Merge pull request #284 from Unity-Technologies/update-loaderallocator-helperapi

Added coreclr_unity_profiler_loader_allocator_get_assembly_load_context_handle api

Author: alexey-zakharov

src/coreclr/dlls/mscoree/mscorwks_ntdef.src

@@ -37,6 +37,7 @@ EXPORTS
         coreclr_unity_profiler_class_get_assembly_load_context_handle
         coreclr_unity_profiler_get_managed_assembly_load_context
         coreclr_unity_profiler_assembly_load_context_get_loader_allocator_handle
+        coreclr_unity_profiler_loader_allocator_get_assembly_load_context_handle
         coreclr_unity_gc_concurrent_mode
         mono_assembly_get_assemblyref
         mono_class_get_name

src/coreclr/dlls/mscoree/mscorwks_unixexports.src

@@ -23,6 +23,7 @@ coreclr_unity_profiler_register
 coreclr_unity_profiler_class_get_assembly_load_context_handle
 coreclr_unity_profiler_get_managed_assembly_load_context
 coreclr_unity_profiler_assembly_load_context_get_loader_allocator_handle
+coreclr_unity_profiler_loader_allocator_get_assembly_load_context_handle
 coreclr_unity_gc_concurrent_mode
 mono_assembly_get_assemblyref
 mono_class_get_name

src/coreclr/vm/mono/mono_coreclr.cpp

@@ -761,8 +761,10 @@ extern "C" EXPORT_API ObjectHandleID EXPORT_CC coreclr_unity_profiler_class_get_
     if (pAssembly == NULL)
         return NULL;
 
+    // Use binder to get access to the managed AssemblyLoadContext handle.
+    // Note that the binder may be NULL if the assembly is being unloaded.
     AssemblyBinder* pAssemblyBinder = pAssembly->GetPEAssembly()->GetAssemblyBinder();
-    if (pAssemblyBinder->IsDefault())
+    if (pAssemblyBinder == NULL || pAssemblyBinder->IsDefault())
         return NULL;
 
     // ManagedAssemblyLoadContext is a handle to the managed AssemblyLoadContext object
@@ -777,8 +779,10 @@ extern "C" EXPORT_API ObjectHandleID EXPORT_CC coreclr_unity_profiler_get_manage
     if (pAssembly == NULL)
         return NULL;
 
+    // Use binder to get access to the managed AssemblyLoadContext handle.
+    // Note that the binder may be NULL if the assembly is being unloaded.
     AssemblyBinder* pAssemblyBinder = pAssembly->GetPEAssembly()->GetAssemblyBinder();
-    if (pAssemblyBinder->IsDefault())
+    if (pAssemblyBinder == NULL || pAssemblyBinder->IsDefault())
         return NULL;
 
     // ManagedAssemblyLoadContext is a handle to the managed AssemblyLoadContext object
@@ -805,6 +809,39 @@ extern "C" EXPORT_API ObjectHandleID EXPORT_CC coreclr_unity_profiler_assembly_l
     return (ObjectHandleID)loaderAllocator->GetLoaderAllocatorObjectHandle();
 }
 
+// Return the AssemblyLoadContext handle for the given LoaderAllocator checking whether or not LoaderAllocator is still alive.
+// LoaderAllocator is the main object that tracks AssemblyLoadContext liveness as AssemblyLoadContext is a simple wrapper around a native 
+// reference to LoaderAllocator.
+extern "C" EXPORT_API ObjectHandleID EXPORT_CC coreclr_unity_profiler_loader_allocator_get_assembly_load_context_handle(void* nativeLoaderAllocator)
+{
+    STATIC_CONTRACT_NOTHROW;
+
+    LoaderAllocator* loaderAllocator = (LoaderAllocator*)nativeLoaderAllocator;
+    if (loaderAllocator == NULL)
+        return NULL;
+
+    // If it is already unloaded there is no need to return the handle
+    if (loaderAllocator->IsUnloaded())
+        return NULL;
+
+    // Ensure that the LoaderAllocator is AssemblyLoaderAllocator
+    LoaderAllocatorID* loaderAllocatorID = loaderAllocator->Id();
+    if (loaderAllocatorID == NULL)
+        return NULL;
+
+    if (loaderAllocatorID->GetType() != LAT_Assembly)
+        return NULL;
+
+    // Use binder to get access to the managed AssemblyLoadContext handle
+    AssemblyLoaderAllocator* assemblyLoaderAllocator = (AssemblyLoaderAllocator*)loaderAllocator;
+    AssemblyBinder* pAssemblyBinder = assemblyLoaderAllocator->GetBinder();
+    if (pAssemblyBinder == NULL)
+        return NULL;
+
+    // ManagedAssemblyLoadContext is a handle to the managed AssemblyLoadContext object
+    return (ObjectHandleID)pAssemblyBinder->GetManagedAssemblyLoadContext();
+}
+
 extern "C" EXPORT_API gboolean EXPORT_CC coreclr_unity_gc_concurrent_mode(gboolean state)
 {
     CONTRACTL
@@ -885,4 +922,4 @@ extern "C" EXPORT_API bool EXPORT_CC coreclr_unity_get_stackframe_info_from_ip(v
     }
 
     return false;
-} 
+}