[cdac] Read types from contract descriptor (dotnet#101994)

- Read/store types from contract descriptor into an internal representation of the type layout info
- Add functions to `Target` for getting type info and contract version
- Add placeholder for thread contract and getting thread store data
  - Add ThreadStore to data descriptor
  - `GetThreadStoreData` continues to return E_NOTIMPL, but will go through trying to use the contract
- Store processed data for the target by its address and data model type
- Add unit tests for getting type info

src/coreclr/debug/runtimeinfo/contracts.jsonc

@@ -9,6 +9,7 @@
 // cdac-build-tool can take multiple "-c contract_file" arguments
 // so to conditionally include contracts, put additional contracts in a separate file
 {
+  "Thread": 1,
   "SOSBreakingChangeVersion": 1 // example contract: "runtime exports an SOS breaking change version global"
 }
 

src/coreclr/debug/runtimeinfo/datadescriptor.h

@@ -103,11 +103,17 @@
 CDAC_BASELINE("empty")
 CDAC_TYPES_BEGIN()
 
-CDAC_TYPE_BEGIN(ManagedThread)
-CDAC_TYPE_INDETERMINATE(ManagedThread)
-CDAC_TYPE_FIELD(ManagedThread, GCHandle, GCHandle, cdac_offsets<Thread>::ExposedObject)
-CDAC_TYPE_FIELD(ManagedThread, pointer, LinkNext, cdac_offsets<Thread>::Link)
-CDAC_TYPE_END(ManagedThread)
+CDAC_TYPE_BEGIN(Thread)
+CDAC_TYPE_INDETERMINATE(Thread)
+CDAC_TYPE_FIELD(Thread, GCHandle, GCHandle, cdac_offsets<Thread>::ExposedObject)
+CDAC_TYPE_FIELD(Thread, pointer, LinkNext, cdac_offsets<Thread>::Link)
+CDAC_TYPE_END(Thread)
+
+CDAC_TYPE_BEGIN(ThreadStore)
+CDAC_TYPE_INDETERMINATE(ThreadStore)
+CDAC_TYPE_FIELD(ThreadStore, /*omit type*/, ThreadCount, cdac_offsets<ThreadStore>::ThreadCount)
+CDAC_TYPE_FIELD(ThreadStore, /*omit type*/, ThreadList, cdac_offsets<ThreadStore>::ThreadList)
+CDAC_TYPE_END(ThreadStore)
 
 CDAC_TYPE_BEGIN(GCHandle)
 CDAC_TYPE_SIZE(sizeof(OBJECTHANDLE))
@@ -116,7 +122,7 @@ CDAC_TYPE_END(GCHandle)
 CDAC_TYPES_END()
 
 CDAC_GLOBALS_BEGIN()
-CDAC_GLOBAL_POINTER(ManagedThreadStore, &ThreadStore::s_pThreadStore)
+CDAC_GLOBAL_POINTER(ThreadStore, &ThreadStore::s_pThreadStore)
 #if FEATURE_EH_FUNCLETS
 CDAC_GLOBAL(FeatureEHFunclets, uint8, 1)
 #else

src/coreclr/vm/threads.h

@@ -4300,6 +4300,15 @@ class ThreadStore
     void OnMaxGenerationGCStarted();
     bool ShouldTriggerGCForDeadThreads();
     void TriggerGCForDeadThreadsIfNecessary();
+
+    template<typename T> friend struct ::cdac_offsets;
+};
+
+template<>
+struct cdac_offsets<ThreadStore>
+{
+    static constexpr size_t ThreadList = offsetof(ThreadStore, m_ThreadList);
+    static constexpr size_t ThreadCount = offsetof(ThreadStore, m_ThreadCount);
 };
 
 struct TSSuspendHelper {

src/native/managed/cdacreader/src/Constants.cs

@@ -8,6 +8,7 @@ internal static class Constants
     internal static class Globals
     {
         // See src/coreclr/debug/runtimeinfo/datadescriptor.h
+        internal const string ThreadStore = nameof(ThreadStore);
         internal const string SOSBreakingChangeVersion = nameof(SOSBreakingChangeVersion);
     }
 }

src/native/managed/cdacreader/src/Contracts/IContract.cs

@@ -0,0 +1,12 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Diagnostics.DataContractReader.Contracts;
+
+internal interface IContract
+{
+    static virtual string Name => throw new NotImplementedException();
+    static virtual IContract Create(Target target, int version) => throw new NotImplementedException();
+}

src/native/managed/cdacreader/src/Contracts/Registry.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.Diagnostics.DataContractReader.Contracts;
+
+internal sealed class Registry
+{
+    // Contracts that have already been created for a target.
+    // Items should not be removed from this, only added.
+    private readonly Dictionary<Type, IContract> _contracts = [];
+    private readonly Target _target;
+
+    public Registry(Target target)
+    {
+        _target = target;
+    }
+
+    public IThread Thread => GetContract<IThread>();
+
+    private T GetContract<T>() where T : IContract
+    {
+        if (_contracts.TryGetValue(typeof(T), out IContract? contractMaybe))
+            return (T)contractMaybe;
+
+        if (!_target.TryGetContractVersion(T.Name, out int version))
+            throw new NotImplementedException();
+
+        // Create and register the contract
+        IContract contract = T.Create(_target, version);
+        if (_contracts.TryAdd(typeof(T), contract))
+            return (T)contract;
+
+        // Contract was already registered by someone else
+        return (T)_contracts[typeof(T)];
+    }
+}

src/native/managed/cdacreader/src/Contracts/Thread.cs

@@ -0,0 +1,58 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Diagnostics.DataContractReader.Contracts;
+
+// TODO: [cdac] Add other counts / threads
+internal record struct ThreadStoreData(
+    int ThreadCount,
+    TargetPointer FirstThread);
+
+internal interface IThread : IContract
+{
+    static string IContract.Name { get; } = nameof(Thread);
+    static IContract IContract.Create(Target target, int version)
+    {
+        TargetPointer threadStore = target.ReadGlobalPointer(Constants.Globals.ThreadStore);
+        return version switch
+        {
+            1 => new Thread_1(target, threadStore),
+            _ => default(Thread),
+        };
+    }
+
+    public virtual ThreadStoreData GetThreadStoreData() => throw new NotImplementedException();
+}
+
+internal readonly struct Thread : IThread
+{
+    // Everything throws NotImplementedException
+}
+
+internal readonly struct Thread_1 : IThread
+{
+    private readonly Target _target;
+    private readonly TargetPointer _threadStoreAddr;
+
+    internal Thread_1(Target target, TargetPointer threadStore)
+    {
+        _target = target;
+        _threadStoreAddr = threadStore;
+    }
+
+    ThreadStoreData IThread.GetThreadStoreData()
+    {
+        Data.ThreadStore? threadStore;
+        if (!_target.ProcessedData.TryGet(_threadStoreAddr.Value, out threadStore))
+        {
+            threadStore = new Data.ThreadStore(_target, _threadStoreAddr);
+
+            // Still okay if processed data is already registered by someone else
+            _ = _target.ProcessedData.TryRegister(_threadStoreAddr.Value, threadStore);
+        }
+
+        return new ThreadStoreData(threadStore.ThreadCount, threadStore.FirstThread);
+    }
+}

src/native/managed/cdacreader/src/Data/ThreadStore.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.Diagnostics.DataContractReader.Data;
+
+internal sealed class ThreadStore
+{
+    public ThreadStore(Target target, TargetPointer pointer)
+    {
+        Target.TypeInfo type = target.GetTypeInfo(DataType.ThreadStore);
+        TargetPointer addr = target.ReadPointer(pointer.Value);
+
+        ThreadCount = target.Read<int>(addr.Value + (ulong)type.Fields[nameof(ThreadCount)].Offset);
+        FirstThread = TargetPointer.Null;
+    }
+
+    public int ThreadCount { get; init; }
+
+    public TargetPointer FirstThread { get; init; }
+}

src/native/managed/cdacreader/src/DataType.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.Diagnostics.DataContractReader;
+
+public enum DataType
+{
+    Unknown = 0,
+
+    int8,
+    uint8,
+    int16,
+    uint16,
+    int32,
+    uint32,
+    int64,
+    uint64,
+    nint,
+    nuint,
+    pointer,
+
+    GCHandle,
+    Thread,
+    ThreadStore,
+}

src/native/managed/cdacreader/src/Legacy/SOSDacImpl.cs

@@ -106,7 +106,25 @@ public int GetBreakingChangeVersion()
     public unsafe int GetThreadFromThinlockID(uint thinLockId, ulong* pThread) => HResults.E_NOTIMPL;
     public unsafe int GetThreadLocalModuleData(ulong thread, uint index, void* data) => HResults.E_NOTIMPL;
     public unsafe int GetThreadpoolData(void* data) => HResults.E_NOTIMPL;
-    public unsafe int GetThreadStoreData(DacpThreadStoreData* data) => HResults.E_NOTIMPL;
+
+    public unsafe int GetThreadStoreData(DacpThreadStoreData* data)
+    {
+        try
+        {
+            Contracts.IThread thread = _target.Contracts.Thread;
+            Contracts.ThreadStoreData threadStoreData = thread.GetThreadStoreData();
+            data->threadCount = threadStoreData.ThreadCount;
+            data->firstThread = threadStoreData.FirstThread.Value;
+            data->fHostConfig = 0;
+        }
+        catch (Exception ex)
+        {
+            return ex.HResult;
+        }
+
+        return HResults.E_NOTIMPL;
+    }
+
     public unsafe int GetTLSIndex(uint* pIndex) => HResults.E_NOTIMPL;
     public unsafe int GetUsefulGlobals(void* data) => HResults.E_NOTIMPL;
     public unsafe int GetWorkRequestData(ulong addrWorkRequest, void* data) => HResults.E_NOTIMPL;