pythonnet/src/runtime/finalizer.cs at master · kmshen/pythonnet · GitHub

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using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Runtime.InteropServices;

using System.Threading;

namespace Python.Runtime

{

public class Finalizer

{

public class CollectArgs : EventArgs

{

public int ObjectCount { get; set; }

}

public class ErrorArgs : EventArgs

{

public Exception Error { get; set; }

}

public static readonly Finalizer Instance = new Finalizer();

public event EventHandler<CollectArgs> CollectOnce;

public event EventHandler<ErrorArgs> ErrorHandler;

public int Threshold { get; set; }

public bool Enable { get; set; }

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]

struct PendingArgs

{

public bool cancelled;

}

[UnmanagedFunctionPointer(CallingConvention.Cdecl)]

private delegate int PendingCall(IntPtr arg);

private readonly PendingCall _collectAction;

private ConcurrentQueue<IPyDisposable> _objQueue = new ConcurrentQueue<IPyDisposable>();

private bool _pending = false;

private readonly object _collectingLock = new object();

private IntPtr _pendingArgs = IntPtr.Zero;

#region FINALIZER_CHECK

#if FINALIZER_CHECK

private readonly object _queueLock = new object();

public bool RefCountValidationEnabled { get; set; } = true;

#else

public readonly bool RefCountValidationEnabled = false;

#endif

// Keep these declarations for compat even no FINALIZER_CHECK

public class IncorrectFinalizeArgs : EventArgs

{

public IntPtr Handle { get; internal set; }

public ICollection<IPyDisposable> ImpactedObjects { get; internal set; }

}

public class IncorrectRefCountException : Exception

{

public IntPtr PyPtr { get; internal set; }

private string _message;

public override string Message => _message;

public IncorrectRefCountException(IntPtr ptr)

{

PyPtr = ptr;

IntPtr pyname = Runtime.PyObject_Unicode(PyPtr);

string name = Runtime.GetManagedString(pyname);

Runtime.XDecref(pyname);

_message = $"{name} may has a incorrect ref count";

}

public delegate bool IncorrectRefCntHandler(object sender, IncorrectFinalizeArgs e);

public event IncorrectRefCntHandler IncorrectRefCntResolver;

public bool ThrowIfUnhandleIncorrectRefCount { get; set; } = true;

#endregion

private Finalizer()

{

Enable = true;

Threshold = 200;

_collectAction = OnPendingCollect;

}

public void CallPendingFinalizers()

{

if (Thread.CurrentThread.ManagedThreadId != Runtime.MainManagedThreadId)

{

throw new Exception("PendingCall should execute in main Python thread");

}

Runtime.Py_MakePendingCalls();

}

public void Collect()

{

using (var gilState = new Py.GILState())

{

DisposeAll();

}

public List<WeakReference> GetCollectedObjects()

{

return _objQueue.Select(T => new WeakReference(T)).ToList();

}

internal void AddFinalizedObject(IPyDisposable obj)

{

if (!Enable)

{

return;

}

if (Runtime.Py_IsInitialized() == 0)

{

// XXX: Memory will leak if a PyObject finalized after Python shutdown,

// for avoiding that case, user should call GC.Collect manual before shutdown.

return;

}

#if FINALIZER_CHECK

lock (_queueLock)

#endif

{

_objQueue.Enqueue(obj);

}

GC.ReRegisterForFinalize(obj);

if (!_pending && _objQueue.Count >= Threshold)

{

AddPendingCollect();

}

internal static void Shutdown()

{

if (Runtime.Py_IsInitialized() == 0)

{

Instance._objQueue = new ConcurrentQueue<IPyDisposable>();

return;

}

Instance.DisposeAll();

if (Thread.CurrentThread.ManagedThreadId != Runtime.MainManagedThreadId)

{

if (Instance._pendingArgs == IntPtr.Zero)

{

Instance.ResetPending();

return;

}

// Not in main thread just cancel the pending operation to avoid error in different domain

// It will make a memory leak

unsafe

{

PendingArgs* args = (PendingArgs*)Instance._pendingArgs;

args->cancelled = true;

}

Instance.ResetPending();

return;

}

Instance.CallPendingFinalizers();

}

private void AddPendingCollect()

{

if(Monitor.TryEnter(_collectingLock))

{

try

{

if (!_pending)

{

_pending = true;

var args = new PendingArgs { cancelled = false };

_pendingArgs = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(PendingArgs)));

Marshal.StructureToPtr(args, _pendingArgs, false);

IntPtr func = Marshal.GetFunctionPointerForDelegate(_collectAction);

if (Runtime.Py_AddPendingCall(func, _pendingArgs) != 0)

{

// Full queue, append next time

FreePendingArgs();

_pending = false;

}

finally

{

Monitor.Exit(_collectingLock);

}

private static int OnPendingCollect(IntPtr arg)

{

Debug.Assert(arg == Instance._pendingArgs);

try

{

unsafe

{

PendingArgs* pendingArgs = (PendingArgs*)arg;

if (pendingArgs->cancelled)

{

return 0;

}

Instance.DisposeAll();

}

finally

{

Instance.FreePendingArgs();

Instance.ResetPending();

}

return 0;

}

private void DisposeAll()

{

CollectOnce?.Invoke(this, new CollectArgs()

{

ObjectCount = _objQueue.Count

});

#if FINALIZER_CHECK

lock (_queueLock)

#endif

{

#if FINALIZER_CHECK

ValidateRefCount();

#endif

IPyDisposable obj;

while (_objQueue.TryDequeue(out obj))

{

try

{

obj.Dispose();

Runtime.CheckExceptionOccurred();

}

catch (Exception e)

{

// We should not bother the main thread

ErrorHandler?.Invoke(this, new ErrorArgs()

{

Error = e

});

}

private void FreePendingArgs()

{

if (_pendingArgs != IntPtr.Zero)

{

Marshal.FreeHGlobal(_pendingArgs);

_pendingArgs = IntPtr.Zero;

}

private void ResetPending()

{

lock (_collectingLock)

{

_pending = false;

}

#if FINALIZER_CHECK

private void ValidateRefCount()

{

if (!RefCountValidationEnabled)

{

return;

}

var counter = new Dictionary<IntPtr, long>();

var holdRefs = new Dictionary<IntPtr, long>();

var indexer = new Dictionary<IntPtr, List<IPyDisposable>>();

foreach (var obj in _objQueue)

{

IntPtr[] handles = obj.GetTrackedHandles();

foreach (var handle in handles)

{

if (handle == IntPtr.Zero)

{

continue;

}

if (!counter.ContainsKey(handle))

{

counter[handle] = 0;

}

counter[handle]++;

if (!holdRefs.ContainsKey(handle))

{

holdRefs[handle] = Runtime.Refcount(handle);

}

List<IPyDisposable> objs;

if (!indexer.TryGetValue(handle, out objs))

{

objs = new List<IPyDisposable>();

indexer.Add(handle, objs);

}

objs.Add(obj);

}

foreach (var pair in counter)

{

IntPtr handle = pair.Key;

long cnt = pair.Value;

// Tracked handle's ref count is larger than the object's holds

// it may take an unspecified behaviour if it decref in Dispose

if (cnt > holdRefs[handle])

{

var args = new IncorrectFinalizeArgs()

{

Handle = handle,

ImpactedObjects = indexer[handle]

};

bool handled = false;

if (IncorrectRefCntResolver != null)

{

var funcList = IncorrectRefCntResolver.GetInvocationList();

foreach (IncorrectRefCntHandler func in funcList)

{

if (func(this, args))

{

handled = true;

break;

}

if (!handled && ThrowIfUnhandleIncorrectRefCount)

{

throw new IncorrectRefCountException(handle);

}

// Make sure no other references for PyObjects after this method

indexer[handle].Clear();

}

indexer.Clear();

}

#endif

}

pythonnet/src/runtime/finalizer.cs at master · kmshen/pythonnet · GitHub

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