInfrequent = 3;
/// <summary>
/// Number of frequent dirty/consume in a row to make this handle volatile.
/// </summary>
private static int VolatileThreshold = 5;
public bool Dirty { get; private set; }
public bool Unmapped { get; private set; }
public ulong Address { get; }
public ulong Size { get; }
public ulong EndAddress { get; }
internal IMultiRegionHandle Parent { get; set; }
internal int SequenceNumber { get; set; }
private event Action _onDirty;
private object _preActionLock = new object();
private RegionSignal _preAction; // Action to perform before a read or write. This will block the memory access.
private readonly List<VirtualRegion> _regions;
private readonly MemoryTracking _tracking;
private bool _disposed;
private int _checkCount = 0;
private int _volatileCount = 0;
private bool _volatile;
internal MemoryPermission RequiredPermission
{
get
{
// If this is unmapped, allow reprotecting as RW as it can't be dirtied.
// This is required for the partial unmap cases where part of the data are still being accessed.
if (Unmapped)
{
return MemoryPermission.ReadAndWrite;
}
if (_preAction != null)
{
return MemoryPermission.None;
}
return Dirty ? MemoryPermission.ReadAndWrite : MemoryPermission.Read;
}
}
internal RegionSignal PreAction => _preAction;
/// <summary>
/// Create a new region handle. The handle is registered with the given tracking object,
/// and will be notified of any changes to the specified region.
/// </summary>
/// <param name="tracking">Tracking object for the target memory block</param>
/// <param name="address">Virtual address of the region to track</param>
/// <param name="size">Size of the region to track</param>
/// <param name="mapped">True if the region handle starts mapped</param>
internal RegionHandle(MemoryTracking tracking, ulong address, ulong size, bool mapped = true)
{
Dirty = mapped;
Unmapped = !mapped;
Address = address;
Size = size;
EndAddress = address + size;
_tracking = tracking;
_regions = tracking.GetVirtualRegionsForHandle(address, size);
foreach (var region in _regions)
{
region.Handles.Add(this);
}
}
/// <summary>
/// Clear the volatile state of this handle.
/// </summary>
private void ClearVolatile()
{
_volatileCount = 0;
_volatile = false;
}
/// <summary>
/// Check if this handle is dirty, or if it is volatile. (changes very often)
/// </summary>
/// <returns>True if the handle is dirty or volatile, false otherwise</returns>
public bool DirtyOrVolatile()
{
_checkCount++;
return Dirty || _volatile;
}
/// <summary>
/// Signal that a memory action occurred within this handle's virtual regions.
/// </summary>
/// <param name="write">Whether the region was written to or read</param>
internal void Signal(ulong address, ulong size, bool write, ref IList<RegionHandle> handleIterable)
{
// If this handle was already unmapped (even if just partially),
// then we have nothing to do until it is mapped again.
// The pre-action should be still consumed to avoid flushing on remap.
if (Unmapped)
{
Interlocked.Exchange(ref _preAction, null);
return;
}
if (_preAction != null)
{
// Copy the handles list in case it changes when we're out of the lock.
if (handleIterable is List<RegionHandle>)
{
handleIterable = handleIterable.ToArray();
}
// Temporarily release the tracking lock while we're running the action.
Monitor.Exit(_tracking.TrackingLock);
try
{
lock (_preActionLock)
{
_preAction?.Invoke(address, size);
_preAction = null;
}
}
finally
{
Monitor.Enter(_tracking.TrackingLock);
}
}
if (write)
{
bool oldDirty = Dirty;
Dirty = true;
if (!oldDirty)
{
_onDirty?.Invoke();
}
Parent?.SignalWrite();
}
}
/// <summary>
/// Force this handle to be dirty, without reprotecting.
/// </summary>
public void ForceDirty()
{
Dirty = true;
}
/// <summary>
/// Consume the dirty flag for this handle, and reprotect so it can be set on the next write.
/// </summary>
public void Reprotect(bool asDirty = false)
{
if (_volatile) return;
Dirty = asDirty;
bool protectionChanged = false;
lock (_tracking.TrackingLock)
{
foreach (VirtualRegion region in _regions)
{
protectionChanged |= region.UpdateProtection();
}
}
if (!protectionChanged)
{
// Counteract the check count being incremented when this handle was forced dirty.
// It doesn't count for protected write tracking.
_checkCount--;
}
else if (!asDirty)
{
if (_checkCount > 0 && _checkCount < CheckCountForInfrequent)
{
if (++_volatileCount >= VolatileThreshold && _preAction == null)
{
_volatile = true;
return;
}
}
else
{
_volatileCount = 0;
}
_checkCount = 0;
}
}
/// <summary>
/// Register an action to perform when the tracked region is read or written.
/// The action is automatically removed after it runs.
/// </summary>
/// <param name="action">Action to call on read or write</param>
public void RegisterAction(RegionSignal action)
{
ClearVolatile();
lock (_preActionLock)
{
RegionSignal lastAction = _preAction;
_preAction = action;
if (lastAction == null && action != lastAction)
{
lock (_tracking.TrackingLock)
{
foreach (VirtualRegion region in _regions)
{
region.UpdateProtection();
}
}
}
}
}
/// <summary>
/// Register an action to perform when the region is written to.
/// This action will not be removed when it is called - it is called each time the dirty flag is set.
/// </summary>
/// <param name="action">Action to call on dirty</param>
public void RegisterDirtyEvent(Action action)
{
_onDirty += action;
}
/// <summary>
/// Add a child virtual region to this handle.
/// </summary>
/// <param name="region">Virtual region to add as a child</param>
internal void AddChild(VirtualRegion region)
{
_regions.Add(region);
}
/// <summary>
/// Signal that this handle has been mapped or unmapped.
/// </summary>
/// <param name="mapped">True if the handle has been mapped, false if unmapped</param>
internal void SignalMappingChanged(bool mapped)
{
if (Unmapped == mapped)
{
Unmapped = !mapped;
if (Unmapped)
{
ClearVolatile();
Dirty = false;
}
}
}
/// <summary>
/// Check if this region overlaps with another.
/// </summary>
/// <param name="address">Base address</param>
/// <param name="size">Size of the region</param>
/// <returns>True if overlapping, false otherwise</returns>
public bool OverlapsWith(ulong address, ulong size)
{
return Address < address + size && address < EndAddress;
}
/// <summary>
/// Dispose the handle. Within the tracking lock, this removes references from virtual regions.
/// </summary>
public void Dispose()
{
if (_disposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
_disposed = true;
lock (_tracking.TrackingLock)
{
foreach (VirtualRegion region in _regions)
{
region.RemoveHandle(this);
}
}
}
}
}