pythonnet/Python.Runtime/assemblymanager.cs at modernisation · sdpython/pythonnet · GitHub

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using System;

using System.Collections;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Diagnostics;

using System.IO;

using System.Linq;

using System.Reflection;

using System.Threading;

namespace Python.Runtime

{

/// <summary>

/// The AssemblyManager maintains information about loaded assemblies

/// namespaces and provides an interface for name-based type lookup.

/// </summary>

internal class AssemblyManager

{

// modified from event handlers below, potentially triggered from different .NET threads

// therefore this should be a ConcurrentDictionary

// WARNING: Dangerous if cross-app domain usage is ever supported

// Reusing the dictionary with assemblies accross multiple initializations is problematic.

// Loading happens from CurrentDomain (see line 53). And if the first call is from AppDomain that is later unloaded,

// than it can end up referring to assemblies that are already unloaded (default behavior after unload appDomain -

// unless LoaderOptimization.MultiDomain is used);

// So for multidomain support it is better to have the dict. recreated for each app-domain initialization

private static ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>> namespaces =

new ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>>();

//private static Dictionary<string, Dictionary<string, string>> generics;

private static AssemblyLoadEventHandler lhandler;

private static ResolveEventHandler rhandler;

// updated only under GIL?

private static Dictionary<string, int> probed = new Dictionary<string, int>(32);

// modified from event handlers below, potentially triggered from different .NET threads

private static ConcurrentQueue<Assembly> assemblies;

internal static List<string> pypath;

private AssemblyManager()

{

}

/// <summary>

/// Initialization performed on startup of the Python runtime. Here we

/// scan all of the currently loaded assemblies to determine exported

/// names, and register to be notified of new assembly loads.

/// </summary>

internal static void Initialize()

{

assemblies = new ConcurrentQueue<Assembly>();

pypath = new List<string>(16);

AppDomain domain = AppDomain.CurrentDomain;

lhandler = new AssemblyLoadEventHandler(AssemblyLoadHandler);

domain.AssemblyLoad += lhandler;

rhandler = new ResolveEventHandler(ResolveHandler);

domain.AssemblyResolve += rhandler;

Assembly[] items = domain.GetAssemblies();

foreach (Assembly a in items)

{

try

{

ScanAssembly(a);

assemblies.Enqueue(a);

}

catch (Exception ex)

{

Debug.WriteLine("Error scanning assembly {0}. {1}", a, ex);

}

/// <summary>

/// Cleanup resources upon shutdown of the Python runtime.

/// </summary>

internal static void Shutdown()

{

AppDomain domain = AppDomain.CurrentDomain;

domain.AssemblyLoad -= lhandler;

domain.AssemblyResolve -= rhandler;

}

/// <summary>

/// Event handler for assembly load events. At the time the Python

/// runtime loads, we scan the app domain to map the assemblies that

/// are loaded at the time. We also have to register this event handler

/// so that we can know about assemblies that get loaded after the

/// Python runtime is initialized.

/// </summary>

private static void AssemblyLoadHandler(object ob, AssemblyLoadEventArgs args)

{

Assembly assembly = args.LoadedAssembly;

assemblies.Enqueue(assembly);

ScanAssembly(assembly);

}

/// <summary>

/// Event handler for assembly resolve events. This is needed because

/// we augment the assembly search path with the PYTHONPATH when we

/// load an assembly from Python. Because of that, we need to listen

/// for failed loads, because they might be dependencies of something

/// we loaded from Python which also needs to be found on PYTHONPATH.

/// </summary>

private static Assembly ResolveHandler(object ob, ResolveEventArgs args)

{

string name = args.Name.ToLower();

foreach (Assembly a in assemblies)

{

string full = a.FullName.ToLower();

if (full.StartsWith(name))

{

return a;

}

return LoadAssemblyPath(args.Name);

}

/// <summary>

/// We __really__ want to avoid using Python objects or APIs when

/// probing for assemblies to load, since our ResolveHandler may be

/// called in contexts where we don't have the Python GIL and can't

/// even safely try to get it without risking a deadlock ;(

/// To work around that, we update a managed copy of sys.path (which

/// is the main thing we care about) when UpdatePath is called. The

/// import hook calls this whenever it knows its about to use the

/// assembly manager, which lets us keep up with changes to sys.path

/// in a relatively lightweight and low-overhead way.

/// </summary>

internal static void UpdatePath()

{

IntPtr list = Runtime.PySys_GetObject("path");

var count = Runtime.PyList_Size(list);

if (count != pypath.Count)

{

pypath.Clear();

probed.Clear();

for (var i = 0; i < count; i++)

{

IntPtr item = Runtime.PyList_GetItem(list, i);

string path = Runtime.GetManagedString(item);

if (path != null)

{

pypath.Add(path);

}

/// <summary>

/// Given an assembly name, try to find this assembly file using the

/// PYTHONPATH. If not found, return null to indicate implicit load

/// using standard load semantics (app base directory then GAC, etc.)

/// </summary>

public static string FindAssembly(string name)

{

char sep = Path.DirectorySeparatorChar;

foreach (string head in pypath)

{

string path;

if (head == null || head.Length == 0)

{

path = name;

}

else

{

path = head + sep + name;

}

string temp = path + ".dll";

if (File.Exists(temp))

{

return temp;

}

temp = path + ".exe";

if (File.Exists(temp))

{

return temp;

}

return null;

}

/// <summary>

/// Loads an assembly from the application directory or the GAC

/// given a simple assembly name. Returns the assembly if loaded.

/// </summary>

public static Assembly LoadAssembly(string name)

{

Assembly assembly = null;

try

{

assembly = Assembly.Load(name);

}

catch (Exception)

{

//if (!(e is System.IO.FileNotFoundException))

//{

// throw;

//}

}

return assembly;

}

/// <summary>

/// Loads an assembly using an augmented search path (the python path).

/// </summary>

public static Assembly LoadAssemblyPath(string name)

{

string path = FindAssembly(name);

Assembly assembly = null;

if (path != null)

{

try

{

assembly = Assembly.LoadFrom(path);

}

catch (Exception)

{

}

return assembly;

}

/// <summary>

/// Loads an assembly using full path.

/// </summary>

/// <param name="name"></param>

/// <returns></returns>

public static Assembly LoadAssemblyFullPath(string name)

{

Assembly assembly = null;

if (Path.IsPathRooted(name))

{

if (!Path.HasExtension(name))

{

name = name + ".dll";

}

if (File.Exists(name))

{

try

{

assembly = Assembly.LoadFrom(name);

}

catch (Exception)

{

}

return assembly;

}

/// <summary>

/// Returns an assembly that's already been loaded

/// </summary>

public static Assembly FindLoadedAssembly(string name)

{

foreach (Assembly a in assemblies)

{

if (a.GetName().Name == name)

{

return a;

}

return null;

}

/// <summary>

/// Given a qualified name of the form A.B.C.D, attempt to load

/// an assembly named after each of A.B.C.D, A.B.C, A.B, A. This

/// will only actually probe for the assembly once for each unique

/// namespace. Returns true if any assemblies were loaded.

/// </summary>

/// <remarks>

/// TODO item 3 "* Deprecate implicit loading of assemblies":

/// Set the fromFile flag if the name of the loaded assembly matches

/// the fully qualified name that was requested if the framework

/// actually loads an assembly.

/// Call ONLY for namespaces that HAVE NOT been cached yet.

/// </remarks>

public static bool LoadImplicit(string name, bool warn = true)

{

string[] names = name.Split('.');

var loaded = false;

var s = "";

Assembly lastAssembly = null;

HashSet<Assembly> assembliesSet = null;

for (var i = 0; i < names.Length; i++)

{

s = i == 0 ? names[0] : s + "." + names[i];

if (!probed.ContainsKey(s))

{

if (assembliesSet == null)

{

assembliesSet = new HashSet<Assembly>(AppDomain.CurrentDomain.GetAssemblies());

}

Assembly a = FindLoadedAssembly(s);

if (a == null)

{

a = LoadAssemblyPath(s);

}

if (a == null)

{

a = LoadAssembly(s);

}

if (a != null && !assembliesSet.Contains(a))

{

loaded = true;

lastAssembly = a;

}

probed[s] = 1;

}

// Deprecation warning

if (warn && loaded)

{

string location = Path.GetFileNameWithoutExtension(lastAssembly.Location);

string deprWarning = "The module was found, but not in a referenced namespace.\n" +

$"Implicit loading is deprecated. Please use clr.AddReference('{location}').";

Exceptions.deprecation(deprWarning);

}

return loaded;

}

/// <summary>

/// Scans an assembly for exported namespaces, adding them to the

/// mapping of valid namespaces. Note that for a given namespace

/// a.b.c.d, each of a, a.b, a.b.c and a.b.c.d are considered to

/// be valid namespaces (to better match Python import semantics).

/// </summary>

internal static void ScanAssembly(Assembly assembly)

{

// A couple of things we want to do here: first, we want to

// gather a list of all of the namespaces contributed to by

// the assembly.

foreach (Type t in GetTypes(assembly))

{

string ns = t.Namespace ?? "";

if (!namespaces.ContainsKey(ns))

{

string[] names = ns.Split('.');

var s = "";

for (var n = 0; n < names.Length; n++)

{

s = n == 0 ? names[0] : s + "." + names[n];

namespaces.TryAdd(s, new ConcurrentDictionary<Assembly, string>());

}

if (ns != null)

{

namespaces[ns].TryAdd(assembly, string.Empty);

}

if (ns != null && t.IsGenericTypeDefinition)

{

GenericUtil.Register(t);

}

public static AssemblyName[] ListAssemblies()

{

var names = new List<AssemblyName>(assemblies.Count);

foreach (Assembly assembly in assemblies)

{

names.Add(assembly.GetName());

}

return names.ToArray();

}

/// <summary>

/// Returns true if the given qualified name matches a namespace

/// exported by an assembly loaded in the current app domain.

/// </summary>

public static bool IsValidNamespace(string name)

{

return !string.IsNullOrEmpty(name) && namespaces.ContainsKey(name);

}

/// <summary>

/// Returns list of assemblies that declare types in a given namespace

/// </summary>

public static IEnumerable<Assembly> GetAssemblies(string nsname)

{

return !namespaces.ContainsKey(nsname) ? new List<Assembly>() : namespaces[nsname].Keys;

}

/// <summary>

/// Returns the current list of valid names for the input namespace.

/// </summary>

public static List<string> GetNames(string nsname)

{

//Dictionary<string, int> seen = new Dictionary<string, int>();

var names = new List<string>(8);

List<string> g = GenericUtil.GetGenericBaseNames(nsname);

if (g != null)

{

foreach (string n in g)

{

names.Add(n);

}

if (namespaces.ContainsKey(nsname))

{

foreach (Assembly a in namespaces[nsname].Keys)

{

foreach (Type t in GetTypes(a))

{

if ((t.Namespace ?? "") == nsname && !t.IsNested)

{

names.Add(t.Name);

}

int nslen = nsname.Length;

foreach (string key in namespaces.Keys)

{

if (key.Length > nslen && key.StartsWith(nsname))

{

//string tail = key.Substring(nslen);

if (key.IndexOf('.') == -1)

{

names.Add(key);

}

return names;

}

/// <summary>

/// Returns the System.Type object for a given qualified name,

/// looking in the currently loaded assemblies for the named

/// type. Returns null if the named type cannot be found.

/// </summary>

public static Type LookupType(string qname)

{

foreach (Assembly assembly in assemblies)

{

Type type = assembly.GetType(qname);

if (type != null)

{

return type;

}

return null;

}

internal static Type[] GetTypes(Assembly a)

{

if (a.IsDynamic)

{

try

{

return a.GetTypes();

}

catch (ReflectionTypeLoadException exc)

{

// Return all types that were successfully loaded

return exc.Types.Where(x => x != null).ToArray();

}

else

{

try

{

return a.GetExportedTypes();

}

catch (FileNotFoundException)

{

return new Type[0];

}

pythonnet/Python.Runtime/assemblymanager.cs at modernisation · sdpython/pythonnet · GitHub

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