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using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection;
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 readonly ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>> namespaces =
new();
#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
// domain-level handlers are initialized in Initialize
private static AssemblyLoadEventHandler lhandler;
private static ResolveEventHandler rhandler;
#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
// updated only under GIL?
private static readonly Dictionary<string, int> probed = new(32);
// modified from event handlers below, potentially triggered from different .NET threads
private static readonly ConcurrentQueue<Assembly> assemblies = new();
// Snapshot; UpdatePath swaps under lock, readers iterate the captured ref.
internal static volatile IReadOnlyList<string> pypath = Array.Empty<string>();
private static readonly object _pypathLock = new();
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()
{
pypath = Array.Empty<string>();
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)
{
var name = new AssemblyName(args.Name);
foreach (var alreadyLoaded in assemblies)
{
if (AssemblyName.ReferenceMatchesDefinition(name, alreadyLoaded.GetName()))
{
return alreadyLoaded;
}
}
return LoadAssemblyPath(name.Name);
}
internal static AssemblyName? TryParseAssemblyName(string name)
{
// workaround for https://github.com/dotnet/runtime/issues/123951
if (name.IndexOfAny(new[] { Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar }) >= 0)
{
return null;
}
try
{
return new AssemblyName(name);
}
catch (FileLoadException)
{
return null;
}
}
/// <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()
{
BorrowedReference list = Runtime.PySys_GetObject("path");
var count = Runtime.PyList_Size(list);
if (count == pypath.Count) return;
lock (_pypathLock)
{
if (count == pypath.Count) return;
var fresh = new List<string>(checked((int)count));
probed.Clear();
for (var i = 0; i < count; i++)
{
BorrowedReference item = Runtime.PyList_GetItem(list, i);
string? path = Runtime.GetManagedString(item);
if (path != null) fresh.Add(path);
}
pypath = fresh;
}
}
/// <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(AssemblyName name)
{
if (name is null) throw new ArgumentNullException(nameof(name));
return FindAssembly(name.Name);
}
/// <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)
{
if (name is null) throw new ArgumentNullException(nameof(name));
return FindAssemblyCandidates(name).FirstOrDefault();
}
static IEnumerable<string> FindAssemblyCandidates(string name)
{
var paths = pypath;
foreach (string head in paths)
{
string path;
if (head == null || head.Length == 0)
{
path = name;
}
else
{
int invalidCharIndex = head.IndexOfAny(Path.GetInvalidPathChars());
if (invalidCharIndex >= 0)
{
using var importWarning = Runtime.PyObject_GetAttrString(Exceptions.exceptions_module, "ImportWarning");
Exceptions.warn($"Path entry '{head}' has invalid char at position {invalidCharIndex}", importWarning.BorrowOrThrow());
continue;
}
path = Path.Combine(head, name);
}
string temp = path + ".dll";
if (File.Exists(temp))
{
yield return temp;
}
temp = path + ".exe";
if (File.Exists(temp))
{
yield return temp;
}
}
}
/// <summary>
/// Loads an assembly from the application directory or the GAC
/// given its name. Returns the assembly if loaded.
/// </summary>
public static Assembly LoadAssembly(AssemblyName name)
{
return Assembly.Load(name);
}
/// <summary>
/// Loads an assembly using an augmented search path (the python path).
/// </summary>
public static Assembly? LoadAssemblyPath(string name)
{
string path = FindAssembly(name);
if (path == null) return null;
return Assembly.LoadFrom(path);
}
/// <summary>
/// Loads an assembly using full path.
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
public static Assembly? LoadAssemblyFullPath(string name)
{
if (Path.IsPathRooted(name))
{
if (File.Exists(name))
{
return Assembly.LoadFrom(name);
}
}
return null;
}
/// <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>
/// 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)
{
if (assembly.GetCustomAttribute<PyExportAttribute>()?.Export == false)
{
return;
}
// 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];
if (namespaces.TryAdd(s, new ConcurrentDictionary<Assembly, string>()))
{
ImportHook.AddNamespace(s);
}
}
}
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 an enumerable collection containing the namepsaces exported
/// by loaded assemblies in the current app domain.
/// </summary>
public static IEnumerable<string> GetNamespaces ()
{
return namespaces.Keys;
}
/// <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 <see cref="Type"/> objects for the given qualified name,
/// looking in the currently loaded assemblies for the named
/// type.
/// </summary>
public static IEnumerable<Type> LookupTypes(string qualifiedName)
=> assemblies.Select(assembly => assembly.GetType(qualifiedName)).Where(type => type != null && IsExported(type));
internal static Type[] GetTypes(Assembly a)
{
if (a.IsDynamic)
{
try
{
return a.GetTypes().Where(IsExported).ToArray();
}
catch (ReflectionTypeLoadException exc)
{
// Return all types that were successfully loaded
return exc.Types.Where(x => x != null && IsExported(x)).ToArray();
}
}
else
{
try
{
return a.GetExportedTypes().Where(IsExported).ToArray();
}
catch (FileNotFoundException)
{
return new Type[0];
}
}
}
static bool IsExported(Type type) => type.GetCustomAttribute<PyExportAttribute>()?.Export != false;
}
}